Performance of poly sulfonamide/nano-silica composite for adsorption of thorium ions from sulfate solution

Abstract

A new composite of poly sulfonamide/nano-silica composite (PSA/silica) was synthesized from the polymerization of sulfonamide in the presence of the prepared nano-silica. The prepared nano-silica, poly sulphonamide (PSA), and PSA/silica composites were utilized for Th(IV) adsorption from sulfate solution. These composites described by XRD, surface area analysis, SEM–EDX, and FT-IR techniques. The influence parameters on the Th(IV) adsorption were pH solution, ionic strength, contact time, adsorbent dose, Th(IV) concentration, and temperature besides the coexisting ions. At best parameters (pH4, 0.1 g adsorbent amount, and 45 min contact time), 200 mg/L Th(IV) ions were quantitatively adsorbed from 100 mL solution. The maximum uptake capacities of the nano-silica, PSA, and PSA/silica composites attained 122, 75, and 197 mg/g at 298 K. From the kinetic and equilibrium data were found to the adsorption processes of three composites fitted well with kinetic model of pseudo-second-order and Langmuir adsorption isotherm model. Thermodynamic studies resulted that negative values for ∆H° indicated an exothermic while positive values ∆S° showed random behavior for Th(IV) adsorption, while negative values of ∆G° indicated spontaneous Th(IV) adsorption. The maximum Th(IV) desorption from the loaded adsorbents performed by 0.1 M/L HCl.