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Title: Continuous Flow Studies for Binding of Cations and Anions from Aqueous Solution-Multicomponent Approach
Authors: Tariq, Madiha
Keywords: Physical Sciences
Issue Date: 2020
Publisher: University of the Punjab , Lahore
Abstract: The present study for removal of cations [Cd(II), Pb(II), Ni(II), Cu(II)] and anions (F- , NO3 - ) from aqueous solution through column studies is based on the adsorption potential of powdered branches from Ficus religiosa, an abundantly accessible plant. Unmodified and xanthate-modified biomass materials were used to investigate the sorption efficiency of cations, while protonated unmodified and xanthate-modified material were used to study the behavior of anion biosorption. Biomass was silica immobilized for the present studies and characterized using available techniques, including elemental analysis (CHNS), potentiometric titration, pHpzc, Fourier transformed infrared spectroscopy (FTIR) and scanning electron microscopy and energy dispersive spectroscopy (SEM-EDS). Breakthrough curves (S shape) were used to describe the removal ability of biosorbents in a continuous flow mode/fixed-bed column using various parameters such as bed depths (5―30 cm), inlet cations/anions concentration (100―300 mg/L) and inlet solution (cations) pH (3―5) at flow rate of 2 mL/min. Biosorption of cations and anions in continuous mode increased with a rise in the pH of the inlet solution and enhanced service time (breakthrough and exhaust time) of a column. Maximum biosorption capacities for Cu(II), Cd(II), Pb(II) and Ni(II) were observed 17.5 mg/g, 13.3 mg/g, 15.0 mg/g and 100 mg/g for UMF respectively. For xanthate-modified biomass, the qe values were increased for Cd(II) 55.2 mg/g, Pb(II) 283.6 mg/g and Ni(II) 28.8 mg/g. Findings suggested that unmodified Ficus religiosa (UMF) required less service time compared to xanthate-modified Ficus religiosa and thus justified the need of modification. The efficiency of defluoridation and denitration were observed on different bed depths (5–30 cm) and inlet concentration (25 to 100 mg/L) at a fixed flow rate of 2 mL/min. 21 The maximum sorption capacity of fluoride and nitrate for protonated Ficus religiosa (PFR) was found to be 9.03 mg/g and 8.85 mg/g, respectively. For protonated, xanthate-modified Ficus religiosa (PXFR) qe values were 19.72 mg/g for fluoride and 23.05 mg/g for nitrate. Binary and ternary cations systems were investigated for Cd(II), Pb(II) and Ni(II) biosorption. Various combinations of initial cation concentrations were used for the Cd(II)/Pb(II) binary system; Pb(II)=Cd(II) (200 mg/L=200 mg/L), Pb(II)>Cd(II) (300 mg/L>100 mg/L) and Pb(II) < Cd(II) (100 mg/L <300 mg/L). The same combinations were used for Pb(II)/Ni(II) and Cd(II)/Ni(II) binary systems. For all binary and ternary cation system bed depth was fixed 15 cm at constant flow rate 2 mL/min. comparison of single and binary system reveals maximum sorption capacity of cations for single metal system because, for the same number of binding groups, the competition between various metal ions increases. Regeneration of the Cd(II), Pb(II) and Ni(II) cations was achieved for UMF and XMF with 0.05 M HCl solutions via column at a constant flow rate and 15 cm bed height. For desorption of anions F- , NO3 - NaOH (0.1M) was used in continuous flow mode. The bed depth service time (BDST), the Thomas and Yoon-Nelson models were effectively applied to the breakthrough data of cations and anion biosorption. The study indicated that the immobilized powdered branches of UMF, XMF, PFR, and PXFR could be used for the effective removal of cations and anions respectively in a continuous flow mode.
Gov't Doc #: 20702
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