Phenol Degradation Rate Research Articles

In-situ growth of three-dimensional copper-based catalyst in 4A zeolite/PES mixed matrix membrane for Fenton-like degradation of phenol

Fenton-like membrane reactors applied to water purification provide a broad solution to address the challenges of catalyst recovery, low reaction efficiency, and high mass transfer resistance in heterogeneous batch reactions. Zeolites as nanocatalyst carriers are promising candidates for advanced purification membranes. Herein, we report a composite catalytic membrane (4A-Cu/PES) for Fenton-like degradation of phenol wastewater, fabricated by in-situ growth of copper nanoflowers on a 4A zeolite/polyethersulfone (PES) mixed matrix membrane, forming a three-dimensional core-shell nanostructured catalyst. Compared with the conventional method, the in-situ growth prevents the copper catalyst from being covered by the polymer and significantly increases the copper loading (3.97 %), thus ensuring efficient catalytic reactions within the membrane pores. Meanwhile, the porous structure of zeolite provides a large specific surface area, facilitating uniform dispersion of copper ions during in situ growth of the catalyst and providing abundant active sites. The membrane exhibited a phenol degradation rate of 93.9 % at pH 6, significantly broadening the pH applicability of the Fenton reaction. Hydroxyl radicals (·OH) were identified as the primary active species in the 4A-Cu/PES-H2O2 system. Moreover, the membrane retained high catalytic activity after five cycles, demonstrating excellent stability. This work provides important insights for designing efficient and stable Fenton-like zeolite catalytic membranes.

A novel strategy for Klebsiella sp. to resist high salt and high phenol environmental stress

Isolating high-performance phenol degradation microorganisms with high salt tolerance and studying their resistance mechanisms are urgent issues. To address these issues, a typical bacteria (Klebsiella sp. YP-1) with high salt and phenol tolerance was isolated. Its strategies for resisting high salt and high phenol stress were studied. The results indicated that Klebsiella sp. YP-1 was able to degrade 1000 mg/L phenol within 44 h at 70 g/L NaCl, which was faster than most microorganisms reported in the literature. Lyxose secreted by Klebsiella sp. YP-1 played an important role on assisting Klebsiella sp. YP-1 to resist stress. Lyxose increased phenol degradation rate by microorganisms due to its protection on cell membrane. Quantum chemical calculation results indicated that lyxose was more likely attacked by free radical than cell membrane. In addition, lyxose could bind to the cell membrane through hydrogen bonds. Thus, lyxose prevented reactive oxygen species from harming cell membranes. Moreover, lyxose has broad protective effect on microbial cell membranes. This study provides a novel idea for microorganisms to resist oxidative stresses.

Steam-Assisted Synthesis of Hectorite Loaded with Fe2O3 and Its Catalytic Fenton Degradation of Phenol

Fe2O3 loaded in the interlayer of hectorite was synthesized using a steam-assisted one-pot method to replace the traditional high-temperature and high-pressure hydrothermal method. The samples were characterized by means of X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and N2 adsorption–desorption isotherms. Fe2O3/hectorite had a layered hectorite structure. Due to the insertion of Fe2O3, the interlayer spacing increased and had a large specific surface area and pore size, benefiting catalytic reactions. Fe2O3/hectorite was used as a catalyst to degrade phenol in wastewater via the Fenton reaction. With this catalyst, the optimal Fenton reaction conditions were determined with an orthogonal test: pH, 3; temperature, 60 °C; and catalyst dosage, 0.5 g dm−3. Under these optimal reaction conditions, the degradation rate of phenol (200 mg dm–3) was 99.27% in 3 h. After five cycles, the degradation rate reached 95.72%, indicating the excellent reusability of this catalyst. In the temperature range 303–330 K, the catalytic degradation kinetics were studied as a pseudo-first-order reaction, and the apparent activation energy was 30.71 kJ/mol.

Synthesis of Iron-Tailing-Based porous ceramic granules for the adsorption of phenol-containing wastewater degradation

To achieve the resource utilization of solid waste and the treatment of phenol-containing wastewater in China, a new type of ceramic granule (TBBFSITFA) with the function of degrading phenol wastewater has been prepared from titanium-containing blast furnace slag (TBBFS), iron tailings (IT), and fly ash (FA) as raw materials to achieve the sustainable development of “treating waste with waste.” The adsorption behavior of TBBFSITFA samples on phenol in an aqueous solution was experimentally investigated. Double-beam ultraviolet–visible spectrophotometer (UV–vis), total organic carbon (TOC) test showed that the optimal raw material ratio of TBBFS: IT: FA = 10:70:20, the degradation rate of phenol reached 95.40%, and the removal rate of TOC was as high as 93.29%. In addition, X-ray photoelectron spectroscopy (XPS), energy spectrometry (EDS), and Fourier transform infrared spectrophotometry (FT-IR) demonstrated that the better the synergistic effect produced by having a suitable Fe3+/Fe2+ ratio and raw material ratio in the TBBFSITFA sample, as well as a high specific surface area, porosity and high surface adsorption of oxygen, the higher the mineralization of the phenol solution. This work provides a low-cost, environmentally friendly, and simple technology for phenol-containing wastewater treatment and a new idea for effectively using solid waste resources.

Enhancement of ozone dissolution and oxidation treatment of phenolic wastewater by a static spiral shear rig with a variable screw pitch

A novel static spiral shear rig (SSSR) with variable screw pitch was developed to enhance the ozone–water mass transfer and the oxidative degradation of phenolic wastewater. The effects of critical operational parameters on the dissolution and mass transfer of ozone in water and the oxidative degradation rate of phenol were investigated with the proposed SSSR. Moreover, the mass transfer and oxidative degradation of phenols with the SSSR were compared to conventional static mixer (CSM) methods. The results showed that the mass transfer coefficient obtained with the SSSR is 5.33 times greater than that obtained with CSM. With the SSSR, the degradation percentage of phenolic wastewater with an initial concentration of 100 mg/L reached 97.09% within 12 min, and the reaction kinetic constant for phenol degradation obtained with the SSSR is 3.68 times higher than that obtained with the CSM. The SSSR dramatically enhances ozone dissolution and mass transfer, resulting in a higher phenol oxidative degradation percentage and a constant kinetic reaction.

New MMO coatings for electro-refinery applications: Promoting the production of carboxylates

Within the new circular economy paradigm, this work evaluates the performance of tailored mixed metal oxides (MMO) anodes, based on ruthenium and antimony, for their application into an electrochemically-assisted organic refinery process. This process is designed to transform pollutants into value-added products with minimal mineralization. Oxidation of synthetic wastes consisting of phenol solutions was used to validate the electrochemical conversion of phenolic wastes into carboxylates, which are then considered as bricks to be used for electrosynthesis or to produce fuels. The MMO anodes were manufactured using two synthesis routes (Pechini method and ionic liquid method), each followed by one of three different heating treatments: furnace, microwave, and CO2 laser. The selection of the optimal electrode for the organic electrorefinery was based on a combination of physical and electrochemical properties, degradation performance of phenol to carboxylates, and long-term stability, looking for a truly sustainable solution. Results indicate that anodes synthesized by the ionic liquid (IL) method, regardless of the heating treatment, demonstrated superior performance, with larger active areas (with furnace 82 mC cm−2, microwave 97 mC cm−2, and laser 127 mC cm−2) and higher phenol degradation rates, resulting in a greater generation of carboxylates during electrolysis, yielding primarily oxalate and achieving up to 40% conversion with furnace heating. However, laser-treated anodes exhibited greater stability than furnace-made ones, attributed to the formation of an insulating TiO2 layer. Although the electrode with the longest service life did not show the best catalytic properties for minimizing mineralization, the observed variations in coatings with identical chemical compositions highlight the importance of this research. This study positions itself at the forefront of developing more efficient and sustainable electrochemical technologies for organic waste treatment.

A novel paraffin-based N/P controlled-release material for biostimulation of phenol biodegradation in groundwater

To address the problem of the weak natural restoration ability of oligotrophic groundwater environments, a novel N/P controlled-release material (CRM) for biostimulation, prepared by an improved method, was developed. CRMs can encapsulate N and P (N/P) salts for sustained release in aquifers. Paraffin-based CRMs can be used to control N/P release rates by adjusting the particle size of CRMs and the mass ratio of the paraffin. The developed CRMs had a more remarkable adaptability to groundwater than other materials. Specifically, 0.4-cm CRMs released N/P stably and efficiently over a wide temperature range (7–25 ℃), and the release properties of various CRMs were not affected by pH. The release of N/P followed Fickian diffusion, and a dissolution-diffusion model was established to elucidate the mechanism of the controlled release. In contrast to bare N/P, CRMs obviously enhanced the biodegradation rate of phenol and prolonged the effectiveness of supplying N/P. The degradation rate of phenol in the CRM system increased by 20.8 %. The different supply modes of N/P, CRMs and bare N/P, resulted in differences in salinity. Metagenomic analysis showed that this difference changed the proportion of various phenol-degrading genera and thus changed the abundance of genes associated with the phenol degradation pathway.

Nonmetallic element-doped graphene aerogel enhances industrial wastewater removal performance via a multifield coupled system of adsorption-catalytic degradation: Insights from experiments and theoretical calculations

In this paper, a multifield coupled system of synergistic adsorption and photo-Fenton degradation was constructed, and BiFeO3-modified nonmetallic element-doped graphene aerogel composites (BiFeO3/X-rGA) were prepared to realize the advanced treatment of phenol and coking wastewater by utilizing consistent adsorption and catalytic degradation sites. Nonmetallic element-doped graphene formed more defective active sites and changed the planar carbon layer structure, which enhanced the adsorption performance of pollutants on the basis of graphene face adsorption and π-π adsorption. Moreover, element doping also modulated the localized electronic structure of graphene and promoted carrier separation, which in turn enhanced the photo-Fenton degradation activity. The phenol degradation rate constant of BiFeO3/P-rGA was 3.29 times greater than that of BiFeO3/rGA, and the removal efficiency in coking wastewater was also greatly improved. In coupled systems, hydroxyl radicals are the predominant active species, and the mechanism by which nonmetallic modifications promote the synergistic performance of graphene aerogel adsorption and catalytic degradation systems was refined based on experimental and DFT results, providing a new idea for the advanced treatment of wastewater.

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.

Degradation of phenol by peroxymonosulfate catalyzed by cerium-doped amino-functionalized metal-organic frameworks (NH2-MIL-101 (Fe, Ce))

As an organic pollutant difficult to be degraded in water bodies, phenol is toxic even at low concentrations. Therefore, studying the degradation technology of phenol is of great significance. In order to investigate the effect of transition metal doping on the performance of oxidative degradation of phenol by the persulfate activated by metal-organic frameworks, the different doping levels of Ce were tested based on the NH2-MIL-101(Fe). Then, NH2-MIL-101(Fe,Ce) with different Fe/Ce ratios was successfully prepared by solvothermal method. They were characterized by means of XRD, SEM, TEM, XPS and FT-IR. Selecting phenol as the target pollutant, the NH2-MIL-101(Fe,Ce)/PMS system was constructed to study the degradation rate. The factors of the different temperature, initial pH, anions, Ce doping ratios, catalyst dosage and PMS concentration were investigated. The mechanism of degradation of phenol for the above system was analyzed through free radical burst test, and the metal ion dissolution of catalytic materials in simulated wastewater treatment process was monitored by ICP-OES instrument. Finally, the intermediate products of phenol in the degradation process were inferred using LC-MS method. The results showed that when the molar ratio of Ce/(Ce+Fe) was 15 %, under the same reaction conditions, NH2-MIL-101(Fe,Ce)-15 % (referred to as NM-15 %) had the highest degradation rate for phenol. After the 50 min, phenol could be almostly completely removed, with K value of 0.059 min−1. This system could achieve the efficient degradation of phenol under the range of pH values (pH=3–9). The results of the free radical burst test and the free radical trapping test showed that the dominant oxidising groups were SO4•−, •OH, •O2− and non-free radical 1O2.

An effective strategy for biodegradation of high concentration phenol in soil via biochar-immobilized Rhodococcus pyridinivorans B403.

High concentration of phenol residues in soil are harmful to human health and ecological safety. However, limited information is available on the in-situ bioremediation of phenol-contaminated soil using biochar as a carrier for bacteria. In this study, bamboo -derived biochar was screened as a carrier to assemble microorganism-immobilized composite with Rhodococcus pyridinivorans B403. Then, SEM used to observe the micromorphology of composite and its bioactivity was detected in solution and soil. Finally, we investigated the effects of free B403 and biochar-immobilized B403 (BCJ) on phenol biodegradation in two types of soils and different initial phenol concentrations. Findings showed that bacterial cells were intensively distributed in/onto the carriers, showing high survival. Immobilisation increased the phenol degradation rate of strain B403 by 1.45 times (37.7mg/(L·h)). The phenol removed by BCJ in soil was 81% higher than free B403 on the first day. Moreover, the removal of BCJ remained above 51% even at phenol concentration of 1,500mg/kg, while it was only 15% for free B403. Compared with the other treatment groups, BCJ showed the best phenol removal effect in both tested soils. Our results indicate that the biochar-B403 composite has great potential in the remediation of high phenol-contaminated soil.

Prediction of Nanoparticle Photoreactivity in Mixtures of Surface Foulants Requires Kinetic (Non-equilibrium) Adsorption Considerations.

The adsorption of foulants on photocatalytic nanoparticles can suppress their reactivity in water treatment applications by scavenging reactive species at the photocatalyst surface, screening light, or competing for surface sites. These inhibitory effects are commonly modeled using the Langmuir-Hinshelwood model, assuming that adsorbed layer compositions follow Langmuirian (equilibrium) competitive adsorption. However, this assumption has not been evaluated in complex mixtures of foulants. This study evaluates the photoreactivity of titanium dioxide (TiO2) nanoparticles toward a target compound, phenol, in the presence of two classes of foulants ─ natural organic matter (NOM) and a protein, bovine serum albumin (BSA) ─ and mixtures of the two. Langmuir adsorption models predict that BSA should strongly influence the nanoparticle photoreactivity because of its higher adsorption affinity relative to phenol and NOM. However, model evaluation of the experimental phenol decay rates suggested that neither the phenol nor foulant surface coverages are governed by Langmuirian competitive adsorption. Rather, a reactivity model incorporating kinetic predictions of adsorbed layer compositions (favoring NOM adsorption) outperformed Langmuirian models in providing accurate, unbiased predictions of phenol degradation rates. This research emphasizes the importance of using first-principles models that account for adsorption kinetics when assumptions of equilibrium adsorption do not apply.

Nitrogen-Doped Biochar for Enhanced Peroxymonosulfate Activation to Degrade Phenol through Both Free Radical and Direct Oxidation Based on Electron Transfer Pathways.

Nowadays, super nitrogen-doped biochar (SNBC) material has become one of the most promising metal-free catalysts for activating peroxymonosulfate (PMS) to degrade organic pollutants. To understand the evolution of SNBC properties with fabrication conditions, a variety of SNBC materials were prepared and characterized by elemental analysis, N2 adsorption-desorption, scanning electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. We systematically investigated the activation potential of these SNBC materials for PMS to degrade phenol. SN1BC-800 with the best catalytic performance was obtained by changing the activation temperatures and the ratio of biochar to melamine. The effects of catalyst dosage, the PMS concentration, pH, and reaction temperature on phenol degradation were studied in detail. In the presence of 0.3 g/L SN1BC-800 and 1 g/L PMS, the removal rate of 20 mg/L phenol could reach 100% within 5 min. According to electron paramagnetic resonance spectra and free radical quenching experiments, a nonfree radical pathway of phenol degradation dominated by 1O2 and electron transfer was proposed. More interestingly, the excellent catalytic performance of the SN1BC-800/PMS system is universally applicable in the degradation of other typical organic pollutants. In addition, the degradation rate of phenol is still over 80% after five reuses, which shows that the SN1BC-800 catalyst has high stability and good application prospects in environmental remediation.

Fine-Tuning the Photocatalytic Activity of the Anatase {1 0 1} Facet through Dopant-Controlled Reduction of the Spontaneously Present Donor State Density.

The present study highlights the importance of the net density of charge carriers at the ground state on photocatalytic activity of the faceted particles, which can be seen as a highly underexplored problem. To investigate it in detail, we have systematically doped {1 0 1} enclosed anatase nanoparticles with Gd3+ ions to manipulate the charge carrier concentration. Furthermore, control experiments using an analogical Nb5+ doped sample were performed to discuss photocatalytic activity in the increased range of free electrons. Overall results showed significant enhancement of phenol degradation rate and coumarin hydroxylation, together with an increase of the designed Gd/Ti ratio up to 0.5 at. %. Simultaneously, the mineralization efficiency, measured as a TOC reduction, was controlled between the samples. The observed activity enhancement is connected with the controlled decrease of the donor state density within the materials, being the net effect of the spontaneously present defects and introduced dopants, witch reduce hydroxylation and the hole trapping ability of the {1 0 1} facets. This allows to fine-tune multi-/single-electron processes occurring over the prepared samples, leading to clear activity maxima for 4-nitrophenol reduction, H2O2 generation, and ·OH formation observed for different donor densities. The optimized material exceeds the activity of the TiO2 P25 for phenol degradation by 52% (377% after surface normalization), showing its suitable design for water treatment. These results present a promising approach to boost photocatalyst activity as the combined result of the exposed crystal facet and dopant-optimized density of ground-state charge carriers.

Integrated system of electro-catalytic oxidation and microbial fuel cells for the treatment of recalcitrant wastewater

The emission of recalcitrant wastewater poses serious threats to the environment. In this study, an integrated approach combining electrocatalytic oxidation (EC) for pretreatment and microbial fuel cells (MFC) for thorough pollutant degradation is proposed to ensure efficient degradation of target substances, with low energy input and enhanced bioavailability of refractory organics. When phenol was used as the pollutant, an initial concentration of 2000 mg/L phenol solution underwent EC treatment under constant current-exponential attenuation power supply mode, resulting in a COD removal rate of 54.53%, and a phenol degradation rate of 99.83%. Intermediate products such as hydroquinone and para-diphenol were detected in the solution. After subsequent MFC treatment, only minor amounts of para-diphenol were left, and the degradation rate of phenol and its intermediate products reached 100%, with an output power density of 110.4 mW m−2. When coal chemical wastewater was used as the pollutant, further examination of the EC-MFC system performance showed a COD removal rate of 49.23% in the EC section, and a 76.21% COD removal rate in the MFC section, with an output power density of 181.5 mW m−2. Microbiological analysis revealed typical electrogenic bacteria (such as Pseudomonas and Geobacter), and specific degrading functional bacteria (such as Stenotrophomonas, Delftia, and Brevundimonas). The dominant microbial communities and their proportions adapted to environmental changes in response to the variation of carbon sources.

One-Step Synthesis of Alkali Metal-Hydroxyl Double Modified Graphite Phase Carbon Nitride and Photocatalytic Degradation of Phenolic Compounds

In this work, potassium ion-hydroxyl double modified graphite phase carbon nitride (KCN–OH) was synthesized in one step by alkali hydrothermal (AH) method. The as-prepared catalysts were characterized by XRD, FT-IR, UV–Vis, N2 adsorption, SEM, XPS, PL, ESR, TPD and EIS. The introduction of potassium ion causes the reduced crystal size, increased specific surface area and promoted electron–hole separation efficiency of as-prepared catalyst. The hydroxyl group not only further improves the electron–hole separation efficiency but, as the electron donor group, can also make stronger interaction between catalyst and acidic phenolic compounds. The photocatalytic degradation of phenol was investigated under visible light. The results show that the phenol degradation rate constant of KCN–OH is 0.22 h[Formula: see text] under visible light, which is over 3.7 and 2.0 times higher than that of neat g-C3N4 and single hydroxyl-modified g-C3N4. KCN–OH also displays outstanding catalytic and structural stability. The possible reaction mechanism is discussed in this paper.

Facet-Dependent Productions of Reactive Oxygen Species from Pyrite Oxidation.

Reactive oxygen species (ROS) are widespread in nature and play central roles in numerous biogeochemical processes and pollutant dynamics. Recent studies have revealed ROS productions triggered by electron transfer from naturally abundant reduced iron minerals to oxygen. Here, we report that ROS productions from pyrite oxidation exhibit a high facet dependence. Pyrites with various facet compositions displayed distinct efficiencies in producing superoxide (O2• -), hydrogen peroxide (H2O2), and hydroxyl radical (•OH). The 48 h •OH production rates varied by 3.1-fold from 11.7 ± 0.4 to 36.2 ± 0.6 nM h-1, showing a strong correlation with the ratio of the {210} facet. Such facet dependence in ROS productions primarily stems from the different surface electron-donating capacities (2.2-8.6 mmol e- g-1) and kinetics (from 1.2 × 10-4 to 5.8 × 10-4 s-1) of various faceted pyrites. Further, the Fenton-like activity also displayed 10.1-fold variations among faceted pyrites, contributing to the facet depedence of •OH productions. The facet dependence of ROS production can greatly affect ROS-driven pollutant transformations. As a paradigm, the degradation rates of carbamazepine, phenol, and bisphenol A varied by 3.5-5.3-fold from oxidation of pyrites with different facet compositions, where the kinetics were in good agreement with the pyrite {210} facet ratio. These findings highlight the crucial role of facet composition in determining ROS production and subsequent ROS-driven reactions during iron mineral oxidation.

Isolation and Identification of Phenol-Degrading Bacteria from Iranian Soil and Leaf Samples.

By considering the importance and role of soil in the health of humanity, it is important to remove the presence of harmful compounds, such as phenol. In this study, four types of soil and leaf samples were collected from Kerman, Iran, and the amounts of heterotrophic and degradation bacteria were determined using the serial dilution and most probable number (MPN) methods. The amount of removed phenol was investigated using the Gibbs method with different concentrations of phenol. Then, an isolate with the highest percentage of phenol degradation was identified as the superior strain using 16 sRNA sequencing. The effects of the different factors, such as the carbon source (1% molasses and 1 g glucose), nitrogen source (0.1 g yeast extract), mixed culture, and time (14 and 28 days), on the biodegradation ability of the superior strain was investigated. A total of 18 bacterial strains were isolated from the samples. Isolate B3 had the highest rate (75%) of phenol degradation, at a concentration of 1000 ppm, meaning it was identified as the superior strain. The molecular analysis results identified this isolate as the Comamonas testosteroni strain F4. This bacterium can degrade 89% of the phenol at 30 °C, 180 rpm, and 800 ppm over 28 days. C. testosteroni did not show a favorable phenol degradation ability in the presence of the investigated carbon sources, while this ability was also reduced in mixed cultures. C. testosteroni bacterial strain isolated from soil samples of pistachio orchards in Kerman, Iran, has a favorable ability to biodegrade phenol.

Recyclable pickering emulsions for enzymatic phenol degradation of oily wastewater

Enzymatic degradation offers a sustainable solution for waterborne phenolic pollutants. However, its application within industrial, non-aqueous contexts — particularly in mitigating phenolic contaminants in oily wastewater — remains significantly challenging. To address this challenge, the present study exploits the potential of Fe3O4 @PDA nanoparticles to form oil-in-water Pickering emulsions for the enzymatic degradation process. The uniform stability of the prepared emulsion, with droplet sizes under 5 µm, protects enzyme activity and expands the water-oil interfacial area, leading to an enhancement in the efficiency of horseradish peroxidase (HRP) catalytic degradation. The application of this emulsion resulted in a substantial increase in the degradation rate of phenol, achieving 100% within 30 min as opposed to an only 13.6% without it. The study also highlights the excellent stability, reusability, and versatility of the Fe3O4 @PDA nanoparticles, enabled by magnetic separation and their ability to form emulsions with diverse oil phases. Consequently, our research offers valuable insights into the development of environmentally sustainable strategies for the degradation of phenolic contaminants in various industrial oily wastewater.

Boron Bifunctional Catalysts for Rapid Degradation of Persistent Organic Pollutants in a Metal-Free Electro-Fenton Process: O2 and H2O2 Activation Process.

Metals usually served as the active sites of the heterogeneous bifunctional electro-Fenton reaction, which faced the challenge of poor stability under acidic or even neutral conditions. Exploring a metal-free heterogeneous bifunctional electro-Fenton catalyst can effectively solve the above problems. In this work, a stable metal-free heterogeneous bifunctional boron-modified porous carbon catalyst (BTA-1000) was synthesized. For the BTA-1000 catalyst, the yield of H2O2 (294 mg/L) significantly increased. The degradation rate of phenol by BTA-1000 (0.242 min-1) increased by an order of magnitude, compared with the porous carbon catalyst (0.0105 min-1). The BTA catalyst could rapidly degrade industrial dye wastewater, and its specific energy consumption was 5.52 kW h kg-1 COD-1, lower than that in previous reports (6.38-7.4 kW h kg-1 COD-1). DFT and XPS revealed that C═O and -BC2O groups jointly promoted the generation of H2O2, and the -BCO2 group played dominant roles in the generation of •OH because the oxygen atom near the electron-giving groups (-BCO2 group) facilitated the formation of hydrogen bond and H2O2 adsorption. This work gained deep insights into the reaction mechanism of the boron-modified porous carbon catalyst, which helped to guide the development of metal-free heterogeneous bifunctional electro-Fenton catalysts.