Synergistic adsorption–photocatalytic removal toward levofloxacin and methylene blue by silver phosphate/strontium ferrite/graphene oxide composite under visible light irradiation

Combination of adsorption and photocatalytic degradation is an effective strategy for rapid elimination of organic pollutants from contaminated water. Herein, in order to improve the dispersion of catalyst, increase the reactive sites and facilitate the recovery of catalyst, a magnetic silver phosphate/strontium ferrite/graphene oxide (ASG) ternary composite was constructed through a two-step method. According to PL, UV–vis and photoelectrochemical characterization and adsorption experimental results, the ASG exhibits enhanced light absorption, reduced band gap, increased photocurrent response and improved adsorption ability compared to Ag 3 PO 4 and Ag 3 PO 4 /SrFeO. ASG showed remarkable adsorption–photocatalytic synergistic removal effect on levofloxacin (LEO) and methylene blue (MB). At room temperature, for 20 mg/L of initial LEO concentration, 0.67 g/L of ASG can absorb 80.7% of LEO, while the removal rate increases up to 95.5% under visible light irradiation within 180 min; for 20 mg/L of initial MB concentration, 0.67 g/L of ASG can absorb 100% of MB with 90 min, while the elimination time can be shortened to 45 min through adsorption–photocatalytic synergy. The cyclic experiments showed that the removal rates of LEO and MB by ASG remained above 80% after 5 adsorption–photocatalytic cycles, indicating that ASG has good stability and availability. In addition, a possible mechanism for removing LEO and MB by ASG is proposed based on the free radical capture experimental, UV–vis and photoelectrochemical results, which provides references for the rational design and construction of magnetic multifunctional photocatalysts for the efficient removal of organic contaminants in practical wastewater. Graphical abstract