Environmental remediation through bimetallic sulphide-derived adsorbents: Prospects and progress

Abstract

The present study explores the cost-effective and simple co-precipitation technique for the synthesis of bimetallic sulphide, Mn-Co-S@CTAB, nanomaterial, a hybrid of Manganese and Cobalt sulphide along with some surface modification through hexadecyltrimethylammonium bromide (CTAB). Congo red (CR) and Malachite green (MG) dyes were adsorbed out of their solutions onto the surface of produced nanomaterial and whole process has been studied. The adsorption mechanisms for the CR and MG sorption onto the surface of Mn-Co-S@CTAB has been proposed on the basis of investigation of thermodynamics and kinetics of the whole sorption process. To investigate the structural and morphological features of the synthesized nanomaterial, a systematic characterisation were done using FT-IR, P-XRD, SEM-EDX, TGA, TEM, XPS and Zeta Potential measurement were conducted. In order to achieve maximum efficiency, the sorption parameters, including the initial dye concentration, adsorbent dosage, temperature, contact time, and pH of the solutions have been optimized. The Mn-Co-S@CTAB demonstrated strong affinity for CR and MG dyes with sorption capacities of 263.15 and 163.93 mg g-1at 303 K. The positive value of enthalpy, ΔH, indicated the adsorption process to be endothermic for both dyes, while negative free energy change, ΔG, indicated the spontaneous nature of adsorption of these dyes. The Freundlich and Temkin isotherm models provided the closest fit to the data for isotherm investigations for CR and MG sorption onto Mn-Co-S@CTAB, while kinetics of reaction in the examined temperature range followed pseudo-second order kinetics.