The removal of Rhodamine B by HO or ClO combined with hydrodynamic cavitation.

Rhodamine B (RhB), widely used as an industrial dye, is a toxic organic that is hazardous to human health and can cause water pollution. In this study, the removal rate of RhB was investigated by the following methods: hydrodynamic cavitation (HC) operated individually, and HC combined with oxidants HO or ClO. The effect of different operating parameters including pressure (2-6 bar) and initial pH (2-8) on the extent of degradation was investigated using an orifice plate as the cavitation device to achieve maximum removal of RhB. Under the parameters of HC, the effect of different loadings was investigated: HO (n(RhB):n(HO) was varied from 1:17.60 to 1:211.28) and ClO (n(RhB):n(ClO) was varied from 1:8.87 to 1:177.53). A combination of cavitation and HO or ClO resulted in degradations of 80.6% and 95.3%. The results indicated that the combination of HC and oxidants was better than the individual HC process for the degradation of RhB. When combining HC with HO or ClO, the synergistic coefficients of 62.54 and 74.79 were obtained. The combination of HC and ClO was proven to be more effective for the removal of RhB compared to HC alone and the hybrid process of HC and HO.