Performance For Phenol Degradation Research Articles

Heterostructural PbO2/Co3O4 composite for anodic oxidation of phenol: An energy-efficient hybrid process

The PbO2/Co3O4 composite electrodes were synthesized using the composite co-deposition method, which involved the incorporation of Co3O4 nanoparticles into a PbO2 coating. These composite electrodes were employed as anodes for phenol electrooxidation in wastewater treatment. The results demonstrate that the PbO2/Co3O4 composite electrode exhibits a three-dimensional porous structure, leading to a significant increase in the electrochemically active surface area. Electrochemical measurements indicate that the composite electrode achieves a minimum oxygen evolution potential of 526.5 mV. Moreover, the electrode facilitates the indirect degradation of phenol, even at low voltage (0.45 V). The unique structure, improved conductivity, and enhanced surface area of the electrode contribute to its exceptional performance in phenol degradation. Additionally, this approach offers the potential for synergistic integration with other treatment methods, providing a sustainable and energy-efficient solution for removing persistent organic compounds from wastewater.

ZnO hierarchical structures with tunable oxygen vacancies for high performance in photocatalytic degradation of phenol

ZnO hierarchical structures were synthesized in a simple and low-cost way and displayed excellent photocatalytic performance. Different ZnO hierarchical structures with tunable oxygen vacancies (OVs) were hydrothermally synthesized with the assistance of sodium carboxymethyl cellulose (CMC) and their photocatalytic performance for phenol degradation under UV–visible light irradiation was investigated. OV-rich hollow ZnO hierarchical structures displayed excellent phenol degradation efficiency of 99.8 %. The recycling test exhibited that the hollow ZnO had high photocatalytic sustainability (phenol degradation efficiency of 94.4 % after 6 cycles). The high photocatalytic performance was attributed to the efficient separation and transfer of photoproduced electron-hole pairs that were realized by the synergistic effect of the abundant oxygen vacancy defects, favorable light absorption and scattering ability of the ZnO hollow structure. The photocatalytic mechanism was proposed that •OH is the dominant active radical, then h+ and •O2− are active radicals in the photocatalytic process of phenol degradation.

Sensitization of TiO2 NPs with curcumin and chlorella and photocatalytic performance for degradation of phenol and organic dyes

Titanium dioxide (TiO2) is the most used semiconductor for heterogeneous photocatalysis. However, there is a limitation to its use because it is only activated under ultraviolet radiation (below 390 nm). Sunlight comprises only 5 % of UV radiation and consequently limits the use of TiO2 as a photocatalyst. Several studies were performed to extend the photocatalytic activity of TiO2 to the visible spectrum. Therefore, in this work two TiO2 NPs (S1 and P25) were sensitized with natural extracts to extend their photocatalytic activity to the visible light. In a previous work of our group TiO2 nanoparticles with a high surface area were synthesized via controlled precipitation method (called S1). In sequence they were wet sensitized with extracts of curcumin and Chlorella pyrenoidosa microalga to extend their photocatalytic activity to the visible light. After sensitization with natural extracts, the samples were characterized. The photoactivity of the NPs was evaluated for the degradation of phenol and the methylene blue, Rhodamine B and methyl orange dyes, under visible light using conventional LED lamps (380 to 780 nm). By XRD analysis all samples showed anatase and rutile as the only phases. The NPs sensitized with the highest content of chlorella and curcumin showed the highest mass loss (16 and 49 wt%, respectively), determined by DSC/TG, proving the adsorption of both extracts. Chemical bonds ascribed to both extracts were observed by the FTIR analysis. In addition, the NPs sensitized with the less content of the extracts presented the higher specific surface areas (∼207 m2/g, by BET analysis). The NPs are stable in water solution, presenting a zeta potential of −33 mV. Chlorella shows a larger absorption spectrum than curcumin. The calculated band gaps are 2.25 eV for chlorella and 2.07 eV for curcumin. Finally, the sensitization did not change the size or shape of the NPs (FESEM). The results of the photocatalytic activity tests show that the sensitized S1 NPs show higher efficiency than the commercial sensitized P25 NPs for the discoloration of the dyes, reaching 97 % for rhodamine B dye.

Continuous Flow Photocatalytic Degradation of Phenol Using Palladium@Mesoporous TiO2 Core@Shell Nanoparticles

Palladium@mesoporous titania core@shell nanoparticles with uniform and narrow particle size distribution were synthesised using a four component ‘‘water in oil’’ microemulsion system. The prepared materials were well characterised using N2 adsorption–desorption measurements, temperature program oxidation, X-ray diffraction, ICP-OES, DRS UV-Vis, PL, TGA and transmission electron microscopy techniques. The core@shell nanoparticles showed very good absorption in both the UV and visible regions and a low bandgap, indicating that the prepared materials are visible-light-active, unlike the pristine TiO2 P25. The activity of the prepared materials was evaluated in the photodegradation of phenol using both UV and visible light, in batch and continuous flow trickle-bed and Taylor flow photoreactors. The prepared 2%Pd@mTiO2 core@shell nanoparticles showed better photocatalytic performance for phenol degradation in visible light in comparison to pristine TiO2 P25 and conventional 0.5%Pd/TiO2 P25 catalysts. The TiO2 P25 and conventional 0.5%Pd/TiO2 P25 catalysts showed gradual catalyst deactivation due to photocorrosion, the deposition of intermediates and Pd metal leaching. In comparison, the 2%Pd@mTiO2 catalyst showed higher catalyst stability and reusability. The 2%Pd@mTiO2 catalysts showed very high and stable phenol degradation (97% conversion) in continuous flow over 52 h. The results showed the feasibility of utilising the developed continuous Taylor flow photoreactor for phenol degradation or as a wastewater treatment plant.

Efficient degradation of phenol by MnOOH-rGO composite with high peroxymonosulfate utilization efficiency

A high-performance, durable, low-cost, and environmentally friendly catalyst is highly desired in advanced oxidation processes (AOPs) for water treatment. Considering the activity of Mn(Ⅲ) and the superior catalytic properties of reduced graphene oxide (rGO) in peroxymonosulfate (PMS) activation, rGO-modified MnOOH nanowires (MnOOH-rGO) were fabricated by a hydrothermal method for phenol degradation. The results showed that the composite synthesized at 120 °C with 1 wt% rGO dopant exhibited the best performance for phenol degradation. Nearly 100% of the phenol was removed by MnOOH-rGO within 30 min, which is higher than the removal rate of pure MnOOH (70%). The effects of catalyst dosages, PMS concentration, pH, temperature, and anions (Cl−, NO3−, HPO42−and HCO3−) on phenol degradation were investigated. The removal rate of chemical oxygen demand (COD) reached 26.4%, with a low molar ratio of PMS to phenol at 5:1 and a high PMS utilization efficiency (PUE) of 88.8%. The phenol removal rate remained more than 90% after five recycle with less than 0.1 mg L−1 leakage of manganese ions. Together with the results of radical quenching experiments, X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance spectroscopy (EPR), electron transfer and 1O2 were proved to dominate the activation process. During the direct electrons transfer process, the electrons transfer from the phenol to PMS by using the Mn(Ⅲ) as the mediate with a stoichiometric ratio between PMS and phenol at 1:2, which mainly contributed to the high PUE. This work provides new insight into a high-performance Mn(Ⅲ) based catalyst on PMS activation with high PUE, good reusability, and environmentally friendly for removing organic pollutants.

Phenol degradation on electrochemically self-doped TiO2 nanotubes via indirect oxidation

Recently, electrochemically self-doped TiO2 nanotubes (<i>R</i>-TiO2 NTs) have emerged as promising anodes in the electrochemical oxidation process for wastewater treatment, owing to their high degradation capability of organic compounds. However, the degradation mechanism of organic compounds on <i>R</i>-TiO2 NTs has not been well demonstrated, and therefore, industrial practices have been limited. This study aimed to elucidate the oxidation mechanism of organic compounds on <i>R</i>-TiO2 NTs by investigating phenol degradation. The performance of phenol degradation on <i>R</i>-TiO2 NTs was comparable to that on the boron-doped diamond (BDD) electrode that is well-known as an excellent anode for phenol degradation. In particular, phenol degradation on <i>R</i>-TiO2 NTs was completely achieved at the electrode potential of 5.0 V while negligible degradation was found at the electrode potential of 2.0 V. In addition, no peaks associated with phenol oxidation in cyclic voltammograms were noticed on <i>R</i>-TiO2 NTs at the potential range between 1.0–2.5 V. Considering direct oxidation is a fundamental factor for phenol degradation at low electrode potential, it contributes less to phenol degradation on <i>R</i>-TiO2 NTs. Therefore, phenol degradation on <i>R</i>-TiO2 NTs is mostly owing to indirect oxidation mediated by hydroxyl radicals.

Accelerated Fe(II) regeneration on Fe-doped oxidized carbon nanotube enabling highly-efficient electro-Fenton process for pollutants removal

Heterogeneous electro-Fenton (e-Fenton) is considered a prospective technology for persistent organic contaminants removal that relies on the strongly oxidizing •OH. However, the efficiency of e-Fenton is still low as the sluggish Fe(II) regeneration caused by the difficulty modulating the electronic structure of Fe(III) center. Herein, the Fe-doped oxidized carbon nanotube catalysts (OCNT-Fe) is prepared to accelerate Fe(II) regeneration by introducing electronegative oxygen-containing groups and inducing local charge distribution of Fe(III) center. The OCNT-1Fe exhibits an excellent e-Fenton performance for phenol degradation with a kinetic rate of 0.11 min−1 at pH 6.5, which is the highest among reported state-of-the-art e-Fenton catalysts. Moreover, OCNT-1Fe catalyst is demonstrated to be more energy efficient in coking wastewater treatment with an energy consumption of 6.5 kW h kgCOD−1 than other e-Fenton systems of 9.2–29.7 kW h kgCOD−1. This work offers a new perspective on the high-performance e-Fenton catalysts design by rationally modulating the electronic structure for organic pollutants removal.

Phenol degradation at high salinity by a resuscitated strain Pseudomonas sp. SAS26: kinetics and pathway

Exploration of novel salt-tolerant phenol-degrading bacterial strains are often limited by unculturability of functional bacteria, as they are prone to entering a viable but non-culturable (VBNC) state in response to complex stressful environmental conditions. Thus, resuscitating the VBNC bacteria provides a huge microbial source to screen effective degraders for bioaugmentation. In this study, a resuscitated strain Pseudomonas sp. SAS26, which exhibited the highest phenol-degrading ability, was selected to investigate its phenol degradation performance at high salinity. The results indicated that SAS26 was capable of efficiently degrading phenol at NaCl concentrations of 0–30 g/L, with decreased efficiency observed at 40–60 g/L. At 10 g/L NaCl, complete degradation of 1800 mg/L phenol was achieved within 48 h. At a higher NaCl concentration of 30 g/L, SAS26 could fully degrade 1500 mg/L phenol within 60 h, with the highest degradation rate of 0.360 g/(g CDW·h) observed at approximately 24 h. The modeling of phenol degradation at high salinity demonstrated that the Webb model was the most appropriate for describing the degradation kinetics, followed by the Yano and Aiba models. Furthermore, the analysis of the enzyme activities and catA gene expression suggested that SAS26 initially converted phenol to catechol via phenol hydroxylase, and then oxidized catechol by the catalysis of catechol 1,2-dioxygenase via the ortho-cleavage pathway. These results revealed the high-efficient phenol-degrading capability of the resuscitated strain SAS26 at high salinity, which shed light on cultivating effective bio-inoculants for treating high-saline phenolic wastewater.

Enhanced Heterogeneous Peroxymonosulfate Activation by MOF-Derived Magnetic Carbonaceous Nanocomposite for Phenol Degradation.

Degradation efficiency and catalyst stability are crucial issues in the control of organic compounds in wastewater by advanced oxidation processes (AOPs). However, it is difficult for catalysts used in AOPs to have both high catalytic activity and high stability. Combined with the excellent activity of cobalt/copper oxides and the good stability of carbon, highly dispersed cobalt-oxide and copper-oxide nanoparticles embedded in carbon-matrix composites (Co-Cu@C) were prepared for the catalytic activation of peroxymonosulfate (PMS). The catalysts exhibited a stable structure and excellent performance for complete phenol degradation (20 mg L-1) within 5 min in the Cu-Co@C-5/PMS system, as well as low metal-ion-leaching rates and great reusability. Moreover, a quenching test and an EPR analysis revealed that ·OH, O2·-, and 1O2 were generated in the Co-Cu@C/PMS system for phenol degradation. The possible mechanism for the radical and non-radical pathways in the activation of the PMS by the Co-Cu@C was proposed. The present study provides a new strategy with which to construct heterostructures for environmentally friendly and efficient PMS-activation catalysts.

Phenol Degradation Performance in Batch and Continuous Reactors with Immobilized Cells of Pseudomonas putida

Phenol is a highly persistent environmental pollutant and is toxic to living organisms. The main objective of this study is to observe the phenol degradation performance by free and immobilized Pseudomonas putida (P. putida) in batch and continuous reactors, respectively. Batch experiments were evaluated to determine the maximum specific growth rate, saturation constant, inhibition constant, and cell yield. These kinetic parameters were used as the input values for the continuous-flow immobilized cells model. The immobilized cells model was validated by experimental results obtained from an immobilized cells continuous reactor. The model-predicted and experimental results showed good agreement for phenol effluent concentration in the continuous mode. In the steady-state condition, high phenol removal was achieved under various hydraulic retention times. The corresponding removal of phenol ranged from 93.3 to 95.9%, while the hydraulic retention times were maintained at 3.1–10.5 h. Furthermore, polyvinyl alcohol-immobilized cells with nanoscale particles were also prepared. The polyvinyl alcohol-immobilized P. putida cells with nanoscale Fe3O4 enhanced the ability of phenol degradation. The experimental results revealed that immobilized cells with nano-Fe3O4 had the highest phenol degradation performance at a low salinity of 1%. However, the advantage of the addition of nano-Fe3O4 was insignificant for phenol degradation at a higher salinity of 5%. The approaches of the batch and continuous column tests were practical in the treatment of actual phenol-containing wastewater.

Efficient activation of peroxymonosulfate by MoS2 intercalated MgCuFe layered double hydroxide for phenol pollutant control

The application of MoS2 as an emerging cocatalyst in wastewater treatment is of great significance, but the efficiency of cocatalyst is often limited due to its easy agglomeration and insufficient interaction with the catalyst. Here, we used layered double hydroxide (LDH) as the catalyst and the growth template of MoS2 to achieve an efficient combination of catalyst and cocatalyst in the removal of organic pollutants by peroxymonosulfate (PMS) activation. The outcomes showed that the MoS2 intercalated LDH composite samples (MLDH) owned excellent phenol degradation performance, reaching nearly 100% removal within 10 min, and the calculated apparent rate constants were 2.3, 5.6, 17.7 and 19.8 times higher than that of the samples of directly growing MoS2 on the LDH (M@LDH), physically blended MoS2 and LDH samples, LDH and MoS2, respectively. Based on the results of electron paramagnetic resonance (EPR) and X-ray photoelectron spectroscopy (XPS), SO4•- had a major impact on the elimination of phenol, Mo(Ⅳ) in MoS2 also participated in and encouraged the Fe(Ⅲ)/Fe(Ⅱ) redox cycle, providing the driving force for the further activation of PMS. Moreover, the effects of pH value, anions, cations and water environment of MLDH during the activation of PMS were also determined, and it was found that under various catalytic environments, MLDH always maintained a high removal rate of phenol and showed strong anti-interference ability. Collectively, the results of this research would offer more possibilities and suggestions for creating highly effective catalysts for wastewater cleanup.

Construction of direct Z-scheme BiOBr/CuI heterojunction for boosting photocatalytic degradation of phenol

First successful preparation of BiOBr/CuI composite catalysts via a hydrothermal method which has excellent performance for phenol degradation. The direct Z-scheme heterojunction of the composite was proved by XPS and EPR.

Bromine functionalized Fe/Cu bimetallic MOFs for accelerating Fe(III)/Fe(II) cycle and efficient degradation of phenol in Fenton-like system

Fe–based metal–organic frameworks (Fe–MOFs) have been widely used in heterogeneous Fenton-like processes. However, the catalytic performance of Fe-MOFs is limited by the relatively slow Fe (III)/Fe (II) redox cycle. For Fe-MOFs, increasing the interfacial electron transfer and reducing the electron density of Fe-MOFs are expected to accelerate the reduction of Fe (III) and improve the catalytic performance. Here, by mixing Fe/Cu metal species and introducing bromine groups, we successfully prepared bromine-functionalized bimetallic MOFs–FeCu(BDC-Br), and we used it to effectively degrade phenol in a Fenton-like process. Compared with most other catalysts, FeCu(BDC-Br) achieved a higher phenol degradation kinetic rate of 0.106 min–1 at a low dose. Effects of pH, humic acid (HA) and coexisting ions on the degradation of phenol were examined. The FeCu(BDC-Br) /H2O2 system can remove phenol in the near neutral pH range of 4–6 and 0–50 mg/L HA range. Chloride ion, sulfate, or phosphate with a concentration of 100 mg/L showed an inhibitory effect on the catalytical performance of phenol degradation. This work provides insights for the preparation of Fe-MOFs Fenton-like catalyst in water/wastewater treatment.

High-activity and excellent-reusability γ-Fe2O3/SiO2 coating on TC4 titanium alloy by plasma electrolytic oxidation for enhanced photo-Fenton degradation.

The immobilized coatings as a kind of promising Fenton-like catalysts with excellent performance and reusability for the efficient degradation of antibiotics and phenol under solar light irradiation is investigated. Herein, the porous γ-Fe2O3/SiO2 immobilized ceramic coating on TC4 titanium alloy as photo-Fenton catalyst was prepared via plasma electrolytic oxidation technology. The as-obtained immobilized coating manifested a remarkable catalytic activity that the removal efficiencies of phenol and various antibiotics could reach more than 92% within 90min, and presented excellent reusability after six runs in phenol removal. The high activity and excellent reusability of γ-Fe2O3 were attributed to the synergistic effect of multiple pathways to jointly produce abundant •OH, and the combination of γ-Fe2O3 and SiO2 in the coating could effectively reduce iron leaching during the heterogeneous photo-Fenton process, respectively. This work provides a novel strategy for the synthesis of high-performance photo-Fenton catalysts to dispose of wastewater in the future.

Promotion of Phenol Electro-oxidation by Oxygen Evolution Reaction on an Active Electrode for Efficient Pollution Control and Hydrogen Evolution.

We report an electrolysis system using NiFe layered double hydroxide/CoMoO4/nickel foam (NFLDH/CMO/NF) as the anode and CMO/NF as the cathode for simultaneous phenol electro-oxidation and water electrolysis. This system shows high performance for both phenol degradation and hydrogen evolution. We demonstrate that the degradation rate of phenol on the active anode is governed by the mass transfer rate at a low phenol concentration (0.5-2 mM) and by the electro-oxidation rate at a high phenol concentration (5 mM). The anodic oxygen evolution reaction (OER) can promote the phenol degradation through enhanced mass transfer efficiency. More importantly, the common deactivation issue of phenol electro-oxidation on the inert anode can be eliminated by the high OER activity of the active anode. The constructed full electrolytic cell only needs a low potential of 1.498 V to achieve 10 mA/cm2 for water electrolysis. The reported promotion effect of phenol degradation by OER as well as the improved anode resistance to deactivation offer new insights into efficient and robust waste-to-resource electrolysis system for water treatment.

Yolk–shell-type gold nanosphere-encapsulated mesoporous silica for catalytic oxidation of organic pollutants in the presence of persulfate

Gold nanosphere-encapsulated mesoporous silica exhibits excellent performance in phenol degradation by providing high surface area, blocking external interfering materials, and preventing leakage of gold nanospheres.

Study on Performance and Mechanism of Phenol Degradation through Peroxymonosulfate Activation by Nitrogen/Chlorine Co-doped Porous Carbon Materials

Study on Performance and Mechanism of Phenol Degradation through Peroxymonosulfate Activation by Nitrogen/Chlorine Co-doped Porous Carbon Materials

Fabrication of Adsorbed Fe(III) and Structurally Doped Fe(III) in Montmorillonite/TiO2 Composite for Photocatalytic Degradation of Phenol

The Fe(III)-doped montmorillonite (Mt)/TiO2 composites were fabricated by adding Fe(III) during or after the aging of TiO2/Ti(OH)4 sol–gel in Mt, named as xFe-Mt/(1 − x)Fe-TiO2 and Fe/Mt/TiO2, respectively. In the xFe-Mt/(1 − x)Fe-TiO2, Fe(III) cations were expected to be located in the structure of TiO2, in the Mt, and in the interface between them, while Fe(III) ions are physically adsorbed on the surfaces of the composites in the Fe/Mt/TiO2. The narrower energy bandgap (Eg) lower photo-luminescence intensity were observed for the composites compared with TiO2. Better photocatalytic performance for phenol degradation was observed in the Fe/Mt/TiO2. The 94.6% phenol degradation was due to greater charge generation and migration capacity, which was confirmed by photocurrent measurements and electrochemical impedance spectroscopy (EIS). The results of the energy-resolved distribution of electron traps (ERDT) suggested that the Fe/Mt/TiO2 possessed a larger amorphous rutile phase content in direct contact with crystal anatase than that of the xFe-Mt/(1 − x)Fe-TiO2. This component is the fraction that is mainly responsible for the photocatalytic phenol degradation by the composites. As for the xFe-Mt/(1 − x)Fe-TiO2, the active rutile phase was followed by isolated amorphous phases which had larger (Eg) and which did not act as a photocatalyst. Thus, the physically adsorbed Fe(III) enhanced light adsorption and avoided charge recombination, resulting in improved photocatalytic performance. The mechanism of the photocatalytic reaction with the Fe(III)-doped Mt/TiO2 composite was proposed.

Revealing the enhancing mechanisms of Fe–Cu bimetallic catalysts for the Fenton-like degradation of phenol

To develop a heterogeneous Fenton-like catalyst with desirable activity and reusability remains a great challenge for the practical degradation of environmental remediation. Herein, we demonstrate a dendritic Fe–Cu bimetallic catalyst consisted of a Cu/Fe3O4 shell and a FeCu core (E100). In comparisons of single Cu, Fe and Fe3O4, E100 performs far better performance for the Fenton-like degradation of phenol, and its dominant Fenton-like active centers are Fe species under acidic pH or Cu species under neutral pH. Particularly, Cu-based Fenton-like reactions are greatly accelerated by galvanic micro-cells effects that come from the special co-existence of Cu/Fe3O4 shell, and subsequently, owing to the Cu leaching from the shell, the inner FeCu core of E100 is able to be exposed and further strengthen Fe-based Fenton-like reactions. Overall, the appropriate synergistic effects endow E100 with superior catalytic activity and reusability than other catalysts. Our work pushes forward a step for understanding the catalytic mechanism of Fe–Cu bimetallic catalysts and provides new sights for fabricating efficient Fenton-like catalysts for environmental remediation.

Fabrication of a dual S-scheme Bi7O9I3/g-C3N4/Bi3O4Cl heterojunction with enhanced visible-light-driven performance for phenol degradation

S-scheme heterostructure can facilitate the separation of carriers while maintain outstanding redox capacity. A series of ternary Bi7O9I3/g-C3N4/Bi3O4Cl photocatalytic system was triumphantly synthesized via oil bath method in this work and used in photocatalytic degradation of phenol. The optimal TOC removal rate reached up to 93.57% under illumination for 160 min, which was slightly lower than phenol photodegradation (about 100%, 100 min). Correspondingly, the apparent rate constants for the decay of phenol are determined to be 0.0211 min−1. The experiment of free radical capture indicated that ·OH and ·O2− were the major oxidizing substances to degrade phenol. The products of phenol photodegradation were identified by high performance liquid chromatography (HPLC) and a possible degradation pathway was proposed. The characterization analysis and density functional theory (DFT) calculations demonstrated that dual S-scheme charge migration was generated at the interface of Bi7O9I3, g-C3N4 and Bi3O4Cl, contributing to an efficient separation of light-excited carriers. In the field of environmental remediation, the discovery of this work could open up promising vistas for designing bismuth-based ternary heterostructures with application potentiality.