Rate effected adsorption profile of selenium-thiocyanate complex onto polyurethane foam

The sorption of preheated selenium-thiocyanate complexes onto polyurethane (PUR) foam has been studied as a function of equilibration time (1-60 min), concentration of selenium (3.80 x 10^-4-4.39 x 10^-3 M) and amount of PUR foam. Maximum sorption (< 98%) has been achieved from 0.5 M hydrochloric acid solution within 20 minutes using 7.25 mg/cm³ PUR foam in the presence of 3.75 x 10^-2 M thiocyanate ions. The sorption data have been subjected to Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherms. The Freundlich parameters 1/n = 0.25 ± 0.02 and of K_F = 1.7 ± 0.2 mmole g^-1, Langmuir constants M = 0.23 ± 0.01 mmole g^-1 and of b = 23 ± 2 dm³ mmole^-1 and of D-R constants, C_m = 0.82 ± 0.04 mmole g^-1, β = -0.0032 ± 0.0002 mole² kJ^-2 and of E = 12.5 ± 0.2 kJ mole^-1 have been evaluated. The kinetic data have been subjected to Morris-Weber, Lagergren and Reichenberg equations and rate constants of intraparticle transport and first order have been computed. Thermodynamic parameters of enthalpy, entropy and Gibbs free energy suggest the endothermic and spontaneous adsorption of Se(IV)-SCN complex onto PUR foam at higher temperature. The influence of common anions and cations on the accumulation of selenium-thiocyanate onto PUR foam has been carried out. The possible sorption mechanism has also been discussed.