Persulfate Activation Research Articles

Multilevel assault dominated by electron-transfer nonradical pathway via electronic metal–support interactions of Bi-C bonds for disinfection

Multilevel assaults on aqueous pathogenic microorganisms were realized by persulfate (PS) activation system with Bi–C based electronic metal-supported interactions (EMSI) of bismuth-embedded carbon chainmail catalyst (Bi@CC) dominated by electron-transfer nonradical pathway. The Bi@CC/PS disinfection system achieved approximately 100 % bacterial inactivation (6.5 log10 cfu/mL) within 35 min. The electron transfer from Bi to the carbon layer via Bi-C bond leading to higher work functions, thus realizing primary assault to the extracellular membrane via bacterial extracellular electron transfer (EET) function. Electron rearrangement of Bi-C is conducive to forming the intermediate complexes (Bi@CC-PS*), leading to higher work functions and enhancing electron transfer pathway (ETP) process to aggravate cell destruction, while radicals (∙OH andSO4∙-) directly attacks the interior cell. The Bi@CC/PS disinfection system possesses excellent environmental adaptability, cycling performance, and safety. This study enriches the heterogeneous mechanism of PS activation and proposes a promising strategy for sewage effluent treatment.

Highly stable carbon-coated nZVI composite Fe0@RF-C for efficient degradation of emerging contaminants

Nanoscale zerovalent iron (nZVI) has garnered significant attention as an efficient advanced oxidation activator, but its practical application is hindered by aggregation and oxidation. Coating nZVI with carbon can effectively addresses these issues. A simple and scalable production method for carbon-coated nZVI composite is highly desirable. The anti-oxidation and catalytic performance of carbon-coated nZVI composite merit in-depth research. In this study, a highly stable carbon-coated core-shell nZVI composite (Fe0@RF-C) was successfully prepared using a simple method combining phenolic resin embedding and carbothermal reduction. Fe0@RF-C was employed as a heterogeneous persulfate (PS) activator for degrading 2,4-dihydroxybenzophenone (BP-1), an emerging contaminant. Compared to commercial nZVI, Fe0@RF-C exhibited superior PS activation performance and oxidation resistance. Nearly 95% of BP-1 was removed within 10 min in the Fe0@RF-C/PS system. The carbon layer promotes the enrichment of BP-1 and accelerates its degradation through singlet oxygen oxidation and direct electron transfer processes. This study provides a straightforward approach for designing highly stable carbon-coated nZVI composite and elucidates the enhanced catalytic performance mechanism by carbon layers.

Ag0, Re0, and Ag@Re heterogeneous persulfate activators for reactive radical based oxidation of water contaminant

Silver-rhenium bi-metallic nanoparticles (Ag-Re) were prepared by the combination of colloidal sols of silver and rhenium at room temperature. The silver and rhenium sols were synthesized by using the chemical reduction of silver nitrate and ammonium perrhenate with sodium borohydride in presence of cetyltrimethylammonium bromide (CTAB). The morphology (shape, size, elemental composition, oxidation states, and crystalline nature) and textural properties (pore size, pore volume, and surface area) of Ag0-Re0 were determined with EDX, SEM, TEM, XPS, XRD, and nitrogen adsorption-desorption isotherm. The Ag0-Re0 was used as heterogeneous persulfate (S2O82−) activator to generate reactive radical species (SO4−• and HO•) for the degradation of xylenol orange (XO) at 434 nm. The Ag-Re exhibits higher XO degradation efficiency than that of mono-metallic Ag0 and Re0 nanoparticles, respectively. The degradation efficiency strongly depends on the concentrations of S2O82−, XO, pH, temperature, and amount of Ag0-Re0. The role of SO4−• and HO• were established by using ethanol, and tertiary butanol as radical scavengers. The activation energy was found to be 85.2, 63.5, and 32.6 kJ/mol, respectively, to the degradation of XO by activated S2O82− with Re0, Ag0, and Ag0-Re0.

Enhancing acetaminophen removal through persulfate activation with ZnCl2-SPI biochar: A study on reactive oxygen species contribution according to acetaminophen concentration

This study investigated the effect of acetaminophen (ACP) removal through the ZnCl2-SPI/persulfate process and evaluated the production of reactive oxygen species (ROS) based on ACP concentration. ACP removal efficiency reached 96 % within 5 min, regardless of the initial concentration (40 μM and 200 μM). The change in pH had a minimal effect on the removal efficiency, and the reactivity improvement increased the removal rate at pH 4 and 10. The persulfate-to-ACP ratio significantly influenced ACP removal, with the minimum ratio required for effective ACP removal being 5. The scavenger test results showed that the effect of O2•− radicals prevailed when ACP concentration was 40 μM, whereas the effect of 1O2 prevailed when ACP concentration was 200 μM. This indicates that ROS contribution depends on the persulfate-to-ACP ratio. When this ratio was high, ZnCl2-SPI and persulfate reacted to generate O2•− radicals via the radical pathway. Conversely, when this ratio was low, ACP and persulfate reacted to generate 1O2 via the nonradical pathway. The difference in these mechanisms was analyzed through electrochemical analysis, confirming that ACP and persulfate reacted via a coupling effect. In conclusion, the ROS generated in the ZnCl2-SPI/persulfate process varied depending on the persulfate-to-ACP ratio, and the ROS generation path can be selectively controlled by adjusting this ratio.

Enhanced activation of persulfate by bimetal and nitrogen co-doped biochar for efficient degradation of refractory organic contaminants: The role of the second metal

The leaching of metal ions limits the application of Fe-biochar catalyst in activating persulfate (PS). In this work, Fe-M (M = Co, Cu) and nitrogen co-doped biochar (Fe-M@N-BC) were synthesized through impregnating bio-waste soybean straw to activate PS for the removal of various refractory organic contaminants (tetracycline (TC), oxytetracycline (OTC), methyl orange (MO) and rhodamine B (RhB)). The catalysts were characterized by XRD, XPS, Raman, BET, TEM, SEM, and the degradation mechanism was investigated through quenching experiments and EPR. The results indicated that the doping of second metal (Co, Cu) has a strong promoting effect on catalytic activity with the order of Co > Cu. Surprisingly, the removal rates of TC, OTC, RhB, MO by Fe–Co@N-BC reached 84.7 %, 90.3 %, 89.4 %, and 91 %, respectively. The excellent catalytic performance of Fe–Co@N-BC was mainly attributed to abundant pyridinic-N, larger specific surface area (270 m2 g−1) and the Co(II)/Co(III) redox cycle promoting the regeneration of Fe(II). Notably, the formation of Co7Fe3 alloy could inhibit the leaching of iron ions and Fe–Co@N-BC possessed excellent reusability. Additionally, non-radical (1O2) was the main active species in the Fe–Co@N-BC/PS system. Finally, the degradation pathway of MO was proposed by HPLC-MS analysis. This research work provided an insight into how to reasonably utilize biological waste to construct highly efficient and stable catalysts for pollutants degradation.

2,3-pyridinedicarboxylic acid-modified MIL-88A(Fe) for enhanced peroxymonosulfate activation to degrade organic contaminants

Metal-organic framework (MOF)-based composites have shown a great application potential in photoassisted persulfate activation process and environmental remediation. Herein, 2,3-pyridinedicarboxylic acid (PDA) is firstly used to improve the catalytic activity of MIL-88A(Fe). The composite catalysts are effectively synthesized using a solvothermal method. At an 80.2 mg modification level of PDA, the catalyst [MIL-88A(Fe)-PDA-3] could achieve 98.20 % removal of AR18 (acid red 18) through the visible-light-assisted peroxymonosulfate (PMS) activation. It is 7.8-fold increase than pristine MIL-88A(Fe). The suitable conditions for AR18 elimination are 0.4 g/L MIL-88A(Fe)-PDA-3, 1.5 mM PMS and pH = 10. The interplay between influencing factors is explored by a response surface methodology. The quenching studies and EPR tests indicate the generation of active species such as ·OH, SO4·−, 1O2, O2·−, and FeIVO in the reaction system, with ·OH playing a significant role for AR18 degradation. A potential mechanism is proposed based on the above results. This study offers a fresh perspective for the development of efficient MOFs materials.

“Frozen” π-π stacking on perylene diimide molecules induces oxygen vacancies synergistic activation of persulfate towards degradation of tetracycline

Oxygen vacancy-rich self-assembled perylene diimide (OV-SA-PDI) supramolecules were prepared via freeze-drying, which froze the molecular backbone by retaining π-π stacking to induce additional OVs. The OVs content on OV-SA-PDI (1.956 × 1013 spins·mm−3) was 1.9 times that of SA-PDI (1.029 × 1013 spins·mm−3) with vacuum drying. The photocatalytic performance of OV-SA-PDI was demonstrated to be excellent in activating persulfate (PS) to degrade tetracycline (TC), achieving a remarkable degradation efficiency of 94.6% in 60 min under visible light (Vis). Mechanistic studies revealed a synergistic interaction among OV-SA-PDI, PS, and Vis to produce an abundance of active species. Vis activated a small portion of PS to produce ∙OH and SO4∙−, whereas the photogenerated electrons generated by OV-SA-PDI directly cleaved the O-O bond to produce abundant SO4∙−. Furthermore, the OVs acted as an electron trap to promote carrier separation and produced 10.0 μM 1O2 within 12 min. The active species were determined to decompose TC into low-toxicity products with lower molecular weights (m/z = 352, 340, and 227). This study presented a novel approach to the introduction of OVs into organic semiconductors and offered a mechanistic analysis of the synergistic relationship between defective organic semiconductors and sulfate radical-based advanced oxidation processes for wastewater treatment.

ZIF-67-derived monolithic bimetallic sulfides as efficient persulfate activators for the degradation of ofloxacin

In this study, we successfully synthesized ZIF-67 material on three-dimensional (3D) nickel foam (NF) substrate by co-precipitation method, and then fixed CoSx on NF by hydrothermal vulcanization method to form CoSx/NF. The optimized CoSx/NF can effectively activate peroxymonosulfate (PMS) and improve the degradation efficiency of ofloxacin (OFL). The effects of PMS dosage, reaction temperature, initial pH and co-existing ions on the degradation effect of OFL were investigated in detail. CoSx/NF (1 piece 2 × 2 cm) and PMS (1 mM) in an aqueous solution (pH = 7) degraded 85 % of OFL (20.0 mg/L) within 45 min. This favorable degradation performance is mainly attributed to the enhanced electron transfer capability introduced by the bimetallic material. In addition, CoSx/NF still maintained high degradation effect and stable structure after 5 cycles. Quenching experiments further revealed that radicals •OH and 1O2 play a major role in degrading OFL. In addition, the degradation pathway, ecotoxicity evaluation and degradation mechanism of OFL were comprehensively investigated. In summary, the CoSx/NF catalyst proved to be a highly efficient, stable and recyclable heterogeneous composite, and opened up the possibility of using Metal-organic framework (MOF) derivatives in fields such as wastewater treatment.

Self-reinforced Synchronization of persulfate activation and photocatalysis by Tri-metal heterojunction catalyst for efficient degradation of Sulfadiazine

The outstanding performance of advanced oxidation processes based on self-generated active species in the decomposition of antibiotics has attracted widespread attention. Herein, a novel heterojunction flower-shaped microsphere Iron-based Hydroxide/Tungstate Antimony Oxide (FSW) composed of nanosheets with synchronous persulfate activation and photocatalytic properties were proposed to achieve efficient degradation of sulfadiazine (SDZ) by enhanced active oxidation species. Constructed FSW/PMS/vis system realized the improved removal of SDZ at pH 2–6, with a degradation efficiency of 96.6 % in just 6 min (electron transfer efficiency, 6.19 × 10–4 A/cm2; kinetic rate, 2-ORR). Investigation of density functional theory demonstrated the superiority of FSW catalysts (Eads = -1.63 eV), indicating that FSW can not only enhance the adsorption of PMS but also activate PMS to generate a large number of free radical ions, realizing rapid carrier movement and effective charge transfer, which highlights the application prospects of the system in eliminating antibiotics in environmental water bodies.

Controllable preparation of MnCo2O4 spinel and catalytic persulfate activation in organic wastewater treatment: Experimental and immobilized evaluation

Transitional metal oxides are excellent candidates as heterogeneous catalysts for activating persulfate towards organics degradation. In this study, MnCo2O4 spinel was successfully prepared using a solvent-free molten method. The catalytic performance was systematically investigated and MnCo2O4 powder catalyst was successfully immobilized on polyurethane (PU) membrane through electrospinning to assess its application potential. The results showed that peroxymonosulfate (0.1 ​g ​L−1) activated by MnCo2O4 (0.1 ​g ​L−1) reached 99.92 ​% degradation in 10 ​min when treating 0.04 ​g ​L−1 rhodamine B as target pollutant. The abundant oxygen vacancies formation, synergistic effect of Co and Mn ions and high electron transfer mobility are contributing to production of reactive oxygen species. Combining with quenching experiment and time-resolved EPR, the contribution of various active species was proposed, of which 1O2 exhibited the dominant role. The flowing reaction run by the MnCo2O4-PU membrane activating PMS exhibited universal degradation on different target pollutants.

A novel cobalt-iron bimetallic hydrochar for the degradation of triclosan in the aqueous solution: performance, reusability, and synergistic degradation mechanism

Low activation performance is a critical issue limiting the practical application of low-cost biochar in the advanced oxidation. Given the high potential of transition metals in the persulfate activation process and abundant oxygen-containing groups of hydrochar, hydrochar derived from cobalt (Co)-modified iron (Fe)-enriched sludge was synthesized and its performance and activation mechanism for the degradation of triclosan were investigated. Co modification significantly altered the morphology of hydrochar, and the increased Co–Fe mass ratios transformed hydrochar from granular to rose-shaped lamellar and then to helical sheet structures. Specific surface area, defect degree, and oxygen-containing groups of hydrochar increased with increasing cobalt-iron mass ratios. The highest removal of triclosan was up to 98% in the hydrochar/peroxymonosulfate (PMS) system under a wide range of pHs (3–10) and still remained higher than 90% after four cycles. Both Radical (mainly hydroxyl radical) and nonradical pathways (singlet oxygen and electron transfer) were evidenced to play roles in the triclosan removal. Fe3+ promoted the regeneration of Co2+ and realized the efficient circulation of Co3+/Co2+. A ternary system consisting of electron donor (triclosan)-electron mediator (hydrochar)-electron acceptor (PMS) provided channels for electron transfer. No measurable Co and Fe were released during the reaction, and the toxicity of degradation intermediates was lower than that of triclosan. Beside triclosan, rhodamine B, bisphenol A, sulfamethoxazole, and phenol were also almost degraded completely in this oxidation system. This study provides a promising way for the enhancement of catalytic activity of carbonaceous material.

Direct electron transfer mediated electrochemical activation of persulfates by reticulated vitreous carbon (RVC) cathode

The electrochemical activation of peroxymonosulfate (PMS) and peroxydisulfate (PDS) for pollutant degradation has gained increasing attention. In this work, reticulated vitreous carbon (RVC) electrodes were prepared at a low cost and investigated for the cathodic activation of PMS/PDS for Acid Orange 7 degradation. The RVC was characterized by SEM, TGA, XRD, Raman spectroscopy, XPS, EIS, and compression test. The superior activity outperformed previous reports in terms of low current density operation (1–10 mA/cm2), high degradation rates (0.13–0.49 min−1), low energy consumption (0.03–0.23 kWh/m3/order) without involvement of catalysts. The process was optimized for current density, PMS dosage, pollutant concentration, pH, water matrix, and supporting electrolyte. Under the optimal current density (3 mA/cm2), the addition of 0.5 mM of PMS boosted the degradation rate by 9.6 times to 0.4470 min−1 and reduced the electrical energy consumption by 90.1 % to 0.0243 kWh/m3/order in 50 mM of Na2SO4. Moreover, up to 117 mg/L of H2O2 was produced in 1 hour by the reduction of oxygen, with current efficiencies between 78–24 %. The process showed little deterioration in 10 cycles, worked for a variety of pollutants, and was not affected by the water matrix. The H-cell experiments confirmed that 90 % degradation took place on the cathode. Scavenging experiments and electrochemical tests suggested that the transitional state of PMS* and O2•− mediated the direct electron transfer mechanism for AO7 degradation. Eighteen degradation products were identified by HPLC-MS and categorized into 4 degradation pathways. Finally, their toxicity was assessed by the ECOSAR programme.

Synthesis of copper/carbon nanofibers by electrostatic spinning toward persulfate activation for treatment of antibiotic wastewater

ABSTRACT Antibiotics in water will cause serious harm to human health and ecosystem. Carbon-based materials and transition metals activated peroxodisulfate (PDS) to produce active species, which can degrade residual antibiotics in water. In this paper, Cu/CNF (carbon nanofibers) composites were first prepared by introducing Cu into CNF using electrostatic spinning technology, which was used to activate PDS to degrade tetracycline (TC). The degradation efficiency of Cu/CNF/PDS was 36.23% higher than that of CNF/PDS. The reason is that introducing Cu can increase the number of surface functional groups and specific surface area of CNF, and then improve the catalytic performance. The functional groups and Cu species are the active sites for catalytic PDS. Moreover, the main ways to degrade TC in the Cu/CNF/PDS system are singlet oxygen (1O2) and electron transfer. Based on the above analysis, we modified CNF with transition metal salts, prepared efficient environmental functional materials, and used them for PDS activation, providing a theoretical basis and technical support for the degradation of antibiotic pollutants and creating new ideas for other research.

Unraveling the outstanding catalytic efficiency of unprocessed bone-derived biochar: A deep dive into the mechanisms of native organic encapsulation and defective nitrogen doping in boosting persulfate activation for tetracycline degradation

Designing efficient non-metallic catalysts for persulfate (PS) activation has attracted broad attention due to their demonstrated immense potential in environmental remediation. In this study, unprocessed pig bone waste was successfully converted into biochars (PBCs) through a straightforward one-step pyrolysis process, which function as efficient PS catalysts for the removal of tetracycline (TC). The results revealed that the endogenous inner layer hydroxyapatite activator (IHA) and the rich native outer layer organic component wrapped with nitrogen-doped additives (OONA) found in raw bone-derived waste biomass collaborate to exert a dual effect of template and surface modification at 900 °C. Notably, under this synergistic action, 900PBC exhibited active defect nitrogen (pyridinic and graphitic nitrogen), sp2-hybridized groups (C = C, C = O, and C = N) and high defect levels (ID/IG = 1.0291), along with a cross-linked micro-mesoporous structure. This unique combination of properties endowed 900PBC with excellent catalytic activity, enabling it to effectively remove 50 mg/L of TC in the PS system within 30 min, primarily through a dual reaction pathway involving oxygen-active species (O2·-, 1O2) and electron transfer (fitting instantaneous-current values to PS concentrations, R2 = 0.95). Density-functional theory calculations confirmed that, within the nitrogen configurations located at defect sites, pyridinic nitrogen exerted a significant influence on the electron cloud density of adjacent carbon networks, subsequently promoting the formation of excited states of PS. Meanwhile, graphitic nitrogen constructed electron bridges with adjacent sp2-hybridized orbitals, facilitating the formation of the metastable complex 900PBC-PS*. Remarkably, 900PBC also exhibited excellent cyclic stability, maintaining a 93 % TC removal rate after four cycles,as well as high tolerance to a broad pH range (3–9), high concentrations of coexisting ions (10 mM), and diverse real-world water bodies. This study offers novel insights into synthesizing high-value biochar from waste bones with high catalytic activity.

Building heteroatom (N, S, B, O) and metal-codoped carbocatalyst as persulfate activator for organic pollutant removal: A miss or match?

The activation of persulfate (PS) by metal (Me)-based catalysts shows great activity due to the compatible redox potential of Me-species. However, the catalytic performance of pristine Me-based catalysts may be restricted by the agglomeration of the Me particles, minimized exposure of active sites, and inevitable leaching. Currently, these drawbacks are being solved with the formation of metal-heteroatom‑carbon (Me-HA-C) materials, in which the major HAs investigated were N, O, S, and B. In Me-HA-C/PS systems, the existence of Me-HA-C interaction brings rise to synergistic catalytic effects, enhancing the overall catalytic reactivity. Herein, we provided a short review on the potential of Me-HA-C materials in PS activation with emphasis on the synergy between the Me- and HA-species during the catalytic reaction. Thereafter, we discussed the performance and proposed future research directions to further escalate the potential of finding an applicable catalytic system based on Me-HA-C materials for water remediation. This review is of value for understanding the intra-actions and synergy between the components of Me-HA-C during catalytic PS activation.

Synthesis of iron-manganese bimetallic materials supported by activated carbon and application of activated persulfate in the degradation of soil contaminated by crude oil

Heterogeneous catalytic processes based on zero-valent iron (ZVI) have been developed to treat soil and wastewater pollutants. However, the agglomeration of ZVI reduces its ability to activate persulfate (PS). In this study, a new Fe–Mn@AC activated material was prepared to activated PS to treat oil-contaminated soil, and using the microscopic characterization of Fe–Mn@AC materials, the electron transfer mode during the Fe–Mn@AC activation of PS was clarified. Firstly, the petroluem degradation rate was optimized. When the PS addition amount was 8%, Fe–Mn@AC addition amount was 3% and the water to soil ratio was 3:1, the petroluem degradation rate in the soil reached to the maximum of 85.69% after 96 h of reaction. Then it was illustrated that sulfate and hydroxyl radicals played major roles in crude oil degradation, while singlet oxygen contributed slightly. Finally, the indigenous microbial community structures remaining after restoring the Fe–Mn@AC/PS systems were analyzed. The proportion of petroleum degrading bacteria in soil increased by 23% after oxidation by Fe–Mn@AC/PS system. Similarly, the germination rate of wheat seeds revealed that soil toxicity was greatly reduced after applying the Fe–Mn@AC/PS system. After the treatment with Fe–Mn@AC/PS system, the germination rate, root length and bud length of wheat seed were increased by 54.05%, 7.98 mm and 6.84 mm, respectively, compared with the polluted soil group. These results showed that the advanced oxidation system of Fe–Mn@AC activates PS and can be used in crude oil-contaminated soil remediation.

Efficient activation of persulfate for tetracycline hydrochloride degradation by biochar prepared from corn stover doped with organic phosphorus sources

Proposed to prepare phosphorus-doped biochar catalyst materials by impregnation pyrolysis method using corn stover and different phosphorus source precursors as raw materials, and the batch-wise research revealed that the phosphorus source precursor, the doping ratio, and the pyrolysis temperature had a significant influence on the biochar properties. The biochar material Pb-C-4–600 prepared with (C4H9)3PO4 as phosphorus source precursor, 1:4 doping ratio, and pyrolysis temperature of 600 ℃ had an ID/IG = 0.914, pore size of 4.91 nm, and specific surface area of 173.9845 m²/g, which was 93.4 times higher than that of the pure biochar. The removal rate of TCH reached 99.77 % in 30 min under the reaction conditions of PMS concentration of 2 g/L, Pb-C-4–600 dosage of 1 g/L, and pH 3. Comparing the efficacy of Pb-C-4–600 and different catalysts for the degradation of TCH by activated PMS under the same reaction conditions, the degradation reaction rate of Pb-C-4–600 was 0.17663 min−1, which was 1.48 times higher than that of N-bio, 1.67 times higher than that of S-bio, and 2.64 times higher than that of B-bio, which further demonstrating the advantages of Pb-C-4–600 in similar composites. The oxidative degradation performance of other typical organic pollutants (BPA, phenol, AO7) was also good. The prominent reactive oxidizing radical in the system of Pb-C-4–600/PMS was SO4·−, and the system could adapt to a wide pH range.

Activation of persulfate by biochar-based catalysts for elimination of refractory organic pollutants: a review

Activation of persulfate by biochar-based catalysts for elimination of refractory organic pollutants: a review

Innovative strategy for the effective utilization of coal waste slag in the Fenton-like process for the degradation of trichloroethylene

In response to environmental concerns at the global level, there is considerable momentum in the exploration of materials derived from waste that are both sustainable and eco-friendly. In this study, CS-Fe (carbon, silica, and iron) composite was synthesized from coal gasification slag (CGS) and innovatively applied as a catalyst to activate PS (persulfate) for the degradation of trichloroethylene (TCE) in water. Scanning electron microscope (SEM), fourier transmission infrared spectroscopy (FTIR), energy dispersive x-ray spectroscopy (EDS), brunauer, emmet, and teller (BET) technique, and x-ray diffractometer (XRD) spectra were employed to investigate the surface morphology and physicochemical composition of the CS-Fe composite. CS-Fe catalyst showed a dual nature by adsorption and degradation of TCE simultaneously, displaying 86.1% TCE removal in 3 h. The synthesized CS-Fe had better adsorption (62.1%) than base material CGS (36.4%) due to a larger BET surface area (770.8 m2 g−1), while 24.0% TCE degradation was recorded upon the activation of PS by CS-Fe. FTIR spectra confirmed the adsorption and degradation of TCE by investigating the used and fresh samples of CS-Fe catalyst. Scavengers and Electron paramagnetic resonance (EPR) analysis confirmed the availability of surface radicals and free radicals facilitated the degradation process. The acidic nature of the solution favored the degradation while the presence of bicarbonate ion (HCO3−) hindered this process. In conclusion, these results for real groundwater, surfactant-added solution, and degradation of other TCE-like pollutants propose that the CS-Fe composite offers an economically viable and favorable catalyst in the remediation of organic contaminants within aqueous solutions. Further investigation into the catalytic potential of coal gasification slag-based carbon materials and their application in Fenton reactions is warranted to effectively address a range of environmental challenges.

Exploiting calcinated CoFe-layered double hydroxide for the photo-persulfate catalytic degradation of sulfamethoxazole

This study synthesized CoFe-layered double oxide (CoFe-LDO) from CoFe-layered double hydroxide (CoFe-LDH) via simple calcination. The resulting CoFe-LDO material was characterized and first employed as a heterogeneous catalyst for sulfamethoxazole (SMX) degradation. The synergic activation of persulfate (PS) by CoFe-LDO in the presence of UV light was demonstrated in a degradation study. The UV/CoFe-LDO/PS system (pronounced as photo-PS system) achieved approximately 98 % SMX removal within 60 min with 0.1 g/L catalyst and 5 mM PS concentration. Compared with the control experiments, the PS was effectively activated by the CoFe-LDO, which degrades SMX in the presence of UV light. The effects of catalyst dosage and PS concentrations were examined, and 0.1 g/L CoFe-LDO and 5 mM PS were determined to be optimal for achieving complete SMX degradation within 60 min. Furthermore, the CoFe-LDO catalyst exhibited superior catalytic activity under weakly acidic pH conditions (i.e., pH 5–6). Reactive oxygen species were identified by scavenging experiments and electron spin resonance, suggesting that SO4•− and •OH radicals as well as 1O2 contributed to the SMX degradation. This finding proposed a plausible mechanism for SMX degradation in the UV/CoFe-LDO/PS system. Furthermore, nine by-products after the photo-PS process were identified, which were supposed to be generated through radical and non-radical pathways. This work offers a simple strategy for developing a sustainable, efficient, and effective catalyst for degrading persistent organic pollutants from water.