Enhancing textile wastewater decolorization: harnessing the power of diverse oxidants in photo-oxidation process with response surface methodology

In the photo-oxidation processes, the oxidants play a vital role in removing color. However, a comprehensive comparison of the three common oxidants’ performance for color removal from textile wastewater has not been conducted. Also, the effect of periodate in the presence of ferrous for color removal has not been investigated extensively. The object of this study was to evaluate and compare the effect of three common oxidants on the removal of color. Central composite design was employed to design the experiments and evaluate the interaction between parameters and their impact on color removal. The photo-oxidation processes were carried out under UV light irradiation (60 W) in the presence of ferrous (Fe²⁺) and three oxidants, namely hydrogen peroxide (H₂O₂), sodium persulfate (SPS), and sodium periodate (SPI). The four main variables were the reaction time, the pH value, the concentration of oxidants, and the concentration of ferrous. Finally, the optimal values for all parameters were shown and these three processes were compared with each other. Although the UV/SPI/Fe²⁺ process had the highest color removal (96%), by considering all parameters, the UV/SPS/Fe²⁺ was a better choice because of its high efficiency, low reaction time, and low oxidant concentration. The results suggested that the photo-Fenton process could not be a good option among these processes, as it required the longest reaction time and highest oxidant concentration while achieving the lowest removal efficiency (82%). The results of this study can help with the decision-making process to select a better process for textile wastewater treatment.