Enhanced activated persulfate oxidation of ciprofloxacin using a low-grade titanium ore under sunlight: influence of the irradiation source on its transformation products

A chemometric approach to the interaction of hydrogen peroxide and thermally activated persulfate in the removal of aromatic compounds

This study evaluates the combined use of H₂O₂ and thermally activated S₂O₈2⁻ (T-PDS) for the degradation of phenolic compounds (PhOH) in wastewater, aiming to limit or eliminate sludge production. Phenolic compounds are common in industrial effluents, and their effective removal is crucial for reducing environmental impact. The study employs Response Surface Methodology (RSM) and Principal Component Analysis (PCA) to optimise critical variables such as temperature, pH, and oxidant concentrations. Optimal conditions were determined to be a temperature of 70 °C, pH 5, and a H2O2/S2O82- molar ratio of 1:6. Under these conditions, the system achieved an 89% PhOH degradation efficiency, reducing the concentration from 10 to 1.2 mg L-1 after 120 min of treatment. The kinetic analysis revealed a rapid initial reduction in PhOH concentration by 38% (from 10 to 6.2 mg L-1) within the first 15 min, followed by a slower degradation phase. This suggests a complex reaction mechanism, likely influenced by oxidant consumption and intermediate formation. The model demonstrated high precision, with R2 values of 0.99 for PhOH and S2O82-and slightly lower for H₂O₂ (R2 = 0.98). A brief cost analysis estimated the treatment cost at €6.86 per cubic meter of wastewater, showing the economic viability of the process. Additionally, eliminating sludge formation reduces operational costs related to sludge management and disposal, making the H2O2/T-PDS system a promising solution for large-scale industrial applications in sustainable wastewater treatment.

Efficient degradation of minocycline by natural bornite-activated hydrogen peroxide and persulfate: kinetics and mechanisms

Natural bornite (NBo), a sulfide mineral of copper and iron, is one of the main mineral raw materials for copper extraction. In this study, NBo-activated hydrogen peroxide (H₂O₂) and persulfate processes (PS) for the degradation of minocycline (MNC) in aqueous solution were systemically investigated and compared. The MNC removal rates with the NBo/PS and NBo/H₂O₂ processes were 86.40% and 87.50%, respectively. The mineralization rate of NBo/PS (33.96%) was higher than that of NBo/H₂O₂ (29.94%) after reaction for 180 min. The effects of oxidant and activator dosage, pH, common inorganic anions (i.e., Cl^-, NO₃^-, and HCO₃^-), and water composition on MNC degradation were systematically evaluated. In addition, the degradation of MNC in natural water matrix and toxicity evaluation was also studied to better evaluate the feasibility of practical application of those two processes. The results of free radical quenching experiments and electron paramagnetic resonance spectroscopy (EPR) showed that HO· was the main activated species in the NBo/H₂O₂ system, while SO₄^·- and HO· were the main activated species in the NBo/PS system. The degradation of MNC in the NBo/PS system was achieved through electron transfer, while the degradation of MNC in the NBo/H₂O₂ system was mainly achieved through free radical addition. The degradation pathway mainly included deamidation reactions, C-C bond breakage and hydroxylation. Reusability of NBo showed that NBo was considerably stable in activating PS and H₂O₂ for degradation of MNC, which was cost-effective activator. This work provides a new perspective on the degradation mechanism of pollutants by Fe-Cu bimetallic sulfide activation of PS and H₂O₂.