Efficient catalytic degradation of crystal violet dye over FeVO4 by spark plasma discharge: an eco-friendly approach for wastewater treatment

Abstract In the present study, catalytic degradation of crystal violet (CV) dye over ferric vanadate (FeVO 4 ) nanocatalyst was evaluated in the presence of spark plasma discharge and without additive oxidants. Spark plasma process, as a green technique and without the need for feed gas, can generate the oxidizing species which are capable of dissociating dye molecules in wastewater. Herein, FeVO 4 was synthesized by a hydrothermal method and thereupon utilized to remove CV dye under spark plasma discharge. FeVO 4 was introduced into the spark plasma system to increase reactive species activation and promote synergistic plasma-catalytic degradation without the need for external oxidants. The structural and morphological properties of the prepared catalyst were examined by XRD, FTIR, FESEM, EDX, and UV-vis DRS. The results indicated that the spark plasma enhanced catalytic activity of FeVO 4 , and subsequently facilitated the decomposition of CV dye. It was determined that the highest dye degradation efficiency occurred at pH 7.7, where about 99.4% of CV with an initial concentration of 10 mg.L −1 was decomposed after 10 min of the spark plasma treatment. Moreover, the results of radical trapping revealed that holes (h + ) and singlet oxygen ( 1 O 2 ) generated by spark plasma are the dominant agents in the oxidation and dye degradation process. Plasma-generated reactive oxygen/nitrogen species interact with the surface of FeVO 4 and increase the oxidative degradation of CV. The kinetic studies of the dye degradation process indicated that the pseudo-first-order kinetic model could explain it well. These results were obtained in the absence of oxidants, which subsequently reduces the cost of dye degradation, enhances operational safety by removing hazardous materials, and simplifies wastewater treatment operations.