Facile synthesis of gC3N4/MoS2 composite for rapid sequestration of lead and methylene blue and its potential application in paint industry wastewater remediation

Abstract

In this study, a composite of graphitic carbon nitride coated Molybdenum Disulphide (gC3N4/MoS2) has been synthesized by thermal polymerization in a very cost-effective facile approach. The study explores the properties of synthesized gC3N4/MoS2 via various characterization techniques. It looks into its applications in the capture of Lead (Pb2+) and Methylene Blue (MB) in single and binary associations in a batch process and finally targets paint industry wastewater treatment. The uniqueness of the work lies in the ease of adsorbent synthesis and rapid sequestration of Pb from aqueous solutions of only Pb, Pb -dye, and Pb from the actual paint industry wastewater. Maximum Pb uptake capacity (qmax) attained was 60.06 mg/g at pH = 4, and Pb2+ concentration = 5–50 mg/L. The adsorption of Pb2+ followed Pseudo second order kinetics (R2 = 0.90–0.97) and Freundlich isotherm model (R2 = 0.90–0.98), where all models were plotted nonlinearly. Similarly, for MB qmax was 32.69 mg/g at pH = 6, and MB concentration = 10–60 mg/L. The adsorption of MB followed PSO and Elovich model with R2 0.96–0.98 and 0.99, respectively, and Freundlich model with R2 = 0.90–0.97. Pb2+ is readily adsorbed on gC3N4/MoS2 in the presence of MB, irrespective of contact time, adsorbent dose, and MB concentration. gC3N4/MoS2 rapidly captures Pb from the actual paint industry wastewater even with multiple competitive cations and anions, both organic and inorganic, with 99 % efficiency. Overall, the adsorbent gC3N4/MoS2 holds promise for treating Pb and dyes containing wastewater in terms of economy in synthesis and adsorption capacity.