Facile fabrication of embedded g-C3N4/MoS2 nano-adsorbent for the removal of persistent rhodamine B contaminant in aqueous solution

Abstract

Industrial wastewater containing different organic, inorganic, and biological components has become a major issue as far as the sustainable growth of society is concerned. The presence of organic dyes in effluents causes several health issues in both human and aquatic life. Herein, pristine inorganic nanocomposite consisting of g-C₃N₄ and MoS₂ (1 : 1 wt%) has been synthesized by a facile calcination method for the selective adsorptive removal of rhodamine B (RhB) in aqueous solutions. Different characterization techniques such as SEM, TEM, EDX, FTIR, XRD, BET, and zeta potential have been used to know the desired properties of the composite materials. The experiments were conducted by varying the dye concentration, adsorbent dosage, and pH to investigate the optimum removal performance of RhB by the prepared composite material. The composite nanomaterial showed fast adsorption, achieving nearly 92.0% removal in the first 15 min, which was much higher than that of individual bare nanomaterials. A BET surface area of 41.59 m² g⁻¹, structural changes as shown in SEM, and a zeta potential of −19.03 mV also support the probable causes for this fast removal. The highest adsorptive removal percentage of RhB was observed to be 97.1% in 90 min at a pH of 7 with 20 ppm initial RhB concentration and 1.0 g L⁻¹ adsorbent dosage for the engineered nanocomposite material. The synthesized composite displayed satisfactory reusability performance, achieving nearly 70% removal of the contaminant after four cycles. The isotherm, kinetic, and thermodynamic studies were also performed to understand the adsorptive performance characteristics of the nanocomposite materials. The system satisfied the Langmuir isotherm (R² = 0.9839) and second-order kinetic model (R² = 0.9999), which may corroborate the chemisorption behavior with the monolayer formation of RhB on the material. In addition, the thermodynamic study observed the endothermic nature and spontaneous reaction process of the system.