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Dr. Ravi Naidu
Centre for Environmental Risk Assessment and Remediation, University of South Australia, SA5095, Australia

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0 Bioavailability
0 Bioremediation
0 Environmental Impact Assessment
0 Environmental Remediation
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Bioavailability
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Heavy Metals
Environmental Remediation
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Journal article
Published: 20 August 2021 in Journal of Cleaner Production
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Adsorption is a promising technology for removal of organic and inorganic contaminants from soil and water system. In this study, magnetically separable mesoporous polymeric beads (NiZnFe4O4[email protected]) were synthesised for efficient removal of methylene blue (MB, cationic dye) under broad solution pH (from pH 3.41 to pH 8.43). Alginate biopolymer were used to stabilize halloysite nanotubes (HNTs) and nickel zinc iron oxide nanoparticles (NiZnFe4O4 < 100 nm). NiZnFe4O4 was incorporated onto the polymer beads to generate the adsorbents' magnetic properties and catalytic degradability. The adsorbent (NiZnFe4O4[email protected]) have higher surface area (122.43 m2/g), suitable mesoporosity (~6.68 nm), larger pore volume (0.11 cm3/g), and abundance of active sites, enabling high adsorption capacity (264 mg/g) of MB. The abundance of hydroxyl, carboxyl, and siloxane groups enabled cationic dye sorption through ionic interaction. The removal efficiency of MB was ~99% under a wide solution pH range from 10 mg/L of MB, in which the adsorbent dose was 2 g/L. Both Langmuir (R2 = 0.99; p < 0.001) and Freundlich (R2 = 0.99; p < 0.001) isotherm models fitted well, whereas trends of kinetics model fitting are pseudo-second-order (R2 = 0.99) > intraparticle diffusion (R2 = 0.93) > pseudo-first-order (R2 = 0.87). Energy-dispersive X-ray spectroscopy (EDS) elemental mapping demonstrated that MB has a co-distribution with silicon, aluminium, and alginate carbon phase but is limited with iron and nickel, indicating HNTs and alginate polymer performed as sorption sites, whereas NiZnFe4O4 performed as a catalyst. The presence (post-sorption) and absence (pre-sorption) of inorganic, total carbon or total organic carbon content at different solution pH, contact time, and initial concentration of MB demonstrated that the adsorbent act as a catalyst as well for degradation of MB. NiZnFe4O4[email protected] triggers efficient removal of MB with the assist of adsorption and catalytic degradation at broad solution pH. A comparison in removal of MB by various adsorbents including, biochars, clays, activated carbon, nanoparticles, polymers, nano composites, graphene oxides, carbon nanotubes, and polymer beads with the result of this study were performed, illustrating competitive sorption capacity of NiZnFe4O4[email protected]

ACS Style

Masud Hassan; Amal Kanti Deb; Fangjie Qi; Yanju Liu; Jianhua Du; Adam Fahy; Ariful Ahsan; Sanjai J. Parikh; Ravi Naidu. Magnetically separable mesoporous alginate polymer beads assist adequate removal of aqueous methylene blue over broad solution pH. Journal of Cleaner Production 2021, 319, 128694 .

AMA Style

Masud Hassan, Amal Kanti Deb, Fangjie Qi, Yanju Liu, Jianhua Du, Adam Fahy, Ariful Ahsan, Sanjai J. Parikh, Ravi Naidu. Magnetically separable mesoporous alginate polymer beads assist adequate removal of aqueous methylene blue over broad solution pH. Journal of Cleaner Production. 2021; 319 ():128694.

Chicago/Turabian Style

Masud Hassan; Amal Kanti Deb; Fangjie Qi; Yanju Liu; Jianhua Du; Adam Fahy; Ariful Ahsan; Sanjai J. Parikh; Ravi Naidu. 2021. "Magnetically separable mesoporous alginate polymer beads assist adequate removal of aqueous methylene blue over broad solution pH." Journal of Cleaner Production 319, no. : 128694.

Original research article
Published: 17 August 2021 in Frontiers in Environmental Science
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Rice consumption is a major dietary source of Cd and poses a potential threat to human health. The aims of this study were to examine the influence of Fe and Cd application on yield and yield components, dynamics of Cd in pore water, translocation factors, daily dietary intake, and estimation of human health risks. A pot experiment was performed under glasshouse conditions where rice cultivars (Langi and Quest) were cultivated in two dissimilar soils under different levels of Cd (0, 1.0, and 3.0 mg kg−1) and Fe (0, 1.0, and 2.0 g kg−1). The results showed that variation in two rice cultivars in terms of yield and yield-related components was dose dependent. Cadmium concentration in soil pore water was decreased over time and increased with increasing Cd levels but decreased with Fe application. Translocation factors (TFs) from root to straw (TFroot-straw) or straw to husk (TFstraw-husk) were higher than root to grain (TFroot-grain) or straw to grain (TFstraw-grain). The Quest cultivar had 20% lower Cd than the Langi cultivar. Application of Fe at the rate of 1 and 2 g kg−1 soil reduced Cd by 23 and 46%, respectively. Average daily intake (ADI) of Cd exceeded the permissible limit (5.8 × 10−3 mg −1 kg−1 bw per week) when rice plant subjected 1 and 3 mg kg−1 Cd stress with or without Fe application. Results also indicated that ADI value was lower in the Quest cultivar as compared to the Langi cultivar. Estimation of human health risk revealed that the non-carcinogenic risks (HQ > 1) and carcinogenic risks (CR > 1.0 × 10−4) increased with increasing Cd levels in the soil. The application of Fe decreased the human health risks from rice consumption which is more pronounced in Fe 2.0 than in Fe1.0 treatments. The rice cultivar grown in soil-1 (pH 4.6) showed the highest health risks as compared to soil-2 (pH 6.6) and the Quest cultivar had lower health risks than the Langi cultivar.

ACS Style

Abu Bakkar Siddique; Mohammad Mahmudur Rahman; Rafiqul Islam; Debapriya Mondal; Ravi Naidu. Response of Iron and Cadmium on Yield and Yield Components of Rice and Translocation in Grain: Health Risk Estimation. Frontiers in Environmental Science 2021, 9, 1 .

AMA Style

Abu Bakkar Siddique, Mohammad Mahmudur Rahman, Rafiqul Islam, Debapriya Mondal, Ravi Naidu. Response of Iron and Cadmium on Yield and Yield Components of Rice and Translocation in Grain: Health Risk Estimation. Frontiers in Environmental Science. 2021; 9 ():1.

Chicago/Turabian Style

Abu Bakkar Siddique; Mohammad Mahmudur Rahman; Rafiqul Islam; Debapriya Mondal; Ravi Naidu. 2021. "Response of Iron and Cadmium on Yield and Yield Components of Rice and Translocation in Grain: Health Risk Estimation." Frontiers in Environmental Science 9, no. : 1.

Journal article
Published: 19 July 2021 in Scientific Reports
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In this study, the intestinal permeability of metal(loid)s (MLs) such as arsenic (As), cadmium (Cd), lead (Pb) and mercury (Hg) was examined, as influenced by gut microbes and chelating agents using an in vitro gastrointestinal/Caco-2 cell intestinal epithelium model. The results showed that in the presence of gut microbes or chelating agents, there was a significant decrease in the permeability of MLs (As-7.5%, Cd-6.3%, Pb-7.9% and Hg-8.2%) as measured by apparent permeability coefficient value (P app), with differences in ML retention and complexation amongst the chelants and the gut microbes. The decrease in ML permeability varied amongst the MLs. Chelating agents reduce intestinal absorption of MLs by forming complexes thereby making them less permeable. In the case of gut bacteria, the decrease in the intestinal permeability of MLs may be associated to a direct protection of the intestinal barrier against the MLs or indirect intestinal ML sequestration by the gut bacteria through adsorption on bacterial surface. Thus, both gut microbes and chelating agents can be used to decrease the intestinal permeability of MLs, thereby mitigating their toxicity.

ACS Style

Shiv Bolan; Balaji Seshadri; Simon Keely; Anitha Kunhikrishnan; Jessica Bruce; Ian Grainge; Nicholas J. Talley; Ravi Naidu. Bioavailability of arsenic, cadmium, lead and mercury as measured by intestinal permeability. Scientific Reports 2021, 11, 1 .

AMA Style

Shiv Bolan, Balaji Seshadri, Simon Keely, Anitha Kunhikrishnan, Jessica Bruce, Ian Grainge, Nicholas J. Talley, Ravi Naidu. Bioavailability of arsenic, cadmium, lead and mercury as measured by intestinal permeability. Scientific Reports. 2021; 11 (1):1.

Chicago/Turabian Style

Shiv Bolan; Balaji Seshadri; Simon Keely; Anitha Kunhikrishnan; Jessica Bruce; Ian Grainge; Nicholas J. Talley; Ravi Naidu. 2021. "Bioavailability of arsenic, cadmium, lead and mercury as measured by intestinal permeability." Scientific Reports 11, no. 1: 1.

Journal article
Published: 09 July 2021 in Environmental Technology & Innovation
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A Green fluorescent protein (GFP) based whole cell bacterial biosensor was prepared using a bacterial strain sensitive to several heavy metals in order to detect bioavailable heavy metals in soils. The transformant, named as Bacillus megaterium VR1 was immobilized in silica matrix using sol–gel technology, and optimized for its effective pH range, cell density, exposure time, and storage stability. The lowest detection limit (LOD) for each metal was also determined. The pH range for the bacterial strain was found to be between pH 5–8.5. The optimum exposure time for the transformed bacterial strain to respond to the lowest tested concentration of heavy metal at 25% of inhibition compared to the control was determined as 4 h, 4 h, and 7 h, for Cd, Cu and Zn, respectively. SiNa/LUDOX 1/1 was selected as the optimum immobilization matrix. Storage up to 2 weeks did not show any reduction in the fluorescence in all the matrices. The linear range of the whole cell bacterial biosensor was determined as 0-10; 0–20 and 0–100 mg/L for Cd, Cu and Zn respectively. The lowest detection limit was determined as 1.42 × 10−4, 3.16 × 10−4, and 2.42 × 10−4 mg/L for Cd, Cu and Zn, respectively.

ACS Style

I.V.N. Rathnayake; Mallavarapu Megharaj; Ravi Naidu. Green fluorescent protein based whole cell bacterial biosensor for the detection of bioavailable heavy metals in soil environment. Environmental Technology & Innovation 2021, 23, 101785 .

AMA Style

I.V.N. Rathnayake, Mallavarapu Megharaj, Ravi Naidu. Green fluorescent protein based whole cell bacterial biosensor for the detection of bioavailable heavy metals in soil environment. Environmental Technology & Innovation. 2021; 23 ():101785.

Chicago/Turabian Style

I.V.N. Rathnayake; Mallavarapu Megharaj; Ravi Naidu. 2021. "Green fluorescent protein based whole cell bacterial biosensor for the detection of bioavailable heavy metals in soil environment." Environmental Technology & Innovation 23, no. : 101785.

Review article
Published: 06 July 2021 in Science of The Total Environment
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Vapour intrusion (VI) is the phenomenon by which volatile organic compounds (VOCs) migrate from the subsurface source through the soil and enter into the overlying buildings, affecting the indoor air quality and ultimately causing health hazards to the occupants. Health risk assessments associated with hydrocarbon contaminated sites and recommendations of site closure are often made by quantifying the VI risks using mathematical models known as ‘vapour intrusion models’ (VIM). In order to predict the health risk, various factors such as the lithological and geochemical conditions of the subsurface, environmental conditions, building operational conditions etc. are commonly evaluated using VIMs. Use of these models can overlook the role of preferential pathways like highly permeable subsurface layers and utility lines which act as the path of least resistance for vapour transport, which can increase the VI risks. The extensive networks of utility lines and sanitary sewer systems in urban areas can significantly exacerbate the uncertainty of VI investigations. The backfill materials like sand and gravel surrounding the utility lines can allow the vapours to easily pass through due to their high porosity as compared to natural formations. Hence, failure to understand the role of preferential pathways on the fate and transport of VOC in the vadose zone can result in more conservative predictions of indoor air vapour concentrations and wrong clean up approaches. This comprehensive review outlines the vapour transport mechanisms, factors influencing VI, VIMs and the role of preferential pathways in predicting indoor air vapour concentrations.

ACS Style

Aravind Unnithan; Dawit Nega Bekele; Sreenivasulu Chadalavada; Ravi Naidu. Insights into vapour intrusion phenomena: Current outlook and preferential pathway scenario. Science of The Total Environment 2021, 796, 148885 .

AMA Style

Aravind Unnithan, Dawit Nega Bekele, Sreenivasulu Chadalavada, Ravi Naidu. Insights into vapour intrusion phenomena: Current outlook and preferential pathway scenario. Science of The Total Environment. 2021; 796 ():148885.

Chicago/Turabian Style

Aravind Unnithan; Dawit Nega Bekele; Sreenivasulu Chadalavada; Ravi Naidu. 2021. "Insights into vapour intrusion phenomena: Current outlook and preferential pathway scenario." Science of The Total Environment 796, no. : 148885.

Research article
Published: 31 May 2021 in ACS Omega
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Halloysite nanotubes (HNT) and ball-milled biochar (BC) incorporated biocompatible mesoporous adsorbents ([email protected]) were synthesized for adsorption of aqueous heavy-metal ions. [email protected] outperformed the BC, HNT, and [email protected] in removing cadmium (Cd), copper (Cu), nickel (Ni), and lead (Pb). Mesoporous structure (∼7.19 to 7.56 nm) of [email protected] was developed containing an abundance of functional groups induced from encapsulated BC and tubular HNT, which allowed heavy metals to infiltrate and interact with the adsorbents. Siloxane groups from HNT, oxygen-containing functional groups from BC, and hydroxyl and carboxyl groups from alginate polymer play a significant role in the adsorption of heavy-metal ions. The removal percentage of heavy metals was recorded as Pb (∼99.97 to 99.05%) > Cu (∼95.01 to 90.53%) > Cd (∼92.5 to 55.25%) > Ni (∼80.85 to 50.6%), even in the presence of 0.01/0.001 M of CaCl2 and Na2SO4 as background electrolytes and charged organic molecule under an environmentally relevant concentration (200 μg/L). The maximum adsorption capacities of Ni, Cd, Cu, and Pb were calculated as 2.85 ± 0.08, 6.96 ± 0.31, 16.87 ± 1.50, and 26.49 ± 2.04 mg/g, respectively. [email protected] has fast sorption kinetics and maximum adsorption capacity within a short contact time (∼2 h). Energy-dispersive X-ray spectroscopy (EDS) elemental mapping exhibited that adsorbed heavy metals co-distributed with Ca, Si, and Al. The reduction of surface area, pore volume, and pore area of HNT-BC[email protected] (after sorption of heavy metals) confirms that mesoporous surface (2–18 nm) supports diffusion, infiltration, and interaction. However, a lower range of mesoporous diameter of the adsorbent is more suitable for the adsorption of heavy-metal ions. The adsorption isotherm and kinetics fitted well with the Langmuir isotherm and the pseudo-second-order kinetic models, demonstrating the monolayer formation of heavy-metal ions through both the physical sorption and chemical sorption, including pore filling, ion exchange, and electrostatic interaction.

ACS Style

Masud Hassan; Yanju Liu; Ravi Naidu; Jianhua Du; Fangjie Qi; Scott W. Donne; Monirul Islam. Mesoporous Biopolymer Architecture Enhanced the Adsorption and Selectivity of Aqueous Heavy-Metal Ions. ACS Omega 2021, 6, 15316 -15331.

AMA Style

Masud Hassan, Yanju Liu, Ravi Naidu, Jianhua Du, Fangjie Qi, Scott W. Donne, Monirul Islam. Mesoporous Biopolymer Architecture Enhanced the Adsorption and Selectivity of Aqueous Heavy-Metal Ions. ACS Omega. 2021; 6 (23):15316-15331.

Chicago/Turabian Style

Masud Hassan; Yanju Liu; Ravi Naidu; Jianhua Du; Fangjie Qi; Scott W. Donne; Monirul Islam. 2021. "Mesoporous Biopolymer Architecture Enhanced the Adsorption and Selectivity of Aqueous Heavy-Metal Ions." ACS Omega 6, no. 23: 15316-15331.

Journal article
Published: 19 May 2021 in Journal of Hazardous Materials
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Recent trends in food waste and its management have increasingly started to focus on treating it as a reusable resource. The hazardous impact of food waste such as the release of greenhouse gases, deterioration of water quality and contamination of land areas are a major threat posed by food waste. Under the circular economy principles, food waste can be used as a sustainable supply of high-value energy, fuel, and nutrients through green techniques such as anaerobic digestion, co-digestion, composting, enzymatic treatment, ultrasonic, hydrothermal carbonization. Recent advances made in anaerobic co-digestion are helping in tackling dual or even multiple waste streams at once with better product yields. Integrated approaches that employ pre-processing the food waste to remove obstacles such as volatile fractions, oils and other inhibitory components from the feedstock to enhance their bioconversion to reduce sugars. Research efforts are also progressing in optimizing the operational parameters such as temperature, pressure, pH and residence time to enhance further the output of products such as methane, hydrogen and other platform chemicals such as lactic acid, succinic acid and formic acid. This review brings together some of the recent progress made in the green strategies towards food waste valorization.

ACS Style

Zeba Usmani; Minaxi Sharma; Abhishek Kumar Awasthi; Gauri Dutt Sharma; Denise Cysneiros; S.Chandra Nayak; Vijay Kumar Thakur; Ravi Naidu; Ashok Pandey; Vijai Kumar Gupta. Minimizing hazardous impact of food waste in a circular economy – Advances in resource recovery through green strategies. Journal of Hazardous Materials 2021, 416, 126154 .

AMA Style

Zeba Usmani, Minaxi Sharma, Abhishek Kumar Awasthi, Gauri Dutt Sharma, Denise Cysneiros, S.Chandra Nayak, Vijay Kumar Thakur, Ravi Naidu, Ashok Pandey, Vijai Kumar Gupta. Minimizing hazardous impact of food waste in a circular economy – Advances in resource recovery through green strategies. Journal of Hazardous Materials. 2021; 416 ():126154.

Chicago/Turabian Style

Zeba Usmani; Minaxi Sharma; Abhishek Kumar Awasthi; Gauri Dutt Sharma; Denise Cysneiros; S.Chandra Nayak; Vijay Kumar Thakur; Ravi Naidu; Ashok Pandey; Vijai Kumar Gupta. 2021. "Minimizing hazardous impact of food waste in a circular economy – Advances in resource recovery through green strategies." Journal of Hazardous Materials 416, no. : 126154.

Review article
Published: 12 May 2021 in Environment International
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Anthropogenic chemical pollution has the potential to pose one of the largest environmental threats to humanity, but global understanding of the issue remains fragmented. This article presents a comprehensive perspective of the threat of chemical pollution to humanity, emphasising male fertility, cognitive health and food security. There are serious gaps in our understanding of the scale of the threat and the risks posed by the dispersal, mixture and recombination of chemicals in the wider environment. Although some pollution control measures exist they are often not being adopted at the rate needed to avoid chronic and acute effects on human health now and in coming decades. There is an urgent need for enhanced global awareness and scientific scrutiny of the overall scale of risk posed by chemical usage, dispersal and disposal.

ACS Style

Ravi Naidu; Bhabananda Biswas; Ian R. Willett; Julian Cribb; Brajesh Kumar Singh; C. Paul Nathanail; Frederic Coulon; Kirk T. Semple; Kevin C. Jones; Adam Barclay; Robert John Aitken. Chemical pollution: A growing peril and potential catastrophic risk to humanity. Environment International 2021, 156, 106616 .

AMA Style

Ravi Naidu, Bhabananda Biswas, Ian R. Willett, Julian Cribb, Brajesh Kumar Singh, C. Paul Nathanail, Frederic Coulon, Kirk T. Semple, Kevin C. Jones, Adam Barclay, Robert John Aitken. Chemical pollution: A growing peril and potential catastrophic risk to humanity. Environment International. 2021; 156 ():106616.

Chicago/Turabian Style

Ravi Naidu; Bhabananda Biswas; Ian R. Willett; Julian Cribb; Brajesh Kumar Singh; C. Paul Nathanail; Frederic Coulon; Kirk T. Semple; Kevin C. Jones; Adam Barclay; Robert John Aitken. 2021. "Chemical pollution: A growing peril and potential catastrophic risk to humanity." Environment International 156, no. : 106616.

Journal article
Published: 27 April 2021 in Environmental Technology & Innovation
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The remediation of petroleum hydrocarbons (TPH) in a contaminated soil by electrokinetic (EK) treatment was studied in the laboratory. The effects of applying a constant electrical current on soil pH, moisture content, electrical conductivity (EC), temperature, and the concentrations of three fractions of TPH (C10–C16, C17–C34 and C35–C40) were investigated. The experiment was run for seven days and soil samples were collected at the end of the 7 day period for analysis of soil pH and TPH concentration. There were extreme pH conditions near the electrodes. At the end of the experiment there was around a 37% reduction of C10–C16 chain compounds compared to the initial concentration of 164 ± 18 mg/kg. The study investigated TPH remediation to a depth of 24 cm, which is significantly more than most studies of EK remediation of TPH-contaminated soils. We observed reductions in TPH concentrations even at a depth of 24 cm. The spatial distribution of reductions in TPH concentrations was also studied and it was observed that more remediation occurred near the cathodes than near the anodes. Further, the greatest reductions in TPH concentrations were recorded near the electrodes in the lowest and middle parts of the experimental set-up. The application of electrokinetics to remediate TPH-contaminatedsoils could be a viable option as an in situ remediation technology.

ACS Style

Anish Saini; Dawit Nega Bekele; Sreenivasulu Chadalavada; Cheng Fang; Ravi Naidu. Electrokinetic remediation of petroleum hydrocarbon contaminated soil (I). Environmental Technology & Innovation 2021, 23, 101585 .

AMA Style

Anish Saini, Dawit Nega Bekele, Sreenivasulu Chadalavada, Cheng Fang, Ravi Naidu. Electrokinetic remediation of petroleum hydrocarbon contaminated soil (I). Environmental Technology & Innovation. 2021; 23 ():101585.

Chicago/Turabian Style

Anish Saini; Dawit Nega Bekele; Sreenivasulu Chadalavada; Cheng Fang; Ravi Naidu. 2021. "Electrokinetic remediation of petroleum hydrocarbon contaminated soil (I)." Environmental Technology & Innovation 23, no. : 101585.

Journal article
Published: 28 January 2021 in Applied Surface Science
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Supported metal nanoclusters (NCs) are an ideal catalytic system from their ultra-small size (90% degradation of MO occurred by 120 ± 5.21, 75 ± 3.15 and 90 ± 3.61 min, respectively. Composites showed excellent catalytic reusability and environmental nontoxicity. Therefore, as effective and safe catalysts, they can shed light on exploring further usage in the environment and industrial set-ups.

ACS Style

Amal Kanti Deb; Bhabananda Biswas; Nirmal Goswami; Emily F. Hilder; Ravi Naidu; Mohammad Mahmudur Rahman. Synthesis of environmentally benign ultra-small copper nanoclusters-halloysite composites and their catalytic performance on contrasting azo dyes. Applied Surface Science 2021, 546, 149122 .

AMA Style

Amal Kanti Deb, Bhabananda Biswas, Nirmal Goswami, Emily F. Hilder, Ravi Naidu, Mohammad Mahmudur Rahman. Synthesis of environmentally benign ultra-small copper nanoclusters-halloysite composites and their catalytic performance on contrasting azo dyes. Applied Surface Science. 2021; 546 ():149122.

Chicago/Turabian Style

Amal Kanti Deb; Bhabananda Biswas; Nirmal Goswami; Emily F. Hilder; Ravi Naidu; Mohammad Mahmudur Rahman. 2021. "Synthesis of environmentally benign ultra-small copper nanoclusters-halloysite composites and their catalytic performance on contrasting azo dyes." Applied Surface Science 546, no. : 149122.

Research article
Published: 15 January 2021 in Environmental Science & Technology
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The influence of soil properties on PFOS sorption are not fully understood, particularly for variable charge soils. PFOS batch sorption isotherms were conducted for 114 temperate and tropical soils from Australia and Fiji, that were well-characterized for their soil properties, including total organic carbon (TOC), anion exchange capacity, and surface charge. In most soils, PFOS sorption isotherms were nonlinear. PFOS sorption distribution coefficients (Kd) ranged from 5 to 229 mL/g (median: 28 mL/g), with 63% of the Fijian soils and 35% of the Australian soils showing Kd values that exceeded the observed median Kd. Multiple linear regression showed that TOC, amorphous aluminum and iron oxides contents, anion exchange capacity, pH, and silt content, jointly explained about 53% of the variance in PFOS Kd in soils. Variable charge soils with net positive surface charges, and moderate to elevated TOC content, generally displayed enhanced PFOS sorption than in temperate or tropical soils with TOC as the only sorbent phase, especially at acidic pH ranges. For the first time, two artificial neural networks were developed to predict the measured PFOS Kd (R2 = 0.80) in the soils. Overall, both TOC and surface charge characteristics of soils are important for describing PFOS sorption.

ACS Style

Anthony C. Umeh; Ravi Naidu; Sonia Shilpi; Emmanuel B. Boateng; Aminur Rahman; Ian T. Cousins; Sreenivasulu Chadalavada; Dane Lamb; Mark Bowman. Sorption of PFOS in 114 Well-Characterized Tropical and Temperate Soils: Application of Multivariate and Artificial Neural Network Analyses. Environmental Science & Technology 2021, 55, 1779 -1789.

AMA Style

Anthony C. Umeh, Ravi Naidu, Sonia Shilpi, Emmanuel B. Boateng, Aminur Rahman, Ian T. Cousins, Sreenivasulu Chadalavada, Dane Lamb, Mark Bowman. Sorption of PFOS in 114 Well-Characterized Tropical and Temperate Soils: Application of Multivariate and Artificial Neural Network Analyses. Environmental Science & Technology. 2021; 55 (3):1779-1789.

Chicago/Turabian Style

Anthony C. Umeh; Ravi Naidu; Sonia Shilpi; Emmanuel B. Boateng; Aminur Rahman; Ian T. Cousins; Sreenivasulu Chadalavada; Dane Lamb; Mark Bowman. 2021. "Sorption of PFOS in 114 Well-Characterized Tropical and Temperate Soils: Application of Multivariate and Artificial Neural Network Analyses." Environmental Science & Technology 55, no. 3: 1779-1789.

Journal article
Published: 07 January 2021 in Chemosphere
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Nitrogen amendment is known to effectively enhance the bioremediation of hydrocarbon-contaminated soil, but the nitrogen metabolism in this process is not well understood. To unravel the nitrogen metabolic pathway(s) of diesel contaminated soil, six types of nitrogen sources were added to the diesel contaminated soil. Changes in microbial community and soil enzyme genes were investigated by metagenomics analysis and chemical analysis through a 30-day incubation study. The results showed that ammonium based nitrogen sources significantly accelerated the degradation of total petroleum hydrocarbon (TPH) (79–81%) compared to the control treatment (38%) and other non-ammonium based nitrogen amendments (43–57%). Different types of nitrogen sources could dramatically change the microbial community structure and soil enzyme gene abundance. Proteobacteria and Actinobacteria were identified as the two dominant phyla in the remediation of diesel contaminated soil. Metagenomics analysis revealed that the preferred metabolic pathway of nitrogen was from ammonium to glutamate via glutamine, and the enzymes governing this transformation were glutamine synthetase and glutamate synthetase; while in nitrate based amendment, the conversion from nitrite to ammonium was restrained by the low abundance of nitrite reductase enzyme and therefore retarded the TPH degradation rate. It is concluded that during the process of nitrogen enhanced bioremediation, the most efficient nitrogen cycling direction was from ammonium to glutamine, then to glutamate, and finally joined with carbon metabolism after transforming to 2-oxoglutarate.

ACS Style

Yongchao Gao; Jianhua Du; Mezbaul Bahar; Hui Wang; Suresh Subashchandrabose; Luchun Duan; Xiaodong Yang; Mallavarapu Megharaj; Qingqing Zhao; Wen Zhang; Yanju Liu; Jianing Wang; Ravi Naidu. Metagenomics analysis identifies nitrogen metabolic pathway in bioremediation of diesel contaminated soil. Chemosphere 2021, 271, 129566 .

AMA Style

Yongchao Gao, Jianhua Du, Mezbaul Bahar, Hui Wang, Suresh Subashchandrabose, Luchun Duan, Xiaodong Yang, Mallavarapu Megharaj, Qingqing Zhao, Wen Zhang, Yanju Liu, Jianing Wang, Ravi Naidu. Metagenomics analysis identifies nitrogen metabolic pathway in bioremediation of diesel contaminated soil. Chemosphere. 2021; 271 ():129566.

Chicago/Turabian Style

Yongchao Gao; Jianhua Du; Mezbaul Bahar; Hui Wang; Suresh Subashchandrabose; Luchun Duan; Xiaodong Yang; Mallavarapu Megharaj; Qingqing Zhao; Wen Zhang; Yanju Liu; Jianing Wang; Ravi Naidu. 2021. "Metagenomics analysis identifies nitrogen metabolic pathway in bioremediation of diesel contaminated soil." Chemosphere 271, no. : 129566.

Original research article
Published: 23 December 2020 in Frontiers in Water
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Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are persistent organic contaminants of concern to human and environmental health. Several literature reviews and laboratory column experiments have been conducted to determine the transport parameters and to describe the fate of PFAS as they migrate in subsurface environments. However, there are very few case studies focusing on contaminated sites with high-resolution field data. Such studies are crucial for the validation of transport simulation models that have been developed from experimental studies, prior to their broader applications. The key purpose of this research was to evaluate lithological separations of PFAS fractions as they are transported in the vadose zone of a historically (1979) contaminated site where Aqueous Film Forming Foam (AFFF) formulations (3M Lightwater™ and Ansulite™) have been used for fire training exercises. Surface and subsurface soils, and groundwater samples were collected across the site and a total of 29 PFAS compounds were selected as target analytes. The results indicated a distinct profile of PFAS concentration with depth at most of the test bores, exhibiting separation of PFAS as transported in vadose zone soils. Perfluorooctanoic acid (PFOA), Perfluorooctane sulfonic acid (PFOS), and Perfluorohexane sulfonic acid (PFHxS) were the predominant compounds detected in the site samples and they have been found in near-surface soils (<3 m) with concentrations declining with depth. The concentration of the 6:2 fluorotelomer sulfonate showed little change with depth in most of the test bore wells. The percentage concentration of each compound relative to the sum of PFAS, and the ratio of PFHxS/PFOS with depth, suggested transformation processes. Despite the relatively high solubility of PFAS, and that the application of AFFF has been ceased for some years at the site, there were still significant concentrations of PFAS adsorbed to the vadose zone soils that acted as ongoing sources of contamination to groundwater.

ACS Style

Dawit N. Bekele; Yanju Liu; Mark Donaghey; Anthony Umeh; Chamila S. V. Arachchige; Sreenivasulu Chadalavada; Ravi Naidu. Separation and Lithological Mapping of PFAS Mixtures in the Vadose Zone at a Contaminated Site. Frontiers in Water 2020, 2, 1 .

AMA Style

Dawit N. Bekele, Yanju Liu, Mark Donaghey, Anthony Umeh, Chamila S. V. Arachchige, Sreenivasulu Chadalavada, Ravi Naidu. Separation and Lithological Mapping of PFAS Mixtures in the Vadose Zone at a Contaminated Site. Frontiers in Water. 2020; 2 ():1.

Chicago/Turabian Style

Dawit N. Bekele; Yanju Liu; Mark Donaghey; Anthony Umeh; Chamila S. V. Arachchige; Sreenivasulu Chadalavada; Ravi Naidu. 2020. "Separation and Lithological Mapping of PFAS Mixtures in the Vadose Zone at a Contaminated Site." Frontiers in Water 2, no. : 1.

Journal article
Published: 15 December 2020 in Chemosphere
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This study examined the influence of soil physicochemical properties on the sorption, desorption and kinetics of beryllium (Be) uptake and release on soils from a legacy waste site in Australia. This information is needed to help explain the current distribution of Be at the site and evaluate potential future environmental risks. Sorption was determined by a batch study and key soil properties were assessed to explain Be retention. The soil was favourable for sorption of Be (up to 99%) due to organic content, negative surface charge, soil oxyhydroxides (Fe/Al/Mn–O/OH) and the porosity of the soil structure. Lesser sorption was observed in the presence of a background electrolyte (NaNO3). Sorption closely followed pseudo second order kinetics and was best described by the Langmuir model. FTIR analysis suggested that chemisorption was the predominant mechanism of Be sorption. Desorption was very low and best described by the Freundlich model. The low desorption reflected the high Kd (up to 6624 L/kg), and the presence of hysteresis suggested partially irreversible binding of Be with active surfaces of the soil matrix (minerals, SOM, oxyhydroxides of Fe/Al/Mn etc.). Intra-particle diffusion of Be and entrapment in the pores contribute to the irreversible binding. The sorption behaviour of Be helped to explain the relative immobility of Be at the site despite the significant quantities of Be disposed. Soil physicochemical properties were significant for Be sorption, through influencing both the uptake and desorption, and this demonstrates the implications of these measurements for evaluating potential future risks to the environment.

ACS Style

Rashidul Islam; Peter Sanderson; Mathew P. Johansen; Timothy E. Payne; Ravi Naidu. The influence of soil properties on sorption-desorption of beryllium at a low level radioactive legacy waste site. Chemosphere 2020, 268, 129338 .

AMA Style

Rashidul Islam, Peter Sanderson, Mathew P. Johansen, Timothy E. Payne, Ravi Naidu. The influence of soil properties on sorption-desorption of beryllium at a low level radioactive legacy waste site. Chemosphere. 2020; 268 ():129338.

Chicago/Turabian Style

Rashidul Islam; Peter Sanderson; Mathew P. Johansen; Timothy E. Payne; Ravi Naidu. 2020. "The influence of soil properties on sorption-desorption of beryllium at a low level radioactive legacy waste site." Chemosphere 268, no. : 129338.

Journal article
Published: 16 November 2020 in Journal of Hazardous Materials
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Prolonged exposure to inorganic arsenic (As) via drinking water is a major concern as it poses significant human health risks. Removal of As is crucial but requires effective and environment-friendly clean-up technology to avoid any additional risk to the environment. In this study, we developed Australian smectite (smec)-supported nano zero-valent iron (nZVI) composite for arsenate i.e., As(V) sorption. We used a range of tools, including X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) and energy dispersion X-ray (EDS) spectroscopy to characterise the material. SEM and TEM images and elemental mapping of the composite reflect that the smectite layer was surrounded by a chain of iron nanobeads evenly distributed on clay particles, which is quite exceptional among currently available nZVIs. The maximum As(V) sorption capacity of this composite was 23.12 mg/g in the ambient conditions. Using X-ray photoelectron spectroscopy we unveiled chemical states of As and Fe before and after the sorption process. Additionally, the release of iron nanoparticles from the composite at various pHs (3−10) were found negligible, which demonstrates the effectiveness of smec-nZVI to remove As(V) from contaminated water without posing any secondary pollutant.

ACS Style

Kh Ashraf Uz-Zaman; Bhabananda Biswas; Mohammad Mahmudur Rahman; Ravi Naidu. Smectite-supported chain of iron nanoparticle beads for efficient clean-up of arsenate contaminated water. Journal of Hazardous Materials 2020, 407, 124396 .

AMA Style

Kh Ashraf Uz-Zaman, Bhabananda Biswas, Mohammad Mahmudur Rahman, Ravi Naidu. Smectite-supported chain of iron nanoparticle beads for efficient clean-up of arsenate contaminated water. Journal of Hazardous Materials. 2020; 407 ():124396.

Chicago/Turabian Style

Kh Ashraf Uz-Zaman; Bhabananda Biswas; Mohammad Mahmudur Rahman; Ravi Naidu. 2020. "Smectite-supported chain of iron nanoparticle beads for efficient clean-up of arsenate contaminated water." Journal of Hazardous Materials 407, no. : 124396.

Review article
Published: 10 November 2020 in Journal of Agricultural and Food Chemistry
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Food is the major cadmium (Cd)-exposure pathway from agricultural soils to humans and other living entities and must be reduced in an effective way. A plant can select beneficial microbes, like plant-growth-promoting rhizobacteria (PGPR), depending upon the nature of root exudates in the rhizosphere, for its own benefits, such as plant growth promotion as well as protection from metal toxicity. This review intends to seek out information on the rhizo-immobilization of Cd in polluted soils using the PGPR along with plant nutrient fertilizers. This review suggests that the rhizo-immobilization of Cd by a combination of PGPR and nanohybrid-based plant nutrient fertilizers would be a potential and sustainable technology for phytoavailable Cd immobilization in the rhizosphere and plant cellular detoxification, by keeping the plant nutrition flow and green dynamics of plant nutrition and boosting the plant growth and development under Cd stress.

ACS Style

Abdul Halim; Mohammad Mahmudur Rahman; Mallavarapu Megharaj; Ravi Naidu. Cadmium Immobilization in the Rhizosphere and Plant Cellular Detoxification: Role of Plant-Growth-Promoting Rhizobacteria as a Sustainable Solution. Journal of Agricultural and Food Chemistry 2020, 68, 13497 -13529.

AMA Style

Abdul Halim, Mohammad Mahmudur Rahman, Mallavarapu Megharaj, Ravi Naidu. Cadmium Immobilization in the Rhizosphere and Plant Cellular Detoxification: Role of Plant-Growth-Promoting Rhizobacteria as a Sustainable Solution. Journal of Agricultural and Food Chemistry. 2020; 68 (47):13497-13529.

Chicago/Turabian Style

Abdul Halim; Mohammad Mahmudur Rahman; Mallavarapu Megharaj; Ravi Naidu. 2020. "Cadmium Immobilization in the Rhizosphere and Plant Cellular Detoxification: Role of Plant-Growth-Promoting Rhizobacteria as a Sustainable Solution." Journal of Agricultural and Food Chemistry 68, no. 47: 13497-13529.

Journal article
Published: 17 October 2020 in Chemosphere
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Metabolic uptake of lead (Pb) is controlled by its bioaccessibility. Most studies have examined bioaccessibility of Pb in the absence of gut microbes, which play an important role in the metabolic uptake of nutrients and metal(loid)s in intestine. In this study, we examined the effect of three gut microbes, from various locations in the gut, on the bioaccessibility of soil ingested Pb. The gut microbes include Lactobacillus acidophilus, Lactobacillus rhamnosus and Escherichia coli. Lead toxicity to these three microbes was also examined at various pH values. Bioaccessibility of Pb was measured using gastric and intestinal extractions. Both Pb spiked and Pb-contaminated shooting range field soils were used to measure Pb bioaccessibility in the presence and absence of gut microbes. The results indicated that Pb toxicity to gut microbes, as measured by LD50 value, decreased with increasing pH, and was higher for Lactobacillus species. Gut microbes decreased the bioaccessible Pb; the effect was more pronounced at low pH, mimicking gastric conditions than in conditions closer to the intestine. Lead adsorption by these microbes increased at the higher pH tested, and E. coli adsorbed higher amounts of Pb than did the Lactobacillus species. The effect of gut microbes on reducing Pb bioaccessibility may be attributed to microbially-induced immobilization of Pb through adsorption, precipitation, and complexation reactions. The study demonstrates that bioaccessibility and subsequently bioavailability of metal(loid)s can be modulated by gut microbes, and it is important to undertake bioaccessibility measurements in the presence of gut microbes.

ACS Style

Shiv Bolan; Balaji Seshadri; Ian Grainge; Nicholas J. Talley; Ravi Naidu. Gut microbes modulate bioaccessibility of lead in soil. Chemosphere 2020, 270, 128657 .

AMA Style

Shiv Bolan, Balaji Seshadri, Ian Grainge, Nicholas J. Talley, Ravi Naidu. Gut microbes modulate bioaccessibility of lead in soil. Chemosphere. 2020; 270 ():128657.

Chicago/Turabian Style

Shiv Bolan; Balaji Seshadri; Ian Grainge; Nicholas J. Talley; Ravi Naidu. 2020. "Gut microbes modulate bioaccessibility of lead in soil." Chemosphere 270, no. : 128657.

Journal article
Published: 29 August 2020 in Chemosphere
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A pot experiment was carried out to evaluate the efficiency of six types of non-stabilised and Na-carboxymethylcellulose (CMC)-stabilised iron oxide nanoparticles (α-FeOOH, α-Fe2O3, and Fe3O4) on the immobilisation of cobalt (Co) in a soil spiked with different concentrations of it (5, 25, 65, 125, 185 mg kg-1). Amendments were added to soil samples at the rate of 0.5%, and the samples incubated for 60-days. The addition of amendments significantly decreased the concentrations of DTPA-Co and MgCl2-Co, compared with the unamended control. The highest decrease in concentration of DTPA-Co and MgCl2-Co was obtained by the application of CMC-stabilised Fe3O4 (MC) when the concentration of soil total Co was low (5 and 25 mg kg-1) and by the use of CMC-stabilised α-FeOOH (GC) when the concentration of soil total Co was high (65, 125, and 185 mg kg-1), as compared to the control. CMC-stabilised iron oxide nanoparticles were more effective than non-stabilised nanoparticles in the immobilisation of Co. To investigate the effectiveness of iron oxide amendments on the chemical species of Co in the soil spiked with 65 mg kg-1 of this metal, sequential extraction was performed. The concentration of EXCH (exchangeable) and CARB (carbonate) bound fractions decreased significantly after treatment by different amendments. In particular, GC reduced the concentration of EXCH and CARB bound fractions by 20.87, and 17.52%, respectively, compared with the control. Also amendments significantly increased the concentration of FeMn-OX (Fe-Mn oxides), and OM (organic matter) bound, and RES (residual) fractions.

ACS Style

Solmaz Bidast; Ahmad Golchin; Ahmad Baybordi; AbbasAli Zamani; Ravi Naidu. The effects of non-stabilised and Na-carboxymethylcellulose-stabilised iron oxide nanoparticles on remediation of Co-contaminated soils. Chemosphere 2020, 261, 128123 .

AMA Style

Solmaz Bidast, Ahmad Golchin, Ahmad Baybordi, AbbasAli Zamani, Ravi Naidu. The effects of non-stabilised and Na-carboxymethylcellulose-stabilised iron oxide nanoparticles on remediation of Co-contaminated soils. Chemosphere. 2020; 261 ():128123.

Chicago/Turabian Style

Solmaz Bidast; Ahmad Golchin; Ahmad Baybordi; AbbasAli Zamani; Ravi Naidu. 2020. "The effects of non-stabilised and Na-carboxymethylcellulose-stabilised iron oxide nanoparticles on remediation of Co-contaminated soils." Chemosphere 261, no. : 128123.

Article
Published: 28 August 2020 in Environmental Monitoring and Assessment
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Global Soil Partnership, Food and Agriculture Organization of the United Nations, Rome, Italy Natalia Rodríguez Eugenio Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRCCARE), University of Newcastle, Callaghan, Australia Ravi Naidu Agriculture, Environment and Food Department, Università del Molise, Campobasso, Italy Claudio Massimo Colombo You can also search for this author in PubMed Google Scholar You can also search for this author in PubMed Google Scholar You can also search for this author in PubMed Google Scholar Correspondence to Natalia Rodríguez Eugenio. Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. This article is part of the Topical Collection on Global Approaches to Assessing, Monitoring, Mapping and Remedying Soil Pollution Reprints and Permissions Eugenio, N.R., Naidu, R. & Colombo, C.M. Global approaches to assessing, monitoring, mapping, and remedying soil pollution. Environ Monit Assess 192, 601 (2020). https://doi.org/10.1007/s10661-020-08537-2 Download citation Received: 31 July 2020 Accepted: 31 July 2020 Published: 28 August 2020 DOI: https://doi.org/10.1007/s10661-020-08537-2

ACS Style

Natalia Rodríguez Eugenio; Ravi Naidu; Claudio Massimo Colombo. Global approaches to assessing, monitoring, mapping, and remedying soil pollution. Environmental Monitoring and Assessment 2020, 192, 1 -2.

AMA Style

Natalia Rodríguez Eugenio, Ravi Naidu, Claudio Massimo Colombo. Global approaches to assessing, monitoring, mapping, and remedying soil pollution. Environmental Monitoring and Assessment. 2020; 192 (9):1-2.

Chicago/Turabian Style

Natalia Rodríguez Eugenio; Ravi Naidu; Claudio Massimo Colombo. 2020. "Global approaches to assessing, monitoring, mapping, and remedying soil pollution." Environmental Monitoring and Assessment 192, no. 9: 1-2.

Review
Published: 12 July 2020 in Science of The Total Environment
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Biochar is a porous, amorphous, stable, and low-density carbon material derived from the carbonization of various biological residues. Biochars have multifunctional properties that make them promising adsorbents for the remediation of organic and inorganic contaminants from soil and water. High temperature treatment (HTT) and the properties of feedstocks are key factors influencing the properties of biochars. Feedstocks have distinctive physicochemical properties due to variations in elemental and structural composition, and they respond heterogeneously to specific pyrolysis conditions. The criteria for the selection of feedstocks and pyrolysis conditions for designing biochars for specific sorption properties are inadequately understood. We evaluated the influence of pyrolysis temperature on a wide range of feedstocks to investigate their effects on biochar properties. With increasing HTT, biochar pH, surface area, pore size, ash content, hydrophobicity and O/C vs. H/C (ratios that denote stability) increased, whereas, hydrophilicity, yield of biochar, O/C, and H/C decreased. Discriminant analysis of data from 533 published datasets revealed that biochar derived from hardwood (HBC) and softwood generally have greater surface area and carbon content, but lower content of oxygen and mineral constituents, than manure- (MBC) and grass-derived biochars (GBC). GBC and MBC have abundant oxygen-containing functional groups than SBC and HBC. The sequence of stability and aromaticity of feedstocks was MBC < GBC < SBC < HBC. Therefore, SBC and HBC are suitable for sorption of hydrophobic molecules. Biochars produced from low HTT are suitable for removal of ionic contaminants, whereas those produced at high HTT are suitable for removal of organic contaminants. The influences of biochar properties on sorption performance of heavy metals and organic contaminants are critically reviewed.

ACS Style

Masud Hassan; Yanju Liu; Ravi Naidu; Sanjai J. Parikh; Jianhua Du; Fangjie Qi; Ian R. Willett. Influences of feedstock sources and pyrolysis temperature on the properties of biochar and functionality as adsorbents: A meta-analysis. Science of The Total Environment 2020, 744, 140714 .

AMA Style

Masud Hassan, Yanju Liu, Ravi Naidu, Sanjai J. Parikh, Jianhua Du, Fangjie Qi, Ian R. Willett. Influences of feedstock sources and pyrolysis temperature on the properties of biochar and functionality as adsorbents: A meta-analysis. Science of The Total Environment. 2020; 744 ():140714.

Chicago/Turabian Style

Masud Hassan; Yanju Liu; Ravi Naidu; Sanjai J. Parikh; Jianhua Du; Fangjie Qi; Ian R. Willett. 2020. "Influences of feedstock sources and pyrolysis temperature on the properties of biochar and functionality as adsorbents: A meta-analysis." Science of The Total Environment 744, no. : 140714.