Comparative Investigation of Cd Adsorption on Alkaline Sandy Clay Loam Soil Treated with Cerium Oxide Nanoparticles, Organic and Inorganic Amendments

Adsorption via various organic and inorganic amendments is a principal mechanism to remediate cadmium contamination and decrease its entry into food chain. In present study, alkaline sandy clay loam soil, the cerium oxide nanoparticles (CeO2-NPs), rice husk biochar (RHB), rock gypsum (RGy) and farm manure (FYM) and alkaline sandy clay loam soil amended (1%) with these amendments were tested for effective Cd adsorption-desorption properties. The soil Langmuir estimated maximum Cd adsorption (Q(max)) was found to be 0.60 mg g(-1) (linear isotherm) and 0.65 mg g(-1) (non-linear isotherm) while among different amendments, CeO2-NPs had the maximum (88.23, 89.33 mg g(-1)) Q(max) and addition of this to soil resulted in 166% and 128% increase, while RHB, RGy and FYM also resulted in substantial increment in Cd Q(max) of soil. Second model was Freundlich isotherm (linear and nonlinear) which shows significant adsorption capacity (K-f) and adsorption intensity (N) on the amended soils. The Temkin isotherm gave us information about equilibrium binding (A) and latent heat of sorption (B) suggesting the adsorption reaction were overall exothermic in nature. The Cd adsorption trend as estimated by pseudo second order kinetic model (PSO) suggest that soil has a net adsorbed Cd (Q(a)) of 0.76 mg g(-1) while a net desorption (Q(d)) of 0.23 was observed making a net 30% desorption. The inclusion of CeO2-NPs in soil (1%) resulted Q(a) of 1.97 mg g(-1) and Q(d) of 0.42 mg g(-1) which is a net 21% desorption. Other amendments RHB, RGy and FYM also resulted in net lower Cd desorption with 22, 27 and 26% Q(d) respectively. The CeO2-NPs is best amendment for effective Cd removal from water.