Cost-effective and efficient degradation of dissolved organic pollutants via intrinsic synergistic adsorption-photocatalysis of commercial activated carbon fiber

This study explores the intrinsic photocatalytic activity of viscose-based activated carbon fibers (ACFs) and their synergistic adsorption-photocatalysis mechanism under visible light. Two commercial ACFs were pretreated, with one further oxidized using nitric acid. Tetracycline (TC) served as the model pollutant. Results revealed that adsorption capacity was positively correlated with defect density, while photocatalytic performance depended on the sp²-hybridized carbon content. After 90 min, TC removal efficiencies for adsorption and combined adsorption-photocatalysis were 17.6 %/91.3 % and 7.3 %/85.5 %, respectively. Excellent mineralization was also achieved, with COD/TOC removal rates of 85.1 %/85.4 % and 73.4 %/75 %. ACFs maintained high TC degradation over a wide pH range (3–9), and the superior sample achieved 99.4 % TC removal within 20 min at an aeration rate of 1.0 L/min. OH and O₂⁻ were identified as the dominant reactive oxygen species. The materials exhibited excellent regeneration capability through high-temperature calcination. Practical application tests confirmed their effectiveness under sunlight and against a range of organic pollutants. These results highlight the potential of pristine viscose-based ACFs as low-cost, sustainable materials for advanced wastewater treatment.