Enhanced diclofenac adsorption and degradation using iron‐loaded modified spent bleaching earth carbon in the presence of clofibric acid: mechanistic insights and toxicity assessment

Abstract BACKGROUND The presence of pharmaceutical active substances such as diclofenac (DCF) and clofibric acid (CA) in aquatic environments poses significant ecological threats. Existing treatments have not fully explored the impact of CA on DCF removal efficiency. This research introduces nZVI/CTAB‐SBE@C, a novel adsorbent developed from industrial spent bleaching earth (SBE), modified with cetyltrimethylammonium bromide (CTAB) and nano zero‐valent iron (nZVI), enhancing both adsorption and degradation of DCF and CA. RESULTS This study investigated the impact of CA on the removal capabilities of nZVI/CTAB‐SBE@C for DCF in a coexisting system. Systematic examinations were conducted on the effects of various parameters, including reaction time, dosage, temperature, actual wastewater, humic acid content and coexisting ions. Results indicated that the presence of CA significantly enhanced the DCF removal efficiency, achieving an optimal rate of 87.3% under conditions of reaction time 2 h, adsorbent dosage 5 g L −1 and temperature 25 °C. Moreover, interactions between Al 3+ ions and the adsorbent matrix notably improved removal efficiencies for both DCF and CA. Analysis revealed that CA facilitated new degradation pathways for DCF, including hydroxylation and decarboxylation reactions. Additionally, the presence of CA reduced the toxicity of degradation intermediates, enhancing environmental safety compared to systems containing only DCF. CONCLUSION This study effectively transforms industrial waste into the efficient nZVI/CTAB‐SBE@C adsorbent. The presence of CA not only boosts DCF removal efficiency but also promotes its safer degradation, thereby reducing the ecological impact of contaminants. © 2024 Society of Chemical Industry (SCI).