Mechanochemical synthesis of zinc-silicon hydrophobic material with efficient charge carrier separation for antibiotic removal in high-salt water under visible light

Persistent antibiotic residues, such as tetracycline (TC), in mariculture wastewater pose significant challenges during the photocatalytic degradation process, including the high salinity-induced occupation of active sites and the high-energy light-induced energy consumption. Herein, a novel hydrophobic porous zinc‑silicon hybrid material (Zn-Si@SMS) was rapidly synthesized at room temperature through H 2 O-assisted grinding of sodium methylsilicate and zinc acetate. The low surface energy groups (–CH 3 ) endow Zn-Si@SMS with hydrophobicity, which facilitates selective pollutant adsorption in saline environments, solving the common issue of salt ion interference. Additionally, oxygen vacancies can enhance visible light absorption and charge carrier separation, thus enabling the direct utilization of visible light. It can also enhance the adsorption of tetracycline, thereby improving degradation efficiency. Specifically, under visible light and in a high-salt environment, Zn-Si@SMS achieves high degradation efficiencies for tetracycline (removal rate >96.2 %). Zn-Si@SMS demonstrates high efficiency in degradation of various antibiotics (tetracycline (removal rate >98.5 %), oxytetracycline (removal rate >96.6 %), doxycycline hydrochloride (removal rate >97.4 %), ciprofloxacin (removal rate >87.5 %), and norfloxacin (removal rate >94.9 %) in highly saline water (NaCl, KNO 3 , KCl, CaCl 2 , NaBr, Na 2 SO 4 ) under natural sunlight and 96 % removal rate in actual seawater within 1 h. This system avoids the use of costly metals (Bi, Cu, In, Ag) and high-temperature synthesis processes (>120 °C). The affordability of Zn-Si@SMS highlights the potential of tetracycline degradation by visible light, offering a green and sunlight-driven solution for water purification.