Carbon loaded zinc sulfo-oxide (C@Zn(S + O)) composite for efficient and rapid adsorptive removal of Congo red dye from wastewater: optimization, thermodynamics, isothermal and kinetics analysis
摘要
Developing hybrid materials with improved surface and structural properties plays key role in advancing wastewater purification methods. In the present study, a carbon-loaded zinc sulfo-oxide composite (C@Zn(S + O)) was prepared and investigated as a novel adsorbent for the remediation of Congo red (CR) dye-contaminated water. The synthesis of the composite was achieved through an uncomplicated wet-chemical procedure and exhibited significant adsorption efficiency, removing approximately 90% of CR under optimized experimental conditions. The adsorption process reached equilibrium quickly, in about 12.5 min, at an optimal pH ~ 7, with a maximum removal capacity recorded to be 245.1 mg g−1. Through comprehensive characterization and adsorption tests, it was revealed that the adsorption was both spontaneous (∆G° falling within −5.42 and −8.76 kJ mol−1) and endothermic (∆H° = 27.05 kJ mol−1), adhering to the Freundlich isotherm model and a pseudo-second order kinetic model. Adsorption occurred through a combination of π–π interactions, hydrogen bonding, Zn-mediated coordination interactions, and pore-filling within the mesoporous structure of the composite. Moreover, the adsorbent showed excellent reusable capabilities with adsorption capacity of 73.6% even after five cycles of use. The findings highlight its great potential as an effective solution for practical dye removal and wastewater treatment applications.
Graphical abstract