Iron oxide/alginate hydrogel composites for removal of tetracycline via adsorption-coupled Fenton-like reaction

Adsorption has been applied as a useable technique for the treatment of tetracycline (TC) contaminated wastewater, however, complete removal of TC without secondary contamination using adsorption is still challenging. Recently, new strategies by coupling adsorption with degradation protocol are considered as promising candidate for water treatment. Herein, iron oxide nanoparticle-doped hydrogel particles (Fe3O4@SiO2–NH2/SA) were prepared by introducing amino-functionalized Fe3O4@SiO2 into Fe2+-crosslinked alginate hydrogel and evaluated as adsorbent-promoted catalyst for TC removal via adsorption-coupled Fenton-like reaction (ACFLR). These composite particles can effectively adsorb TC molecules by π-π interaction, hydrogen bonding and electrostatic interaction, leading to a relatively high adsorption capacity at 588.41 mg g−1. Interestingly, the adsorption and concentration of TC on the adsorbent would facilitates its degradation via Fenton-like reaction, since the decreased distance of neighboring TC and Fenton-like catalytic sites enhanced the efficiency of short-lived reactive oxygen species. The removal efficiency of TC by ACFLR was up to 98.76% at 4 h, which is strongly enhanced compare to that obtained by adsorption alone (44.73%). Results above indicate that the hydrogel composite is potential adsorbent-promoted catalyst for the effective removal of TC in aqueous environment via ACFLR.