Optimizing the removal of Reactive Blue21 using non-metallic carbon nitride photocatalyst by Response Surface Methodology

Due to their special molecular structure, industrial effluents, such as effluents containing colored compounds, have one or more benzene rings with a resistant structure. This type of colored compounds is toxic and difficult to decompose. These effluents should be treated before being discharged into the environment, and thus treating the wastes containing dyes is one of the major environmental challenges and need to be conducted using an appropriate approach. In this study, an advanced oxidation method using a non-metallic carbon-nitride photocatalyst was used to remove the Reactive Blue21 dye. Carbon-nitride photocatalyst was prepared from urea-formaldehyde resin precursor with urea to a formaldehyde ratio of 1.25 The structure and properties of the photocatalyst produced were evaluated and confirmed using SEM, FT-IR, XRD and DRS analyses. The efficiency of the as-prepared photocatalyst was evaluated according to its capability for degradation of Reactive Blue21. Finally, to achieve maximum dye removal via the photocatalytic process, the effective parameters such as solution pH, the dose of the photocatalyst, and exposure time were optimized according to response surface methodology (RSM). The results showed that all three parameters are significantly effective in color removal. However, the effect of decreasing pH and color concentration was greater than increasing the amount of photocatalyst. Also, under optimal conditions, the percentage of paint removed was more than 99%. Based on the obtained results, the carbon nitride photocatalyst synthesized in this research can be used as an ideal cheap material to remove textile dyes from industrial wastewater.