Phenol Removal Research Articles

Laccase‐Copper Nanohybrids as Highly Active Catalysts for Bio‐degradation

AbstractPhenolic contamination is one of the crucial concerns for the safety of drinking water. Enzymatic degradation is a green and efficient manner for phenolic compounds removal from water. However, enzymatic degradation of phenolic pollutants in water is limited as a result of the low activity, stability and reusability of the enzyme. Herein, we propose a novel strategy to degrade phenolic pollutants in water by using an enzyme‐metal hybrid catalyst constructed by in situ formation of ultrafine Cu nanoparticles on the cross‐linked Laccase aggregates. The designed Cu/Lac CLEAs showed excellent performance on phenolic pollutants removal due to the cooperative catalysis between Lac CLEA and Cu NPs and the enrichment of phenolic pollutants in hybrid catalyst. The degradation efficiency of 2,4,6‐trichlorophenol catalyzed by Cu/Lac CLEAs was improved by 33 % compared to the Lac CLEAs, while Cu NPs barely catalyzed the degradation process of phenolic pollutants. The Cu/Lac CLEAs hybrid catalyst exhibit high catalytic activity at room temperature in a wide pH range of 5–8, making the degradation of phenolic pollutants more practically operational. In other words, this study develops a novel hybrid catalyst for the efficient removal of pollutants from water.

Sustainable Management of Agro-Food Wastes Derived from the Olive Mill and Sugar Industry and Clinoptilolite to Produce Novel Adsorptive Materials

Novel sorbents were produced using sustainable and eco-friendly methods, aimed at minimizing environmental impact while utilizing industrial by-products and natural minerals. Olive stones and molasses derived from olive mill and sugar industries, respectively, and an abundant, natural and low-cost mineral, clinoptilolite, were combined in the following proportions: 80/20 clinoptilolite/stone, 80/10/10 clinoptilolite/stone/molasses, 50/50 stone/molasses, w/w. Then, physical carbonization (CL80OL20C, CL80OL10M10C, OL50M50C) or chemical activation (CL80OL20A, CL80OL10M10A, OL50M50A) took place. The adsorbents were characterized through Raman, FT-IR, BET and SEM-EDS analysis. The CL80OL20A material presents the highest ratio of C/O in EDS analysis and the lowest ID/IG in Raman spectroscopy. The increase in the specific surface area is as follows: OL50M50C < OL50M50A < CL80OL10M10C < CL80OL20C < CL80OL20A < CL80OL10M10A. Three applications were conducted: two with dyes (methylene blue and methyl red) in aqueous means and one in olive mill wastewaters for the removal of total phenols and their addition to rice, increasing the total phenolic content and producing novel foods. The well-fitted application of the pseudo-second order kinetic model to the experimental data has shown that chemisorption is the prevailing mechanism. The adsorbed amount of the recovered phenols to rice ranges from 0.14 to 0.93 mg/g. Consequently, olive and sugar by-products can be used as filters either to adsorb dangerous organic compounds or to recover bioactive compounds from wastewater, preventing their disposal in the environment, which could otherwise lead to severe negative effects on the ecosystems.

Efficient Electrosynthesis of Valuable para-Benzoquinone from Aqueous Phenol on NiRu Hybrid Catalysts.

Electrocatalytic oxidation of aqueous phenol to para-benzoquinone (p-BQ) offers a sustainable approach for both pollutant abatement and value-added chemicals production. However, achieving high phenol conversion and p-BQ yield under neutral conditions remains challenging. Herein, we report a Ni(OH)2-supported Ru nanoparticles (NiRu) hybrid electrocatalyst, which exhibits a superior phenol conversion of 96.5% and an excellent p-BQ yield of 83.4% at pH 7.0, significantly outperforming previously reported electrocatalysts. This exceptional performance benefits from the triple synergistic modulation of the NiRu catalyst, including enhanced phenol adsorption, increased p-BQ desorption, and suppressed oxygen evolution. By coupling a flow electrolyzer with an extraction-distillation separation unit, the simultaneous phenol removal and p-BQ recovery are realized. Additionally, the developed electrocatalytic system with the NiRu/C anode displays good stability, favorable energy consumption, and reduced greenhouse gas emissions for phenol-containing wastewater treatment, demonstrating its potential for practical applications. This work offers a promising strategy for achieving low-carbon emissions in phenol wastewater treatment.

Efficient Electrosynthesis of Valuable para‐Benzoquinone from Aqueous Phenol on NiRu Hybrid Catalysts

Electrocatalytic oxidation of aqueous phenol to para‐benzoquinone (p‐BQ) offers a sustainable approach for both pollutant abatement and value‐added chemicals production. However, achieving high phenol conversion and p‐BQ yield under neutral conditions remains challenging. Herein, we report a Ni(OH)2‐supported Ru nanoparticles (NiRu) hybrid electrocatalyst, which exhibits a superior phenol conversion of 96.5% and an excellent p‐BQ yield of 83.4% at pH 7.0, significantly outperforming previously reported electrocatalysts. This exceptional performance benefits from the triple synergistic modulation of the NiRu catalyst, including enhanced phenol adsorption, increased p‐BQ desorption, and suppressed oxygen evolution. By coupling a flow electrolyzer with an extraction‐distillation separation unit, the simultaneous phenol removal and p‐BQ recovery are realized. Additionally, the developed electrocatalytic system with the NiRu/C anode displays good stability, favorable energy consumption, and reduced greenhouse gas emissions for phenol‐containing wastewater treatment, demonstrating its potential for practical applications. This work offers a promising strategy for achieving low‐carbon emissions in phenol wastewater treatment.

Inhibition of inorganic chlorinated byproducts formation during electrooxidation treatment of saline phenolic wastewater via synergistic cathodic generation of H2O2

The electrochemical treatment of saline wastewater is prone to the formation of inorganic chlorinated byproducts, being a significant challenge for this technology. In this study, we introduce an electrooxidation system utilizing a self-supporting nitrogen-doped carbon-based cathode embedded in carbon cloth (N@C-CC), designed to generate H₂O₂. This system aims to rapidly neutralize free chlorine produced at the anode, a precursor to inorganic chlorinated byproducts, thereby reducing their formation. Our results demonstrate that using the N@C-CC cathode in saline wastewater treatment yielded considerably lower concentrations of ClO₃⁻ and ClO₄⁻ (0.08 mM and 0.024 mM, respectively), which were only 20.5% and 22.7% of the levels produced using a Pt cathode without H₂O₂ generation. Moreover, the presence of cathodically generated H₂O₂ that quenches free chlorine did not significantly impact the degradation performance of phenol. Electron paramagnetic resonance tests and quenching experiments indicated that 1O₂ was primarily responsible for phenol removal. Validation with real wastewater demonstrated reductions of 68.6% and 56.3% in ClO3− and ClO4− concentrations, respectively, while effectively removing other pollutants. This study thus offers a compelling method for mitigating the formation of inorganic chlorinated byproducts during the electrooxidation of saline wastewater.

A comparative study on removal of phenol from wastewater using batch anaerobic and anoxic MBBR

A comparative study on removal of phenol from wastewater using batch anaerobic and anoxic MBBR

In situ treatment of contaminated soil using persulfate activated by sulfidated zero-valent iron

Soil contamination with hazardous substances like phenol poses significant environmental and health risks. In situ soil mixing can be a promising technological solution to this challenge. A persulfate and sulfidated zero-valent iron (S-ZVIbm) system for remediating contaminated soil was developed and tested to be suited to in situ soil mixing. S-ZVIbm was synthesized using a ball mill process, and the optimal sulfur to iron molar ratio for effectively removing phenol from soil removal without pyrophoric risks was 0.12. Soil slurry experiments were performed, and the best phenol oxidation results (high stoichiometric efficiency and sustained oxidation after mixing) were achieved at a persulfate to S-ZVIbm molar ratio of 2:1 and a persulfate to phenol molar ratio of 8:1. A high organic matter content of the silty clay fraction of the soil strongly suppressed persulfate activation, so suppressed phenol removal and increased persulfate consumption. Electron spin resonance and radical scavenging tests confirmed that hydroxyl and sulfate radicals were present during the degradation of phenol. While sulfate radicals predominantly facilitated degradation in the soil, both sulfate and hydroxyl radicals were crucial in the aqueous phase in the absence of soil organic matter. In situ soil mixing simulation tests indicated that the persulfate and S-ZVIbm doses and the mixing rate and duration strongly affected the efficacy of the system, and the optimal conditions for phenol removal were determined. The results indicated that the persulfate/S-ZVIbm system could be tuned to achieve sustained persulfate activation and to remediate contaminated soil employing in situ soil mixing technique.

TiO2-embedded dual-layer mullite hollow fiber membranes for efficient removal of Persistent organic pollutants from wastewater

Persistent organic pollutants (POPs) are toxic pollutants that harm the environment and ecosystems. This study presents a novel approach to develop a dual-layer hollow fiber ceramic membrane for phenolic compound removal. A co-extrusion-based phase inversion process and co-sintering techniques were employed to fabricate the membrane, and the effects of TiO2 loadings on the outer layer were investigated. Characterization techniques, including FTIR, SEM, EDX, and zeta potential analysis, were used to analyze the mullite and TiO2 powders and membranes. The membrane’s performance was evaluated through rejection tests of POPs at various concentrations (10, 500, and 1000 ppm) and fouling assessments were conducted. The results showed that the M−MT0.6 membrane, with a mean pore size of 0.0245 μm, effectively rejected benzoic acid (81.45 %), gallic acid (91.45 %), and hydroquinone (74.49 %) from wastewater, achieving the highest permeate flux (1320.50 L/m2·h) for gallic acid at 10 ppm. Additionally, M−MT0.6 exhibited minimal fouling over a 1-h filtration cycle, with the lowest fouling rate (35.1 %) recorded at 1000 ppm for BA, attributed to effective backwashing. However, higher fouling rates were observed at 10 ppm for BA (90.10 %) and HQ (83.50 %). Overall, this study demonstrates the potential of the novel membrane for effective removal of POPs from industrialwastewater.

Performance study of phenol sequestration from agricultural wastewater by chemical activated Montmorillonite

Agricultural by-products possess potential as cost-effective adsorbents for the remediation of phenolic contaminants in environmentally treated wastewater. This research focuses on the utilization of Algerian montmorillonite clay, specifically modified montmorillonite (Mo-5N), treated with 5N hydrochloric acid (HCl), compared to its untreated form (Mo-0N), for phenol sequestration from pesticide-laden waters. We employed various analytical techniques, such as chemical analysis, X-ray diffraction (XRD), and Fourier Transform Infrared (FTIR) spectroscopy, to characterize these adsorbents. The adsorption behavior was scrutinized under varying conditions, including pH, contact time, phenol concentration, and temperature. The maximum adsorption capacities achieved were 119.12 mg/g for Mo-5N and 100.89 mg/g for Mo-0N under optimal conditions of pH 5.72, a contact time of 120 minutes, and a temperature of 40°C. The kinetics of adsorption were best described by the pseudo-second-order and Elovich models, while the Freundlich isotherm model aptly described the equilibrium data. Thermodynamic analyses revealed that the phenol removal process using both forms of montmorillonite is spontaneous and endothermic. This study demonstrates the efficacy of Algerian montmorillonite clay in the removal of phenolic pesticides from agricultural wastewater.

Porous fluorine-cerium nanosheets anchored with FeOOH quantum dots for synergistic enhanced visible-light-driven photo-Fenton degradation of phenol

The utilization of two-dimensional (2D) materials to construct heterogeneous catalysts provides opportunities for environmental remediation, while the incorporation of porous structures can further enhance catalytic performance. In this work, a porous 2D FeOOH/fluorine-cerium (F-Ce) nanosheet composite was designed and synthesized by a simple impregnation-precipitation method. The unique 2D porous structure of F-Ce promoted the high dispersion of FeOOH quantum dots (QDs) (∼1.4 nm) and their tight integration to form S-scheme heterojunctions. This structure offered a greater number of active sites, and significantly improved the capacity of light absorption and the separation and migration efficiency of photogenerated carriers, thus improving catalytic activity. This catalyst achieved a phenol removal rate of 98.1 % within 20 min during the photo-Fenton reaction, which significantly surpasses pure FeOOH (32.9 %) and F-Ce (21.7 %) alone. In particular, the optimized 14FeOOH/F-Ce catalyst achieved more than 95.0 % degradation efficiency within a remarkably short period of 5 min. Mott Schottky and in situ irradiated X-ray photoelectron spectroscopy (ISI-XPS) studies demonstrated that the S-scheme charge transfer mechanism of this heterojunction synergistically enhanced the catalytic activity of the Fenton-like reaction. This study provides valuable insights for designing efficient 2D porous heterojunction catalysts for visible-light-driven Fenton applications.

Elimination of phenol by sonoelctrochemical process utilizing graphite, stainless steel, and titanium anodes: optimization by taguchi approach

Phenol is one of the worst-damaging organic pollutants, and it produces a variety of very poisonous organic intermediates, thus it is important to find efficient ways to eliminate it. One of the promising techniques is sonoelectrochemical processing. However, the type of electrodes, removal efficiency, and process cost are the biggest challenges. The main goal of the present study is to investigate the removal of phenol by a sonoelectrochemical process with different anodes, such as graphite, stainless steel, and titanium. The best anode performance was optimized by using the Taguchi approach with an L16 orthogonal array. the degradation of phenol sonoelectrochemically was investigated with three process parameters: current density (CD) (25, 50, 75, and 100 mA/cm2), time (1, 2, 3, 4 h), and phenol concentration (100, and 200 mg/l). Signal-to-noise (S/N) ratio and analysis of variance (ANOVA) were utilized to examine the impact of each factor. The optimal conditions for phenol removal were 100 mA/cm2, 100 mg/l of phenol, and 4 hours of electrolysis. Under optimal operating conditions, the phenol removal efficiency was 80.99%. The CD was the most influential factor on phenol elimination effectiveness, while the phenol concentration had the least impact.

Low-Cost Flocculant Coated MIL-88B as Highly Efficient and Stable Fenton-Like Catalyst for Phenol Removal

Low-Cost Flocculant Coated MIL-88B as Highly Efficient and Stable Fenton-Like Catalyst for Phenol Removal

Assistance of aminated straw on enhanced biodegradation of phenol through bacteria and potential prediction of machine learning for bioremediation

ABSTRACT How to treat phenol-containing wastewater harmlessly is an urgent problem to be solved. In this study, a kind of biomaterial was prepared through strain PAO1 immobilized on aminated straw to enhance the phenol removal rate and efficiency. The aminated straw assisted PAO1 to increase the phenol degraded concentration from 1,900 to 1,500 mg/L, and shorten the degraded time by 44 h at 1,500 mg/L phenol. The immobilized PAO1 could remove phenol at pH 10 and 11, which was 2.7 and 3.8 times higher than free bacteria, respectively. In addition, the immobilized PAO1 could totally remove phenol, which was twice as high as that of free bacteria, at 4% NaCl stress. Furthermore, the removal efficiency of immobilized PAO1 was higher than that of free bacteria under the stress of various metal ions, especially for Co2+ and Pb2+. The determination coefficients R2 and root mean square error showed that the back propagation artificial neural network model could predict the degradation of phenol under various conditions, saving time and economic cost. The present study envisions that this biomaterial has great potential in the bioremediation of organic pollutions.

Continuous oxidation of organic contaminates in soil by polylactic acid-coated KMnO4

Potassium permanganate (KMnO4), as a versatile and safe solid source of MnO4-, received substantial attention from researchers as a potential soil oxidant reagent. In this study, we prepared polylactic acid (PLA)-coated KMnO4 (KMnO4@PLA) to control MnO4- release. The experimental results indicated that the optimal preparation scheme for KMnO4@PLA was a particle size of 1–2 mm, a solid-liquid ratio of 1:3, and a core-shell ratio of 1:3. And the release lifetimes of MnO4- from KMnO4@PLA in aqueous and quartz sand media were 200 hours and 310 hours, respectively, which were 2400 and 33 times longer than the release lifetimes of raw KMnO4. The controlled release of MnO4- from KMnO4@PLA was achieved through the hydrolysis of PLA. And the release process adhered to first-order reaction kinetics and displayed Fickian diffusion characteristics. Moreover, the removal of phenol by KMnO4@PLA in aqueous, quartz sand, and soil media were investigated through batch and flow column experiments. Compared with the raw KMnO4, the KMnO4@PLA exhibited a stronger ability to degrade phenol, due to the mildly acidic nature of the PLA shell. These findings demonstrated that KMnO4@PLA has significant advantages for the remediation of organically contaminated soils.

Photoactivation of sulfite by FeTiO3 for organic pollutant degradation: Performance and mechanism

In recent years, the exploration of sulfite (S(IV))-based advanced oxidation processes has attracted increasing attention due to its high performance in the degradation of aqueous organic contaminants. In this study, we investigated the activation of S(IV) by ilmenite (FeTiO3) under photo irradiation using phenol as a substrate. The FeTiO3/S(IV)/photo system demonstrated a remarkable phenol removal rate, achieving 81.4 % degradation within 30 min under optimal conditions. The photocatalytic mechanism involves the generation of electron-hole pairs in FeTiO3, with photogenerated holes activating the adsorbed S(IV) on the catalyst’s surface to produce various free radicals, among which SO4− is identified as the primary active species. Density functional theory calculations further suggest that electron transfer between ilmenite and S(IV) may occur via a Fe-O-S bridge. Additionally, the approach demonstrates satisfactory reusability of the photocatalyst and consistent effectiveness in real-water matrices. This study contributes to the development of more efficient, cost-effective, and environmentally friendly water treatment strategies by providing a deeper understanding of the proposed FeTiO3/S(IV)/photo system.

A study on the application of a composite MIL88A(Fe)/TiO2 in a hexagonal photoreactor for phenol removal: Response surface methodology and kinetic modeling

A study on the application of a composite <scp>MIL88A</scp>(Fe)/<scp>TiO₂</scp> in a hexagonal photoreactor for phenol removal: Response surface methodology and kinetic modeling

Preparation of nano SnO2-Sb2O3 composite electrode by cathodic deposition for the elimination of phenol by Sonoelectrochemical oxidation

Abstract The preparation of composite metal oxide to attain high efficiency in removing phenol from wastewater has a great concern. In the present study, the focus would be on adopting antimony-tin oxide coating onto graphite substrates instead of titanium; besides the effect of SbCl3 concentration on the SnO2-Sb2O3 composite would be examined. The performance of this composite electrode as the working electrode in the removal of phenol by sonoelectrochemical oxidation will be studied. The antimony-tin dioxide composite electrode was prepared by cathodic deposition with SnCl2 . 2H2O solution in a mixture of HNO3 and NaNO3, with different concentrations of SbCl3. The SnO2-Sb2O3 deposit layer’s structure and morphology were examined and the 4 g/l SbCl3 gave the more crystallized with nanoscale electrodeposition. The highest removal of phenol was 100% at a temperature of 30 oC, with a current density (CD) of 25 mA/cm2.

Green synthesis of zinc oxide nanoparticles for the removal of phenol from textile wastewater

This study investigated the use of zinc oxide nanoparticles (ZnO NPs) as an adsorbent for removing total phenols from textile wastewater. The ZnO NPs were synthesized by reducing Zn(NO3)2⋅6H2O using an extract from Neem leaves (Azadirachta indica). Characterization of the adsorbent was performed using Fourier Transform Infrared (FTIR) spectroscopy to identify functional group modifications, high-resolution scanning electron microscopy (HRSEM) for structural orientation, energy dispersive spectroscopy (EDS) for elemental analysis, and X-Ray diffraction analysis (XRD) for crystallinity, revealing particle crystallinity around 200 nm. Adsorption experiments were conducted over contact times of 20–60 min, with adsorbent loadings between 0.2 and 1 g/100 mL, and temperatures ranging from 30 to 50 °C. Optimal phenol removal, achieving 55.93% (0.67 mg/L), occurred at 43.40 min, 33.70 °C, and an adsorbent dosage of 0.69 g/L of textile wastewater. The phenol adsorption process using ZnO NPs was exothermic, spontaneous, and required low energy, fitting well with the Langmuir isotherm and following a pseudo-second-order kinetic model.

Degradation of phenol from water by Rhodococcus ruber promoted by MgO nanoparticles

How to improve the treatment efficiency has always been a key problem that needs to be solved in the bio-degradation of phenolic pollutant. The nanomaterials could improve the activity and tolerance of microorganisms, as well as the metabolic efficiency for pollutants under certain conditions. In this research, the effect of nano magnesium oxide (Nano-MgO) on the degradation of phenol by Rhodococcus ruber ATCC 31338 was studied. Moreover, the degradation mechanism of Rhodococcus ruber and Nano-MgO composite system was studied. Results showed that the addition of Nano-MgO could improve the phenol removal efficiency. With the presence of Nano-MgO at 100 mg/L to 300 mg/L, Rhodococcus ruber showed better growth and efficiency in removing phenol. However, when the concentration of Nano-MgO achieved 400 mg/L, the growth of Rhodococcus ruber was inhibited. Enzyme activity experiments suggested that the presence of Nano-MgO had a significant positive effect on the enzyme activity of catechol 1,2-dioxygenase (C12O) and catechol 2,3-dioxygenase (C23O), especially to C23O. The present of Nano-MgO might change the cleavage pathway of catechol. In addition, phosphorus is a limiting factor for the growth of Rhodococcus ruber. The addition of MgO-P materials prepared by encapsulating phosphorus on Nano-MgO can achieve efficient degradation of phenol by Rhodococcus ruber in the phosphorus loss system. This result also proved that nanomaterials can enhance the removal efficiency of organic matter by microorganisms. This study could provide a new solution for improving the microbial degradation rate of phenolic substances.

Evaluation of reduced graphene oxide from cotton waste as an efficient phenol adsorbent in aqueous media.

The elimination of organic substances, such as phenol, in conventional and biological processes, has been considered a challenge for the petroleum industry. In this work, reduced graphene oxide (rGO), obtained from cellulosic biomass (CB-rGO), as cotton waste, was employed as a phenol adsorbent in an aqueous solution simulating refinery effluent. The CB-rGO was characterized using HRTEM, Raman, XRD, FTIR, BET, and zeta analysis. The behavior of variables such as pH, contact time, temperature, CB-rGO mass, and adsorbate concentration on the characteristics of the adsorption process were continuously investigated. These parameters of the adsorption process were evaluated across a range of adsorbent concentrations from 100 to 300mg/L, pH in the range of 2-11, adsorbent mass 5-25mg, contact time of 0-180min, and temperature of 20-60°C. The adsorption isotherm data were better described by the Freundlich equation compared to the Langmuir and Sips models, despite the small difference in R2 values. Mechanism diffusion was analyzed using the Boyd model and confirmed to be the rate-limiting step in the adsorption process. The endothermic nature of this CB-rGO adsorption process with phenol was confirmed by verifying the thermodynamic data. This successful removal of phenol from synthetic effluents highlights the promising potential of this adsorbent obtained from an industrial residue and being an ecologically more sustainable alternative compared to the synthesis of other materials identified to remove this contaminant.