Enhanced adsorption performance and regeneration of magnetic Fe3O4 nanoparticles assisted extracellular polymeric substances in sulfonamide-contaminated water.

It is still unclear about the superiority of the nanoscale Fe3O4-assisted extracellular polymeric substances (EPS) compared to traditional EPS and its application feasibility in sulfonamide-contaminated aqueous system. This study reported eco-friendly and reusable EPS/Fe3O4 was applied in the sulfonamide-contaminated water treatment, including sulfamethoxazole (SMX), sulfamerazine (SM1), sulfamethazine (SM2) and sulfadiazine (SDZ), respectively. EPS/Fe3O4 exhibited the adsorption performance of 77.93%, 74.13%, 65.62%, and 56.64% for SMX, SM1, SM2 and SDZ, respectively, increased by 7.93%, 19.02%, 13.78% and 9.93% compared to traditional EPS. The initial pH value tuned adsorption performance via varying existing species of each sulfonamides. The adsorption process could be well fitted by Freundlich and pseudo-second-order kinetics models. Moreover, the multiple evidences from SEM, FTIR, zeta potential and XRD explained the adsorption mechanisms (i.e., chemisorption, ion exchange, hydroxyl group and hydrophobicity). Desorption and recycle adsorption experiments demonstrated the well regeneration ability of EPS/Fe3O4 as biosorbent (67.12% adsorption performance for SMX after five adsorption-desorption cycles), suggesting EPS/Fe3O4 was considered as a superior choice for sulfonamide-contaminated water treatment compared to the unrecyclable EPS.