Removal of Zn(II) ions from aqueous solution using BPHA-impregnated polyurethane foam

Zn(II) ions sorption onto N-Benzoyl-N-Phenylhydroxylamine (BPHA) impregnated polyurethane foam (PUF) has been studied extensively using radiotracer and batch techniques. Maximum sorption (similar to 98%) of Zn(II) ions (8.9 x 10(-6) M) onto sorbent surface is achieved from a buffer of pH 8 Solution in 30 minutes using 7.5 mg/mL of BPHA-impregnated polyurethane foam at 283 K. The sorption data follow Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherms. The Langmuir constants Q = 18.01 +/- 0.38 mu mole g(-1) and b = (5.39 +/- 0.98) x 10(3) L mole(-1) have been computed. Freundlich constants l/n = 0.29 +/- 0.01 and C-m 111.22 +/- 12.3 mu mole g(-1) have been estimated. Sorption capacity 31.42 +/- 1.62 mu mole g(-1) beta = -0.00269 +/- 0.00012 kJ(2) mole(-2) and energy 13.34 +/- 0.03 kJ mole(-1) have been evaluated using D-R isotherm. The variation of sorption with temperature yields Delta H = -77.7 +/- 2.8 kJ mole(-1), Delta S = -237.7 +/- 9.3 J mole(-1) K-1 and Delta G = -661.8 +/- 117.5 kJ mol(-1) at 298 K reflecting the exothermic and spontaneous nature of sorption. Cations like Fe(III), Ce(III), Al(III), Pb(II) and Hg(II) and anions, i.e., oxalate, EDTA and tartrate, reduce the sorption significantly, while iodide and thiocyanate enhanced the sorption of Zn(II) ions onto BPHA-impregnated polyurethane foam.