Interfacial Si–O–Zr bonds induced well dispersed zirconia on magnetic mesoporous silicas for enhanced tetracycline removal

Constructing recoverable materials with both high adsorption capacity and excellent photocatalytic performance towards antibiotics elimination is very meaningful and challenging in wastewater remediation. In this work, we demonstrate a simple interface engineering strategy to design well dispersed zirconia on core–shell structured magnetic mesoporous silica microspheres (MMS) for efficient removal of tetracycline hydrochloride (TC). With ultrahigh specific surface area (682.0 m2/g) and interfacial Si-O-Zr serving as active sites, the optimal sample (MMS-Zr10) exhibits enhanced TC adsorption capacity of 266.5 mg/ZrO2 g, which is 19.2-fold than that of pure ZrO2. Simultaneously, the photocatalytic degradation rate constant of TC over MMS-Zr10 in the presence of peroxydisulfate (PDS) is 12.5 times that of ZrO2 under visible light irradiation, which may be attributed to the enhanced light harvest capability and high charge separation efficiency facilitated by interfacial Zr–O–Si charge transfer channels. Furthermore, in consecutive adsorption cycles in both deionized (DI) water solution and actual wastewater, no obvious decline in TC removal % is observed. The TC adsorption is mainly governed by pore filling, hydrogen bonding and electrostatic interactions; whilst O2•−, h+, SO4•−, •OH and 1O2 species are responsible for enhanced photocatalytic degradation of TC.