Publications by authors named "N Sivarajasekar"

5 Publications

  • Page 1 of 1

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

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

Ultrasound assisted pectic polysaccharide extraction and its characterization from waste heads of Helianthus annus.

Carbohydr Polym 2017 Oct 19;173:707-713. Epub 2017 Jun 19.

Department of Food Technology, Kongu Engineering College, Perundurai 638 060, Erode, Tamil Nadu, India.

The main aim of this current work is to extract pectin from waste heads of Helianthus annus by ultrasound and optimize the process variables (ultrasound power (USP), pH, time of sonication (TS) and ratio of solid to liquid (RSL) on maximal recovery of pectin using central composite statistical experimental design. In addition to that, extracted pectin at optimal condition was characterized and compared with commercial pectin. The optimal extraction process condition was USP of 375w, pH of 3.2, TS of 32min and RSL of 1:15g/ml. Mean experimental pectin yield of 8.89±0.024% was well accord with predicted pectin yield (8.91%). Analysis of chemical composition and Fourier transform infrared spectroscopy of extracted pectin did not show any significant difference with commercial pectin. XRD analysis illustrated a similar crystalline profile in both extracted and commercial pectin. Morphological analysis was performed on fresh and extracted samples using scanning electron microscopy.
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http://dx.doi.org/10.1016/j.carbpol.2017.06.018DOI Listing
October 2017

Ultrasound assisted citric acid mediated pectin extraction from industrial waste of Musa balbisiana.

Ultrason Sonochem 2017 Mar 24;35(Pt A):204-209. Epub 2016 Sep 24.

Department of Biotechnology, Kumaraguru College of Technology, Coimbatore, Tamil Nadu 641049, India.

The objectives of the present work are to extract pectin from industrial waste of Musa balbisiana by ultrasound assisted citric acid mediated extraction method and optimization was done through central composite statistical experimental design under response surface methodology. The outcomes of this study exhibited that, process variables (ultrasound power, pH and extraction time) had considerable influence on the pectin extraction. Second order mathematical equation was constructed to predict the data through regression analysis. The optimal extraction process condition was ultrasound power of 323w, pH of 3.2, extraction time of 27min and SL (solid-liquid) ratio of 1:15g/ml. The mean experimental yield of pectin (8.99±0.018%) was fine accord among predicted yield of pectin (9.02%).
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http://dx.doi.org/10.1016/j.ultsonch.2016.09.019DOI Listing
March 2017
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