Valorization of blueberry pomace and red mud to zero valent iron biochar for antibiotic degradation with diminishment of toxic reagents.

Converting sewage sludge into biochar shows promise as an eco-friendly and cost-effective method for remediating pollutants. In this study, aerobic digested sewage sludge was evaluated as a low-cost carbon-based catalyst through a facile one-pot pyrolysis process. The sludge biochar (SBC) was then used as a persulfate (PS) activator for the degradation of Bisphenol-A (BPA). The effect of pyrolysis temperature on the physicochemical properties of SBC and catalytic activity was observed. Then, chemical quenching analysis was carried out to identify reactive species. Increasing the pyrolysis temperature from 350 to 700 °C resulted in an enhancement of the degradation rate constant of BPA from 0.95 × 10-2 min-1 to 8.9 × 10-2 min-1. SBC pyrolyzed at 350 °C (A350), characterized by a high iron content (40%wt) in the form of amorphous Fe (e.g., ferrihydrite) and C=C functional group promoting the radical formation which is dominated by presence of hydroxyl radicals. However, iron in an amorphous form limited the catalytic activity of A350. By contrast, non-radical pathway dominates SBC pyrolyzed at 700 °C (A700) with highest BPA removal as the result of more hydrophobic nature (lower O/C) therefore attracting more BPA and PS to the biochar surface. Graphitic structure of A700 (lower ID/IG) supports the mediated electron transfer pathway for persulfate activation. A pH range of 2–9 and the of inorganic anions (e.g., Cl-,NO3-,SO4-, and HCO3-) had negligible effects on the A700 system. This study introduces a novel approach to the value-added reuse of sewage sludge as an efficient persulfate activator for pollutant remediation with good resistance to water matrices conditions.

In this work, the activation of persulfate (PS) using a vortex diode-based hydrodynamic cavitation (HC) system for the degradation of ethylene glycol (EG) and propylene glycol (PG) in aqueous media was evaluated. Glycol degradation in a PS activated system was determined under varying glycol concentrations (100-1000mg/L), PS-to-glycol molar ratios (0.06-3.04), and operating temperatures (25-55°C). Degradation kinetics followed a first-order model, with the per-pass rate constant for PG at temperatures below 30°C calculated at 2.7 × 10-4 per pass, while EG showed negligible degradation under similar conditions. At elevated temperatures (> 55°C), the rate constants increased to 6.02 × 10-4 per pass for EG and 3.9 × 10-4 per pass for PG, indicating the strong thermal enhancement synergistic with cavitational effects. HC/PS system demonstrated almost twofold higher cavitation yield and faster treatment time for 90% degradation compared to electrical heating/PS system. Complete degradation (> 90%) required a PS: glycol ratio greater than 4. The degradation intermediates identified included formic acid, acetic acid, propanoic acid, and hydroxy-acetaldehyde, suggesting sulfate and hydroxyl radical-driven pathways. Techno-economic analysis revealed that HC/PS used significantly less energy (233.4-645.9kWh/m3) than electrical heating/PS (718.9-1043kWh/m3), indicating its superior energy efficiency. The operational cost including oxidant costs for glycol degradation using HC/PS system was found to be 3.55 times more economical than conventional thermal activation, with a threefold reduction in treatment time (6h vs. 18h for 90% degradation). These findings establish HC as a scalable, energy-efficient, and cost-effective method for the oxidative treatment of glycol-rich wastewater streams.

Co-nZVI@ATP activated persulfate for the degradation of Bisphenol S: Treatment efficiency and mechanism.

Despite extensive work on FeOCl-based photocatalysts, few studies have explored rare-earth (Ce) doping to simultaneously tune bandgap, suppress charge recombination, and enhance visible light-driven persulfate (PS) activation for the degradation of emerging contaminants. This study synthesized FeOCl/Ce composite photocatalysts via a partial pyrolysis method and systematically characterized their physicochemical properties. The results show that Ce doping significantly lowers the bandgap energy of the photocatalyst, enhances its visible light absorption ability, and effectively suppresses the recombination of photogenerated electron-hole pairs, thereby markedly improving photocatalytic performance under visible light. Analyses including XRD, EDS, XPS, and FT-IR confirm that Ce is incorporated into the FeOCl matrix and modulates the radial growth behavior of FeOCl without altering its intrinsic crystal structure. Morphological observations reveal that FeOCl/Ce exhibits a uniform nanosheet layered structure, with larger particles formed by the aggregation of smaller nanosheets. The nitrogen adsorption-desorption isotherm of FeOCl/Ce shows characteristics of Type IV with a relatively small BET surface area. The broadened optical absorption edge of FeOCl/Ce and the results of PL spectra and I-T curves further confirm its enhanced visible light absorption capacity and reduced electron-hole recombination compared to pure FeOCl. At an initial caffeine (CAF) concentration of 10 μM, FeOCl/Ce dose of 0.5 g/L, PS concentration of 1 mM, and initial pH of 5.06, the FeOCl/Ce-catalyzed PS system under visible light irradiation can degrade 91.2% of CAF within 30 min. An acidic environment is more favorable for CAF degradation, while the presence of SO42-, Cl-, and NO3- inhibits the process performance to varying degrees, possibly due to competitive adsorption on the photocatalyst surface or quenching of reactive species. Cyclic stability tests show that FeOCl/Ce maintains good catalytic performance over multiple runs. Mechanistic analysis indicates that •OH and holes are the dominant reactive species for CAF degradation, while PS mainly acts as an electron acceptor to suppress electron-hole recombination. Overall, the FeOCl/Ce photocatalytic system demonstrates high efficiency, good stability, and visible light responsiveness in CAF degradation, with potential applications for removing CAF and other emerging organic pollutants from aquatic environments.

Photodegradation of tetracycline hydrochloride by biochar/Cu ₂ O coupled with persulfate: Insights into the factors and intermediates toxicity

Fluoroquinolones are a major issue in aquatic ecosystems due to their persistence, potential to induce antibiotic resistance, and inability to be effectively removed using conventional treatment methods. Several advanced oxidation processes have been studied for their degradation; however, there is still a lack of knowledge about their degradation mechanisms and the precise roles played by reactive species. In this context, the study investigated the heterogeneous activation of persulfate (PS) to degrade fluoroquinolones (FQs), such as moxifloxacin (MFX), in iron-rich soil (Cat) under ultrasound irradiation (US). The analysis of the soil catalyst revealed the presence of quartz (35%), iron oxides (33%), and alumina (26%) as the predominant constituents of the sample. The mineral phase analysis indicated the presence of magnetite, hematite, and alumina. Then, the outcomes of the specific surface area, micropore volume, and total pore volume were determined to be 19 m2 g−1, 6 m3 g−1 and 9.10 m3 g−1, respectively. The MFX/PS/US/Cat system demonstrated 89% degradation and 56% mineralization after 300 min. However, the optimized concentrations of i-PrOH, t-BuOH, and CHCl3 were 50, 100, and 50 mM, respectively, in order to trap the radicals SO4•−, OH•, and O2•−. The study examined the individual contributions of SO4•−, OH•, and O2•− radicals to the overall process of MFX degradation. The results indicated that SO4•− was the primary radical, with a contribution of 52%, followed by OH• with 43%, and O2•− with 5%. Finally, the investigation revealed that laterite exhibited both good catalytic activity and reusability over several cycles. The development of this new process could stimulate the creation of cost-effective technology for water remediation through the effective removal of fluoroquinolones.

Thermal desorption coupled with persulfate oxidation for removing soil organic pollutants: Key role of soil organic matter passivation.

Efficient degradation of carbamazepine by electro-Fenton coupled with persulfate activation by FeCo-PBA catalyst and its mechanism.

This study investigated reductions in carbonaceous and nitrogenous disinfection byproduct (DBP) precursors in algae-laden water using vacuum ultraviolet (VUV), VUV with persulfate (PS) (VUV/PS), ultraviolet (UV), and UV with PS (UV/PS) processes. The effect of PS doses (5 and 50 mg/L) on dissolved organic matter (DOM) removal was evaluated. DOM (as the DBP precursor) was measured using dissolved organic carbon (DOC), dissolved organic nitrogen (DON), and UV absorbance at 254 nm, as well as characterized by fluorescence excitation–emission matrix (EEM) spectroscopy. The results showed that the VUV/PS (PS dose of 50 mg/L) process was the most effective, removing 30%–46% DOC and 27% DON in 60 min. The EEM results revealed that the VUV/PS process reduced all fluorophores—including humic-like, fulvic-like, tyrosine protein-like, and tryptophan protein-like—by more than 88%. The DOC removal and fluorescence loss corresponded with the trihalomethane formation potential (THMFP) reductions. Chloroform and dichloroacetonitrile were the predominant species among THMFP and haloacetonitrile formation potential (HANFP), respectively. However, brominated DBPs, which are known to be more toxic than chlorinated DBPs, were also detected. These processes achieved greater THMFP reductions compared to the UV and UV/PS processes. Overall, the VUV and VUV/PS processes show potential for future application in enhancing the treatment of algae-laden water.

In this study, we investigated the performance of iron-loaded biochar (Fe-BC) derived from mulberry branches in activating persulfate (PS) for the efficient degradation of sulfamethoxazole (SMX). The Fe-BC/PS system exhibited superior catalytic activity towards SMX degradation, achieving 97% removal within 60 min. The degradation efficiency was found to be highly dependent on preparation conditions, including calcination temperature, the type of iron salt, and biomass feedstock. Reactive species such as hydroxyl radicals (•OH), sulfate radicals (SO4•−), and iron (IV) (Fe(IV)) were identified as key contributors to SMX degradation, with Fe(IV) playing a dominant role. The influence of water quality parameters, such as inorganic ions, pH, and natural organic matter (NOM), on the degradation of SMX was also examined. Proposed degradation pathways revealed the stepwise oxidation of SMX into smaller intermediates, ultimately leading to mineralization. Our findings highlight the potential of Fe-BC/PS systems as a sustainable and effective approach for the remediation of sulfonamide antibiotics in aquatic environments.

Abstract Pharmaceutical residues, particularly ciprofloxacin (CIP), are frequently detected in aquatic environments and pose significant risks to ecosystems and human health. This study investigates the visible-light photocatalytic degradation of CIP using Co²⁺-modified Zn₀.₆₆₇Al₀.₃₃₃-layered double hydroxide (LDH) materials, with persulfate (PS) as a co-activator. The hydrotalcite-like compounds Zn₀.₆₆₇Al₀.₃₃₃(OH)₂(CO₃)₀.₁₆₇•0.5H₂O, denoted as nCoZnH, were synthesized by co-precipitation.These were further calcined at 500 °C for 5 hours to obtain nCoZnH500. Both uncalcined and calcined materials were characterized structurally and physicochemically. Results revealed that nCoZnH maintained the typical hydrotalcite layered structure, with Co²⁺ ions effectively incorporated into brucite-like layers through isomorphic substitution of Zn²⁺. Upon calcination, partial retention of the LDH structure was observed, accompanied by the formation of ZnO and Co₃O₄ phases. The BET surface area of nCoZnH500 was markedly higher than that of uncalcined counterparts. Co²⁺ modification also significantly reduced the bandgap energy, thereby enhancing visible-light-induced photocatalytic activity. Among all samples, 1.0CoZnH and 2.0CoZnH500 exhibited the highest degradation efficiencies, 78.0 ± 1.87% and 70.9 ± 2.31%, respectively, for 10 ppm CIP under visible light. Furthermore, the photocatalytic activity of the synthesized materials was influenced by the Co: Al molar ratio, initial CIP concentration, persulfate (S₂O₈²⁻) dosage, and solution pH. The 2.0CoZnH500 sample demonstrated superior stability compared to 1.0CoZnH, with only a 9.1% reduction in the CIP removal efficiency after four consecutive cycles, maintaining a degradation efficiency of 59.7%. These findings indicate that the synergy between Co²⁺ doping and PS activation effectively boosts CIP degradation. The developed materials offer promising potential for the treatment of pharmaceutical wastewater under visible light irradiation.

Persulfate-based radical-induced oxidative humification of chicken manure and simultaneous removal of pollutants.

Oxidation of urea to nitrate via persulfate activation under far-UVC light improves ultrapure water production.

Enhanced photo-ozonation for on-board marine oily wastewater treatment: An integrated study on efficiency and microbial trajectory.

The activation of persulfate (PS) to oxidize and degrade 2,4-dichlorophenol (2,4-DCP) in aqueous solution represents a prevalent advanced oxidation technology. This study established a PS activation system using sulfide-modified nanoscale zero-valent iron supported on biochar (S-nZVI@BC). The optimal conditions included a PS:2,4-DCP mass ratio of 70:1 and S-nZVI@BC:PS of 1.5:1. The activator had excellent stability after being reused five times, which lead to high cost-effectiveness and sustainable usability. This system exhibited broad pH adaptability (3–11), with enhanced efficiency under acidic/neutral conditions. Chloride ion, nitrate, and carbonate had effects during the degradation. During the initial degradation phase, S-nZVI@BC played a primary role, with a greater contribution rate of adsorption than reduction. Fe0 played a dominant role in the PS activation process; reactive species—including HO•, SO4•−, and O2•−—were identified as key agents in subsequent degradation stages. The overall degradation processes comprised three distinct stages: dechlorination, ring-opening, and mineralization.

ABSTRACT Persulfate (PS) and hydrogen peroxide (HP) are both in-situ chemical oxidation (ISCO) oxidants employed for remediating the dense non-aqueous phase liquid (DNAPL) trichloroethylene (TCE). This study aims to compare Fe2+-activated PS and HP in treating TCE within a one-dimensional column containing either silica sand or sandy soils. The initial phase is focused on assessing the transport behavior of reagents with different injection combinations and sequences. Notably, simultaneous injection of citric acid (CA) chelated Fe2+ activator and HP or PS showed an enhanced activation effect compared to other conditions. In the second phase, the study adopted a simultaneous injection approach for treating TCE DNAPL. In both oxidation systems, TCE effluent concentrations in the soil column were higher than those in the silica sand column. This difference can be attributed to oxidation rinsing out of soil organic matter, thereby increasing TCE release into the aqueous phase. The instability and decomposition of HP to form O2 during the experiment disrupted and flushed out TCE, resulting in a further increase in TCE effluent concentration. The study estimated the distribution of TCE mass balance under various reaction conditions. The results of this study can be valuable as a reference for ISCO remediation using Fe2+-activated PS or HP.

In situ chemical oxidation (ISCO) is a highly effective remediation technique for the complete mineralization of organically contaminated soil. This study focused on the oxidative remediation of polycyclic aromatic hydrocarbons (PAHs) in contaminated soil using a composite oxidant system composed of monohydrated citric acid (CA) chelated with ferrous sulfate heptahydrate (FS) and activated sodium persulfate (PS) and sodium percarbonate (SPC). The effects of four individual factors-PS dosage, SPC dosage, FS addition, and CA addition-on PAH degradation were examined. Optimization of the test conditions using response surface methodology demonstrated that the dual oxidant system significantly increased the degradation rate of PAHs. The optimal process conditions were identified as follows: PS concentration of 52.66g/kg, SPC concentration of 30.24g/kg, FS concentration of 47.71g/kg, CA concentration of 6.80g/kg, a water-soil ratio of 1:1, a reaction time of 4 days, and a final total PAH removal rate of 69.65%. Another way to explain this is that a molar ratio of 6.3:5.5:4.9:1 for PS/SPC/FS/CA in this system can achieve maximum degradation efficiency. The dual-oxidant system investigated in this study exhibits significant potential for the remediation of PAHs in soil.

Persulfate salts to combat bacterial resistance in the environment through antibiotic degradation and biofilm disruption.

Electron beam/persulfate-induced second-scale upcycling of wastewater polyvinyl alcohol with ultra-low chemical input.