Graphene oxide and chitosan composite material using as a high-efficiency and low-cost granular adsorbent for methylene blue removal was fabricated via self-assembling method. The effects of pH value, contact time, initial concentration, adsorbent dose, temperature, and recyclic stability on the adsorption performance of methylene blue in aqueous solution were investigated in detail. Desorption process with the effects of solvents, contact time, and temperature were also conducted carefully in this study. The adsorption kinetics and adsorption isotherm of dye adsorption process showed that dye adsorption process was fitted to the pseudo-second-order kinetic model and the Freundlich adsorption isotherm, indicating a physical adsorption process with multilayer adsorption. The intra-particle diffusion model indicated that the dye adsorption by the granular adsorbent was strongly happened during the first 4 h. The thermodynamic study showed that the adsorption was a spontaneous and exothermic process and dye ions were condensed onto the surface of adsorbent. The maximum adsorption capacity of dye on the granular adsorbent was calculated as 951.35 mg/g and the adsorbent could maintain its adsorption performance after six cycles. In general, this study provided an efficient, cost-effective, and recyclable the granular adsorbent for dye separation from aqueous solution.

Residual antibiotics and organic dyes in wastewater have gained the current challenge all over the world because of their toxicity to humans and the environment. In this study, the bimetallic porous FeZn-ZIFs materials were successfully prepared under mild conditions at room temperature and atmospheric pressure and characterized by various techniques. The FeZn-ZIFs were used as a heterogeneous catalyst to remove tetracycline antibiotics (TC) and methyl violet 2B dyes (MV) in an aqueous solution by activating peroxymonosulfate (PMS) and peroxydisulfate (PDS), respectively. The catalytic activity of FeZn-ZIFs towards TC and MV under different oxidant dosages, the catalyst dosage, the initial pollutant concentration, contact time, and reaction temperature were optimized. The results indicated that FeZn-ZIFs was an efficient catalyst for removing TC and MV based on advanced oxidant processes, having a removal capacity of 92% at TC concentration of 50 mg·L ⁻¹ and 95% MV concentration of 20 mg·L ⁻¹ . More importantly, this bimetallic catalyst was identified the superior structural stability when the removal efficiency of TC and MV was maintained at approximately 90% after five cycles. In short, the FeZn-ZIFs and PMS/PDS system exhibited a promising application prospect for antibiotic and dye-containing wastewater treatment.