Enhanced Cr(VI) degradation efficiency of Zn doped CuFeS₂ composites under visible light irradiation

Harmful metal ions and persistent organic pollutants in textile wastewater create a significant environmental problem. This study explore the photocatalytic activity of Sol-Gel synthesized CuFeS₂ composites doped with varying concentrations of Zn (1, 5, and 10 mol%) for the degradation of harmful Cr(VI) ions under visible light irradiation. XRD results showed that CuFeS₂@Zn 10 mol% composites exhibited a smaller crystallite size (11 nm) than the pure CuFeS₂ sample (23 nm) and FTIR analysis indicates Zn²⁺ incorporation into the CuFeS₂ structure. FESEM analysis shows a transition from a platelet to an amorphous morphology upon Zn doping. Band gap energy decreased from 2.41 eV to 2.09 eV for CuFeS₂@Zn 10 mol% composites. XPS peak shifts in Cu 2p, Fe 2p, and S 2p spectra after Zn doping indicate successful incorporation of Zn into the CuFeS₂ structure. BET analysis revealed an increase in surface area from 49 m²/g for pure CuFeS₂ to 139 m²/g for CuFeS₂@Zn 10 mol%.The CuFeS₂@Zn 10 mol% catalyst facilitated the reduction of Cr₂O₇²⁻ to Cr³⁺ within 100 min with a rate constant of 3.041 min⁻¹. 6 mg of CuFeS₂@Zn 10 mol% catalyst (prepared at pH 6) degraded Cr(VI) completely within 60 min. The Zn doped CuFeS₂ catalysts generated a greater number of h⁺ and e⁻, promoting Cr(VI) reduction through enhanced light absorption, improved charge separation, and greater redox capability. This study offers important findings for the design and development of highly efficient photocatalysts for toxic metal ion wastewater remediation.

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