Publications by authors named "Fawzi Banat"

37 Publications

Recent developments in porous ceramic membranes for wastewater treatment and desalination: A review.

J Environ Manage 2021 Sep 7;293:112925. Epub 2021 Jun 7.

Department of Chemical Engineering, Khalifa University, 127788, Abu Dhabi, United Arab Emirates. Electronic address:

The development of membrane technology has proved vital in providing a sustainable and affordable supply of clean water to address the ever-increasing demand. Though liquid separation applications have been still dominated by polymeric membranes, porous ceramic membranes have gained a commercial foothold in microfiltration (MF) and ultrafiltration (UF) applications due to their hydrophilic nature, lower fouling, ease of cleaning, reliable performance, robust performance with harsh feeds, relative insensitivity to temperature and pH, and stable long-term flux. The enrichment of research and development on porous ceramic membranes extends its focus into advanced membrane separation technologies. The latest emerging nanofiltration (NF) and membrane distillation (MD) applications have witnessed special interests in constructing porous membrane with hydrophilic/functional/hydrophobic properties. However, NF and MD are relatively new, and many shortcomings must be addressed to compete with their polymeric counterparts. For the last three years (2018-2020), state-of-the-art literature on porous ceramic membranes has been collected and critically reviewed. This review highlights the efficiency (permeability, selectivity, and antifouling) of hydrophilic porous ceramic membranes in a wide variety of wastewater treatment applications and hydrophobic porous ceramic membranes in membrane distillation-based desalination applications. A significant focus on pores characteristics, pore sieving phenomenon, nano functionalization, and synergic effect on fouling, the hydrophilic porous ceramic membrane has been discussed. In another part of this review, the role of surface hydrophobicity, water contact angle, liquid entry pressure (LEP), thermal properties, surface micro-roughness, etc., has been discussed for different types of hydrophobic porous ceramic membranes -(a) metal-based, (b) silica-based, (c) other ceramics. Also, this review highlights the potential benefits, drawbacks, and limitations of the porous membrane in applications. Moreover, the prospects are emphasized to overcome the challenges in the field.
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http://dx.doi.org/10.1016/j.jenvman.2021.112925DOI Listing
September 2021

Valorization of groundnut shell via pyrolysis: Product distribution, thermodynamic analysis, kinetic estimation, and artificial neural network modeling.

Chemosphere 2021 Jun 15;283:131162. Epub 2021 Jun 15.

Department of Chemical Engineering, Khalifa University, P.O. Box 127788, Abu Dhabi, United Arab Emirates. Electronic address:

Pyrolysis of agricultural biomass is a promising technique for producing renewable energy and effectively managing solid waste. In this study, groundnut shell (GNS) was processed at 500 °C in an inert gas atmosphere with a gas flow rate and a heating rate of 10 mL/min and 10 °C/min, respectively, in a custom-designed fluidized bed pyrolytic-reactor. Under optimal operating conditions, the GNS-derived pyrolytic-oil yield was 62.8 wt.%, with the corresponding biochar (19.5 wt.%) and biogas yields (17.7 wt.%). The GC-MS analysis of the GNS-based bio-oil confirmed the presence of (trifluoromethyl)pyridin-2-amine (18.814%), 2-Fluoroformyl-3,3,4,4-tetrafluoro-1,2-oxazetidine (16.23%), 5,7-dimethyl-1H-Indazole (11.613%), N-methyl-N-nitropropan-2-amine (6.5%) and butyl piperidino sulfone (5.668%) as major components, which are used as building blocks in the biofuel, pharmaceutical, and food industries. Furthermore, a 2 × 5 × 1 artificial neural network (ANN) architecture was developed to predict the decomposition behavior of GNS at heating rates of 5, 10, and 20 °C/min, while the thermodynamic and kinetic parameters were estimated using a non-isothermal model-free method. The Popescu method predicted activation energy (E) of GNS biomass ranging from 111 kJ/mol to 260 kJ/mol, with changes in enthalpy (ΔH), Gibbs-free energy (ΔG), and entropy (ΔS) ranging from 106 to 254 kJ/mol, 162-241 kJ/mol, and -0.0937 to 0.0598 kJ/mol/K, respectively. The extraction of high-quality precursors from GNS pyrolysis was demonstrated in this study, as well as the usefulness of the ANN technique for thermogravimetric analysis of biomass.
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http://dx.doi.org/10.1016/j.chemosphere.2021.131162DOI Listing
June 2021

Nano-activated carbon derived from date palm coir waste for efficient sequestration of noxious 2,4-dichlorophenoxyacetic acid herbicide.

Chemosphere 2021 Jun 5;282:131103. Epub 2021 Jun 5.

Department of Chemical Engineering, Khalifa University, P.O. Box 127788, Abu Dhabi, United Arab Emirates. Electronic address:

Alarming water contamination rates by toxic herbicides have drawn attention to treat these pollutants using efficient, easy, and economic techniques. In this work, date-palm coir (DPC) waste-based nano-activated carbon (DPC-AC) was successfully prepared and examined for adsorptive removal of toxic 2,4-dichlorophenoxyacetic acid (2,4-DPA) herbicide from synthetic wastewater. The DPC-AC was synthesized via a single-step carbonization-KOH activation approach. The nanosorbent displayed a flaky morphology with graphitic structure and oxygen-rich surface functionalities. The nanocarbon with a mean particle size of 163 nm possessed a high specific surface area of 947 m/g with an average pore size of 2.28 nm. High 2,4-DPA removal efficiency of 98.6% was obtained for the optimal adsorption conditions of pH 2, dosage 0.15 g, rotational speed 100 rpm, time 90 min, and initial 2,4-DPA concentration of 100 mg/L. Langmuir isotherm best described the equilibrium behavior with a theoretical maximum of 50.25 mg/g adsorption capacity for the system. Pseudo-second order model was more appropriate in quantifying the kinetics for all initial feed concentrations. Thermodynamically, the adsorption process was spontaneous, endothermic, and involved low activation energy. A plausible mechanism for the adsorption-desorption of 2,4-DPA onto DPC-AC is also discussed. Cost analysis and regenerability studies proved the economic value ($3/kg) and reusable nature of DPC-AC without any significant loss in its performance. Overall, this study highlights the advantages of DPC waste valorization into efficient nanoadsorbent and the sequestration of noxious 2,4-DPA herbicide from its aqueous streams using this nanosorbent.
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http://dx.doi.org/10.1016/j.chemosphere.2021.131103DOI Listing
June 2021

Adsorptive removal of noxious atrazine using graphene oxide nanosheets: Insights to process optimization, equilibrium, kinetics, and density functional theory calculations.

Environ Res 2021 Jun 6;200:111428. Epub 2021 Jun 6.

Department of Chemical Engineering, Khalifa University, P.O. Box 127788, Abu Dhabi, United Arab Emirates.

Atrazine is a toxic herbicide whose alarming rate of contamination in the drinking water and wastewater poses a severe threat to the environment and human health. Here in this study, the graphene oxide (GO) nanosheets were prepared using Hummers' method with minor modification and studied as a potential adsorbent for atrazine removal from simulated wastewater. The spectroscopy and microscopic analysis confirmed the successful formation of GO with a multilayer structure resembling the crumpled sheets with random stacking. The Response Surface Methodology (RSM) employing Box Behnken design (BBD) was successfully developed to predict the optimal conditions for maximal atrazine removal as adsorbent dosage 121.45 mg/L; initial feed concentration 27.03 mg/L; temperature 27.69 °C, pH 5.37, and time 180 min. The atrazine adsorption onto GO was found to be higher in acidic pH and lower temperature. Density functional theory (DFT) calculation of adsorbent-adsorbate complex in the implicit solvent medium suggests adsorption affinity energy of -24.4 kcal/mol for atrazine. A careful observation of the molecules configuration and binding energy showed that the π-π interactions and hydrogen bonds played a significant role in the adsorption phenomena. Langmuir isotherm suited well to the adsorption process with a maximum adsorption capacity of 138.19 mg/g, at 318 K. The fitness of kinetic models for atrazine adsorption onto GO nanosheets were in following order Ho < Sobkowsk-Czerwi < Avrami model based on their correlation coefficient (R) values. Reusability analysis showed that GO nanosheets could be effectively recycled using 0.01 N NaOH up to six cycles of atrazine removal. Thus, this study provided a theoretical and experimental basis for the potential application of GO nanosheets as a novel adsorbent for the removal of hazardous atrazine.
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http://dx.doi.org/10.1016/j.envres.2021.111428DOI Listing
June 2021

High-Grade Biofuel Synthesis from Paired Electrohydrogenation and Electrooxidation of Furfural Using Symmetric Ru/Reduced Graphene Oxide Electrodes.

ACS Appl Mater Interfaces 2021 Jun 19;13(21):24643-24653. Epub 2021 May 19.

Department of Chemical Engineering, Khalifa University, P.O. Box 127788, Abu Dhabi 127788, United Arab Emirates.

Electrochemical hydrogenation is a challenging technoeconomic process for sustainable liquid fuel production from biomass-derived compounds. In general, half-cell hydrogenation is paired with water oxidation to generate the low economic value of O at the anode. Herein, a new strategy for the rational design of Ru/reduced graphene oxide (Ru/RGO) nanocomposites through a cost-effective and straightforward microwave irradiation technique is reported for the first time. The Ru nanoparticles with an average size of 3.5 nm are well anchored into the RGO frameworks with attractive nanostructures to enhance the furfural's paired electrohydrogenation (ECH) and electrooxidation (ECO) process to achieve high-grade biofuel. Furfural is used as a reactant with the paired electrolyzer to produce furfuryl alcohol and 2-methylfuran at the cathode side. Simultaneously, 2-furic acid and 5-hydroxyfuroic acid along with plenty of H and e are generated at the anode side. Most impressively, the paired electrolyzer induces an extraordinary ECH and ECO of furfural, with the desired production of 2-methylfuran (yield = 91% and faradic efficiency (FE) of 95%) at = 97%, outperforming the ECH half-cell reaction. The mechanisms of the half-cell reaction and paired cell reaction are discussed. Exquisite control of the reaction parameters, optimized strategies, and the yield of individual products are demonstrated. These results show that the Ru/RuO nanocomposite is a potential candidate for biofuel production in industrial sectors.
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http://dx.doi.org/10.1021/acsami.1c02231DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8289174PMC
June 2021

Hybrid capacitive deionization of NaCl and toxic heavy metal ions using faradic electrodes of silver nanospheres decorated pomegranate peel-derived activated carbon.

Environ Res 2021 06 14;197:111110. Epub 2021 Apr 14.

Department of Chemical Engineering, Khalifa University, P.O. Box 127788, Abu Dhabi, United Arab Emirates. Electronic address:

Capacitive deionization (CDI) is an evolving technology for eradicating salt and toxic heavy metal ions from brackish wastewater. However, traditional CDI electrodes have lower salt adsorption capacity and inadequate adsorption of selective metal ions for long-term operations. Herein, Ag nanospheres incorporated pomegranate peel-derived activated carbon (Ag/P-AC) was prepared and implied to the CDI process for removing NaCl, toxic mono-, di-, and trivalent metal ions. Morphological analysis revealed that the 80-100 nm-sized Ag nanospheres were uniformly decorated on the surfaces of P-AC nanosheets. The Ag/P-AC has a higher specific surface area (640 m g), superior specific capacitance (180 F g at 50 mV s) and a lower charge transfer resistance (0.5 Ω cm). CDI device was fabricated by Ag/P-AC as an anode, which adsorbed anions and P-AC as cathode for adsorption of positively charged ions at 1.2 V in an initial salt concentration of 1000 mg L. An asymmetric Ag/P-AC//P-AC exhibited a maximum NaCl adsorption capacity of 36 mg g than symmetric P-AC//P-AC electrodes (22.7 mg g). Furthermore, Pb(II), Cd(II), F, and As(III) ions were successfully removed from simulated wastewater by using Ag/P-AC//P-AC based CDI system. These asymmetric CDI-electrodes have an excellent prospect for the removal of salt and toxic contaminants in industrial wastewater.
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http://dx.doi.org/10.1016/j.envres.2021.111110DOI Listing
June 2021

Synthesis of TiO/RGO with plasmonic Ag nanoparticles for highly efficient photoelectrocatalytic reduction of CO to methanol toward the removal of an organic pollutant from the atmosphere.

Environ Pollut 2021 Jul 23;281:116990. Epub 2021 Mar 23.

Department of Chemical Engineering, Khalifa University, P.O. Box 127788, Abu Dhabi, United Arab Emirates. Electronic address:

The synergistic photoelectrochemical (PEC) technology is a robust process for the conversion of CO into fuels. However, designing a highly efficient UV-visible driven photoelectrocatalyst is still challenging. Herein, a plasmonic Ag NPs modified TiO/RGO photoelectrocatalyst (Ag-TiO/RGO) has been designed for the PEC CO reduction into selective production of CHOH. HR-TEM analysis revealed that Ag and TiO NPs with average sizes of 4 and 7 nm, respectively, were densely grown on the few-micron-sized 2D RGO nanosheets. The physicochemical analysis was used to determine the optical and textural properties of the Ag-TiO/RGO nanohybrids. Under VU-Vis light illumination, Ag-TiO/RGO photocathode possessed a current density of 23.5 mA cm and a lower electrode resistance value of 125 Ω in CO-saturated 1.0 M KOH-aqueous electrolyte solution. Catalytic studies showed that the Ag-TiO/RGO photocathode possessed a remarkable PEC CO reduction activity and selective production of CHOH with a yield of 85 μmol L cm, the quantum efficiency of 20% and Faradic efficiency of 60.5% at onset potential of -0.7 V. A plausible PEC CO reduction mechanism over Ag-TiO/RGO photocathode is schematically demonstrated. The present work gives a new avenue to develop high-performance and stable photoelectrocatalyst for PEC CO reduction towards sustainable liquid fuels production.
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http://dx.doi.org/10.1016/j.envpol.2021.116990DOI Listing
July 2021

Effect of date fruit waste extract as an antioxidant additive on the properties of active gelatin films.

Food Chem 2021 Sep 20;355:129631. Epub 2021 Mar 20.

Department of Chemical Engineering, PI Campus, Khalifa University, Abu Dhabi, United Arab Emirates. Electronic address:

In this work, date-fruit syrup waste extract (DSWE) was used as an antioxidant additive to develop active gelatin films with enhanced food preservation properties. The effect of DSWE content (5, 10, 15, and 25 wt%) on the mechanical, physical, and antioxidant properties of the gelatin films were analyzed. Total phenolic content and antioxidant assay analysis revealed that the active compounds in blend films are highly migrated to the aqueous phase than the fatty medium. In the canola oil stability studies, gelatin/25 wt% DSWE film immersed oil sample exhibited low peroxide (POV) and p-anisidine (PV) values of 28.6 and 7.1, respectively, compared to the control oil (POV = 41.7 and PV = 13.1) in the air atmosphere and 45 °C for 30 days. Totox values of canola oil samples were decreased as a function of DSWE content in the films, indicating that polyphenols in DSWE are significantly resistant to oil's lipid oxidation.
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http://dx.doi.org/10.1016/j.foodchem.2021.129631DOI Listing
September 2021

Preparation of TiO/SiO ceramic membranes via dip coating for the treatment of produced water.

Chemosphere 2021 Jun 19;273:129684. Epub 2021 Jan 19.

Center for Membranes and Advanced Water Technology (CMAT), Department of Chemical Engineering, Khalifa University of Science and Technology, P.O. Box 127788, Abu Dhabi, United Arab Emirates. Electronic address:

Produced water, a by-product generated from the oil and gas extraction processes, represents a major challenge in the oil and gas industry as it is generally characterized with a very high salinity and oil content. Currently used ceramic membranes for oil-water separation suffer from the low water flux in spite of their several distinctive advantages. To overcome this limitation and to increase the water flux and oil rejection, commercial ceramic TiO membranes were dip coated with silica (SiO) nanoparticles at different concentrations of 0.25, 0.50, 0.75, and 1.0 wt %. Coated membranes were characterized using scanning electron microscopy (SEM), energy-dispersive x-ray sSpectroscopy (EDS), Fourier-transform infrared spectroscopy (FTIR) and Raman Spectroscopy and contact angle. Results showed that SiO nanoparticles were successfully deposited on the surface of the ceramic membranes confirming the dip coating approach. Furthermore, water flux of 817, 2724, 3636, 627, and 1292 L m h (LMH) was reported at control, 0.25, 0.50, 0.75 and 1.0 wt%; respectively. Also, contact angle reported 75°, 50°, 40°, 24°, 0° at control, 0.25, 0.50, 0.75 and 1.0 wt%; respectively. Finally, total organic carbon (TOC) in the treated water samples reported 100, 28, 11, 9, 10, 13 mg L at control, 0.25, 0.50, 0.75 and 1.0 wt%, respectively. This study can be a preliminary to further studies that accommodate industry-like conditions to help decrease the gap between ideal laboratory setups and harsh real life conditions to fully optimize and exploit the advantages of ceramic membranes in oil-water separation.
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http://dx.doi.org/10.1016/j.chemosphere.2021.129684DOI Listing
June 2021

Supercritical carbon dioxide extraction of plant phytochemicals for biological and environmental applications - A review.

Chemosphere 2021 May 2;271:129525. Epub 2021 Jan 2.

Department of Chemical Engineering, Khalifa University, 127788, Abu Dhabi, United Arab Emirates. Electronic address:

Recently, supercritical fluid CO extraction (SFE) has emerged as a promising and pervasive technology over conventional extraction techniques for various applications, especially for bioactive compounds extraction and environmental pollutants removal. In this context, temperature and pressure regulate the solvent density and thereby effects the yield, selectivity, and biological/therapeutic properties of the extracted components. However, the nature of plant matrices primarily determines the extraction mechanism based on either density or vapor pressure. The present review aims to cover the recent research and developments of SFE technique in the extraction of bioactive plant phytochemicals with high antioxidant, antibacterial, antimalarial, and anti-inflammatory activities, influencing parameters, process conditions, the investigations for improving the yield and selectivity. In another portion of this review focuses on the ecotoxicology and toxic metal recovery applications. Nonpolar properties of Sc-CO create strong solvent strength via distinct intermolecular interaction forces with micro-pollutants and toxic metal complexes. This results in efficient removal of these contaminants and makes SFE technology as a superior alternative for conventional solvent-based treatment methods. Moreover, a compelling assessment on the therapeutic, functional, and solvent properties of SFE is rarely focused, and hence this review would add significant value to the SFE based research studies. Furthermore, we mention the limitations and potential of future perspectives related to SFE applications.
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http://dx.doi.org/10.1016/j.chemosphere.2020.129525DOI Listing
May 2021

Surface functionalized highly porous date seed derived activated carbon and MoS nanocomposites for hydrogenation of CO into formic acid.

J Hazard Mater 2021 May 25;409:124980. Epub 2020 Dec 25.

Department of Chemical Engineering, Khalifa University, P.O. Box 127788, Abu Dhabi, United Arab Emirates. Electronic address:

In recent years, substantial progress has been made towards developing effective catalysts for the hydrogenation of CO into fuels. However, the quest for a robust catalyst with high activity and stability still remains challenging. In this study, we present a cost-effective catalyst composed of MoS nanosheets and functionalized porous date seed-derived activated carbon (f-DSAC) for hydrogenation of CO into formic acid (FA). As-fabricated MoS/f-DSAC catalysts were characterized by FE-SEM, XRD, Raman, FT-IR, BET, and CO-TPD analyses. At first, bicarbonate (HCO) was successfully converted into FA with a high yield of 88% at 200 °C for 180 min under 10 bar H atmosphere. A possible reaction pathway for the conversion of HCO into FA is postulated. The catalyst has demonstrated high activity and long-term stability over five consecutive cycles. Additionally, MoS/f-DSAC catalyst was effectively used for the conversion of gaseous CO into FA at 200 °C under 20 bar (CO/H = 1:1) over 15 h. The catalyst exhibited a remarkable TOF of 510 h with very low activation energy of 12 kJ mol, thus enhancing the catalytic conversion rate of CO into FA. Thus, this work demonstrates the MoS/f-DSAC nanohybrid system as an efficient non-noble catalyst for converting CO into fuels.
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http://dx.doi.org/10.1016/j.jhazmat.2020.124980DOI Listing
May 2021

Improved permeability and antifouling performance of polyethersulfone ultrafiltration membranes tailored by hydroxyapatite/boron nitride nanocomposites.

Chemosphere 2021 Apr 18;268:129306. Epub 2020 Dec 18.

Center for Membranes and Advanced Water Technology (CMAT), Khalifa University of Science and Technology, P.O. Box 127788, Abu Dhabi, United Arab Emirates; Department of Chemical Engineering, Khalifa University of Science and Technology, P.O. Box 127788, Abu Dhabi, United Arab Emirates. Electronic address:

To extend the use of polyethersulfone (PES) ultrafiltration membranes in water process engineering, the membrane's wettability and anti-fouling properties should be further improved. In this context, hydroxyapatite/boron nitride (HAp/BN) nanocomposites have been prepared and intercalated into PES membranes using a non-solvent-induced phase separation process. High-quality 2D transparent boron nitride nanosheets (BN NSs) were prepared using an environmentally friendly and green-template assisted synthesis method in which 1D hexagonal hydroxyapatite nanosheets (HAp NRs) were uniformly distributed and hydrothermally immobilized at 180 °C. SEM, XRD, and Raman spectroscopy techniques were used to characterize the HAp/BN nanocomposites. PES membranes intercalated with various nanocomposite amounts (0-4 wt %) were also characterized by permeability, porosity, and contact angle measurements. Additional pathways for water molecule transport were promoted by the high surface area of the BN NSs, resulting in high permeability. Membrane wettability and antifouling properties were also improved by the inclusion of negative charge groups (OH and PO) on HAp. Hybrid membranes containing 4 wt% HAp/BN showed the best overall performance with ∼97% increase in water flux, 90% rejection of bovine serum albumin (BSA), high water flux recovery ratio, low irreversible fouling, and high reversible fouling pattern. The intercalation of HAp/BN with the PES matrix therefore opens up a new direction to enhance the PES UF membranes' hydrophilicity, water flux, and antifouling capacity.
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http://dx.doi.org/10.1016/j.chemosphere.2020.129306DOI Listing
April 2021

Emerging contaminants in the water bodies of the Middle East and North Africa (MENA): A critical review.

Sci Total Environ 2021 Feb 7;754:142177. Epub 2020 Sep 7.

Center for Membranes and Advanced Water Technology (CMAT), Department of Chemical Engineering, Khalifa University of Science and Technology, P.O. Box 127788, Abu Dhabi, United Arab Emirates. Electronic address:

Many emerging contaminants (ECs) are not currently removed by conventional water treatment methods and consequently, often reach the aquatic environment. In the absence of proper management strategies, ECs can accumulate in water bodies, which poses potential environmental and health risks. This paper critically reviews, for the first time, the reported occurrence and treatment of ECs in the Middle Eastern and North Africa (MENA) region. The paper also provides recommendations to properly manage EC risks. In the MENA region, pharmaceuticals and personal care products (PPCPs) have been detected in surface water, seawater, groundwater, and wastewater treatment plants. A focus on surface water in the published literature suggests that studies are skewed towards worldwide trends, whereas studies on ECs in seawater are of great importance in the study region. The types of PPCPs detected in the MENA region vary, but anti-inflammatories and antibiotics dominate. In comparison, microplastics have mainly been studied in surface waters and seawater with much less focus on drinking water. The majority of microplastics in the region are secondary types resulting from the degradation of larger plastic debris; polyethylene (PE) and polypropylene (PP) fibers are the most frequently detected polymers, which are indicative of local anthropogenic sources. Research progress on ECs varies between countries, having received more attention in Iran and Tunisia. Most MENA countries have now begun monitoring water bodies for ECs; however, studies are still lacking in some countries including Sudan, Djibouti, Syria, Ethiopia, and Bahrain. Based on this review, critical knowledge gaps and research needs are identified. Countries in the MENA region require further research on a broader range of EC types. Overall, water pollution due to the use and release of ECs can be tackled by improving public awareness, public campaigns, government intervention, and advanced monitoring and treatment methods.
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http://dx.doi.org/10.1016/j.scitotenv.2020.142177DOI Listing
February 2021

Augmented biohydrogen production from rice mill wastewater through nano-metal oxides assisted dark fermentation.

Bioresour Technol 2021 Jan 12;319:124243. Epub 2020 Oct 12.

Department of Chemical Engineering, Khalifa University, P.O. Box 127788, Abu Dhabi, United Arab Emirates.

This study highlights biohydrogen production enrichment through NiO and CoO nanoparticles (NPs) inclusion to dark fermentation of rice mill wastewater using Clostridium beijerinckii DSM 791. NiO (~26 nm) and CoO (~50 nm) NPs were intrinsically prepared via facile hydrothermal method with polyhedral morphology and high purity. Dosage dependency studies revealed the maximum biohydrogen production characteristics for 1.5 mg/L concentration of both NPs. Biohydrogen yield was improved by 2.09 and 1.9 folds higher for optimum dosage of NiO and CoO respectively, compared to control run without NPs. Co-metabolites analysis confirmed the biohydrogen production through acetate and butyrate pathways. Maximum COD reduction efficiencies of 77.6% and 69.5% were observed for NiO and CoO inclusions respectively, which were higher than control run (57.5%). Gompertz kinetic model fitted well with experimental data of NPs assisted fermentation. Thus, NiO and CoO inclusions to wastewater fermentation seems to be a promising technique for augmented biohydrogen production.
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http://dx.doi.org/10.1016/j.biortech.2020.124243DOI Listing
January 2021

Designed assembly of Ni/MAX (TiAlC) and porous graphene-based asymmetric electrodes for capacitive deionization of multivalent ions.

Chemosphere 2021 Mar 21;266:129048. Epub 2020 Nov 21.

Department of Chemical Engineering, Khalifa University, P.O. Box 127788, Abu Dhabi, United Arab Emirates. Electronic address:

The contamination of aquatic ecosystems by fluoride and heavy metal ions constitute an environmental hazard and has been proven to be harmful to human health. This study explores the feasibility of using asymmetric capacitive deionization (CDI) electrodes to remove such toxic ions from wastewater. An asymmetric CDI cell was fabricated using 2D Ni/MAX as an anode and 3D porous reduced graphene oxide (pRGO) as a cathode for the electrosorption of F, Pb, and As(III) ions. A simple microwave process was used for the synthesis of Ni/MAX composite using fish sperm DNA (f-DNA) as a cross-linker between MAX nanosheets (NSs) and the metallic Ni nanoparticles (NPs). Further, pRGO anode was prepared through effective reduction of RGO using lemon juice as green reducing agent with the assist of f-DNA as a structure-directing agent for the formation of 3D network. With this tailored nanoarchitecture, pRGO and Ni/MAX electrodes exhibited a high specific capacitance of 760 and 385 F g, respectively. The fabricated Ni/MAX and pRGO based CDI system demonstrated a high electrosorption capacity of 68, 76, and 51 mg g for the monovalent F, divalent Pb, and trivalent As(III) ions at 1.4 V in neutral pH. Furthermore, Ni/MAX//pRGO system was successfully applied for the removal of total F(T), Pb(T), and As(T) ions from real industrial wastewater and contaminated groundwater. The present findings indicate that the fabricated Ni/MAX//pRGO electrode has excellent electrochemical properties that can be exploited for the removal of anionic and cationic metal ions from aqueous solutions in a CDI based system.
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http://dx.doi.org/10.1016/j.chemosphere.2020.129048DOI Listing
March 2021

Polyvinylidene fluoride (PVDF)-α-zirconium phosphate (α-ZrP) nanoparticles based mixed matrix membranes for removal of heavy metal ions.

Chemosphere 2021 Mar 7;267:128896. Epub 2020 Nov 7.

Center for Membranes and Advanced Water Technology (CMAT), Department of Chemical Engineering, Khalifa University, P.O. Box 127788, Abu Dhabi, United Arab Emirates. Electronic address:

The removal of heavy metal ions from industrial wastewater is essential as they pose serious threats to human health and the environment. In this study, novel poly(vinylidene fluoride) (PVDF)-alpha-zirconium phosphate (PVDF-α-ZrP) mixed matrix membranes (MMM) were prepared via the phase inversion method. Membranes with different α-ZrP nanoparticles (NPs) loadings (0.25, 0.50, 0.75, or 1.00 wt%) were fabricated. The impacts of α-ZrP NP loading on the membrane's morphology, functionality, surface charge, and hydrophilicity were evaluated. Fourier-transform infrared and the energy-dispersive X-ray spectroscopy were performed to verify the presence of α-ZrP NPs in the fabricated membranes. The PVDF membranes became more hydrophilic after incorporating the α-ZrP NPs. The thermal and mechanical stability and porosity of the PVDF-α-ZrP MMM were higher than those of the pristine PVDF membrane. The increased hydrophilicity, pore size and porosity and reduced surface roughness of the PVDF-α-ZrP membrane led to significant flux increase and reduced fouling propensity. The PVDF-α-ZrP membrane containing 1.00 wt% α-ZrP was capable of removing 42.8% (Cd), 93.1% (Cu), 44.4% (Ni), 91.2% (Pb), and 44.2% (Zn) from an aqueous solution at neutral pH during filtration.
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http://dx.doi.org/10.1016/j.chemosphere.2020.128896DOI Listing
March 2021

Biosorption potential of Phoenix dactylifera coir wastes for toxic hexavalent chromium sequestration.

Chemosphere 2021 Apr 28;268:128809. Epub 2020 Oct 28.

Department of Chemical Engineering, Faculty of Science and Engineering, University of Nottingham Malaysia, 43500, Selangor Darul Ehsan, Malaysia. Electronic address:

Valorization of waste phytomass into valuable components provide new functionality to these biowastes and annul problems associated with their safe disposal. In this study, date palm (Phoenix dactylifera) coir (DPC) waste was tested for its toxic hexavalent chromium (Cr(VI)) ions biosorption. The DPC biosorbent was subjected to SEM, EDX, FTIR, TGA and N adsorption/desorption characterization studies. Results showed that the cellulose-rich DPC surface contained mesopores with a wide number of functional groups and possessed suitable surface attributes for Cr(VI) ions sequestration. Batch biosorption tests established the Cr(VI) ions sequestration potential of the DPC biosorbent with a maximum chromium removal efficiency of 87.2% for a 100 ppm initial feed concentration at pH 2, dosage 0.3 g, temperature 30 °C, contact time 60 min and agitation speed 100 rpm. Langmuir isotherm fitted well (R = 0.9955) with the experimental data while the kinetic analysis showed that Cr(VI) ions sequestration by DPC followed the pseudo-second order model. Biosorption thermodynamics revealed the exothermic nature and low-temperature preference for the effective binding of chromium ions on DPC. Regeneration of the biosorbent using NaOH wash showed a nearly steady Cr(VI) ions removal efficiency (with a loss <10%) by the DPC till four recycle runs. Economic analysis showed a very low production cost of $1.09/kg for the DPC biosorbent with a total cost of $4.36/m for a scale-up batch process wastewater treatment plant. Thus, a low-cost, effectual and sustainable biosorbent for effective treatment of Cr(VI) ions polluted water streams has been reported.
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http://dx.doi.org/10.1016/j.chemosphere.2020.128809DOI Listing
April 2021

Comparative study of lactic acid production from date pulp waste by batch and cyclic-mode dark fermentation.

Waste Manag 2021 Feb 8;120:585-593. Epub 2020 Nov 8.

Department of Chemical Engineering, Khalifa University of Science and Technology, P.O. Box 127788, Abu Dhabi, United Arab Emirates.

Biowaste valorization into lactic acid (LA) by treatment with indigenous microbiota has recently gained considerable attention. LA production from date pulp waste provides an opportunity for resource recovery, reduces environmental issues, and possibly turns biomass into wealth. This study aimed to compare the performance of batch and cyclic fermentation processes in LA production with and without enzymatic pretreatment. The fermentation studies were conducted in the absence of an external inoculum source (relying on indigenous microbiota) and without the addition of nutrients. The highest LA volumetric productivity (3.56 g/liter/day), yield (0.07 g/g-TS), and concentration (21.66 g/L) were attained with enzymatic pretreated date pulp in the cyclic-mode fermentation at the optimized conditions. The productivity rate of LA was enhanced in the cyclic-mode as compared to the batch process. Enzymatic pretreatment increased the digestibility of cellulose that led to higher LA yield. An Artificial Neural Network model was developed to optimize the process parameters and to predict the LA concentration from date pulp waste in both fermentation processes. The main advantage of the ANN approach is the ability to perform quick predictions without resource-consuming experiments. The model predicted optimal conditions well and demonstrated good agreement between experimental and predicted data.
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http://dx.doi.org/10.1016/j.wasman.2020.10.029DOI Listing
February 2021

Sulfide remediation from wastewater using hydrothermally synthesized δ-MnO/porous graphitic carbon as adsorbent.

Environ Res 2021 05 7;196:110429. Epub 2020 Nov 7.

Department of Chemical Engineering, Khalifa University, P.O. Box 127788, Abu Dhabi, United Arab Emirates. Electronic address:

A facile hydrothermal assisted in-situ precipitation technique was employed for synthesizing highly efficient porous graphitic carbon/manganese dioxide (PGC/MnO) nanocomposite adsorbent using calcium alginate as carbon precursor. Morphological and structural characterization using scanning electron microscopy equipped with energy dispersive X-ray spectroscopy, transmission electron microscopy, and X-ray diffraction techniques confirmed the interconnected nanoporous architecture and birnessite (δ) MnO polymorph evenly distributed on the PGC structure. The synergistic effect of PGC and MnO was exploited for enhanced sulfide removal from wastewater via adsorptive oxidation. The effect of different experimental parameters, including solution pH, initial sulfide concentration, adsorbent dosage, and contact time on removal efficiency was investigated. The equilibrium and kinetic data for sulfide adsorption by PGC/MnO nanocomposite fitted well with Langmuir isotherm and pseudo-second-order kinetic model, respectively. The maximum uptake capacity of sulfide by the nanocomposite was determined as 500 mg/g with complete sulfide removal. Further, it was estimated that a typical field application using the synthesized nanocomposite adsorbent would require 0.5-1 g/L per 200 mg/L of sulfide contaminated wastewater. Based on the experimental results, a schematic of the adsorptive oxidation mechanism of PGC/MnO nanocomposite is proposed.
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http://dx.doi.org/10.1016/j.envres.2020.110429DOI Listing
May 2021

WITHDRAWN: Sustainable liquid membrane separation using interfacial engineering of deep eutectic solvent and cellulose acetate.

J Hazard Mater 2020 Oct 27:124345. Epub 2020 Oct 27.

College of Food Science and Technology, Nanjing Agricultural University, Nanjing, 210095, Jiangsu, China.

This article has been withdrawn at the request of the editor. The Publisher apologizes for any inconvenience this may cause. The full Elsevier Policy on Article Withdrawal can be found at https://www.elsevier.com/about/our-business/policies/article-withdrawal.
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http://dx.doi.org/10.1016/j.jhazmat.2020.124345DOI Listing
October 2020

Microalgae harvesting using colloidal gas aphrons generated from single and mixed surfactants.

Chemosphere 2021 Jun 12;273:128568. Epub 2020 Oct 12.

Department of Chemical Engineering, Khalifa University of Science and Technology, Abu Dhabi, P.O. Box: 127788, United Arab Emirates. Electronic address:

Harmful algal blooms (HABs) caused by microalgae are becoming increasingly common and pose serious threats to human health, aquaculture, and marine environments and, therefore, their removal is becoming essential. Colloidal gas aphrons (CGAs), a recent technology adapted in flotation, showed promise in removing several contaminants from aqueous solutions. This study aimed to investigate the potency of CGAs in removing several microalgae strains (Spirulina platensis, Nannochloropsis oculata, and Chlorella vulgaris) from aqueous solutions. Surfactants, including cationic hexadecyl trimethyl ammonium bromide (HTAB), anionic sodium dodecylbenzene sulfonate (SDBS), sodium dodecyl sulfate (SDS), and their mixes, were used to prepare stable CGAs. The effect of different environmental parameters like algae concentration, pH, and salinity, on removing Spirulina platensis was thoroughly investigated. Operating conditions, including surfactant type, flotation time, flowrate, and solution temperature, were optimized. At pH 5 and 50 °C, Spirulina platensis, Chlorella vulgaris, and mixed microalgae were fully removed using CGAs produced from cationic HTAB surfactant. About 95% removal of Nannochloropsis oculata was achieved using mixed surfactant CGAs. The results obtained from this work demonstrated the promising potential of CGAs produced from both single and mixed surfactants in harvesting various microalgae from aqueous media.
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http://dx.doi.org/10.1016/j.chemosphere.2020.128568DOI Listing
June 2021

Green synthesis of zinc oxide nanoparticles using Phoenix dactylifera waste as bioreductant for effective dye degradation and antibacterial performance in wastewater treatment.

J Hazard Mater 2021 01 26;402:123560. Epub 2020 Jul 26.

Department of Chemical Engineering, Faculty of Science and Engineering, University of Nottingham Malaysia, 43500 Selangor Darul Ehsan, Malaysia. Electronic address:

Production of multi-functional zinc oxide nanoparticles (ZnO-NPs) for wastewater treatment through green-approaches is a desirable alternative for conventional synthesis routes. Biomass waste valorization for nanoparticles synthesis has received increased research attention. The present study reports date pulp waste (DPW) utilization as an effective bio-reductant for green-synthesis of ZnO-NPs. A simple and eco-friendly process with low reaction time and calcination temperature was adopted for DPW mediated ZnO-NPs (DP-ZnO-NPs) synthesis. Microscopic investigations of DP-ZnO-NPs confirmed the non-agglomeration and spherical nature of particles with mean diameter of 30 nm. EDX and XPS analysis defined the chemical composition and product purity of DP-ZnO-NPs. UV and photoluminescence studies exhibited surface plasmonic resonance at 381 nm and fluorescent nature of DP-ZnO-NPs. FTIR studies established a formation mechanism outline for DP-ZnO-NPs. XRD and Raman investigations confirmed the crystalline and hexagonal wurtzite phase of DP-ZnO-NPs. DSC/TG analysis displayed the thermal stability of DP-ZnO-NPs with <10 wt% loss upto 700 °C. Photocatalytic degradation of hazardous methylene blue and eosin yellow dyes using DP-ZnO-NPs, showed rapid decomposition rate with 90 % degradation efficiency. Additionally, DP-ZnO-NPs demonstrated significant antibacterial effects on various pathogenic bacteria in terms of zone-of-inhibition measured by disc-diffusion method. Thus, the as-prepared DP-ZnO-NPs is suitable for industrial wastewater treatment.
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http://dx.doi.org/10.1016/j.jhazmat.2020.123560DOI Listing
January 2021

High performance nanofiber-supported thin film composite forward osmosis membranes based on continuous thermal-rolling pretreated electrospun PES/PAN blend substrates.

Chemosphere 2020 Dec 19;261:127687. Epub 2020 Jul 19.

School of Earth Sciences and Environmental Engineering, Gwangju Institute of Science and Technology (GIST), 261, Cheomdangwagi-ro, Buk-gu, Gwangju, 61005, Republic of Korea; Center for Membranes, Advanced Materials Division, Korea Research Institute of Chemical Technology (KRICT), Daejeon, 34114, Republic of Korea. Electronic address:

One of the major challenges facing the practical application of forward osmosis (FO) membranes is the need for high performance. Thus, the fabrication of highly permselective FO membranes is of great importance. The objective of this study was to improve the wettability/hydrophilicity of electrospun nanofiber (ESNF)-based substrates for the fabrication of nanofiber-supported thin film composite (NTFC) membranes for FO application. This study explored the impact of electrospun polyethersulfone/polyacrylonitrile (PES/PAN) nanofibers as the blend support to produce NTFC membranes. The blending of PES/PAN in the spinning dope was optimized. The blending of hydrophilic PAN (0-10 wt%) in PES affects the fiber diameter, hydrophilicity, water uptake, and roughness of the ESNF membrane substrates. Continuous thermal-rolling pretreatment was performed on the ESNF substrates prior to interfacial polymerization for polyamide active layer deposition. The results indicated that the fabricated NTFC membrane achieved significantly greater water flux (L/m h) while retaining a low specific salt flux (g/L) compared to traditional TFC membranes. The NTFC membrane flux increased with an increase in PAN content in the ESNF substrate. According to the FO performance results, the NTFC-10 (PES/PAN blend ratio of 90:10) exhibited optimal performance: a high water flux of 42.1 and 52.2 L/m h for the FO and PRO modes, respectively, and low specific salt flux of 0.27 and 0.24 g/L for the FO and PRO modes, respectively, using 1 M NaCl as the draw solution. This demonstrated the higher selectivity and water flux achieved by the developed NTFC membranes compared to the traditional TFC membranes.
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http://dx.doi.org/10.1016/j.chemosphere.2020.127687DOI Listing
December 2020

Adsorptive oxidation of sulfides catalysed by δ-MnO decorated porous graphitic carbon composite.

Environ Pollut 2020 Nov 16;266(Pt 3):115218. Epub 2020 Jul 16.

Department of Chemical Engineering, Khalifa University, P.O. Box 127788, Abu Dhabi, United Arab Emirates.

Removal of dissolved sulfide contaminants from aqueous model solution using bio-derived porous graphitic carbon (PGC) impregnated with δ-MnO was investigated. The composite adsorbent was synthesized using the chemical wet deposition method wherein MnO was deposited on carbon walls through an in-situ reaction between permanganate and ethanol. Formation of transition metal oxide of manganese in the form of birnessite nanoparticles on interconnected PGC cell structure was confirmed by transmission electron microscopy, scanning electron microscopy, elemental analysis, and X-Ray diffraction characterization studies. The composite nanomaterial was tested for sulfide removal from aqueous solution at various conditions, including the pH, adsorbent dosage, initial solution concentration, and contact time. Adsorption results demonstrated an excellent adsorption capacity of ca. 90% within 20 min of contact time at 298 K. Equilibrium data collected from batch adsorption experiments fitted well with the Langmuir isotherm model (K = 190 L/mg; R = 0.99). The maximum adsorption capacity of the composite was estimated as 526.3 mg S/g at highly alkaline conditions compared to ca. 340 mg/g for a δ-MnO adsorbent. Adsorptive oxidation of sulfides on composite MnO-PGC adsorbent was found to be controlled by the chemisorption process in accordance with the pseudo-second-order reaction model. Characterization of spent adsorbents revealed that sulfide was removed through adsorptive oxidation resulting in the formation of agglomerated particles of metal sulfate complexes and elemental sulfur. Analysis of reaction mechanism revealed that both MnO and PGC played a role in the adsorptive oxidation of sulfides to CaSO and elemental sulfur.
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http://dx.doi.org/10.1016/j.envpol.2020.115218DOI Listing
November 2020

Synthesis of polyethersulfone (PES)/GO-SiO mixed matrix membranes for oily wastewater treatment.

Water Sci Technol 2020 Apr;81(7):1354-1364

Center for Membrane and Advanced Water Technology (CMAT), Department of Chemical Engineering, Khalifa University of Science and Technology, P.O. Box 127788, Abu Dhabi, United Arab Emirates E-mail:

The treatment of oily wastewater continues to pose a challenge in industries worldwide. Membranes have been investigated recently for their use in oily wastewater treatment due to their efficiency and relatively facile operational process. Graphene oxide (GO) and silica (SiO) nanoparticles have been found to improve membrane properties. In this study, a polyethersulfone (PES) based GO-SiO mixed matrix membrane (MMM) was fabricated, using the phase inversion technique, for the treatment of oil refinery wastewater. The PES/GO-SiO membrane exhibited the highest water flux (2,561 LMH) and a 38% increase in oil removal efficiency by comparison to a PES membrane. Compared to PES/GO and PES/SiO membranes, the PES/GO-SiO MMM also displayed the best overall properties in terms of tensile strength, water permeability, and hydrophilicity.
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http://dx.doi.org/10.2166/wst.2019.347DOI Listing
April 2020

Biosorption performance of date palm empty fruit bunch wastes for toxic hexavalent chromium removal.

Environ Res 2020 08 24;187:109694. Epub 2020 May 24.

Department of Chemical Engineering, Faculty of Science and Engineering, University of Nottingham Malaysia, 43500, Selangor Darul Ehsan, Malaysia. Electronic address:

Biosorption ability of date palm empty fruit bunch (DPEFB) was examined for the removal of toxic hexavalent chromium (Cr) ions from synthetic wastewater. The pretreated DPEFB biosorbent was studied for its morphology and surface chemistry through Scanning electron microscopy, Energy dispersive elemental analysis and Fourier transform infrared spectroscopy. Effect of biosorption parameters such as pH, biosorbent dosage, contact time, temperature, initial feed concentration and agitation speed on the Cr ions removal efficiency by DPEFB was critically evaluated. The isoelectric point for the DPEFB sorbent was observed at pH 2, above which it was dehydronated to capture the positively charged Cr ions. Batch biosorption studies showed that an optimal chromium removal efficiency of 58.02% was recorded by the DPEFB biosorbent for pH 2, dosage 0.3 g, 100 rpm agitation speed, 120 min contact time, 50 mg/L initial feed concentration and 30 °C operational temperature. Thermodynamic analysis showed that the binding of Cr ions on DPEFB surface was exothermic, stable and favorable at room temperature. Equilibrium behavior of chromium binding on DPEFB was more aligned to Temkin isotherm (R = 0.9852) highlighting the indirect interactions between Cr ions and the biosorbent. Kinetic modeling revealed that the biosorption of Cr ions by DPEFB obeyed pseudo-second order model than the pseudo-first order and intra-particle diffusion models. Reusability studies of the DPEFB sorbent showed that NaNO was an effective regenerant and the biosorbent can be efficiently reused up to three successive biosorption-desorption cycles for chromium removal. In summary, the results clearly showed that the DPEFB biowaste seems to be an efficient, economic and eco-friendly biosorbent for sustainable removal of toxic hexavalent chromium ions from domestic and industrial wastewater streams.
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http://dx.doi.org/10.1016/j.envres.2020.109694DOI Listing
August 2020

Sustainable synthesis of graphene-based adsorbent using date syrup.

Sci Rep 2019 12 2;9(1):18106. Epub 2019 Dec 2.

Department of Chemical Engineering, Khalifa University - SAN Campus, PO Box: 127788, Abu Dhabi, United Arab Emirates.

Here we demonstrate, a facile in-situ strategy for the synthesis of environmentally benign and scalable graphene sand hybrid using date syrup as a sustainable carbon source through pyrolysis at 750 °C. Raman and SEM images revealed that the as-prepared date syrup-based graphene sand hybrid (D-GSH) had imperfections with macroporous 2-D graphene sheet-like structures stacked on the inorganic sand support. The applicability of the D-GSH for decontaminating the water from cationic (Methyl Violet, MV) and anionic (Congo Red, CR) dye and heavy metals (Pb and Cd) was tested. Batch experiments demonstrated that D-GSH showcased exceptional capability for both dye and heavy metals removal with fast adsorption following pseudo-second-order kinetics. The adsorption capacities for MV, Pb, and Cd were respectively 2564, 781 and 793 mg/g at 25 °C, the highest capacity graphene-based adsorbent reported in the literature to date. In addition, D-GSH also exhibited high adsorption capacity for anionic dye, CR (333 mg g) and good recyclability (3 cycles) for all the contaminants. The thermodynamic studies further confirmed that the adsorption of all contaminants was thermodynamically feasible, spontaneous and endothermic with ∆H° of 48.38, 89.10, 16.89 and 14.73 kJ/mol for MV, CR, Pb and Cd, respectively. Thus, utilization of a simple one-step strategy to produce graphenic sand hybrid using date syrup helped in developing a cost-effective and environmentally friendly dye and heavy metal scavenger that can be used as a one-step solution for water decontamination.
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http://dx.doi.org/10.1038/s41598-019-54597-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6889283PMC
December 2019

Fabrication of Chitosan/PVA/GO/CuO patch for potential wound healing application.

Int J Biol Macromol 2020 Jan 14;143:744-762. Epub 2019 Oct 14.

Department of Nanotechnology, SRM Institute of Science and Technology, Kattankulathur, Kancheepuram Dist, Tamil Nadu 603 203, India. Electronic address:

Wound healing is a common issue in our day to day life. Our immune system repairs the damaged tissue by itself and its a time-consuming process. The GO/CuO nanocomposite (NC) was synthesized through the sol-gel method. XRD, FT-IR, Raman, and TEM analysis were used to analysis the physico-chemical properties of the sample. The GO/CuO patches were prepared using chitosan (Cs)/poly vinyl alcohol (PVA) due to its biocompatibility and biodegradable nature. The obtained patches showed better antimicrobial and wound healing property than recently reported materials. The GO/CuO NC plays a major part in angiogenesis process and in the synthesis, stabilization of extracellular matrix skin proteins. Thus, GO/CuO NC enhance the wound healing mechanism by increasing cell proliferation, antimicrobial property and rapid initiation of inflammatory. Moreover, the antimicrobial activity of CuO, GO, GO/CuO and GO/CuO patch were tested against bacteria causing wound infections. Cs/PVA patch and Cs/PVA/GO/CuO patch were analyzed for swelling, evaporation and degradation behavior. Increase in cell viability and migration of NIH3t3 cells by NC patch shows a potential way for wound healing applications.
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http://dx.doi.org/10.1016/j.ijbiomac.2019.10.029DOI Listing
January 2020

Enhanced electrochemical performances of peanut shell derived activated carbon and its FeO nanocomposites for capacitive deionization of Cr(VI) ions.

Sci Total Environ 2019 Nov 6;691:713-726. Epub 2019 Jul 6.

Department of Nanoscience and Technology, Bharathiar University, Coimbatore 641 046, Tamil Nadu, India.

Capacitive deionization (CDI) is one of the most efficient and emerging techniques for the removal of toxic metal ions from aqueous solutions. In this study, mesoporous peanut shell derived activated carbon (PSAC) was prepared by low temperature pyrolysis at 500 °C. Subsequently, a novel iron oxide/PSAC (FeO/PSAC) nanocomposite adsorbent was prepared via facile one-pot hydrothermal synthesis method at 180 °C. Nucleation growth mechanism and appropriate characterizations of prepared nanocomposites were investigated. The obtained FeO/PSAC possessed a highly mesoporous structure, and a large specific surface area (680 m/g). The electrochemical analysis showed that the obtained FeO/PSAC nanocomposites exhibited higher capacitance (610 F/g at 10 mV/s), good stability and low internal resistance. A batch mode adsorption and CDI based Cr(VI) removal studies were conducted. Effects of solution pH and cycle time on Cr(VI) electrosorption capacity were further investigated. The FeO/PSAC based electrodes exhibit a maximum electrosorption capacity of 24.5 mg/g at 1.2 V, which was remarkably larger than other reported materials. The fabricated composite displayed higher electrosorption capacity with rapid time and a favorable reduction of Cr (VI) to Cr(III). Studies indicated that the FeO/PSAC based CDI electrode possesses a good potential to be applied for the removal of toxic metal ions from wastewater.
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http://dx.doi.org/10.1016/j.scitotenv.2019.07.069DOI Listing
November 2019

Synthesis of super hydrophilic cellulose-alpha zirconium phosphate ion exchange membrane via surface coating for the removal of heavy metals from wastewater.

Sci Total Environ 2019 Nov 3;690:167-180. Epub 2019 Jul 3.

Center for Membrane and Advanced Water Technology (CMAT), Department of Chemical Engineering, Khalifa University of Science and Technology, Masdar City Campus, P.O. Box 127788, Abu Dhabi, United Arab Emirates. Electronic address:

In this study, commercial cellulose membranes were surface coated with alpha‑zirconium phosphate nanoparticles (α-ZrP-n) to study their impact on the overall removal efficiency of heavy metals from synthetic metal mixture wastewater solution. A total of four homogeneous solutions (0.25, 0.50, 0.75, and 1.00 wt%) of α-ZrP-n were prepared by sonicating the nanoparticles in deionized water. These solutions were used to surface coat the commercial cellulose membranes. The Scanning Electron Microscopy (SEM) along with Energy Dispersive Spectroscopy (EDS) were used to confirm the attachment of α-ZrP-n on the cellulose membrane surface. Furthermore, the structural characteristics of the α-ZrP-n modified cellulose membranes were also studied. The water contact angle results showed that all coated membranes remained super-hydrophilic. The porosity of the membranes decreased to 48% with the addition of 1.00 wt% α-ZrP-n compared to 65% for the pristine membrane. The mechanical strength has improved from 3.4 MPa for the pristine membrane to about 4 MPa for the 1.00 wt% α-ZrP-n membrane. Similarly, the thermal stability was found to be slightly enhanced as evidenced by the increase in decomposition temperature to 280 and 285 °C in the 0.75 and 1.00 wt% α-ZrP-n membranes, respectively. Furthermore, a removal efficiency of 97.0 ± 0.6, 98.0 ± 0.5, 99.5 ± 0.2, and 91.5 ± 2.0% for Cu (II), Zn (II), Ni (II), and Pb (II), respectively, was observed with the 0.50 wt% α-ZrP-n membrane. This removal was achieved at a flux of 41.85 ± 0.87 × 10 LMH. Increasing the α-ZrP-n concentration further did not show any improvement in the overall removal efficiency. However, it led to 46% flux reduction in the 1.00 wt% α-ZrP-n membrane. The mechanism of removal of the heavy metal ions was postulated to be a combination of ion exchange and electrostatic attraction of the strong negatively charged α-ZrP-n membranes and the free metal ions in the wastewater solution.
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http://dx.doi.org/10.1016/j.scitotenv.2019.07.009DOI Listing
November 2019
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