Comparative Study on the Adsorption Characteristics of Anionic, Cationic, and Non-Ionic Dyes by PVDF-PVA/GO Composite Membrane

The printing and dyeing wastewater has high chromaticity, biorefractory properties, and significant toxicity. In this study, PVDF-PVA/GO was synthesized for dyes' adsorption with various chemical properties. Incorporating graphene oxide (GO) into the composite substantially enhanced the hydrophilicity and electronegativity of the PVDF membrane. Results indicated that the adsorption efficiencies for rhodamine B (RhB) and methylene blue (MB) are higher than those of methyl orange (MO) and bromocresol green (BCG). At an initial pH of 8, the maximum adsorption capacities for RhB and MB were 11.81 and 9.25 mg/g, respectively, while MO and BCG indicated considerably lower capacities of 0.59 and 0.63 mg/g, respectively. The cyclic utilization of the PVDF-PVA/GO revealed minimal degradation in adsorption efficiency. The adsorption kinetics of the four dyes primarily follow intra-particle diffusion mechanisms, resulting in the binding of dye molecules to the PVDF-PVA/GO membrane through electrostatic interactions. Notably, competitive adsorption phenomena were observed in mixed dye systems, especially between RhB and MB. Comparative analyses indicated an increased adsorption capacity for MB in the mixed dye system, accompanied by a notable reduction in the adsorption capacity of RhB. This study provides a theoretical foundation for the remediation of printing and dyeing wastewater. PVDF-PVA/GO membrane was prepared for the printing and dyeing wastewater treatment.The loading of GO significantly improved the hydrophilicity of PVDF membranes.Anionic, cationic, and non-ionic dyes exhibited opposite adsorption.There are differences in adsorption between single-dye and mixed-dye systems.