Activation of persulfate using CuS synthesized by ultrafast solid-state reaction for removal of organic pollutants from wastewater: Economical synthesis, catalytic performance, and mechanism

Abstract

The article presents a simple, ultrafast, economical, and efficient method for the synthesis of CuS with designed morphologies via solid-state reaction at room temperature. The morphology and structure of CuS were investigated using XRD, Raman spectra, FE-SEM, and HRTEM. Using different precursors as a sulfur source produced CuS samples with different morphologies. The prepared CuS was successfully used for catalytic activation of persulfate (PS) and applied for degradation of RhB as a model organic pollutant. The efficiency was significantly affected by the sample morphology where CuS prepared by Na2S displayed a superior PS activation performance with RhB degradation. Complete removal of RhB over CuS-Na2S/PS system was obtained within 5 min with a rate constant of 0.25 min−1 which is 10.86 and 5.20 times larger than that CuS-Tu/PS and CuS-S2O32−/PS, respectively. The impact of operating parameters, such as PS dosage, catalyst dosage, the initial pH, and interfering ions on the CuS-Na2S/PS system was optimized in detail. The potential mechanism for the catalytic activity of CuS was confirmed via using different radical quenchers, and the results indicated that both the OH. and SO4− radicals were generated during the PS activation process, while the OH. radical played a crucial role in the degradation process. Further, CuS-Na2S/PS system showed excellent efficiency for the removal of different cationic and anionic organic pollutants. The sample showed acceptable efficiency and good stability after 3 consecutive runs. Finally, the XRD patterns of CuS-Na2S/PS system before and after the recycling process are similar which confirmed its stability and reusability.