Enhanced Heterogeneous Catalysis of Peroxymonosulfate Using Chitosan/Co-ZSM-5 Composite Spheres for Rapid Water Decontamination

The discharge of organic contaminants into the environment has recently become a major concern. This study examines the removal of two target contaminants: the tetracycline antibiotic (TC) and Eosin Y dye, by synthesizing catalysts from two waste streams: used silica gel from column chromatography and chitosan (CS) from crustacean waste. First, Zeolite Socony Mobil-5 zeolite (ZSM-5) was synthesized from used silica gel through a hydrothermal process. Next, ZSM-5 was doped with cobalt nitrate at various loadings to produce cobalt-doped ZSM-5 (Co-ZSM-5). The Co-ZSM-5 particles served as catalysts to activate peroxymonosulfate (PMS) for degrading TC. The optimal cobalt loading was 10%, resulting in 70% degradation of TC after 100 min at 0.15 g/L PMS. To improve handling and separation of the catalyst, the 10Co-ZSM-5 particles were immobilized within cross-linked CS, forming CS/10Co-ZSM-5 composite spheres. The composite spheres showed superior performance in degrading Eosin Y, achieving complete degradation within 10 min at a dosage of 6 g/L, with an Eosin Y concentration of 10 mg/L and a PMS concentration of 1.5 g/L. Both radical and nonradical pathways were involved in degrading Eosin Y, and superoxide was the major reactive oxygen species. The composite spheres remained effective when tested in real water samples. Additionally, they could be reused for at least three cycles while maintaining high stability and low cobalt leaching. Toxicity assessment through mung bean germination indicated a decrease in the toxicity of Eosin Y following treatment. Moreover, the catalyst could effectively degrade other dyes, including rhodamine B and Reactive Black 5. In addition to remediating hazardous water contaminants, this study offers a sustainable method for the use of industrial and crustacean waste.