Optimized synthesis of CA/EDTA modified cotton fiber Fe complex as a sustainable hybrid photocatalyst for accelerating simultaneous removal of Cr(VI) and azo dye

Tartaric acid (TA), citric acid (CA), or butanetetracarboxylic acid ((BTCA)) was mixed with Na2EDTA to modify cotton fiber. Fe3+ ions were then used to coordinate with the resulting modified cotton fiber to produce a novel hybrid photocatalyst for enhancing simultaneous removal of Cr(VI) and azo dye from water. High concentration of TA or CA improved the activity of photocatalyst for Cr(VI) reduction and dye oxidation. CA/EDTA modified cotton Fe complex showed a better Cr removal efficiency than the other two complexes. Cr removal efficiency was further improved when the same molar ratio of CA and Na2EDTA was used. Increasing Fe content of the photocatalyst significantly improved its catalytic performance, especially at the acidic condition. The highest Cr removal efficiency was obtained at Fe content of 0.049 mmol g−1. Moreover, Cr species and dye molecules could almost entirely be removed using 50.0 g L−1 of CA/EDTA modified cotton Fe complex.