Hierarchical CC/PANI/Fe(EDTA)x architectures: stable visible-light photocatalysts with synergistic carrier enhancement for sustainable Cr(VI) reduction

Solar photocatalysis offers a sustainable solution for chromium-laden wastewater remediation. Herein, we constructed a hierarchical CC/PANI/Fe(EDTA)_x photocatalyst through in situ growth of one-dimensional PANI nanoarrays doped with Fe(EDTA)_x on activated carbon cloth (CC) for the enhanced photocatalytic reduction of Cr(VI) based on the synergistic PANI/Fe(EDTA)_x interactions. The experimental results indicated that the doping of Fe(EDTA)_x onto the surface of CC/PANI facilitated directional charge migration and reduced the recombination efficiency of photogenerated carriers. In addition, EDTA and FeSO₄ concentrations significantly influenced activity, where optimal coordination minimized Fe leaching and maximized electron transfer. The optimized CC/PANI/Fe(EDTA)_x sample (CPFeE-5) achieved exceptional photocatalytic performance with 98.65% Cr(VI) removal within 80 min of visible light exposure. It was also suggested that lower pH (pH = 2) favored Cr(VI) reduction, yielding a rate constant 12.08 times and 21.15 times higher than at pH = 4 and pH = 6, respectively. Moreover, stability tests revealed an efficiency retention of 81.20% after five cycles, with straightforward separation achieved and structural integrity maintained, as evidenced by XRD and SEM analysis. All of these findings revealed that a stable supported photocatalyst platform through synergistic carrier engineering was established in this work, demonstrating practical potential for solar-driven wastewater detoxification.