Insight into the adsorption thermodynamics, kinetics, and photocatalytic studies of polyaniline/SnS2 nanocomposite for dye removal

Abstract

The study aims to address the synthesis, the kinetics of adsorption, and photocatalytic application of Polyaniline/tin sulfide (PANI/SnS2) nanocomposite against brilliant blue (BB) dye. PANI/SnS2 was prepared by in-situ polymerization of the aniline to which hydrothermally synthesized SnS2 was added. Adsorption thermodynamics and kinetics of PANI/SnS2 were discussed against the BB dye using Langmuir and Freundlich adsorption isotherm. Maximum adsorption capacity (qm) and adsorption equilibrium constant (K) were found to be 165.2 mg g−1, and 0.027 min−1. Moreover, Adsorption kinetics were studied by the pseudo-first and second-order reactions. The adsorption rate constant k1 and diffusion rate constant k2 were found to be 0.1274 and 0.0233 min−1. PANI and SnS2 with tunable band gap energy, adsorption, and redox property exhibited excellent activity towards the photodegradation of BB dye. The effect of heterojunction between PANI/SnS2 was observed by an increased rate of transfer of electrons. The rate constant was highest in the case of PANI/SnS2 (20%), which is 0.0172 min−1 and a maximum of 96.2% of BB dye was degraded in 45 min. The hydroxyl (•OH) and superoxide (•O2−) radicals were generated during photocatalysis that degrades the BB dye into nontoxic products, which were confirmed by the trapping experiment. The obtained results indicate the excellent adsorption and photocatalytic activity of PANI/SnS2 nanocomposite.