Publications by authors named "Meththika Vithanage"

90 Publications

Mechanistic interaction of ciprofloxacin on zeolite modified seaweed (Sargassum crassifolium) derived biochar: Kinetics, isotherm and thermodynamics.

Chemosphere 2021 May 4;281:130676. Epub 2021 May 4.

Ecosphere Resilience Research Center, Faculty of Applied Sciences, University of Sri Jayewardenepura, Nugegoda, Sri Lanka. Electronic address:

Modification of biochar for efficient removal of antibiotics from water could be a valuable approach in the environmental applications. In this study, a brown seaweed (Sargassum crassifolium) was pyrolyzed at 500 °C and the obtained biochar (SWBC) was modified with zeolite through the slurry method maintaining the ratio at 1:5 (zeolite: biochar) (SWBC-Z). Batch adsorption experiments were conducted to evaluate the adsorption tendency of SWBC and SWBC-Z for the removal of ciprofloxacin (CPX) from water via pH edge, kinetics, isotherm and thermodynamic experiments. The highest adsorption was in the pH range of 6.5-8, supported by the electrostatic attractions and hydrogen bonding with zwitterionic CPX. Experimental kinetics data was well-fitted to the pseudo-second-order and Elovich models (R of 0.992 and 0.976, respectively), while the Langmuir and Freundlich isotherm models best described the isotherm data (R of 0.954 and 0.976, respectively). The maximum adsorption capacity of 93.65 mg g was recorded for the SWBC-Z. The models predicted chemisorption and physisorption interactions on the heterogenous biochar surface. Well-defined peaks of silanol groups in the FTIR spectrum of SWBC-Z and its electron microscopy confirmed the incorporation of zeolite minerals. Post adsorption FTIR analysis elucidated the changes in the surface functional groups of the SWBC-Z. Thermodynamic data revealed spontaneous and exothermic reaction between CPX and both the biochars. It was concluded that modification of pristine biochar with zeolite imparted greater surface area and additional active sites, which subsequently enhanced the overall CPX adsorption by the SWBC-Z.
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http://dx.doi.org/10.1016/j.chemosphere.2021.130676DOI Listing
May 2021

Co-hydrothermal carbonization of swine and chicken manure: Influence of cross-interaction on hydrochar and liquid characteristics.

Sci Total Environ 2021 Sep 27;786:147381. Epub 2021 Apr 27.

Korea Biochar Research Center, APRU Sustainable Waste Management Program & Division of Environmental Science and Ecological Engineering, Korea University, Seoul 02841, Republic of Korea. Electronic address:

Swine and chicken manures are abundant solid wastes that can be converted into carbonaceous materials through hydrothermal carbonization (HTC). Owing to their unique biochemical compositions, co-HTC of these two types of manures may have significant implications for the generated products. We investigated the co-HTC of swine manure and chicken manure to understand the influence of the interaction between contrasting manures on the properties of the derived products. The results indicated that co-HTC treatment enhanced the formation of solid product and improved the C and N contents, heating value, and energy yield of the resulting hydrochar. Regarding the ignition temperature and comprehensive combustion index, the combustion properties of the hydrochar were enhanced owing to the mutual effect of the HTC intermediates. Additionally, the interaction of the intermediates significantly impacted the transfer of nitrogenous species and generation of organic acids and organic polymers with fused-ring structures. Therefore, co-HTC processing of animal manures could potentially provide a sustainable pathway for the conversion of animal waste into solid products with improved characteristics compared to those produced by treating the two feedstocks separately.
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http://dx.doi.org/10.1016/j.scitotenv.2021.147381DOI Listing
September 2021

Anammox bacteria in treating ammonium rich wastewater: Recent perspective and appraisal.

Bioresour Technol 2021 Apr 28;334:125240. Epub 2021 Apr 28.

Ecosphere Resilience Research Centre, Faculty of Applied Sciences, University of Sri Jayewardenepura, Nugegoda, Sri Lanka. Electronic address:

The discovery of anammox process has provided eco-friendly and low-cost means of treating ammonia rich wastewater with remarkable efficiency. Furthermore, recent studies have shown that the possibility of operating the anammox process under low temperatures and high organic matter contents broadening the application of the anammox process. However, short doubling time and extensive levels of sensitivity towards nutrients and environmental alterations such as salinity and temperature are the limitations in practical applications of the anammox process. This review article provides the recent yet comprehensive viewpoint on anammox bacteria and the key perspectives in applying them as an efficient strategy for wastewater treatment.
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http://dx.doi.org/10.1016/j.biortech.2021.125240DOI Listing
April 2021

Distribution, behaviour, bioavailability and remediation of poly- and per-fluoroalkyl substances (PFAS) in solid biowastes and biowaste-treated soil.

Environ Int 2021 May 5;155:106600. Epub 2021 May 5.

Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI 48824, USA; Department of Agronomy, Kansas State University, Manhattan, KS 66506, USA.

Aqueous film-forming foam, used in firefighting, and biowastes, including biosolids, animal and poultry manures, and composts, provide a major source of poly- and perfluoroalkyl substances (PFAS) input to soil. Large amounts of biowastes are added to soil as a source of nutrients and carbon. They also are added as soil amendments to improve soil health and crop productivity. Plant uptake of PFAS through soil application of biowastes is a pathway for animal and human exposure to PFAS. The complexity of PFAS mixtures, and their chemical and thermal stability, make remediation of PFAS in both solid and aqueous matrices challenging. Remediation of PFAS in biowastes, as well as soils treated with these biowastes, can be achieved through preventing and decreasing the concentration of PFAS in biowaste sources (i.e., prevention through source control), mobilization of PFAS in contaminated soil and subsequent removal through leaching (i.e., soil washing) and plant uptake (i.e., phytoremediation), sorption of PFAS, thereby decreasing their mobility and bioavailability (i.e., immobilization), and complete removal through thermal and chemical oxidation (i.e., destruction). In this review, the distribution, bioavailability, and remediation of PFAS in soil receiving solid biowastes, which include biosolids, composts, and manure, are presented.
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http://dx.doi.org/10.1016/j.envint.2021.106600DOI Listing
May 2021

Mitigation of petroleum-hydrocarbon-contaminated hazardous soils using organic amendments: A review.

J Hazard Mater 2021 Mar 22;416:125702. Epub 2021 Mar 22.

Global Centre for Environmental Remediation, The University of Newcastle, Callaghan, NSW 2308, Australia. Electronic address:

The term "Total petroleum hydrocarbons" (TPH) is used to describe a complex mixture of petroleum-based hydrocarbons primarily derived from crude oil. Those compounds are considered as persistent organic pollutants in the terrestrial environment. A wide array of organic amendments is increasingly used for the remediation of TPH-contaminated soils. Organic amendments not only supply a source of carbon and nutrients but also add exogenous beneficial microorganisms to enhance the TPH degradation rate, thereby improving the soil health. Two fundamental approaches can be contemplated within the context of remediation of TPH-contaminated soils using organic amendments: (i) enhanced TPH sorption to the exogenous organic matter (immobilization) as it reduces the bioavailability of the contaminants, and (ii) increasing the solubility of the contaminants by supplying desorbing agents (mobilization) for enhancing the subsequent biodegradation. Net immobilization and mobilization of TPH have both been observed following the application of organic amendments to contaminated soils. This review examines the mechanisms for the enhanced remediation of TPH-contaminated soils by organic amendments and discusses the influencing factors in relation to sequestration, bioavailability, and subsequent biodegradation of TPH in soils. The uncertainty of mechanisms for various organic amendments in TPH remediation processes remains a critical area of future research.
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http://dx.doi.org/10.1016/j.jhazmat.2021.125702DOI Listing
March 2021

Ethylbenzene and toluene interactions with biochar from municipal solid waste in single and dual systems.

Environ Res 2021 Jun 30;197:111102. Epub 2021 Mar 30.

Environmental Chemodynamics Research Group, National Institute of Fundamental Studies, Kandy, 20000, Sri Lanka; Ecosphere Resilience Research Centre, Faculty of Applied Sciences, University of Sri Jayewardenepura, Nugegoda, 10250, Sri Lanka. Electronic address:

The present study investigated adsorptive removal of toluene and ethylbenzene from the aqueous media via using biochar derived from municipal solid waste (termed "MSW-BC") in a single and binary contaminant system at 25-45 °C. The adsorption was evaluated at different pH (3-10), experimental time (up to 24 h), and initial adsorbate concentrations (10-600 μg/L) in single and binary contaminant system. A fixed-bed column experiment was also conducted using MSW-BC (0.25%) and influent concentration of toluene and ethylbenzene (4 mg/L) at 2 mL/min of flow rate. The adsorption of toluene and ethylbenzene on the MSW-BC was mildly dependent on the pH, and the peak adsorption ability (44-47 μg/g) was recorded at a baseline pH of ~8 in mono and dual contaminant system. Langmuir and Hill are the models that match the isotherm results in a single contaminant environment for both toluene (R of 0.97 and 0.99, respectively) and ethylbenzene (R of 0.99 and 0.99, respectively) adsorption. In the binary system, the isotherm models matched in the order of Langmuir > Hill > Freundlich for toluene, whereas Hill > Freundlich > Langmuir for ethylbenzene. The adsorption in the batch experiment was likely to take place via cooperative and multilayer adsorption onto MSW-BC involving hydrophobic, π- π and n- π attractions, specific interaction such as hydrogen-π and cation-π interactions, and van der Waals interactions. The thermodynamic results indicate exothermic adsorption occurred by physical attractions between toluene and ethylbenzene, and MSW-BC. The breakthrough behavior of toluene and ethylbenzene was successfully described with Yoon-Nelson and Thomas models. The data demonstrate that the low-cost adsorbent derived from the municipal solid waste can be utilized to remove toluene and ethylbenzene in landfill leachate.
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http://dx.doi.org/10.1016/j.envres.2021.111102DOI Listing
June 2021

Carbon-based adsorbents for fluoroquinolone removal from water and wastewater: A critical review.

Environ Res 2021 Jun 29;197:111091. Epub 2021 Mar 29.

Korea Biochar Research Center, APRU Sustainable Waste Management Program & Division of Environmental Science and Ecological Engineering, Korea University, Seoul, South Korea. Electronic address:

This review summarizes the adsorptive removal of Fluoroquinolones (FQ) from water and wastewater. The influence of different physicochemical parameters on the adsorptive removal of FQ-based compounds is detailed. Further, the mechanisms involved in the adsorption of FQ-based antibiotics on various adsorbents are succinctly described. As the first of its kind, this paper emphasizes the performance of each adsorbent for FQ-type antibiotic removal based on partition coefficients of the adsorbents that is a more sensitive parameter than adsorption capacity for comparing the performances of adsorbents under various adsorbate concentrations and heterogeneous environmental conditions. It was found that π-π electron donor-acceptor interactions, electrostatic interactions, and pore-filling were the most prominent mechanisms for FQ adsorption by carbon and clay-based adsorbents. Among all the categories of adsorbents reviewed, graphene showed the highest performance for the removal of FQ antibiotics from water and wastewater. Based on the current state of knowledge, this review fills the gap through methodolically understanding the mechanism for further improvement of FQ antibiotics adsorption performance from water and wastewater.
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http://dx.doi.org/10.1016/j.envres.2021.111091DOI Listing
June 2021

Weathering of microplastics and interaction with other coexisting constituents in terrestrial and aquatic environments.

Water Res 2021 May 5;196:117011. Epub 2021 Mar 5.

Department of Agronomy, Throckmorton Plant Sciences Center, Kansas State University, Manhattan, Kansas 66506, United States.

Weathering of microplastics (MPs, < 5 mm) in terrestrial and aquatic environments affects MP transport and distribution. This paper first summarizes the sources of MPs, including refuse in landfills, biowastes, plastic films, and wastewater discharge. Once MPs enter water and soil, they undergo different weathering processes. MPs can be converted into small molecules (e.g., oligomers and monomers), and may be completely mineralized under the action of free radicals or microorganisms. The rate and extent of weathering of MPs depend on their physicochemical properties and environmental conditions of the media to which they are exposed. In general, water dissipates heat better, and has a lower temperature, than land; thus, the weathering rate of MPs in the aquatic environment is slower than in the terrestrial environment. These weathering processes increase oxygen-containing functional groups and the specific surface area of MPs, which influence the sorption and aggregation that occur between weathered MPs and their co-existing constituents. More studies are needed to investigate the various weathering processes of diverse MPs under natural field conditions in soils, sediments, and aquatic environments, to understand the impact of weathered MPs in the environment.
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http://dx.doi.org/10.1016/j.watres.2021.117011DOI Listing
May 2021

Functionalizing non-smectic clay via methoxy-modification for enhanced removal and recovery of oxytetracycline from aqueous media.

Chemosphere 2021 Aug 4;276:130079. Epub 2021 Mar 4.

Ecosphere Resilience Research Centre, Faculty of Applied Sciences, University of Sri Jayewardenepura, Sri Lanka. Electronic address:

Kaolinite and methoxy-modified kaolinite were used as novel adsorbents for oxytetracycline (OTC) removal and recovery from aqueous media. Batch adsorption experiments were performed to study the effect of pH, ionic strengths, initial concentration, and contact time on OTC adsorption. The adsorbents were characterized using powder X-ray diffraction (PXRD), Fourier-transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) before and after adsorption. Adsorption of OTC reached its maximum when solution pH increased up to 6 for 0.001 M ionic strength, above which adsorption decreased further when solution pH increased. Freundlich and Langmuir's models best fit the equilibrium data with a strong dependency on OTC adsorption capacity giving its maximum at 36 mg g. Binding is postulated for OTC adsorption on pristine kaolinite as a special case of Hill model with independent binding interaction of OTC adsorption onto the clay that affects the adjacent sites on the pristine kaolinite, in contrast with the adsorption of OTC on methoxy-modified kaolinite. Nitrogen peaks of the XPS spectra indicated changes in the oxidation states of C-N bonds in the N1s peaks by forming tertiary amide C-N and methoxy O-CH bonds which corroborated with the results from FTIR spectra. Removal efficiencies and spectroscopic results indicate that performance on methoxy-modified kaolinite is a promising modification on the clay for recovering antibiotics from wastewater.
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http://dx.doi.org/10.1016/j.chemosphere.2021.130079DOI Listing
August 2021

Carbon sequestration value of biosolids applied to soil: A global meta-analysis.

J Environ Manage 2021 Apr 30;284:112008. Epub 2021 Jan 30.

Department of Agronomy, Throckmorton Plant Sciences Center, Kansas State University, Manhattan, KS, 66506-5501, United States.

Biosolids produced at wastewater treatment facilities are extensively used in agricultural land and degraded mine sites to improve soil health and soil organic carbon (SOC) stocks. Many studies have reported increases in SOC due to application of biosolids to such sites. However, lack of a comprehensive quantification on overall trends and changes of magnitude in SOC remains. Here, we performed a meta-analysis to identify drivers with a relationship with SOC stocks. A meta-regression of 297 treatments found four variables with a relationship with SOC stocks: cumulative biosolids carbon (C) input rate, time after application, soil depth and type of biosolids. The cumulative biosolids C input rate was the most influencing driver. The highest mean difference for SOC% of 3.3 was observed at 0-15 cm soil depth for a cumulative C input of 100 Mg ha at one year after biosolids application. Although years after biosolids application demonstrated a negative relationship with SOC stocks, mineralization of C in biosolids-applied soils is slow, as indicated with the SOC% decrease from 4.6 to 2.8 at 0-15 cm soil depth over five years of 100 Mg ha biosolids C input. Soil depth illustrated a strong negative effect with SOC stocks decreasing by 2.7% at 0-15 cm soil depth at a cumulative biosolids C input of 100 Mg ha over a year. Overall, our model estimated an effect of 2.8 SOC% change, indicating the application of biosolids as a viable strategy for soil C sequestration on a global scale.
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http://dx.doi.org/10.1016/j.jenvman.2021.112008DOI Listing
April 2021

Computational and experimental assessment of pH and specific ions on the solute solvent interactions of clay-biochar composites towards tetracycline adsorption: Implications on wastewater treatment.

J Environ Manage 2021 Apr 27;283:111989. Epub 2021 Jan 27.

Ecosphere Resilience Research Centre, Faculty of Applied Sciences, University of Sri Jayewardenepura, Nugegoda, Sri Lanka; Instrument Center, Faculty of Applied Sciences, University of Sri Jayewardenepura, Nugegoda 10250, Sri Lanka. Electronic address:

Experimental and computational investigations have been conducted in this study to assess the influence of municipal waste pyrolyzed biochar impregnated clay composites on antibiotic removal as a material for wastewater treatment and simultaneous value-addition for waste. The surface potential (zeta potential) of the pristine biochar and composite samples are found to be within the range ~10 to ~ -40 mV in the pH range 2-10. The presence of different inorganic salt solutions influences the electrophoretic mobility of the dispersed phase in a suspension, as well as its zeta potential. In addition of Na salt solutions, the Na ions undergo electrostatic interaction with the negatively charged biochar samples and form a double layer at the interface of biochar and ionic salt solution. Molecular dynamics simulations have been employed to understand experimental findings, ions adsorption and solute-solvent interactions at the molecular level of two biochar B7 (seven benzene rings, one methoxy, one aldehyde and two hydroxyls groups) and B17 (seventeen benzene rings, one methoxy, two hydroxyls and two carboxylic acid groups) in salts aqueous solutions. The results confirm that hydroxyls and carboxylate groups of biochar are responsible for solute-solvent interactions. Successful removal of tetracycline antibiotics is observed with 26 mg/g maximum adsorption capacity with montmorillonite biochar composite. This study confirms that interactions between amide and hydroxyl groups of tetracycline with hydroxyl and carboxylate groups of biochar play the key role in the adsorption process. The solution pH and presence of different background electrolytes effectively influence the process of solute-solvent interactions as well as adsorption efficacy towards tetracycline adsorption.
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http://dx.doi.org/10.1016/j.jenvman.2021.111989DOI Listing
April 2021

Interactions between microplastics, pharmaceuticals and personal care products: Implications for vector transport.

Environ Int 2021 04 23;149:106367. Epub 2021 Jan 23.

Korea Biochar Research Center, APRU Sustainable Waste Management Program & Division of Environmental Science and Ecological Engineering, Korea University, Seoul 02841, South Korea. Electronic address:

Microplastics are well known for vector transport of hydrophobic organic contaminants, and there are growing concerns regarding their potential adverse effects on ecosystems and human health. However, recent studies focussing on hydrophilic compounds, such as pharmaceuticals and personal care products (PPCPs), have shown that the compounds ability to be adsorbed onto plastic surfaces. The extensive use of PPCPs has led to their ubiquitous presence in the environment resulting in their cooccurrence with microplastics. The partitioning between plastics and PPCPs and their fate through vector transport are determined by various physicochemical characteristics and environmental conditions of specific matrices. Although the sorption capacities of microplastics for different PPCP compounds have been investigated extensively, these findings have not yet been synthesized and analyzed critically. The specific objectives of this review were to synthesize and critically assess the various factors that affect the adsorption of hydrophilic compounds such as PPCPs on microplastic surfaces and their fate and transport in the environment. The review also focuses on environmental factors such as pH, salinity, and dissolved organics, and properties of polymers and PPCP compounds, and the relationships with sorption dynamics and mechanisms. Furthermore, the ecotoxicological effects of PPCP-sorbed microplastics on biota and human health are also discussed.
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http://dx.doi.org/10.1016/j.envint.2020.106367DOI Listing
April 2021

Efficacy of agricultural waste derived biochar for arsenic removal: Tackling water quality in the Indo-Gangetic plain.

J Environ Manage 2021 Mar 2;281:111814. Epub 2021 Jan 2.

Discipline of Earth Sciences, Indian Institute of Technology Gandhinagar, Gujarat, 382355, India. Electronic address:

Arsenic (As), a geogenic and extremely toxic metalloid can jeopardize terrestrial and aquatic ecosystems through environmental partitioning in natural soil-water compartment, geothermal and marine environments. Although, many researchers have investigated the decontamination potential of different mesoporous engineered bio sorbents for a suite of contaminants, still the removal efficiency of various pyrolyzed agricultural residues needs special attention. In the present study, rice straw derived biochar (RSBC) produced from slow pyrolysis process at 600 °C was used to remove As (V) from aqueous medium. Batch experiments were conducted at room temperature (25 ± 2 °C) under different initial concentrations (10, 30, 50, 100 μg L), adsorbent dosages (0.5-5 μg L), pH (4.0-10.0) and contact times (0-180 min). The adsorption equilibrium was established in 120 min. Adsorption process mainly followed pseudo-second order kinetics (R ≥ 0.96) and Langmuir isotherm models (R ≥ 0.99), and the monolayer sorption capacity of 25.6 μg g for As (V) on RSBC was achieved. Among the different adsorbent dosages and initial concentrations used in the present study, 0.2 g L (14.8 μg g) and 100 μg L (13.1 μg g) were selected as an optimum parameters. A comparative analysis of RSBC with other pyrolyzed waste materials revealed that RSBC had comparable adsorption ability (per unit area). These acidic groups are responsible for the electron exchange (electrostatic attraction, ion-exchange, π-π/n-πinteractions) with the anionic arsenate, which facilitates optimum removal (>60%) at 7 < pH < pH. The future areas of research will focus on decontamination of real wastewater samples containing mixtures of different emerging contaminants and installation of biofilter beds that contains different spent adsorbents/organic substrates (including biochar) for biopurification study in real case scenario.
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http://dx.doi.org/10.1016/j.jenvman.2020.111814DOI Listing
March 2021

Immobilization and retention of caffeine in soil amended with Ulva reticulata biochar.

J Environ Manage 2021 Mar 1;281:111852. Epub 2021 Jan 1.

Ecosphere Resilience Research Center, Faculty of Applied Sciences, University of Sri Jayewardenepura, Nugegoda, 10250, Sri Lanka. Electronic address:

The goal of the present study was to evaluate the immobilization and retention of caffeine (CFN) in soil and the influence of biochar for the CFN transport in agricultural soil. The biochar was produced from the Ulva reticulata seaweed biomass (ULBC) under the slow-pyrolysis with a heating rate of 7 °C/min at 500 °C and characterized using XRD and FTIR. The CFN retention and transport abilities in loamy sand and ULBC amended (2.5%) soil were evaluated under various pH values range of 3-10 and at various CFN concentrations using batch and column experiments. The surface orientation of ULBC was portrayed as the randomized distribution of hetero and homogeneous nature. The highest retention capacity (40 μg/g) was obtained at pH 4.0. Soil amendment with ULBC shows a higher retention affinity towards CFN, of up to 150 μg/g than soil, with minimal pH dependence. The maximum CFN adsorption capacities of soil and amended soils were 420 and 820 μg/g, respectively, based on the Langmuir model. Batch experiments suggested the adsorption of CFN by the biochar amended loamy soil is governed by the electrostatic attraction. The column experiment data demonstrated a high transport potential of CFN in the loamy sand; however, a strong cumulative reduction of transport (58%) was observed with the application of ULBC into the loamy sand. Thus, the addition of seaweed biochar as an amendment in soils with biosolids and wastewater irrigation may reduce the mobilization of CFN to the aquatic system and possibly reduce plant uptake.
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http://dx.doi.org/10.1016/j.jenvman.2020.111852DOI Listing
March 2021

Macro, colloidal and nanobiochar for oxytetracycline removal in synthetic hydrolyzed human urine.

Environ Pollut 2020 Dec 18;267:115683. Epub 2020 Sep 18.

Ecosphere Resilience Research Center, Faculty of Applied Sciences, University of Sri Jayewardenepura, Nugegoda, Sri Lanka. Electronic address:

Macro (BC), colloidal (CBC) and nanobiochar (NBC) were examined for the particle size effect for adsorptive removal of oxytetracycline (OTC) and co-occurring nutrients, which are present in synthetic hydrolyzed human urine. The surface morphologies and functionality of biochars were characterized using Scanning Electron Microscopy (SEM), Brunauer-Emmett-Teller (BET) specific surface area and Fourier Transform Infra-Red (FTIR) Spectroscopy. Experiments for the removal of OTC were performed at the natural pH (pH 9.0) of hydrolyzed human urine using solid-solutions of 3 types of chars (1 g/L) with a contact time of 5 h, at initial OTC concentration of 50 mg/L where isotherm experiments were investigated with OTC concentrations from 25 to 1000 mg/L. The highest maximum adsorption capacity of 136.7 mg/g was reported for CBC, while BC reported slightly low value (129.34 mg/g). Interestingly, NBC demonstrated a two-step adsorption process with two adsorption capacities (16.9 and 113.2 mg/g). Colloidal biochar depicted the highest adsorption for NH, PO, and SO nutrients. All 3 types of chars showed strong retention with a poor desorption (6% in average) of OTC in synthetic hydrolyzed urine medium. CBC and NBC demonstrated both physisorption and chemisorption, whereas the OTC removal by BC was solely via physisorption. Nevertheless, CBC biochar demonstrated the best performance in adsorptive removal of OTC and nutrients in hydrolyzed human urine and its capability towards wastewater treatment. As the removal of nutrients were low, the treated urine can possibly be used as a safe fertilizer.
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http://dx.doi.org/10.1016/j.envpol.2020.115683DOI Listing
December 2020

Anammox, biochar column and subsurface constructed wetland as an integrated system for treating municipal solid waste derived landfill leachate from an open dumpsite.

Environ Res 2020 10 13;189:109880. Epub 2020 Jul 13.

Ecosphere Resilience Research Center, Faculty of Applied Sciences, University of Sri Jayewardenepura, Nugegoda, Sri Lanka. Electronic address:

This study aims to treat nitrogen-rich landfill leachate from Karadiyana open dumpsite, Sri Lanka, through an integrated treatment train consists of an anammox process, Municipal Solid Waste derived biochar column followed by a biochar embedded subsurface constructed wetland. Characterization of leachate was done and the leachate pollution index (LPI) was estimated. Meanwhile, leachate was treated through a treatment system comprising an anammox reactor having 140 mm diameter and 250 mm height, a biochar reactor having the same dimensions with 1.3 kg of MSW biochar, and a laboratory-scale constructed wetland of 1 × 0.3 × 0.45 m. The influent and effluent quality was assessed for the samples taken in 24 h intervals. The analysis indicated that the leachate was high in COD (4000-14,000 mg/L), ammonia (760-900 mg/L), nitrate (60-126 mg/L), and phosphorus (33-66 mg/L). Ammonia and nitrite were removed 94 and 99% by anammox unit, respectively. Nitrate, phosphate, COD and conductivity were significantly removed by the constructed wetland system in 78, 70, 65 and 61%, respectively, whereas biochar barricades extended support for removal of the contaminants and color. The combined treatment system demonstrated treatment efficiencies as 100% of ammonia, 98.7% of nitrite, 98.2% of nitrate, 80.9% of phosphate, 79.7% of COD, and 69.9% of conductivity. Thus, it can be concluded that the anammox, combined with biochar embedded treatment train is promising to treat landfill leachate, having a high pollutant index.
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http://dx.doi.org/10.1016/j.envres.2020.109880DOI Listing
October 2020

Making Waves Perspectives of Modelling and Monitoring of SARS-CoV-2 in Aquatic Environment for COVID-19 Pandemic.

Curr Pollut Rep 2020 Sep 12:1-12. Epub 2020 Sep 12.

Department of Environmental and Civil Engineering, Toyama Prefectural University, Imizu, 9390398 Japan.

Prevalence of SARS-CoV-2 in the aquatic environment pertaining to the COVID-19 pandemic has been a global concern. Though SARS-CoV-2 is known as a respiratory virus, its detection in faecal matter and wastewater demonstrates its enteric involvement resulting in vulnerable aquatic environment. Here, we provide the latest updates on wastewater-based epidemiology, which is gaining interest in the current situation as a unique tool of surveillance and monitoring of the disease. Transport pathways with its migration through wastewater to surface and subsurface waters, probability of infectivity and ways of inactivation of SARS-CoV-2 are discussed in detail. Epidemiological models, especially compartmental projections, have been explained with an emphasis on its limitation and the assumptions on which the future predictions of disease propagation are based. Besides, this review covers various predictive models to track and project disease spread in the future and gives an insight into the probability of a future outbreak of the disease.
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http://dx.doi.org/10.1007/s40726-020-00161-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7486595PMC
September 2020

Biochar based sorptive remediation of steroidal estrogen contaminated aqueous systems: A critical review.

Environ Res 2020 12 11;191:110183. Epub 2020 Sep 11.

Ecosphere Resilience Research Center, Faculty of Applied Sciences, University of Sri Jayewardenepura, Nugegoda, CO 10250, Sri Lanka. Electronic address:

Remediation of steroidal estrogens from aqueous ecosystems is of prevailing concern due to their potential impact on organisms even at trace concentrations. Biochar (BC) is capable of estrogen removal due to its rich porosity and surface functionality. The presented review emphasizes on the adsorption mechanisms, isotherms, kinetics, ionic strength and the effect of matrix components associated with the removal of steroidal estrogens. The dominant sorption mechanisms reported for estrogen were π-π electron donor-acceptor interactions and hydrogen bonding. Natural organic matter and ionic species were seen to influence the hydrophobicity of the estrogen in multiple ways. Zinc activation and magnetization of the BC increased the surface area and surface functionalities leading to high adsorption capacities. The contribution by persistent free radicals and the arene network of BC have promoted the catalytic degradation of adsorbates via electron transfer mechanisms. The presence of surface functional groups and the redox activity of BC facilitates the bacterial degradation of estrogens. The sorptive removal of estrogens from aqueous systems has been minimally reviewed as a part of a collective evaluation of micropollutants. However, to the best of our knowledge, a critique focusing specifically and comprehensively on BC-based removal of steroidal estrogens does not exist. The presented review is a critical assessment of the existing literature on BC based steroidal estrogen adsorption and attempts to converge the scattered knowledge regarding its mechanistic interpretations. Sorption studies using natural water matrices containing residue level concentrations, and dynamic sorption experiments can be identified as future research directions.
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http://dx.doi.org/10.1016/j.envres.2020.110183DOI Listing
December 2020

Microbe mediated immobilization of arsenic in the rice rhizosphere after incorporation of silica impregnated biochar composites.

J Hazard Mater 2020 Nov 4;398:123096. Epub 2020 Jun 4.

Office of the Dean, Faculty of Applied Sciences, Jayewardenepura, Nugegoda, Sri Lanka.

This study mechanistically addressed for the first time, the contradiction between the application of many biochars to paddy soil and increased arsenic (As) release as employed by most of previous studies. Three types of biochar containing natural and chemical forms of Si: (i) unmodified rice husk biochar (RHBC), (ii) RHBC modified with Si fertilizer (Si-RHBC), and (iii) RHBC modified with nanoparticles of montmorillonite clay (NM-RHBC) were applied in As-contaminated paddy soil to examine their potential to control the mobility of As in the soil-microbe-rice system. Both Si-RHBC and NM-RHBC decreased As concentration in porewater by 40-65 %, while RHBC decreased by 30-44 % compared to biochar unamended soil from tillering to maturing stage. At tillering stage, RHBC, Si-RHBC and NM-RHBC amendments significantly decreased As(III) concentration in the rice rhizosphere by 57, 76 and 73 %, respectively compared to the control soil. The immobilization of As is due to: (i) lowering of microbe mediated As release from iron minerals, (ii) oxidation of As(III) to As(V) by aioA gene, and (iii) adsorption on a Si-ferrihydrite complex. The decrease of more toxic As(III) and its oxidation to less mobile As(V) by Si-rich biochar amendments is a promising As detoxification phenomenon in the rice rhizosphere.
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http://dx.doi.org/10.1016/j.jhazmat.2020.123096DOI Listing
November 2020

Caffeine removal by Gliricidia sepium biochar: Influence of pyrolysis temperature and physicochemical properties.

Environ Res 2020 10 5;189:109865. Epub 2020 Jul 5.

Ecosphere Resilience Research Center, Faculty of Applied Sciences, University of Sri Jayewardenepura, Nugegoda, 10250, Sri Lanka. Electronic address:

The present study aimed to envisage the effect of physicochemical properties on the performance of Gliricidia sepium biochar (GBC) pyrolyzed at 300, 500, and 700 °C in the removal caffeine (CFN); a pharmaceutical and personal care product, from water. The physicochemical properties of GBC were characterized by proximate and ultimate analysis, BET, SEM, FTIR, and Raman spectroscopy. The adsorption batch experiment was carried out at various pH values (pH 3-10), mixing times (up to 24 h), and initial CFN concentration (10-500 mg/L). The FTIR analysis revealed the loss of polar functional groups on the surface of GBC derived at high temperatures. The red-shifted and blue-shifted Raman peaks indicate the condensation of small molecules on GBC. The GBC derived at 700 °C demonstrated high CFN adsorption capacity (16.26 mg/g) due to its high surface area and aromaticity. The highest adsorption of CFN was occurred at acidic pH range from 3.5 to 4.5 due to the existence of non-specific attraction between CFN and GBC. The kinetics and isotherm experimental data were fitted with Elovich and fractional power kinetic regression, Freundlich, and Temkin isotherm models, which suggested the adsorption of CFN on the GBC by mixed mechanisms; physisorption and chemisorption including π-π interactions, hydrogen bonding, n-π interactions, electrostatic attraction, and electron donor-acceptor attraction. Moreover, both surface area and aromaticity index have demonstrated a high positive correlation for CFN adsorption, signifying the importance of controlling physicochemical properties based on the end-user purpose of biochar.
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http://dx.doi.org/10.1016/j.envres.2020.109865DOI Listing
October 2020

Implications of layered double hydroxides assembled biochar composite in adsorptive removal of contaminants: Current status and future perspectives.

Sci Total Environ 2020 Oct 28;737:139718. Epub 2020 May 28.

Department of Environmental and Biological Sciences, University of Eastern Finland, P. O. Box 1627, FI-70211 Kuopio, Finland. Electronic address:

In recent years, biochar composites have received considerable attention for environmental applications. This paper reviews the current state of research on Layered Double Hydroxides (LDHs) tailored biochar composites in terms of their synthesis methods, characteristics, and their use as adsorbents for the removal of various pollutants from water, highlighting and discussing the key advancement in this area. The adsorption potential of LDHs-biochar composites for different inorganic and organic contaminants, important factors affecting composites' properties and the adsorption process, and the mechanisms involved in adsorption are discussed in this review. Though the adsorption capacities are high for the composites studied, partition coefficient which suggest the performance of composites remain low for most adsorbents. Despite the recent progress in the synthesis of LDHs-biochar composites, further research is needed to improve the performance of composites for different classes of aquatic pollutants, and to test their applicability in pilot-scale with real wastewater under real environmental conditions.
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http://dx.doi.org/10.1016/j.scitotenv.2020.139718DOI Listing
October 2020

Green synthesis of graphitic nanobiochar for the removal of emerging contaminants in aqueous media.

Sci Total Environ 2020 Mar 28;706:135725. Epub 2019 Nov 28.

Ecosphere Resilience Research Center, Faculty of Applied Sciences, University of Sri Jayewardenepura, Nugegoda, Sri Lanka. Electronic address:

This study reports the preparation of nanobiochar (NBC) via top-down approach of bioenergy waste-derived dendro biochar through mechanised grinding in order to assess its capacity to remove emerging contaminants, such as antibiotics, agrochemicals, and potentially toxic elements from aqueous media. Preconditioned biochar was disc milled in ethanol media, and the resulting colloidal biochar was dispersed in water to obtain the NBC fraction by centrifugation. Adsorption edge and isotherm experiments were carried out at pH 3 to 8 and NBC dosages of 0.5 g/L for oxytetracycline (OTC), glyphosate (GL), hexavalent chromium (CrVI), and cadmium (CdII). NBC was characterised by scanning electron microscopy, X-ray photoelectron spectroscopy, Brunauer-Emmett-Teller surface area, and Fourier transform infrared spectroscopy, which demonstrated the flakey and graphitic nature of the NBC particles with a surface area of 28 m/g and the presence of different functional groups, such as OH, CO, NH, and CH. The best pH for OTC and Cd(II) was 9, whereas the best pH levels for GL and Cr(VI) were 7 and 4, respectively. Isotherms depicted a positive cooperative adsorption mechanism by providing the best fit to the Hills equation, with high removal capacities for four contaminants. Dendro NBC showed the best performance, demonstrated by the high partition coefficient for the removal of OTC, GL, Cr(VI), and Cd(II) over various types of adsorbents. The overall results indicated that graphitic NBC produced by mechanical grinding of dendro biochar is a promising material for the removal of OTC, GL, Cr(VI), and Cd(II) from aqueous media.
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http://dx.doi.org/10.1016/j.scitotenv.2019.135725DOI Listing
March 2020

Halloysite nanoclay supported adsorptive removal of oxytetracycline antibiotic from aqueous media.

J Hazard Mater 2020 02 26;384:121301. Epub 2019 Sep 26.

Ecosphere Resilience Research Center, Faculty of Applied Sciences, University of Sri Jayewardenepura, Nugegoda, Sri Lanka. Electronic address:

Halloysite nanoclay was utilized to retain aqueous oxytetracycline (OTC) which is extensively used in the veterinary industry. The micro-structure and functionality of the nanoclay were characterized through spectroscopic techniques before and after adsorption. The OTC removal experiments were performed at different pH conditions (pH 3.0-9.0), ionic strengths (0.001, 0.01, 0.1 M NaNO) and contact time (up to 32 h) at an initial 25 mg/L OTC concentration with 1.0 g/L halloysite. Oxytetracycline adsorption was pH dependent, and the best pH was observed in the range of pH 3.5-5.5 at a 0.001 M ionic strength. At pH 3.5, the maximum OTC adsorption amount was 21 mg/g which translated to 68% removal of the initial OTC loading. Positively charged inner lumen and negatively charged outer lumen of the tubular halloysite structure led to form inner-sphere complexes with the anionic and cationic forms of OTC, respectively. A rapid adsorption of OTC was observed in the kinetic study where 62% OTC was adsorbed in 90 min.. Pseudo-second order equation obeyed by the kinetic data indicated that the adsorption was governed by chemisorption, whereas Hill isotherm equation was the most fitted with a maximum adsorption capacity of 52.4 mg/g indicating a cooperative adsorption phenomenon.
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http://dx.doi.org/10.1016/j.jhazmat.2019.121301DOI Listing
February 2020

Floating duckweed mitigated ammonia volatilization and increased grain yield and nitrogen use efficiency of rice in biochar amended paddy soils.

Chemosphere 2019 Dec 8;237:124532. Epub 2019 Aug 8.

School of Environmental and Resource Sciences, Zhejiang A&F University, Hangzhou, Zhejiang, 311300, China; School of Environment and Chemical Engineering, Foshan University, Foshan, 528000, Guangdong, China. Electronic address:

Biochar (BC) potentially accelerates ammonia (NH) volatilization from rice paddy soils. In this regard, however, application the floating duckweed (FDW) to biochar-amended soil to control the NH volatilization is not studied up-to-date. Therefore, the impacts of BC application with and without FDW on the NH and nitrous oxide (NO) emissions, NUE and rice grain yield were evaluated in a soil columns experiment. We repacked soil columns with Hydragric Anthrosol and Haplic Acrisol treated in triplicates with Urea, Urea + BC and Urea + BC + FDW. Total NH losses from Hydragric Anthrosol and Haplic Acrisol were 15.2-33.2 kg N ha and 19.6-39.7 kg N ha, respectively. Urea + BC treatment recorded 25.6-43.7% higher (p < 0.05) NH losses than Urea treatment, attributing to higher pH value of floodwater. Floating duckweed decreased soil pH and therefore significantly reduced (p < 0.05) the NH volatilizations from the two soils by 50.6-54.2% over Urea + BC and by 34.2-38.0% over Urea treatment. Total NO emissions from Hydragric Anthrosol and Haplic Acrisol were 1.19-3.42 kg N ha and 0.67-2.08 kg N ha, respectively. Urea + BC treatment increased NO emissions by 58.8-68.7% and Urea + BC + FDW treatment further increased NO emission by 187.4-210.4% over Urea treatment. Higher ammonium content of the topsoil, explained the NO increases in the Urea + BC and Urea + BC + FDW treatments. Urea + BC slightly reduced the rice grain yield and NUE, while the Urea + BC + FDW promoted both rice yield and NUE. Our data indicate that co-application of FDW along with BC in paddy soil could mitigate the NH volatilization and enhance the rice grain yield and NUE.
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http://dx.doi.org/10.1016/j.chemosphere.2019.124532DOI Listing
December 2019

Sorption process of municipal solid waste biochar-montmorillonite composite for ciprofloxacin removal in aqueous media.

Chemosphere 2019 Dec 16;236:124384. Epub 2019 Jul 16.

Ecosphere Resilience Research Centre, Faculty of Applied Science, University of Sri Jayewardenepura, Sri Lanka; Molecular Microbiology and Human Diseases, National Institute of Fundamental Studies, Kandy 20000, Sri Lanka. Electronic address:

This study evaluates a novel adsorbent for ciprofloxacin (CPX) removal from water using a composite derived from municipal solid waste biochar (MSW-BC) and montmorillonite (MMT). The composite adsorbent and pristine materials were characterized using powder X-Ray Diffraction (PXRD), Fourier-Transform Infrared (FTIR) spectroscopy, and Scanning Electron Microscope (SEM) before and after the adsorption. Batch experiments were conducted to study the mechanisms involved in the adsorption process. Ciprofloxacin sorption mechanisms were interpreted in terms of its pH-dependency and the distribution coefficients. The SEM images confirmed the successful binding of MMT onto the MSW-BC through flaky structure along with a porous morphology. Encapsulation of MMT onto MSW-BC was exhibited through changes in the basal spacing of MMT via PXRD analysis. Results from FTIR spectra indicated the presence of functional groups for both pristine materials and the composite that were involved in the adsorption reaction. The Hill isotherm model and pseudo-second-order and Elovich kinetic models fitted the batch sorption data, which explained the surface heterogeneity of the composite and cooperative adsorption mechanisms. Changes made to the MSW-BC through the introduction of MMT, enhanced the active sites on the composite adsorbent, thereby improving its interaction with ionizable CPX molecules giving high sorption efficiency.
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http://dx.doi.org/10.1016/j.chemosphere.2019.124384DOI Listing
December 2019

Clay-polymer nanocomposites: Progress and challenges for use in sustainable water treatment.

J Hazard Mater 2020 02 29;383:121125. Epub 2019 Aug 29.

Korea Biochar Research Centre & Division of Environmental Science and Ecological Engineering, Korea University, Seoul, Republic of Korea. Electronic address:

Contaminant removal from water involves various technologies among which adsorption is considered to be simple, effective, economical, and sustainable. In recent years, nanocomposites prepared by combining clay minerals and polymers have emerged as a novel technology for cleaning contaminated water. Here, we provide an overview of various types of clay-polymer nanocomposites focusing on their synthesis processes, characteristics, and possible applications in water treatment. By evaluating various mechanisms and factors involved in the decontamination processes, we demonstrate that the nanocomposites can overcome the limitations of individual polymer and clay components such as poor specificity, pH dependence, particle size sensitivity, and low water wettability. We also discuss different regeneration and wastewater treatment options (e.g., membrane, coagulant, and barrier/columns) using clay-polymer nanocomposites. Finally, we provide an economic analysis of the use of these adsorbents and suggest future research directions.
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http://dx.doi.org/10.1016/j.jhazmat.2019.121125DOI Listing
February 2020

Microwave and open vessel digestion methods for biochar.

Chemosphere 2020 Jan 8;239:124788. Epub 2019 Sep 8.

College of Chemical Sciences, Institute of Chemistry Ceylon, Rajagiriya, CO 10107, Sri Lanka. Electronic address:

Digestion of biomass derived carbonaceous materials such as biochar (BC) can be challenging due to their high chemical recalcitrance and vast variations in composition. Reports on the development of specific sample digestion methods for such materials remain inadequate and thus require considerable attention. Nine different carbonaceous materials; slow-pyrolyzed tea-waste and king coconut BC produced at 300 °C, 500 °C and 700 °C, sludge waste BC produced at 700 °C, wet fast-pyrolyzed Douglas-Fir BC and steam activated coconut shell BC have been tested to evaluate a relatively fast and convenient open-vessel digestion method using seven digestion reagents including nitric acid (NA), fuming nitric acid (FNA), sulfuric acid (SA), NA/SA, FNA/SA, NA/HO and SA/HO mixtures. From the tested digestion reagents, SA/HO mixture dissolved low temperature produced BC (LTBC) within 2 h with occasional shaking and no external heating. Except peroxide mixtures, the other reagents were used to evaluate microwave digestion (MWD) efficiency. Nitric acid mixture was capable of only completely digesting LTBC in the MWD procedure whereas FNA, NA/SA and FNA/SA mixtures resulted in the successful dissolution of all tested carbonaceous materials. Amongst them, FNA provided the least matrix effect in the quantification of the four metals tested using flame atomic absorption spectrophotometry. Tested recoveries for FNA were satisfactory as well. It was concluded that FNA is a preferable reagent for microwave digestion of BC.
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http://dx.doi.org/10.1016/j.chemosphere.2019.124788DOI Listing
January 2020

Hexavalent chromium removal from water by microalgal-based materials: Adsorption, desorption and recovery studies.

Bioresour Technol 2019 Dec 26;293:122064. Epub 2019 Aug 26.

Department of Environmental and Biological Sciences, University of Eastern Finland, P.O. Box 1627, FI-70211 Kuopio, Finland. Electronic address:

The current study presents a comprehensive comparison towards the potential of different microalgal-based materials for the removal of hexavalent chromium (Cr(VI)) from water. Among the tested materials, microalgal biochar showed the highest removal efficiency (100%) of Cr(VI). The highest monolayer estimated adsorption capacities were 23.98, 25.19 and 24.27 mg/g at 5, 22 and 35 °C, respectively. Experimental data showed good compliance with pseudo-second-order kinetic model. The results of continuous column studies showed that the column removal efficiency increased from 52.33 to 57.58% by increasing the adsorbent dose from 0.125 to 0.200 g. Desorption efficiency of Cr(VI) by 0.1 M NaOH was increased from 51.16 to 59.41% by sonication bath as compared to roller shaker. More than 97% of desorbed Cr(VI) was recovered in less than 10 min by BaCl. This study shows that non-living microalga materials are more effective than living cells in the removal and recovery of Cr(VI) from water.
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http://dx.doi.org/10.1016/j.biortech.2019.122064DOI Listing
December 2019

Heavy metal dissolution mechanisms from electrical industrial sludge.

Sci Total Environ 2019 Dec 14;696:133922. Epub 2019 Aug 14.

Korea Biochar Research Center & Division of Environmental Science and Ecological Engineering, Korea University, Seoul 02841, Republic of Korea. Electronic address:

In this paper, we investigate the release of heavy metals from sludge produced from an electrical industry using both organic and inorganic acids. Single and sequential extractions were conducted to assess heavy metals in different phases of the sludge. Metal release from sludge was investigated in the presence of three inorganic acids (nitric, sulfuric, and phosphoric) and three organic acids (acetic, malic, and citric) at concentrations ranging from 0.1 to 2.0 mol L. Sequential extraction indicated the presence of Cu primarily in the carbonate fraction, Pb in the residual fraction, and Ni in the FeMn oxide fraction. The cumulative release rates of heavy metals (i.e., Pb, Cu, and Ni) by 1.0 mol L of acid increased with the use of the following acids in the order of: malic < sulfuric < acetic < phosphoric < citric < nitric. Acetic acid exhibited the highest release of Cu, at a rate of 72.62 × 10 mol m s at pH 1, and malic acid drove the release of Pb at a maximum rate of 3.90 × 10 mol m s. Meanwhile, nitric acid provided the maximum rate of Ni release (0.23 × 10 mol m s) at pH 1. The high rate of metal release by organic acids is explained through ligand-promoted mechanisms that enhance the release of metal ions from the sludge. The results from our study emphasize that an understanding of the metal release mechanism is key to selecting the optimal acid for the maximum recovery of heavy metals.
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http://dx.doi.org/10.1016/j.scitotenv.2019.133922DOI Listing
December 2019

Occurrence and cycling of trace elements in ultramafic soils and their impacts on human health: A critical review.

Environ Int 2019 10 31;131:104974. Epub 2019 Jul 31.

University of Wuppertal, School of Architecture and Civil Engineering, Institute of Foundation Engineering, Water- and Waste-Management, Laboratory of Soil- and Groundwater-Management, Pauluskirchstraße 7, 42285 Wuppertal, Germany; University of Sejong, Department of Environment and Energy, Seoul 05006, Republic of Korea. Electronic address:

The transformation of trace metals (TMs) in natural environmental systems has created significant concerns in recent decades. Ultramafic environments lead to potential risks to the agricultural products and, subsequently, to human health. This unique review presents geochemistry of ultramafic soils, TM fractionation (i.e. sequential and single extraction techniques), TM uptake and accumulation mechanisms of ultramafic flora, and ultramafic-associated health risks to human and agricultural crops. Ultramafic soils contain high levels of TMs (i.e. Cr, Ni, Mn, and Co) and have a low Ca:Mg ratio together with deficiencies in essential macronutrients required for the growth of crops. Even though a higher portion of TMs bind with the residual fraction of ultramafic soils, environmental changes (i.e. natural or anthropogenic) may increase the levels of TMs in the bioavailable or extractable fractions of ultramafic soils. Extremophile plants that have evolved to thrive in ultramafic soils present clear examples of evolutionary adaptations to TM resistance. The release of TMs into water sources and accumulation in food crops in and around ultramafic localities increases health risks for humans. Therefore, more focused investigations need to be implemented to understand the mechanisms related to the mobility and bioavailability of TMs in different ultramafic environments. Research gaps and directions for future studies are also discussed in this review. Lastly, we consider the importance of characterizing terrestrial ultramafic soil and its effect on crop plants in the context of multi-decadal plans by NASA and other space agencies to establish human colonies on Mars.
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http://dx.doi.org/10.1016/j.envint.2019.104974DOI Listing
October 2019