Phenol depletion by thermally activated peroxydisulfate at 70°C

The ability of thermal activated peroxydisulfate (PS) of mineralizing phenol at 70 °C from contaminated waters is investigated. Phenol in concentrations of 10⁻⁴ to 5 × 10⁻⁴ M is quantitatively depleted by 5 × 10⁻³ to 10⁻² M activated PS in 15 min of reaction. However, mineralization of the organic carbon is not observed. Instead, an insoluble phenol polymer-type product is formed. A reaction mechanism including the formation of phenoxyl radicals and validated by computer simulations is proposed. High molecular weight phenolic products are formed by phenoxyl radical H-abstraction reactions. This is not the case for the room temperature degradation of phenol by sulfate radicals where sulfate addition to the aromatic ring mainly leads to the generation of hydroxycyclohexadienyl radicals leading to hydroxybenzenes and oxidized open chain products. Therefore, a change in the reaction mechanism is observed with increasing temperature, and thermal activation of PS at 70 °C does not lead to the mineralization of phenol. Thus PS activation at 70 °C may be considered a potential method to reduce the load of phenol in polluted waters by polymerization.     

Improving sludge dewaterability via Fe2+ chelated citrate activated peroxydisulfate oxidation

Citrate (Ct) was chosen as a typical chelator used in the Fe²⁺-peroxydisulfate (PDS) process to improve sludge dewaterability.The PDS-Fe²⁺-Ct process exhibited better performance in sludge dewatering than PDS-Fe²⁺.Specifically,with a PDS dosage of 1.2 mmol/g VS,the molar ratio of PDS/Fe²⁺and Ct/Fe²⁺were 4:5 and 1:4,respectively,the capillary suction time decreased from 155.8 to 24.8sec,and the sludge cake water content decreased from 82.62%t...     

Construction of ternary CuO/CuFe2O4/g-C3N4 composite and its enhanced photocatalytic degradation of tetracycline hydrochloride with persulfate under simulated sunlight

In this study, a graphitic carbon nitride（g-C₃N₄） based ternary catalyst Cu O/Cu Fe₂O₄/gC₃N₄（CCCN） is successfully prepared thorough calcination method. After confirming the structure and composition of CCCN, the as-synthesized composites are utilized to activate persulfate（PS） for the degradation of organic contaminant. While using tetracycline hydrochloride（TC） as pollutant surrogate, the effects of initial p H, PS and catalyst ...     

MnFe2O4 nanoparticles as new catalyst for oxidative degradation of phenol by peroxydisulfate

Manganese ferrite nanopowder was prepared by thermal decomposition at 400°C of the gel synthesized from manganese and iron nitrates and polyvinyl alcohol. X-ray diffractometry evidenced that manganese ferrite was formed as single crystalline phase at this temperature. Scanning electron microscope images evidenced the formation of very fine spherical particles(d 11 nm) of manganese ferrite, with specific surface area of 147 m~2/g.The powder obtained at 400°C was used as a catalyst for the oxidative degradation of phenol in aqueous solutions, in the presence of potassium peroxydisulfate as oxidant. High phenol removal efficiencies above 90% were reached at: pH 3–3.5, phenol initial concentration around 50 mg/L, peroxydisulfate:phenol mass ratio 10:1, and catalyst dose 3 g/L. Total organic carbon measurements showed that the degradation of phenol goes, under these conditions, to mineralization in an extent of 60%.     

Enhanced activation of peroxydisulfate by strontium modified BiFeO3perovskite for ciprofloxacin degradation

A series of Sr-doped BiFeO₃ perovskites (Bi_1-xSr_xFeO₃, BSFO) fabricated via sol-gel method was applied as peroxydisulfate (PDS) activator for ciprofloxacin (CIP) degradation. Various technologies were used to characterize the morphology and physicochemical features of prepared BSFO samples and the results indicated that Sr was successfully inserted into the perovskites lattice. The catalytic performance of BiFeO₃ was significantly boosted by strontium doping. Specifically, Bi_0.9Sr_0.1FeO₃ (0.1BSFO) exhibited the highest catalytic performance for PDS activation to remove CIP, where 95% of CIP (10 mg/L) could be degraded with the addition of 1 g/L 0.1BSFO and 1 mmol/L PDS within 60 min. Moreover, 0.1BSFO displayed high reusability and stability with lower metal leaching. Weak acidic condition was preferred to neutral and alkaline conditions in 0.1BSFO/PDS system. The boosted catalytic performance can be interpreted as the lower oxidation state of Fe and the existence of affluent oxygen vacancies generated by Sr doping, that induced the formation of singlet oxygen (¹O₂) which was confirmed as the dominant reactive species by radical scavenging studies and electron spin resonance (ESR) tests. The catalytic oxidation mechanism related to major ¹O₂ and minor free radicals was proposed. Current study opens a new avenue to develop effective A-site modified perovskite and expands their application for PDS activation in wastewater remediation.