Dual-sonochemical activation of α-Fe2O3@Illite for Fenton oxidation of phenol and real wastewater application: Mechanistic insights and by-product evolution

Abstract

• A novel dual-sonochemical Fenton process using 5 % Fe@SCRT for effective phenol degradation. • α-Fe 2 O 3 @Illite exhibits high catalytic activity and stability under acidic conditions. • Mechanistic investigation confirms the dominant role of ● OH and ● O 2 – radicals in phenol oxidation. • Detoxification is confirmed through fish survival and seed germination tests, ensuring environmental safety. • Cost assessment demonstrates the process as a feasible, eco-friendly approach for real wastewater treatment. This study developed a dual-sonochemical activation strategy to enhance phenolic Fenton oxidation at 200 mg/L, employing iron-impregnated Illite (5 % Fe@SCRT) as a heterogeneous catalyst. Complete removal of phenol from the aqueous solution was achieved by optimizing the degradation process at pH 3, 1 g/L catalyst dose, and 10 mM H 2 O 2 within 80 min. The mechanistic study, supported by scavenger tests, provided evidence that hydroxyl radicals and superoxide radicals played a dominant role in the oxidation of phenolics. The results of this experiment show evidence of various by-products, among others, hydroquinone, catechol, and organic acids; therefore, these by-products provide insight into the degradation pathway. Structural, morphological, and chemical characterizations (FTIR, XRD, BET, CEC, Laser Granulometry, XRF, and SEM-EDX) confirmed the stability and efficiency of the catalyst over multiple cycles. An economic analysis of the process further supports the economic feasibility of the Sono-Fenton process, highlighting energy consumption as a major contributor to overall expenditure. Detoxification was confirmed by fish survival and seed germination tests, where the treated water showed low toxicity. In addition to tests on synthetic phenol solutions, the developed dual-sonochemical Fenton system was effectively applied to real olive mill wastewater (OMW), achieving significant pollutant removal and demonstrating the catalyst’s practical applicability. These results present great promise for Sono-Fenton oxidation with 5 % Fe@SCRT as a green and efficient method for the removal of organic pollutants found in wastewater.