Two-step fabrication of cellulose embedded Fe3O4/Fe3+ composite beads as catalyst in degradation of sulfamethoxazole in floating bed reactor

Abstract

In this study, magnetite particles were successfully embedded in sodium carboxymethyl cellulose as beads using FeCl3 as the cross-linker in two step-method and it was used as a Fenton-like catalyst to degrade sulfamethoxazole in aqueous solution. The surface morphology and functional groups influence of the Na-CMC magnetic beads was studied using FTIR and SEM analysis. The nature of synthesized iron oxide particles was confirmed as magnetite using XRD diffraction. The structural arrangement of Fe3+ and iron oxide particles with CMC polymer was discussed. The influential factors for SMX degradation efficiency were investigated including the pH of the reaction medium (4.0), catalyst dosage (0.2 g L−1) and initial SMX concentration (30 mg L−1). The results showed that under optimal conditions 81.89% SMX degraded in 40 min using H2O2. The reduction in COD was estimated to be 81.2%. SMX degradation was initiated neither by the cleaving of C–S nor C–N followed by some chemical reactions. Complete mineralization of SMX was not achieved which could be due to an insufficient amount of Fe particles in CMC matrix that are responsible for the generation of *OH radicals. It was explored that degradation followed first order kinetics. Fabricated beads were successfully applied in a floating bed column in which the beads were allowed to float in sewage water spiked with SMX for 40 min. A total reduction of 79% of COD was achieved in treating sewage water. The beads could be used 2–3 times with significant reduction in catalytic activity. It was found that the degradation efficiency was attributed to a stable structure, textural property, active sites and *OH radicals.