School Of Environment And Earth Sciences
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Item Adsorption of Zn(II) on Pristine and SPLP/TCLP Leached Rice Straw Biochar: an Interplay of Precipitation and Ion Exchange(Institute for Ionics, 2022-11-15T00:00:00) Bhardwaj, Akanksha; Nag, Shilpa; Hussain, Khadim; Arora, Meenu; Pandey, Puneeta; Babu, J. NagendraThe inorganic mineral content in biochar influences the adsorption of Zn(II) metal ions. Metal ion adsorption on mineral rich rice straw biochar is influenced upon washing. Rice straw slow pyrolysis biochar BC1-3, respectively, prepared at 400, 500, and 600��C, were leached under Toxicity Characteristic Leaching Procedure (TCLP) and Synthetic Precipitation Leaching Procedure (SPLP) conditions to furnish BT1-3 and BS1-3, respectively. The Zn(II) adsorption studies were carried out for pH and dose optimization, initial concentration, isotherm fit, and kinetic studies. The Zn(II) adsorption by B(C/S/T)1�3 showed Langmuir and Freundlich isotherm, with pseudo-second-order kinetics at optimum pH 5 and dose 1�g/L. The adsorption of Zn(II) followed the trend BC3(qm 47�mg/g) > BC2 > BC1 > BS2 > BS1 > BS3 > BT2 > BT1 > BT3 (qm 3.5�mg/g), i.e., metal ion adsorption decreased with extent of leaching. The Zn(II) adsorption on biochar involved precipitation as dominant factor for metal ion adsorption on the biochars followed by ion exchange and proton exchange. The precipitation of Zn(II) ions in case of BC1-3 is attributed to the pH of biochar, which increases with proportion of minerals to organic content in biochar. In case of biochar BS1-3 and BT1-3, ion exchange and proton exchange mechanisms driven by demineralization are responsible for Zn(II) adsorption. The adsorption mechanism for Zn(II) on biochar is supported by XPS, solid state NMR studies. Graphical Abstract: [Figure not available: see fulltext.] � 2022, The Author(s), under exclusive licence to Springer Nature Switzerland AG.Item Effect of temperature and fly ash content on the catalytically pyrolyzed rice straw biochar�fly ash composites for methylene blue adsorption(John Wiley and Sons Ltd, 2022-09-26T00:00:00) Bhardwaj, Akanksha; Nag, Shilpa; Hussain, Khadim; Pandey, Puneeta; Babu, J. NagendraRice straw and fly ash are the wastes produced in abundance which need immediate attention for their management. In the present study, the in situ pyrolysis of rice straw in presence of fly ash was carried out and the resultant composites were studied for adsorption of methylene blue (MB). Slow pyrolysis of rice straw in presence of fly ash is evaluated using thermogravimetric analysis (TGA) and Coats�Redfern equation for pseudo-first-order reaction kinetics, respectively. The activation energy (Ea) for the pyrolysis of rice straw was 41.75 kJ/mol which was lowered to 37.39 kJ/mol in presence of fly ash. Biochar fly ash composites BFA41�3, BFA51�3, and BFA61�3 were prepared at three 400�C, 500�C, and 600�C pyrolysis temperature, respectively, the subscript indicating three different ratios of rice straw and fly ash (1:3, 1:1, and 3:1 w/w ratio). The composites BF4�61�3 were neutral to alkaline in pH, due to the presence of basic oxide and carbonates minerals. BFA4�61�3 was studied for batch adsorption of MB and optimized for pH, dose, and initial concentration of adsorbate. The maximum MB adsorption capacity of 25.91 mg/g was reported for the composite BFA41. MB adsorption efficiency (qe) followed the trend BFA41�3 > BFA51�3 > BFA61�3, which indicates a strong influence of biochar surface functional groups on dye adsorption, as reiterated by the multiple linear regression (MLR) analysis. Stripping of MB was achieved using methanol as a stripping agent for MB-adsorbed BFA4�61�3 with desorption efficiency of 7% to 11% in the first cycle and 23% to 100% in the second cycle. Thus, the biochar fly ash composite with optimum ion exchangeable functional organic moieties would be suitable for dye remediation and waste generated in the process could find application in soil amelioration. � 2022 Curtin University and John Wiley & Sons Ltd.Item 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. NagendraToxicity 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.Item Effect of arsenic on the growth and physiology of triticum aestivum L. seedings(Central University of Punjab, 2012) Nag, Shilpa; Mittal, SunilThe effects of Arsenic (As) were investigated on four varieties of T. aestivum viz. PBW 343, PBW 550, PBW 621 and HD 2967 to elucidate the toxicity of As on morphological, physiological, biochemical and antioxidant processes of plant in early stage. The results showed that seed germination, root length, shoot length and biomass decreased gradually with increase in concentrations of As (125-750'M) and this decrease was biologically significant. The photosynthetic and respiratory activity of the test plants was also investigated. The decrease in chlorophyll and carotenoids content with increase in As content indicates negative effect of As on the photosynthetic pigments. However, the total cellular respiration increased with increase in As concentration and this probably may be due to the enhancement in respiratory enzymes which leads to high production of energy by the respective cells. The contents of water soluble carbohydrates and proteins increased with increasing As concentrations while their hydrolyzing enzymes i.e. ? amylase and protease were decreasing with increase in As concentration. The activity of antioxidant enzymes, superoxide dismutase and peroxidase followed the increasing trend indicating the induction of oxidative stress under high concentration of As. Further, among the various varieties HD 2967 was the most tolerant variety and PBW 550 was most affected varietyItem Mutagenic Effect in Vegetables by Pesticides(Krishi Sanskriti Publications, 2013) Nag, Shilpa; Jain, A.K.; M.S., DhanyaThe advent of pesticides in vegetable crops is to control insects, pathogens and weeds aimed at increasing the crop yield, but the applied pesticides are not fully reaching the target pests. It escapes to environment or accumulates in crops resulting in some deleterious changes. The disturbances were observed in physiological and cytological levels of the affected plants by blocking mitosis and producing mitotic and meiotic chromosome abnormalities. Some pesticides like acetamiprid, carbendazim, chlorpyriphos, cypermethrin, dichlorvos, dicofol, dimethoate, fenvalarate, indoxcarb, mancozeb, monocrotophos, profenophos, quinalphos, zineb etc. proved to be mutagens. Researchers reported abnormalities like chromosomes with inactivated centromeres, isochromosome, picnosis, vagrant, stickiness, bridges, precocious separation and lagging chromosomes, reduction in mitotic index, micronuclei, multipolar cells, sister chromatid exchanges, c- mitosis are common in vegetables. Such abnormalities were observed in kharif vegetables like Lycopersicon esculentum, Capsicum annum, Solanum melongena, Abelmoschus esculentus, Cucumis sativus, Vicia faba, Phaseolus vulgaris and rabi vegetables like Allium cepa, Coriandrum sativum, Raphanus sativus, Solanum tuberosum, Pisum sativum etc. The pesticides act as potent environmental mutagens that possess a threat to cause alterations in genetic makeup in vegetables.