Integration of SnFe2O4 nanoparticles onto BiOBr nanosheets to form a new 0D/2D Z-scheme nanocomposite for ameliorating synchronous visible light photocatalytic eradication of organic pollutants and Cr(VI) in wastewater

The escalating contamination of aquatic environments with organics and heavy metals, especially 2,4-dichlorophenoxyacetic acid (2,4-D) and hexavalent chromium (Cr(VI)), underscoring the urgent need for advanced and efficient remediation approaches. This work introduced novel 0D/2D SnFe2O4/BiOBr (SFO@BOB) nanocomposites which synthesized via a facile solvothermal route to enhance the synchronous photocatalytic 2,4-D degradation and Cr(VI) reduction. The integration of SFO nanoparticles onto BOB nanosheets efficiently restrained the photocarrier recombination and extended optical absorption of BOB to longer wavelengths. Hence, the optimized 20-SFO@BOB nanocomposite displayed an exceptional photocatalytic efficacy, outperforming individual BOB, SFO and physical mixture of 20-SFO + BOB. Such enhanced photoactivity mainly attributed to the Z-scheme charge transfer between BOB and SFO, thereby accelerating the photocarrier separation and maintaining high redox capability during photocatalysis. Furthermore, 20-SFO@BOB demonstrated robust tolerance across various water matrices, encompassing a wide pH range, diverse coexisting interference ions and humic acid. Along with the good versatility in treating real aquaculture effluent-containing a mixture of prevalent organic pollutants (2,4-D, paraquat, tetracycline and malachite green) and Cr(VI), the significant potential of 20-SFO@BOB for practical use was proven. Meanwhile, the toxicity results also validated that the photocatalytically treated aquaculture effluent did not demonstrate significant mortality on zebrafish. The hydroxyl radical played critical role in 2,4-D degradation, whereas Cr(VI) reduction was chiefly driven by photogenerated electrons. This research provided a new avenue for constructing multifunctional 0D/2D Z-scheme nanocomposite photocatalyst for sustainable and effective effluent treatment.