Peroxymonosulfate System Research Articles

Rational design of waste anode graphite-derived carbon catalyst to activate peroxymonosulfate for atrazine degradation

As the rapidly growing number of waste lithium-ion batteries (LIBs), the recycling and reutilization of anode graphite is of increasing interest. Converting waste anode graphite into functional materials may be a sensible option. Herein, a series of carbonaceous catalysts (TG) were successfully prepared using spent anode graphite calcined at various temperatures and applied for activating peroxymonosulfate (PMS) to degrade atrazine (ATZ). The catalyst obtained at 800 °C (TG-800) showed the optimum performance for ATZ removal (99.2% in 6 min). Various experimental conditions were explored to achieve the optimum efficiency of the system. In the TG-800/PMS system, free radicals (e.g., SO4·−, HO·), singlet oxygen (1O2), together with a direct electron transfer pathway all participated in ATZ degradation, and the ketonic (CO) group was proved as the leading catalytic site for PMS activation. The potential degradation routes of ATZ have also been presented. According to the toxicity assessment experiments, the toxicity of the intermediate products decreased. The reusability and universal applicability of the TG-800 were also confirmed. This research not only provides an efficient PMS activator for pollutant degradation, but also offers a meaningful reference for the recovery of waste anode graphite to develop environmentally functional materials.

Levofloxacin removal by 2D-Vermiculite loaded with NiCo2O4 activated peroxymonosulfate: Performance and mechanism

The presence of antibiotics in wastewater threatens the human living environment. Activated peroxymonosulfate (PMS) method is often used for catalytic degradation of antibiotics. However, how to reduce catalyst cost and ensure efficient degradation of antibiotics at the same time is a sticky issue for the activated PMS method. Two-dimensional vermiculite flakes (2D-VMT) is cost-effective and can be used as catalyst carriers for PMS activation. Hence, we exfoliated 2D-VMT from natural vermiculite and prepared NiCo2O4 loaded 2D-VMT (NiCo2O4/2D-VMT) catalyst. Levofloxacin (LVX), as a normal antibiotic, was used to evaluate the catalytic capacity of NiCo2O4/2D-VMT in PMS systems. Also, LVX degradation mechanism through NiCo2O4/2D-VMT activated PMS were explored here. XRD, EDS, TEM, and HRTEM analysis all demonstrated NiCo2O4 nanoparticles were successfully anchored on 2D-VMT. NiCo2O4/2D-VMT had a high specific surface area and abundant active sites. The NiCo2O4/2D-VMT/PMS system, with a 15% mass ratio of NiCo2O4 to 2D-VMT (15%-CN/2D-VMT), achieved LVX removal efficiency of 87% and LVX removal rate of 0.034 min−1. 1O2 and SO4·- were the major ROS for LVX degradation. The reversible redox cycle between Co(III)/Co(II) and Ni(III)/Ni(II) played a crucial role in activating PMS to generate ROS for LVX degradation process. Also, based on intermediates identification by LC-MS, possible degradation pathways of LVX were proposed and their ecotoxicological evolution was assessed by using the ECOSAR software. 15%-CN/2D-VMT may be a worth recommended loaded catalyst for antibiotics removal in environmental remediation, owing to its high reusability and excellent renewability.

Comparative study of organic removal by pre-adsorption oxidation and synchronous adsorption oxidation processes: Performance and mechanism

Both adsorption and oxidation occur and contribute to organics removal in carbonaceous materials based advanced oxidation processes, while the correction of adsorption and oxidation, and the role of adsorption in the veritable removal of organic are not clear. Herein, we investigated the performance of carbamazepine (CBZ) removal by peroxymonosulfate (PMS) activated by magnetic Fe-doped biochar through two models of pre-adsorption oxidation and synchronous adsorption oxidation processes. The adsorption process was better fitted by pseudo-second-order kinetic model and the adsorption mechanism was obtained by comprehensive analysis of equilibrium adsorption capacities, surface functional groups, specific surface area, pore volume, and ID/IG value. It is noted that pre-adsorption highly inhibited the further oxidation of CBZ in 0.5Fe@LSBC700/PMS system due to the occupied catalytic active sites. Total CBZ removal in pre-adsorption oxidation (45 %) was inferior to synchronous adsorption oxidation (∼100 %), as well as the veritable CBZ oxidation removal of 27 % for pre-adsorption oxidation vs ∼100 % in synchronous adsorption oxidation at 30 min. Oxidation degradation of CBZ based on radical oxidation was identified by quenching experiments and electron paramagnetic resonance measurements. This work is conducive to identifying the role of adsorption during the removal of organics in the adsorption-oxidation process, as well as veritable adsorption and oxidation removal of organics.

The “4 + 1” strategy fabrication of iron single-atom catalysts with selective high-valent iron-oxo species generation

Single-atom catalysts (SACs) with atomic dispersion active sites have exhibited huge potentials in peroxymonosulfate (PMS)-based Fenton-like chemistry in water purification. However, four-N coordination metal (MN4) moieties often suffer from such problems as low selectivity and narrow workable pH. How to construct SACs in a controllable strategy with optimized electronic structures is of great challenge. Herein, an innovative strategy (i.e., the "4 + 1" fabrication) was devised to precisely modulate the first-shell coordinated microenvironment of FeN4 SAC using an additional N (SA-FeN5). This leads to almost 100% selective formation of high-valent iron-oxo [Fe(IV)═O] (steady-state concentration: 2.00 × 10-8 M) in the SA-FeN5/PMS system. In-depth theoretical calculations unveil that FeN5 configuration optimizes the electron distribution of monatomic Fe sites, which thus fosters PMS adsorption and reduces the energy barrier for Fe(IV)═O generation. SA-FeN5 was then attached to polyvinylidene difluoride membrane for a continuous flow device, showing long-term abatement of the microcontaminant. This work furnishes a general strategy for effective PMS activation and selective high-valent metal-oxo species generation by high N-coordination number regulation in SACs, which would provide guidance in the rational design of superior environmental catalysts for water purification.

Mn doped nitrogen containing carbon activating peroxymonosulfate for enhancing sulfadiazine degradation via single oxygen pathway: Performance and mechanism

In this work, manganese (Mn) with different contents doped CNs (CNs-Mn) was prepared via the thermal polymerization of the mixture of melamine, β-lactose and manganese sulfate and used as peroxymonosulfate (PMS) activator for sulfadiazine (SD) degradation. The optimum CNs-Mn(ii) delivered admirable PMS activation efficiency toward SD degradation and the contents of oxidized N and Mn2+ in catalysts displayed strongly positive correlation with SD degradation constant. Electron paramagnetic resonance (EPR) and quenching experiments revealed that the content of generated 1O2 species was higher than other radicals and 1O2 dominated SD degradation in the CNs-Mn(ii)/PMS system. The density functional theory (DFT) calculation analysis revealed a novel direct evolutionary pathway of 1O2 formation, that is the cleavage of S-O and O–H of PMS lead to two O atoms to form 1O2. Furthermore, CNs-Mn(ii) displayed good stability, anti-interference ability and performed well in the wide pH range of 4.5 ∼ 9.5. This study would give new insights into 1O2 generation mechanism and essential atomic-scale understanding of the roles of oxidized N and Mn species in 1O2 generation during Mn doped N containing carbon activating PMS process, as well as develop one new strategy to promote 1O2 generation efficiency.

Activation of peroxymonosulfate with ZIF-67-derived Co/N-doped porous carbon nanocubes for the degradation of Congo red dye

In this study, porous carbon nanocubes encapsulated magnetic metallic Co nanoparticles (denoted as Co@N-PCNC) was prepared via pyrolyzing ZIF-67 nanocubes precursor at 600 °C and characterized by various technologies. It was used to activate peroxymonosulfate (PMS) to degrade Congo red (CR) dye efficiently. Over 98.45% of 50 mg L−1 CR was degraded using 0.033 mM PMS activated by 75 mg L−1 Co@N-PCNC within 12 min. The free radical quenching experiments were performed to reveal the nature of the reactive oxygen species radicals generated throughout the catalytic oxidation of CR. The effects of common inorganic anions and the water matrix on CR removal were studied. Moreover, the results of the kinetic study revealed the suitability of the pseudo-first-order and Langmuir–Hinshelwood kinetic models for illustrating CR degradation using the Co@N-PCNC/PMS system. Ultimately, the Co@N-PCNC displayed good operational stability, and after five cycles, the CR removal rate can still maintain over 90% after 12 min.

Simultaneous incorporation of Co and Fe into sulfur-vacancy-enriched MoS2 enhances the activation of peroxymonosulfate

Developing efficient and low-cost catalysts in peroxymonosulfate (PMS)-based advanced oxidation processes is vital but challenging. Here, a series of Co,Fe co-doped MoS2 with abundant S vacancies were prepared and utilized as PMS activators. The OTC removal efficiency (92.0%) in 1-Co,Fe-MoS2/PMS system was significantly higher than that (53.5%) in MoS2/PMS system. SO4•–/•OH, O2•−, and 1O2 played dominant roles, while high-valent metal and electron transfer mechanism played limited roles for OTC removal in both systems. The contributions of reactive species in 1-Co,Fe-MoS2/PMS system ranked as follows: 1O2 > SO4•–/•OH > O2•−, while that was O2•− > SO4•–/•OH >1O2 in MoS2/PMS system. Co and Fe doping promoted the generation of S vacancy in MoS2. Co(II)/Co(III), Fe(II)/Fe(III) and Mo(IV)/Mo(VI) all contributed to the activation of PMS, but Co and Fe sites were the major active sites of 1-Co,Fe-MoS2. Moreover, 1-Co,Fe-MoS2 was deposited on a polytetrafluoroethylene membrane, and exhibited excellent catalytic effect for OTC removal via a flow-through setup. Thus, this study provided a promising Co,Fe-MoS2/PMS process for organic pollutant removal.

CuFeS2/MXene-Modified Polyvinylidene Fluoride Membrane for Antibiotics Removal through Peroxymonosulfate Activation

In this research, the CuFeS2/MXene-modified polyvinylidene fluoride (PVDF) membrane was prepared to activate peroxymonosulfate (PMS) to remove moxifloxacin (MOX) and its morphology; surface functional groups and hydrophilicity were also studied. The parameters of the catalytic membrane/PMS system were optimized, with an optimal loading of 4 mg/cm2 and a PMS dosage of 0.20 mM. High filtration pressure, alkaline conditions, and impurities in water could inhibit MOX removal. After continuous filtration, the removal efficiency of MOX using the catalytic membrane/PMS system and PVDF membrane was 68.2% and 9.9%, respectively. Batch filtration could remove 87.8% MOX by the extra 10 min contact time between the catalytic membrane and solution. During the filtration process, CuFeS2/MXene on the surface of the catalytic membrane activated PMS to produce SO4•−, HO•, and 1O2, and MOX was removed through adsorption and degradation. Taking humic acid (HA) as the model foulant, reversible fouling resistance in the catalytic membrane/PMS system was 22.8% of the PVDF membrane. The catalytic membrane/PMS system weakened the formation of the cake layer by oxidizing HA into smaller pollutants and followed the intermediate blocking cake filtration model. The novelty of this research was to develop a CuFeS2/MXene–PVDF membrane-activated PMS system and explore its application in antibiotics removal.

M−N3 Configuration on Boron Nitride Boosts Singlet Oxygen Generation via Peroxymonosulfate Activation for Selective Oxidation

AbstractSinglet oxygen (1O2) is an essential reactive species responsible for selective oxidation of organic matter, especially in Fenton‐like processes. However, due to the great limitations in synthesizing catalysts with well‐defined active sites, the controllable production and practical application of 1O2 remain challenging. Herein, guided by theoretical simulations, a series of boron nitride‐based single‐atom catalysts (BvBN/M, M=Co, Fe, Cu, Ni and Mn) were synthesized to regulate 1O2 generation by activating peroxymonosulfate (PMS). All the fabricated BvBN/M catalysts with explicit M−N3 sites promoted the self‐decomposition of the two PMS molecules to generate 1O2 with high selectivity, where BvBN/Co possessed moderate adsorption energy and d‐band center exhibited superior catalytic activity. As an outcome, the BvBN/Co‐PMS system coupled with membrane filtration technology could continuously transform aromatic alcohols to aldehydes with nearly 100 % selectivity and conversion rate under mild conditions, suggesting the potential of this novel catalytic system for green organic synthesis.

The activation of PMS for PFOA degradation by adjustable metal stripping Fe/Co/N@BC catalysts: Degradation performance with single-line oxygen and high-valent metal oxides as the main active substances

In this study, a modified biochar (P-Fe/Co/N@BC) catalyst was prepared with wood chips as raw material by hydrothermal method for the activation of peroxymonosulfate (PMS) and degradation of perfluorooctanoic acid (PFOA). Scanning electron microscopy (SEM), x-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS) characterization methods were used to demonstrate the presence of FeNx, CoNx, Fe-Co and CO active sites, which contribute to the improvement of the PMS activation capacity for single-line oxygen (1O2). Electron paramagnetic resonance spectroscopy (EPR), reactive oxygen species (ROS) scavenging experiments and methyl phenyl sulfoxide (PMSO) conversion experiments were performed to clarify the main mechanisms of PFOA degradation by reactive species. Further, 1O2, sulfate radical (SO4−), hydroxyl radical (OH), high-valent metal oxides (Fe(IV) and Co(IV)) were jointly involved in the degradation of PFOA, and nonradical were the main activation pathway of PMS. In particular, Fe3+ decomposed from Fe(IV) in the presence of Fe0 and Co2+ decomposed from Co(IV) are able to enhance iron cycling and cobalt cycling, respectively. Meanwhile, Co0 accelerates the conversion of Co3+ to Co2+. The findings suggested that the removal rate of the P-Fe/Co/N@BC-PMS system (99 %) was much higher than that of the P-Fe-N-C/PMS (68.9 %) over 180 min. It emphasized that the incorporation of PTFE (polytetrafluoroethylene) can regulate metal leaching significantly and improve the cycling stability of the catalysts. This study aimed to prepare efficient and stable modified biochar catalysts to activate PMS, which provided an effective solution to the problem of metal ion leaching from metal-modified biochar materials.

Degradation of Tetracycline through peroxymonosulfate activation with Co/Fe-LDH modified magnetic hydrochar: Synergistic effect and low toxicity

In this work, 2LDH-CoFe2O4@BHC catalyst was prepared by modifying magnetic corncob-based hydrochar (CoFe2O4@BHC) with Co/Fe layered double hydroxide (Co/Fe-LDH), which was used to activate peroxymonosulfate (PMS) for tetracycline (TC) degradation. 2LDH-CoFe2O4@BHC demonstrated effective activation of PMS and rapid removal of TC (100 %) within 10 min by leveraging structural modulation and synergistic interactions among multiple components. In contrast, BHC (26.02 %), CoFe2O4 (59.25 %), and CoFe2O4@BHC (61.88 %) presented poor removal efficiency. Furthermore, it was shown that both the free radicals (SO4•-) and non-free radicals (1O2) were essential in the degradation process, and the catalytic mechanism was revealed to be a synergistic process with the characterization results from in-situ Raman, electrochemical characterization, and X-ray photoelectron spectroscopy (XPS). The catalytic performance of 2LDH-CoFe2O4@BHC was also evaluated using a self-developed fixed-bed reactor, demonstrating its strong stability and resistance to interference during long-term operation. The potential degradation pathway of TC in the 2LDH-CoFe2O4@BHC + PMS system was suggested based on the quadrupole time-of-flight mass spectrometry (QTOF/MS) findings. It was found that the toxicity of the intermediates produced by TC degradation significantly reduced. This study presented an insight for the decomposition of organic pollutants by synthetic biochar-loaded catalysts.

LaCoO3@Fe3O4 as peroxymonosulfate activator derived from spent lithium battery cathode materials for degradation of sulfamethoxazole in water

To reduce the various hazards of SMX to aquatic ecosystems, in this study, magnetically separable LaCoO3@Fe3O4 catalysts for the degradation of sulfamethoxazole (SMX) in water by activated peroxymonosulfate (PMS) were successfully prepared by using cobalt oxalate recovered from spent batteries using sol–gel, hydrothermal, and high-temperature calcination methods. The main factors influencing the reaction and the effect of coexisting ions on the degradation efficiency of SMX were investigated. The results showed that under optimal conditions ([SMX] = 30 mg, [LaCoO3@Fe3O4] = 10 mg/L, [PMS] = 30 mg/L, pH (initial) = 7.02), the LaCoO3@Fe3O4/PMS system degraded SMX up to 93 % in 15 min. The degradation of SMX in the LaCoO3@Fe3O4/PMS system was shown to be achieved by a combination of radical (SO4•-/•OH/•O2–) and non-radical (1O2) pathways by quenching experiments and electron paramagnetic resonance spectroscopy (EPR) analysis. Then, three possible degradation pathways were proposed using LC-MS, and Ecological Constitutive Relationship (ECOSAR) analysis showed that the toxicity of the intermediate products was all lower than that of SMX, indicating that the system is feasible for SMX degradation. This study provides a new idea for activating PMS for the degradation of antibiotics in water by preparing catalysts using precious metals from recycled batteries.

Performance and mechanistic studies of rapid atenolol degradation through peroxymonosulfate activation by V, Co, and bamboo carbon catalyst.

Developing the Co-based catalysts with high reactivity for the sulfate radical (SO4-·)-based advanced oxidation processes (SR-AOPs) has been attracting numerous attentions. To improve the peroxymonosulfate (PMS) activation process, a novel Co-based catalyst simultaneously modified by bamboo carbon (BC) and vanadium (V@CoO-BC) was fabricated through a simple solvothermal method. The atenolol (ATL) degradation experiments in V@CoO-BC/PMS system showed that the obtained V@CoO-BC exhibited much higher performance on PMS activation than pure CoO, and the V@CoO-BC/PMS system could fully degrade ATL within 5min via the destruction of both radicals (SO4-· and O2-··) and non-radicals (1O2). The quenching experiments and electrochemical tests revealed that the enhancing mechanism of bamboo carbon and V modification involved four aspects: (i) promoting the PMS and Co ion adsorption on the surface of V@CoO-BC; (ii) enhancing the electron transfer efficiency between V@CoO-BC and PMS; (iii) activating PMS with V3+ species; (iv) accelerating the circulation of Co2+ and Co3+, leading to the enhanced yield of reactive oxygen species (ROS). Furthermore, the V@CoO-BC/PMS system also exhibited satisfactory stability under broad pH (3-9) and good efficiency in the presence of co-existing components (HCO3-, NO3-, Cl-, and HA) in water. This study provides new insights to designing high-performance, environment-friendly bimetal catalysts and some basis for the remediation of antibiotic contaminants with SR-AOPs.

Selective oxidation behavior based on iron-doped MOF derived carbon-based catalysts: Active site regulation and degradation mechanism analysis

Selective removal of target organic pollutants in complex water quality of municipal sewage is extremely important for the deep treatment of water quality. Here, energetic MOF and Fe-MOF are doped in electrostatic spinning process to adjust the structure and composition of the catalysts, active oxygen species (ROSs), realizing the selective removal of organic pollutants. Non-azo and azo pollutants are selected as target pollutants. Catalysts PCFe-8 with Fe nanoclusters, EPCFe-8 with Fe-Nx, and EPC-8 without Fe doping are used to activate peroxymonosulfate (PMS) for degrading pollutants. The results show that the PCFe-8/PMS system can produce the most SO4− and exhibit superior removal of azo pollutants, whereas the degradation behavior of non-azo pollutants is more inclined to occur in the EPCFe-8/PMS system and the EPC-8/PMS system. This work provides a reference for elucidating the relationship between catalyst structure and components, types of ROSs, and selective degradation of pollutants.

Air-engaged synthesis of yeast biomass-derived porous O, P-codoped biochar as metal free catalyst towards water decontamination

Facile and sustainable preparation of effective metal-free catalysts using natural biomass as a feedstock is essential but challenging for peroxymonosulfate activation in degrading organic pollutants in wastewater. In this study, we develop an air-engaged pyrolysis method to successfully prepare O, P dual-doped porous carbon material (Yeast-T) using biomass yeast as a feedstock. Among the samples, Yeast-650 exhibits the highest performance in activating peroxymonosulfate towards the destruction of methyl orange, achieving a removal efficiency of 98 % in 30 min and a rate constant of 0.226 min-1. The non-radical pathway, with singlet oxygen as the active substance, dominates the destruction of methyl orange over the Yeast-650/peroxymonosulfate system. Based on the detected intermediates, four possible pathways for methyl orange degradation by the Yeast-650/peroxymonosulfate system are unveiled. The toxicity analysis of the degradation products was evaluated by calculating and comparing the radicle length of mung bean in different solutions and the germination of wheat seeds in different solutions. This study presents a simple and feasible air-mediated synthetic method for high-performance metal-free peroxymonosulfate activators in the removal of organic pollutants.

Activation of peroxymonosulfate and peroxydisulfate by nitrogen-doped carbon nanotubes for effective degradation of neonicotinoid insecticides

Nitrogen-doped carbon nanotubes (N-CNTs) have been considered as an excellent metal-free activator for persulfate-based advanced oxidation processes. However, the critical role of N-doping in the activation of peroxymonosulfate (PMS) and peroxydisulfate (PDS) remains a significant difference even opposed in scientific understanding. Herein, the CNTs and N-CNTs were used to active PMS and PDS for degradation of neonicotinoid insecticides (NNIs), one of the emerging refractory organic pollutants. The N-CNTs achieve 92.6% of nitenpyram (Nit) degradation within only 10 min under PMS system, much higher than that of CNTs/PMS system (∼10%). Moreover, the N-CNTs can active PMS to conduct degradation through a combined 1O2 and electron transfer process with k of 4.94 × 10−2 L·mg−1·min−1, which was quite different from N-CNTs/PDS system (single electron transfer process, k = 1.84 × 10−3 L·mg−1·min−1). A positive correlation between degradation rates of five NNIs and their electron-donating ability is established, further verifying the importance of electron transfer in NNIs degradation. This study proves the superiority of N-CNTs/PMS over N-CNTs/PDS in Nit degradation and the underlying mechanisms, and reveals the importance of electron-donating ability of NNIs in their degradation by N-CNTs/PMS. These findings are of great significance for their removal from the environment.

New insight into wastewater treatment by activation of sulfite with humic acid under visible light irradiation

Sulfite (S(IV)), as an alternative to persulfate, has demonstrated its cost-effectiveness and environmentally friendly nature, garnering increasing attention in Advanced Oxidation Processes (AOPs). Dissolved organic matter (DOM) commonly occurred in diverse environments and was often regarded as an interfering factor in sulfite-based AOPs. However, less attention has been paid to the promotion of the activation of sulfite by excited DOM, which could produce various reactive intermediates. The study focused on the activation of sulfite using visible light (VL) - excited humic acid (HA) to efficiently degrade many common organic pollutants, which was better than peroxydisulfate (PDS) and peroxymonosulfate (PMS) systems. Quenching experiments and electron paramagnetic resonance (EPR) analysis revealed that the triplet states of HA (3HA*) activated sulfite through energy transfer, resulting in the production of SO4·−, O2·−, and 1O2. The most significant active species found in the degradation of roxarsone (ROX) was 1O2, which was a non-radical pathway and exhibits high selectivity for pollutant degradation. This non-radical pathway was not commonly observed in traditional sulfite-based AOPs. Additionally, the coexistence of various inorganic anions, such as NO3−, Cl−, SO42−, CO32−, and PO43−, had little effect on the degradation of ROX. Furthermore, DOM from different natural water demonstrated efficient activation of S(IV) under light conditions, opening up new possibilities for applying sulfite-based advanced oxidation to the remediation of organic pollution in diverse sites and water bodies. In summary, this research offered promising insights into the potential application of sulfite-based AOPs, facilitated by photo-excited HA, as a new strategy for efficiently degrading organic pollutants in various environmental settings.

Porous-carbon/manganese composite catalyst transformed from waste biomass as peroxymonosulfate activator for carbamazepine degradation

Activation of peroxymonosulfate (PMS) with solid catalysts for organic pharmaceutical degradation still faces challenge due to the demand of inexpensive catalysts. In this study, manganese-oxidizing microalgae (MOM) and its associated biogenic manganese oxides (BMO) were employed to prepare biomass-transformed porous-carbon/manganese (B-PC/Mn) catalyst through high-temperature calcination (850 °C). Remarkably, 100 % of carbamazepine (CBZ) was degraded within 30 min in the B-PC/Mn/PMS system. The degradation kinetic constant was 0.1718 min−1, which was 44.0 times higher than that of the biomass-transformed porous carbon mixed with MnOx activated PMS system. 1O2 was generated in the B-PC/Mn/PMS system, which is responsible for CBZ degradation. The MOM-BMO-associated structure greatly increased the specific surface areas and the contents of the C = O and pyrrolic-N groups, which facilitated PMS activation. The structure also induced the generation of Mn5C2, which exhibited a strong adsorption towards PMS. This study provides a novel strategy for preparing catalysts by using waste biomass.

Degradation of Bisphenol A by Nitrogen-Rich ZIF-8-Derived Carbon Materials-Activated Peroxymonosulfate.

Bisphenol A (BPA), representing a class of organic pollutants, finds extensive applications in the pharmaceutical industry. However, its widespread use poses a significant hazard to both ecosystem integrity and human health. Advanced oxidation processes (AOPs) based on peroxymonosulfate (PMS) via heterogeneous catalysts are frequently proposed for treating persistent pollutants. In this study, the degradation performance of BPA in an oxidation system of PMS activated by transition metal sites anchored nitrogen-doped carbonaceous substrate (M-N-C) materials was investigated. As heterogeneous catalysts targeting the activation of peroxymonosulfate (PMS), M-N-C materials emerge as promising contenders poised to overcome the limitations encountered with traditional carbon materials, which often exhibit insufficient activity in the PMS activation process. Nevertheless, the amalgamation of metal sites during the synthesis process presents a formidable challenge to the structural design of M-N-C. Herein, employing ZIF-8 as the precursor of carbonaceous support, metal ions can readily penetrate the cage structure of the substrate, and the N-rich linkers serve as effective ligands for anchoring metal cations, thereby overcoming the awkward limitation. The research results of this study indicate BPA in water matrix can be effectively removed in the M-N-C/PMS system, in which the obtained nitrogen-rich ZIF-8-derived Cu-N-C presented excellent activity and stability on the PMS activation, as well as the outstanding resistance towards the variation of environmental factors. Moreover, the biological toxicity of BPA and its degradation intermediates were investigated via the Toxicity Estimation Software Tool (T.E.S.T.) based on the ECOSAR system.

Boosting peroxymonosulfate activation with a composite of highly dispersed FeS2 nanoparticles anchored on N-doped biochar for efficient tetracycline degradation

The rational design of inexpensive peroxymonosulfate (PMS) activators with high efficiencies is still in high demand. Herein, a composite with highly dispersed FeS2 anchored on nitrogen-doped biochar (FeS2@NBC) was prepared via a hydrothermal process and used for PMS activation to degrade the pollutant tetracycline (TC). Benefiting from in situ growth of FeS2 on the NBC surface, FeS2@NBC alleviated the side effects caused by FeS2 agglomeration, and the synergistic catalytic effect of the FeS2 nanoparticles and N-doped biochar resulted in excellent performance. The optimal FeS2@NBC/PMS system could degrade 87.6 % of TC within 10 min, and it exhibited adaptability to pH changes and the presence of common inorganic anions. A comprehensive study involving radical scavenging experiments, electron paramagnetic resonance (EPR) spectroscopy, electrochemical tests and XPS analyses revealed that the singlet oxygen (1O2) and hydroxyl radical (•OH) were the dominant reactive oxygen species (ROS), the sulfate radical (SO4•−) and electron transfer were involved in the TC degradation process. Moreover, three degradation pathways were indicated by LC−MS detection, and the toxicities of the degradation intermediates were predicted and evaluated. Finally, FeS2@NBC showed excellent reusability and stability after five cycles of TC degradation. This work provides a reference for designing efficient catalysts that can be combined with metal sulfides and biochar for efficient PMS activation.