Degradation Of Refractory Organic Pollutants Research Articles

Insights into the PMS activation towards phenol removal mechanism by a Ti3C2-MXene doped BiVO4 photocatalyst

In the field of water treatment, photocatalysis and the peroxomonosulfate (PMS) deep oxidation process have emerged as potential solutions for the degradation of refractory organic pollutants. In this study, a novel BiVO4/Ti3C2 composite photocatalytic material was successfully synthesized using a hydrothermal method. The energy band structure of this material was utilized to establish Schottky barriers, enhancing the separation of photogenerated carriers. This, in turn, facilitated the activation of PMS under visible light, generating reactive species that effectively degraded phenol. The results demonstrate that in the BT-3/PMS system, the degradation rate of phenol reached 87.2 % within 60 min, with a maximum degradation rate constant of 0.02537 min−1. This represents an 8.8-fold improvement compared to pure BiVO4 and a 5.2-fold improvement compared to pure PMS. Free radical tests indicated that SO4·- was the primary reactive species involved in the degradation process. This study offers a promising approach for the design of efficient and stable Schottky junction photocatalysts that can be activated by visible light and PMS to effectively degrade organic pollutants.

Development of a novel polydopamine-imprinted MOFs targeted for removal of refractory organic pollutants: Synergistic mechanisms of adsorption and degradation

In this study, a novel dopamine-imprinted MOFs (metal organic frameworks) was developed for the first time to achieve targeted degradation of refractory organic pollutants (ROPs) in advanced oxidation process. The targeted adsorption and degradation capacity of sulfamethoxazole (SMX) by molecularly imprinted catalyst (Fe-MOFs@MIP) was 3.17 times and 5.47 times that of Fe-MOFs, respectively. The results showed that the polydopamine (PDA) imprinted layer not only enhanced the targeted adsorption of SMX, but also improved the activity of the catalyst by promoting electron transfer. The physicochemical properties of Fe-MOFs@MIP were investigated. In situ Fourier transform infrared spectroscopy and molecular dynamics theory were used to investigate targeted adsorption mechanism. The active species were identified by quenching experiments and electron paramagnetic resonance (EPR). The reaction sites of SMX were predicted using density functional theory (DFT) and the possible degradation pathways of SMX were proposed. Finally, the targeted degradation mechanism of Fe-MOFs@MIP was elucidated. This study has a guiding significance for the deep removal of refractory organic pollutants in wastewater.

Assembly of Amorphizing Porous Bimetallic Metal‐Organic Frameworks Spheres with Zn─O─Fe Cluster and Coordination Deficiency via Ligand Competition for Efficient Electro‐Fenton Catalysis

AbstractElectro‐Fenton process stands out as a highly promising approach for generating reactive oxygen‐containing radicals to address the escalating issue of environmental pollution. However, the long‐term goal of application necessitates ongoing pursuit of high‐quality catalysts with both sufficient activity and stability. Herein, a general route is reported for large‐scale synthesis of amorphizing porous bimetallic metal‐organic framework (MOF) spheres with Zn─O─Fe structure and coordination deficiency through facile and low‐cost synthesis of ligand competition. Assisted by a coordination modulator, deprotonation of terephthalic acid is accelerated and rapid synthesis of amorphous bimetallic MOF spheres is successfully achieved at room temperature. As inactive metal Zn is introduced into metal clusters of MOFs, the cycling efficiency of Fe3+/Fe2+ is improved and a secondary building unit of Zn─O─Fe is constructed, greatly accelerating electron conduction rate. Compared to crystalline spindle cMIL‐88B(Fe2Zn) by traditional solvothermal route, amorphous aMIL‐88B(Fe2Zn) has a unique spherical porous structure with larger surface area, higher conductivity, and more exposed active sites. Endowed with unique textural and surface chemistry, aMIL‐88B(Fe2Zn) exhibits superior catalytic activity in the degradation of refractory organic pollutants. The progress offers a feasible way to rational design of iron‐based hybrid MOF materials with tunable structures and enhance properties for various applications.

Nitrogen-doped carbon aerogel supported SnO2 anode for electrocatalytic degradation of phenol: Enhanced generation of free radicals

To obtain a high-efficiency and low-cost electrocatalytic anode for environmental pollutant degradation, a nitrogen doped graphene aerogel supported tin oxide (SnO2-NGA) composite catalyst was prepared and SnO2-NGA/Ti anode was fabricated. The influence of nitrogen doping content on electrocatalytic activity of the catalysts was investigated. The effects of current density and initial solution pH on degradation efficiency were studied. The SnO2-N3.0GA/Ti anode shows good catalytic activity for phenol degradation. The conversion of phenol and COD removal by SnO2-N3.0GA/Ti reached 83.6% and 61.2% within 4 h when applied current density was 5.00 mA/cm2 and initial pH was 3.0. The SnO2-N3.0GA/Ti electrode has higher specific surface area, and lower charge transfer resistance. The nitrogen atoms doping increased the content of pyridinic N species, which is beneficial for providing more in-situ catalytic active sites and enhancing the production of reactive oxygen species, especially hydroxyl radical (•OH). This work provides a novel strategy for synthesis of electrocatalytic anode with enhanced activity for degradation of refractory organic pollutants in water.

Preparation of La-doped ZnFe LDH immobilized on polydimethylsiloxane sponge for the peroxymonosulfate-assisted photocatalytic degradation of rifampicin

In this study, La-doped ZnFe layered double hydroxide (La-ZnFe LDH) was immobilized on polydimethylsiloxane (PDMS) sponges and applied in the photocatalytic degradation process for the activation of peroxymonosulfate (PMS). The La-ZnFe LDH, PDMS sponge, and PDMS@La-ZnFe LDH samples were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDX), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), Fourier transform infrared (FT-IR) analyses, and contact angle goniometer. The immobilized catalyst had a porous structure with a specific surface area of 5.94 m2 g−1 and a pore volume of 1.36 cm3 g−1. The PDMS@La-ZnFe LDH has the high potential to degrade rifampicin by activating PMS with a notable synergistic factor of 3.38. The optimum operating conditions for the degradation of 15 mg L−1 of rifampicin were determined as 0.2 mmol L−1 of PMS, 100 W of light intensity, and pH of 8, conducting the degradation efficiency to 92.8% within 360 min. According to the radical quenching tests, h+, •OH, SO4•−, and O2•− exhibited an important role in the rifampicin degradation. Besides, the PDMS@La-ZnFe LDH sponge possessed excellent reusability during the PMS-activated photocatalytic process after seven consecutive runs. Furthermore, the treatment of rifampicin from real wastewater was also evaluated. GC-MS analysis was carried out to determine the generated by-products during the photocatalytic degradation process. Briefly, La-ZnFe LDH catalyst immobilized with PDMS sponges can be a promising reusable and durable photocatalyst for the degradation of refractory organic pollutants.

Visible light active Ti3+ self-doped mesoporous TiO2 photocatalyst with efficient photocatalytic performance for the degradation of chlorpyrifos

ABSTRACT In the present research, Ti3+ self-doped TiO2 photocatalyst (Ti3+-TiO2) was fabricated through a facial in-situ NaBH4 reduction approach. The as-prepared Ti3+-TiO2 were characterised using FESEM-EDS, TEM, HRTEM, XRD, UV-DRS, PL, EIS, and BET methods. The photocatalytic performance of the Ti3+-TiO2 was assessed through the degradation of chlorpyrifos (CPY) as an organophosphorus pesticide under visible LED light irradiation. The Ti3+-TiO2 exhibited excellent photocatalytic degradation efficiency at initial CIP concentration = 1 mg L−1, pH = 7, catalyst dosage = 0.2 g L−1, and reaction time of 50 min with 97%, which is 4.62 times higher than that of pristine TiO2. The extraordinarily boosted photocatalytic activity of Ti3+-TiO2 can be attributed to mesoporous nanostructure, oxygen vacancy, and Ti3+ self-doping, which facilitates visible light harvesting and accelerates charge carrier separation and transport. In addition, Ti3+-TiO2 shows outstanding mineralisation capability and recycling performance in degrading CPY. Coexisting water anions (NO3 −, Cl−, SO4 2-, HCO3 −) and HA inhibited the degradation of CPY. Their inhibition effects of selected anions followed the order of HCO3 − > SO4 2-> NO3 − > Cl−. Besides, a possible reaction mechanism of the photocatalytic process was recommended based on evidence from the radical scavenging test and photoelectrochemical measurements. The energy consumption value in this study was much less than that reported in other studies. Collectively, the findings show that Ti3+-TiO2 photocatalyst has tremendous potential in solar photocatalytic degradation of refractory organic pollutants.

Highly efficient photocatalytic degradation of refractory organic pollutants onto designed boron nitride: Morphology control and oxygen doping

Hexagonal boron nitride (h-BN) exhibits enormous potential for photocatalysis, while its performance is restricted by insufficient light absorption and rapid electron-hole pairs recombination. To address this, BN photocatalysts with various morphologies and oxygen doping were rationally prepared in this study. The results showed that band gap control and charge transfer ability regulation were achieved by oxygen doping and morphology designing. The optimized BN photocatalysts (s-BN) with 3D hierarchical spherical-like structure presented an ultra-thin edge, high oxygen content (6.1 at%), and high specific surface area (446 m2g−1), resulting in enhanced light absorption, efficient charge transfer, and abundant surface reactions. The photocatalytic tetracycline degradation efficiency and rate constant of s-BN were 18.11 times and 51.02 times higher than that of commercial h-BN, respectively. The mechanism study identified the primary active species for s-BN as superoxide radicals and holes, which facilitated the mineralization of tetracycline during the degradation process. This study provides a novel strategy for the development of high-performance and stable BN photocatalysts for efficient photocatalytic degradation of refractory organic pollutants.

Enhancing persulfate activation by carbon − based Mn − Fe nanoparticles for groundwater ISCO treatment: Efficiency, stability and mechanism

Persulfate − based in situ chemical oxidation (ISCO) is a promising approach for groundwater treatment due to its potential. However, the development of catalysts with sufficient activity and stability in persulfate oxidation remains a long − term goal. In this study, we aimed to address this challenge by preparing bimetallic nanoparticles coated with porous nitrogen − doped graphene shells, known as MnFe − NC, to activate peroxydisulfate (PDS). The unique structural feature of MnFe − NC, with metallic crystal nanoparticles encapsulated in carbon shells, ensured excellent persulfate activation performance of MnFe − NC, even during repeated cycles and extended periods of storage. To evaluate the practical application of MnFe − NC, MnFe − NC/PDS was installed in sand columns for the ISCO of sulpiride (SPR), achieving removal efficiencies of approximately 100 % during a continuous 7 − day reaction process. MnFe − NC/PDS exhibited remarkable tolerance to pH changes and environmental interference commonly encountered in groundwater treatment scenarios. Combined with density functional theory calculations, Mn5C2 and Fe2N were identified as the key active site for MnFe − NC activation of PDS. The decomposition mechanism of SPR in the system was further analyzed, including the cleavage of C–N/C–C, denitration reaction, and substitution reaction. These findings provide important insights into the intricate processes involved in the degradation of refractory organic pollutants. The developed MnFe − NC catalyst for PDS − based ISCO exhibits great potential in the remediation of refractory organic pollutant − contaminated groundwater.

CoOOH with a highly negative CB band for visible-light-driven photocatalytic degradation of refractory organic pollutants in peroxymonosulfate system: Enhanced performance and multi-path synergetic mechanisms

To date, cobalt ions/oxides were proven to be the best peroxymonosulfate (PMS) activator in the homogeneous/heterogeneous system. Interestingly, we found out that CoOOH with a narrow band gap (2.18 eV) and highly negative CB band (−1.73 eV) showed a good potential to be a visible-light-driven photocatalyst for PMS activation. The results turned out that the reaction rate constant of typical refractory contaminants in the Vis-CoOOH/PMS system was about 2–5 times higher than that in the Dark-CoOOH/PMS system. The photogenerated electron (e−) and hole (h+) can react with PMS, which significantly facilitates charge separation. Meanwhile, the e− on the highly negative CB band can react with oxygen to generate O2•−, which simultaneously accelerates the cycle Co(III)/Co(II) to generate radicals (O2•−, •OH and SO4•−) and non-radical (1O2). As a result, multiple ROS was involved in the degradation of contaminants. Especially, O2•− with a longer half-life over 1O2 is identified as the dominant ROS, enhancing the utilization of radicals and the effective attack with contaminants. Therefore, this study first reports the great potential of CoOOH as a visible-light photocatalyst and reveals the multi-path mechanism of the synergistic visible-light-driven photocatalysis and PMS activation for removing refractory contaminants in wastewater.

CuCoFe-LDHs activated sodium percarbonate (SPC) for the degradation of ciprofloxacin

Sodium percarbonate (SPC) is widely used in Fenton-like technology for the organic wastewater treatment because of its low costs and convenient transportation. However, low utilization efficiency of hydrogen peroxide limits its application. In this work, a catalyst (CuCoFe-LDHs) was designed to activate SPC for degrading ciprofloxacin (CIP) effectively in heterogeneous Fenton system with higher H2O2 utilization rate (62 %) and higher stability (degradation rate of CIP decreased 5.6 % after five cycles). Since SPC was dissolved in water, H2O2 and CO32- were generated, and CO32- was transferred to HCO3- subsequently along with the variation of pH value. Plenty of •OH and •O2- was generated, and most of •OH was directly reacted with CIP. However, •O2-, was prone to react with HCO3- to form •CO3-, and then for degrading CIP. Compare with CuMgFe-LDHs catalyst, the electrochemical impedance spectroscopy (EIS) showed that CuCoFe-LDHs with stronger electron transfer ability. Therefore, the Co atom could facilitate the generation of specific free radical via enhancing electron transfer rate for the degradation of CIP in CuCoFe-LDHs. In summary, this study provides a cheap, recyclable, efficient and environmentally friendly wastewater treatment method for the degradation of refractory organic pollutants.

Perborate accelerated copper-immobilized carbon nanofibers activating peroxymonosulfate process for sulfadiazine degradation: Performance and mechanisms understanding

In this work, perborate (BO3−) was applied to promote the degradation of sulfadiazine (SDZ) in copper-immobilized carbon nanofibers (Cu-CNF-x) activated peroxymonosulfate (PMS) system. Results showed that in BO3−/Cu-CNF-3/PMS ternary system, 100% of SDZ (40 μM) could be efficiently eliminated in 5 min with 0.1 g/L Cu-CNF-3, 1 mM BO3− and 1 mM PMS; while Cu-CNF-3/PMS and BO3−/PMS systems only achieved 58.4% and 47.3% degradation in 30 min. In initial pH range of 5.0–9.0, the ternary system removed over 92.6% of SDZ, and the treated solution pH maintained neutral, effectively relieving the water acidification introduced by PMS. Electron paramagnetic resonance analysis and radical scavenger tests evidenced the production of SO4−•, •OH, 1O2 and H2O2BO•O•−. Mechanisms analysis proposed the activation process as follows: initially, BO3− promptly activated PMS to generate H2O2BO•O•− via electrophilic substitution reaction, and H2O2 was produced due to the decomposition of BO3−; thereafter, PMS was activated by Cu-CNF-x to yield SO4−•, •OH and 1O2; the obtained H2O2 was then utilized by Cu-CNF-x to produce •OH and 1O2 as well. Density functional theory (DFT) calculations showed that the adsorption energy (Ead) between PMS and Cu-CNF-x was 0.43 eV. BO3− greatly increased the Ead of PMS on Cu-CNF-x by ten times to 4.75 eV, which extremely promoted the PMS activation. This work provided a novel strategy of BO3−/Cu-CNF-3/PMS for the efficient degradation of refractory organic pollutants, and managed to understand the synergistic role of BO3− to PMS based heterogeneous catalytic processes.

Manganese-nitrogen co-doped biochar (MnN@BC) as particle electrode for three-dimensional (3D) electro-activation of peroxydisulfate: Active sites enhanced radical/non-radical oxidation

A novel manganese-nitrogen co-doped biochar (MnN@BC) was synthesized and used as particle electrodes in three-dimensional (3D) electro-activation of peroxydisulfate (PDS) for the degradation of refractory organic pollutants. All the spectroscopy (EDS, XRD, XPS, FTIR, and Raman) results indicated that Mn-N nanoclusters were successfully deposited and embedded in BC. The material appeared graphitized structure with more defects after Mn-N doping. MnN@BC in 3D electro-activation of PDS (E/MnN@BC/PDS) exhibited excellent performance in carbamazepine (CBZ) removal, with removal efficiency and degradation rates of 96.84% and 0.0582 min-1, respectively. Besides, MnN@BC was favorable for adsorption, electron transfer, and reactive oxidizing species (ROS) formation. MnN@BC had good recyclability in the E/MnN@BC/PDS system by the recycled experiments and characterization. Furthermore, quenching experiments, probe experiments, and electron paramagnetic resonance (EPR) analyses suggested that •OH and 1O2 were the main ROS in the E/MnN@BC/PDS system, and the non-radical oxidation take a key part. In addition, this system achieved excellent CBZ degradation under wide pH range of 3–11, had good tolerance to natural organic matter and inorganic ions, and was efficient to various water matrices and other refractory organic pollutants. These findings provided new insights into particle electrode design and mechanisms enhancement in electro-activated PDS systems.

Facile assembly of CoS/Ag2MoO4 nanohybrids for visible light-promoted Z-type-induced synergistically improved photocatalytic degradation of antibiotics

Antibiotics have distinguished as hazardous emerging pollutants in environment, since they do not fully decomposed. Semiconductor photocatalysis are a promising technology for degradation of refractory organic pollutants under visible illumination. The assembly of compatible photocatalytic heterojunctions with suitable band structures achieves a promising approach for boosting the photodegradation performance. Herein, novel heterogeneous structured CoS/Ag2MoO4 nanohybrids were simply constructed via precipitation and tested by range of characterization procedures (XRD, UV–vis DRS, FESEM, TEM, PL, EIS, N2-adsorption/desorption, and EDX). At a specific conditions (photocatalyst dose 0.3 g/L, pH natural, and levofloxacin (LFX) antibiotic concentration 20 ppm), the CoS/Ag2MoO4 nanohybrid presented LFX degradation performance of 98.6 % in 90 min of solar-simulated illumination, which is exceeding that of pristine Ag2MoO4 (42%) and bare CoS (27%). The mechanism together with the photodegradation pathways were clarified in details. It is demonstrated that the extended range of visible light absorption and improved charge carriers separation induced by the plasmonic Z-type heterojunction formed between Ag2MoO4 and CoS were in charge for the enhancement of photocatalytic efficiency. The present work can contribute to develop effective and rapid photocatalysts for environmental requirements.

Dissolved organic matter promotes photocatalytic degradation of refractory organic pollutants in water by forming hydrogen bonding with photocatalyst

Removing refractory organic pollutants in real water using photocatalysis is a great challenge because coexisting dissolved organic matter (DOM) can quench photogenerated holes and thus prevent generation of reactive oxygen species (ROS). Herein, for the first time, we develop a hydrogen bonding strategy to avoid the scavenging of photoexcited holes, by which DOM even promotes photocatalytic degradation of refractory organic pollutants. Theoretical calculations combined with experimental studies reveal the formation of hydrogen bonding between DOM and a hydroxylated S-scheme heterojunction photocatalyst (Mo-Se/OHNT) consisting of hydroxylated nitrogen doped TiO2 (OHNT) and molybdenum doped selenium (Mo-Se). The hydrogen bonding is demonstrated to change the interaction between DOM and Mo-Se/OHNT from DOM-Ti (IV) to a hydrogen bonded complexation through the hydroxyl/amine groups of DOM and the OHNT in Mo-Se/OHNT. The formed hydrogen network can stabilize excited-state of DOM and inject its electron to the conduction band rather than the valence band of the OHNT upon light irradiation, realizing the key to preventing hole quenching. The electron-hole separation in Mo-Se/OHNT is consequently improved for generating more ROS to be involved in removing refractory organic pollutants. Moreover, this hydrogen bonding strategy is generalized to nitrogen doped zinc oxide and graphitic carbon nitride and applies to real water. Our findings provide a new insight into handling the DOM problem for photocatalytic technology towards water and wastewater treatment.

The collaborative incentive effect in adsorption-photocatalysis: A special perspective on phosphorus recovery and reuse

Achieving efficient recovery and direct utilization of phosphorus as one of the important components of the green economy is a huge challenge. Herein, we innovatively constructed a coupling adsorption-photocatalytic (CAP) process using synthetic dual-functional Mg-modified carbon nitride (CN-MgO). The CAP could utilize the recovered phosphorus from wastewater to promote the in-situ degradation of refractory organic pollutants via CN-MgO, where its phosphorus adsorption capacity and photocatalytic activity were significantly and synergistically increased. It was specifically reflected in the high phosphorus adsorption capacity of CN-MgO (218 mg/g), which was 153.5 times that of carbon nitride (1.42 mg/g), and its theoretical maximum adsorption capacity could reach 332 mg P/g. Subsequently, the phosphorus-enriched sample (CN-MgO-P) was employed as a photocatalyst to remove tetracycline with a reaction rate (k = 0.07177 min−1) 2.33 times higher than that of carbon nitride (k = 0.0327 min−1). Notably, the coordinated incentive mechanism present in this CAP between adsorption and photocatalysis may be attributed to the more adsorption sites of CN-MgO and the facilitation of hydroxyl production through adsorbed phosphorus, which ensured the feasibility of creating environmental value from the phosphorus in wastewater by means of CAP. This study provides a new perspective on the recovery and reuse of phosphorus resources in wastewater and the integration of environmental technologies in multiple fields.

Fluorine and nitrogen dual-doped carbon material as metal-free peroxymonosulfate activator for efficient tetracycline degradation: Radical-free mechanism

Persulfate-based advanced oxidation technology holds great potential for antibiotic treatment. However, its low activity, metal ion leaching, and poor stability mainly limit the practical application. Fluorine-nitrogen heteroatomic dual-doping carbon material (F, N-CM) was successfully prepared using ZIF-8 metal–organic frameworks as a precursor. F, N-CM exhibited high peroxymonosulfate (PMS) activation capability for tetracycline (TC) degradation. The incorporation of F and N dopants in F, N-CM created abundant defects and active sites, facilitating the activation of PMS. Notably, the presence of fluorine atomic lone electron pairs significantly enhanced electron transfer from PMS to TC. The high degradation performance of the F, N-CM/PMS system was primarily attributed to radical-free pathways involving singlet oxygen and electron transfer. Furthermore, F, N-CM demonstrated good stability for PMS activation and could be regenerated through simple calcination. This research provides a novel strategy for developing metal-free carbon materials with dual-doped heteroatoms as effective catalyst for PMS activation and degradation of refractory organic pollutants.

Boron-doped diamond nanofilm on a Ti substrate possessing fast charge transfer: Strategy toward cost-effective electrochemical oxidation of refractory organic pollutants

This study suggests a breakthrough toward the high-cost issue of electrochemical degradation of refractory organic pollutants caused by adopting a boron-doped diamond (BDD) electrode. Specifically, effect of charge transfer capability of the BDD electrode on electrochemical oxidation of 4-chlorophenol (4-CP) and perfluorooctanoic acid (PFOA) is explored. Thin BDD nanofilm (thickness of ~400 nm) on a Ti substrate (BDD@Ti) was prepared to overcome the delamination of the BDD on the Ti via hot-filament chemical vapor deposition under optimum conditions. When compared with a commercial electrode (C-BDD, micron BDD film on a Nb substrate), inevitable metal-carbide layer formed at interface between BDD film and metal substrate is much thinner than that of C-BDD. The unique structural features of BDD@Ti facilitate a much faster charge transfer and degradation of both 4-CP and PFOA than C-BDD, which is attributed to shortening of electron pathway from surface to conductive substrate.

Visible-light-induced activation of peroxymonosulfate by N-CuMe2Pc nanorods decorated on siloxene sheets for degradation of Rhodamine B

Exploring highly efficient photocatalysts is critical for integration of photocatalysis and peroxymonosulfate (PMS) activation. Herein, N-CuMe2Pc/Siloxene nanocomposites were fabricated by immobilizing the N-CuMe2Pc nanorods onto the surface of ultrathin Siloxene nanosheets to activate PMS for efficient photodegradation of (Rhodamine B) RhB. The prepared nanocomposites possess excellent photoabsorption capability and separation efficiency of photogenerated carriers. As expected, the nanocomposites exhibit superior catalytic activity and stability in PMS activation toward RhB photodegradation with highest removal efficiency of 95.3%, which is higher than that of Siloxene and N-CuMe2Pc. The active species in photocatalytic process and degradation pathways were determined through radical quenching studies. The reaction mechanism was systematically illustrated based on the intermediates detection and band structures. This study provides an experimental basis for further understanding of the photocatalytic oxidation behavior of metal phthalocyanine modified two-dimensional semiconductor materials, and is helpful to promote the research and application of photocatalytic degradation of refractory organic pollutants.

Metal-free electro-Fenton degradation of perfluorooctanoic acid with efficient ordered mesoporous carbon catalyst

Heterogeneous electro-Fenton with in situ generated H2O2 and •OH is a cost-effective method for the degradation of refractory organic pollutants, in which the catalyst is an important factor affecting its degradation performance. Metal-free catalysts can avoid the potential risk of metal dissolution. However, it remains great challenge to develop efficient metal-free catalyst for electro-Fenton. Herein, ordered mesoporous carbon (OMC) was designed as a bifunctional catalyst for efficient H2O2 and •OH generation in electro-Fenton. The electro-Fenton system showed fast perfluorooctanoic acid (PFOA) degradation with kinetics constant of 1.26 h−1 and high total organic carbon (TOC) removal efficiency of 84.0 % after 3 h reaction. The •OH was the main species responsible for PFOA degradation. Its generation was promoted by the abundant oxygen functional groups such as C-O-C and the nano-confinement effect of mesoporous channels on OMCs. This study indicated that OMC is an efficient catalyst for metal-free electro-Fenton system.

A reverse electrodialysis cell-modified photocatalytic fuel cell for efficient electricity and hydrogen generation from the degradation of refractory organic pollutants.

Wastewater treatment is typically energy-intensive. To achieve carbon neutrality, new wastewater treatment technologies that have high efficiency and low energy consumption must be developed. In this study, a reverse electrodialysis (RED) cell-modified photocatalytic fuel cell (PRC) for efficient electricity and hydrogen generation from the degradation of refractory organic pollutants is developed and evaluated. A hydrogen evolution cathode was developed and optimized by doping 1.53wt. % Ni-N-C on CoP/NF. The bias voltage generated from the RED stack accelerated the separation of photoinduced holes and electrons on the photoanode, which enhances ampicillin (AMP) degradation and hydrogen production. The RED stack and electrode reactions respectively contribute 72.3 % and 27.7 % to the electricity production of PRC. The output current and cumulative hydrogen generation reach 2.2-3.0mA and 500 μmol/L respectively with 81.8 % AMP removal. Increasing high concentration (HC), flow rate of NH4HCO3 solutions and AMP concentration could increase the electricity and hydrogen generation. Acidic environment is helpful to improve the reaction rate of hydrogen evolution. We believe this study would provide a promising option for wastewater remediation.