Adsorptive performance of an amine-functionalized poly(hydroxyethylmethacrylate)-grafted tamarind fruit shell for vanadium(V) removal from aqueous solutions

A novel adsorbent (PGTFS-NH3+Cl-) bearing -NH(3)(+)Cl(-)functional moiety was prepared from tamarind fruit shell (TFS) through graft copolymerization of hydroxyethylmethacrylate onto TFS in the presence of N N methylenebisacrylamide as a cross linking agent using K2S2O8/Na2S2O3 initiator system followed by transmidation and hydrochloric acid treatment The applicability of PGTFS-NH3+Cl- for the effective removal of vanadium(V) ions from aqueous solutions was investigated The maximum adsorption was observed in the pH range 3 0-60 The adsorption was fond to be concentration dependent and exothermic and the equilibrium was established within 4h The adsorption follows reversible second-order kinetics and the low E-a (-406 kj/mol) indicated a diffusion controlled process Equilibrium studies demonstrated that the adsorption process obeys Langmuir isotherm model and the maximum adsorption capacity of PGTFS-NH3+Cl- towards V(V) was 45 86 mg/g at 30 C The values of change in entropy (Delta S-0) and heat of adsorption (Delta H-0) for V(V) adsorption on PGTFS-NH3 Cl- were estimated as -47 20 J/mol K and -15 64 kJ/mol respectively The values of isosteric heat of adsorption (Delta H-l) were also calculated at different surface coverages The results indicate that PGTFS-NH3+Cl- used possessed nearly homogeneous surface sites The PGTFS-NH3+Cl- was evaluated for its efficiency in V(V) recovery from simulated groundwater The spent PGTFS-NH3+Cl- was regenerated using 02 M NaOH with up to 96% recovery and the adsorbent was reused in four adsorption-desorption cycles without any substantial loss in adsorption capacity (C) 2010 Elsevier B V All rights reserved