Interfacial charge-transfer in CoAl-LDH/CoOx for photocatalytic dye degradation and UV/H2O2 assisted real-wastewater treatment

Photocatalysis can decolorize dye-laden wastewaters using light, but practical catalysts often suffer from narrow absorption, charge recombination, and stability limits. Here we synthesize a carbonate-intercalated cobalt–aluminum layered double hydroxide hosting cobalt-oxide nanocluster (CoAl-LDH/CoOx) via a one-pot hydrothermal route and evaluate its performance for dye decolorization and UV/H2O2 treatment of real textile wastewater. Under UV irradiation, CoAl-LDH/CoOx accelerates discoloration of methyl orange (MO) and Congo red (CR), following pseudo-first-order kinetics (e.g., MO: ∼98% removal at 5 mg L−1 in 100 min; CR: ∼100% at 100 mg L−1 in 100 min; kapp up to 0.14 min−1). On real textile wastewater (ADMI0 = 608.1), UV/H2O2 with 0.5 g L−1 catalyst achieved ∼80% American Dye Manufacturer's Institute (ADMI) removal in 120 min at 48.96 mM H2O2; outdoor sunlight tests removed 82.5% (raw influent) and 50.8% (biologically treated effluent) over 20 h. Scavenger tests and EPR spin-trapping implicate h+ and ˙O2− as dominant species under UV, with ˙OH contributing when H2O2 is present. Five-cycle tests indicate stable activity. The one-pot CoAl-LDH/CoOx heterostructure provides a robust, recyclable platform for interfacial charge-transfer-assisted photocatalysis on realistic effluents and motivates follow-up on mineralization and leaching.