Department Of Environmental Science And Technology

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    Uranium and Fluoride Removal from Aqueous Solution Using Biochar: A Critical Review for Understanding the Role of Feedstock Types, Mechanisms, and Modification Methods
    (MDPI, 2022-12-13T00:00:00) Thakur, Anjali; Kumar, Rakesh; Sahoo, Prafulla Kumar
    Uranium (U) and fluoride (F?) are the major global geogenic contaminants in aquifers and pose serious health issues. Biochar, a potential adsorbent, has been widely applied to remediate geogenic and anthropogenic contaminants. However, there is a lack of research progress in understanding the role of different feedstock types, modifications, adsorption mechanisms on physico-chemical properties of biochar, and factors affecting the adsorption of U and F? from aqueous solution. To fill this lacuna, the present review gives insight into the U and F? removal from aqueous solution utilizing biochar from various feedstocks. Feedstock type, pyrolysis temperature, modifications, solution pH, surface area, and surface-charge-influenced biochar adsorption capacities have been discussed in detail. Major feedstock types that facilitated U and F? adsorption were crop residues/agricultural waste, softwood, grasses, and animal manure. Low-to-medium pyrolyzing temperature yielded better biochar properties for U and F? adsorption. Effective modification techniques were mainly acidic and magnetic for U adsorption, while metal oxides, hydroxides, alkali, and magnetic modification were favourable for F? adsorption. The major mechanisms of U adsorption were an electrostatic attraction and surface complexation, while for F? adsorption, the major mechanisms were ion exchange and electrostatic attraction. Lastly, the limitations and challenges of using biochar have also been discussed. � 2022 by the authors.
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    Effect of Pyrolysis Temperature on Mechanistic Transformation for Adsorption of Methylene Blue on Leached Rice-Straw Biochar
    (John Wiley and Sons Inc, 2022-02-09T00:00:00) Bhardwaj, Akanksha; Nag, Shilpa; Dahiya, Amarjeet; Pandey, Puneeta; Arora, Meenu; Babu, J. Nagendra
    Toxicity characteristic leaching procedure (TCLP) leached biochar is studied for adsorption of methylene blue (MB). Rice straw biochar obtained from slow pyrolysis at 400, 500, and 600��C, respectively, is TCLP leached to furnish leached biochar, BL4, BL5, and BL6. The leached biochar BL4�6 have been characterized for pH, CHN analysis, ash, zeta potential, surface area morphology and functional groups. Batch adsorption studies are optimized for pH (3�9), adsorbent dose (0.5�4�g�L?1), and initial MB concentration (20�135�mg�L?1). Nonlinear fitting to Langmuir, Freundlich, and Redlich-Peterson adsorption isotherm with due statistical treatment and error function analysis is carried out. Leached biochar, BL4, BL5, and BL6, is characterized by the dominance of carboxylic acid, lactone, and phenols moieties, respectively. The MB adsorption on leached biochar exhibits maximum adsorption of 26.87, 51.34, and 18.83�mg�g?1 for BL4, BL5, and BL6, respectively. The underlying mechanism for adsorption of MB using BL5, is characterized by non-ionic lactone ring opening in presence of MB under alkaline conditions that is supported by X-ray photoelectron spectroscopy(XPS) and Fourier transformed infrared spectroscopy (FTIR) studies. Desorption of MB and regeneration from BL5 is studied with methanol and 0.1 m HCl as stripping solvent for four cycles. Recovery of MB is better with methanol in comparison to 0.1 m HCl. � 2022 Wiley-VCH GmbH.
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    Thermo-chemical decomposition of wheat crop residue in presence of fly--ash and its application for soil amelioration
    (Central University of Punjab, 2013) Singh, Rishikesh; Babu, J.N.
    In the present work, pyrolysis of wheat crop residue is studied in the presence and absence of fly-ash at three different pyrolysis temperatures (viz., 2500C, 3500C and 4500C) with a temperature hold time of 1 to 4 hours. Biochar yield, in absence of fly-ash, was found to decrease with increase in pyrolysis temperature and hold time. Biochar yield was found to increase significantly with increase in fly-ash content at 2500C, whereas, a significant decrease in biochar yield was observed with increase in fly-ash content at 4500C. The biochar/fly-ash composite samples were characterized by FTIR, SEM, CHNS analysis and other physico-chemical parameters like pH, EC, alkalinity, total P, K, Na and extractable micronutrient content. pH, EC, alkalinity, total P, K and Na contents were found to be modulated by increase in fly-ash content and pyrolysis temperature. Further, effect of the biochar/fly-ash composites on the soil amelioration were studied and found to have a significant effect on soil physico-chemical properties like, water holding capacity (WHC), pH, EC, CEC, exchangeable cations, organic carbon, available P and micronutrients content