Chemistry - Research Publications

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Subject: search.filters.subject.Kinetics

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    Synergistic effect of pistachio shell powder and nano-zerovalent copper for chromium remediation from aqueous solution
    (Springer Science and Business Media Deutschland GmbH, 2021-07-06T00:00:00) Kumar, Sandeep; Brar, Ravinderdeep Singh; Babu, J. Nagendra; Dahiya, Amarjeet; Saha, Sandip; Kumar, Avneesh
    Pistachio shell powder supported nano-zerovalent copper (ZVC@PS) material prepared by borohydride reduction was characterized using SEM, FTIR, XRD, TGA/DTA, BET, and XPS. SEM, XRD, and XPS revealed the nano-zerovalent copper to consist of a core-shell structure with CuO shell and Cu(0) core with a particle size of 40�100 nm and spherical morphology aggregated on PS biomass. ZVC@PS was found to contain 39% (w/w %) Cu onto the pistachio shell biomass. Batch sorption of Cr(VI) from the aqueous using ZVC@PS was studied and was optimized for dose (0.1�0.5 g/L), initial Cr(VI) concentration(1�20 mg/L), and pH (2�12). Optimized conditions were 0.1 g/L doses of sorbent and pH=3 for Cr(VI) adsorption. Langmuir and Freundlich adsorption isotherm models fitted well to the adsorption behavior of ZVC@PS for Cr(VI) with a pseudo-second-order kinetic behavior. ZVC@PS (0.1g/L) exhibits qmax for Cr(VI) removal up to 110.9 mg/g. XPS and other spectroscopic evidence suggest the adsorption of Cr(VI) by pistachio shell powder, coupled with reductive conversion of Cr(VI) to Cr(III) by ZVC particles to produce a synergistic effect for the efficient remediation of Cr(VI) from aqueous medium. Graphical abstract: [Figure not available: see fulltext.] � 2021, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.
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    Sorptive removal of arsenite [As(III)] and arsenate [As(V)] by fuller's earth immobilized nanoscale zero-valent iron nanoparticles (F-nZVI): Effect of Fe 0 loading on adsorption activity
    (Elsevier Ltd, 2016) Yadav R.; Sharma A.K.; Babu J.N.
    Fuller's earth immobilized nanoscale zerovalent iron (F-nZVI 1-8) were synthesized by borohydride reduction method. The iron loading of fuller's earth immobilized nZVI was varied from 5 to 50% (w/w) in these F-nZVI 1-8. The F-nZVI 1-8 were characterized by FE-SEM-EDX, FTIR, BET, XRD and TGA. The FE-SEM analysis showed an increase in agglomeration of nZVI on the immobilized material with increase in the loading of Fe 0 . F-nZVI 1-8 were studied for adsorptive removal of As(III) and As(V) from aqueous solution, with an emphasis on the effect of Fe 0 loading of adsorbent on arsenic remediation. Iron loading has a significant role in adsorption of As(III) and As(V) on F-nZVI, with increase in adsorption with optimum iron loading of 20% (w/w) on fuller's earth (F-nZVI-4). However, increase in loading above 20%, resulted in no significant increase in As(III) and As(V) adsorption. The adsorption results fitted well with Langmuir and Freundlich isotherm models and the maximum adsorption capacity of F-nZVI-4 for As(III) and As(V) were observed to be 50.08 and 91.42 mg/g, respectively. The adsorption isotherm and kinetic studies indicate a rapid removal of As(III) and As(V) from the aqueous solution in the presence of F-nZVI 1-8, with an substantially high rate of removal for arsenic with F-nZVI-4.
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    Role of Macromolecular Crowding on Stability and Iron Release Kinetics of Serum Transferrin
    (American Chemical Society, 2017) Kumar, Sandeep; Sharma, Deepak; Kumar, Rajesh
    The macromolecular crowding influences the structural stability and functional properties of transferrin (Tf). The equilibrium as well as kinetic studies of Tf at different concentrations of crowding agents (dextran 40, dextran 70, and ficoll 70) and at a fixed concentration of dextran 40 under different concentrations of NaCl at pH 7.4 and 5.6 (?1) revealed that (i) the crowder environment increases the diferric-Tf (Fe2Tf) stability against iron loss and overall denaturation of the protein, (ii) both in the absence and presence of crowder, the presence of salt promotes the loss of iron and overall denaturation of Fe2Tf which is due to ionic screening of electrostatic interactions, (iii) the crowder environment retards iron release from monoferric N-lobe of Tf (FeNTf) by increasing enthalpic barrier, (iv) the retardation of iron release by crowding is enthalpically dominated than the entropic one, (v) both in the absence and presence of crowder, the presence of salt accelerates the iron release from FeNTf due to ionic screening of electrostatic interactions and anion binding to KISAB sites, and (vi) the crowders environment is unable to diminish (a) the salt-induced destabilization of Fe2Tf against the loss of iron and overall denaturation and (b) the anion effect and ionic screening of diffusive counterions responsible to promote iron release from FeNTf. ? 2017 American Chemical Society.