Phenolic Pollutants Research Articles

Syngas production from phenolic pollutants via a series of hydroxylation, ring cleavage, and aqueous-phase reforming catalyzed by a hydrotalcite-supported Fe–Mn–Ni alloy

A trifunctional catalyst facilitating a series of hydroxylation, oxidative ring opening, and aqueous-phase reforming reactions was developed to convert phenolic wastewater into syngas.

Electron-deficient Fe3O4@AC-NH2@Cu-MOF nanoparticles for enhanced degradation of electron-rich benzene derivatives via synergistic adsorption and catalytic oxidation.

Benzene derivatives in wastewater have negative impacts on ecosystems and human health, making their removal prior to discharge imperative. In this study, Fe3O4@AC-NH2@Cu-opa (AC-NH2 = aminoclay, Cu-opa = [Cu(opa)(bipy)0.5(H2O)]n (H2opa = 3-(4-oxypyridinium-1-yl) phthalic acid)) nanoparticles (NPs) were synthesized as adsorbent and catalyst for phenolic compound removal from wastewater. Fe3O4@AC-NH2@Cu-opa NPs demonstrated outstanding performance in the adsorption of phenol, exhibiting a remarkable adsorption capacity of up to 166.39 mg g-1 according to the Langmuir model. The composite also exhibited higher Fenton activity toward the degradation of electron-rich organic phenolic pollutants, with a rate approximately 3.4 times higher than that of Fe3O4 alone. The high catalytic activity of the composite was attributed to the large surface area and abundant active sites of the 2D charge-separated Cu-MOF. Meanwhile, the superparamagnetism of the Fe3O4 core enabled magnetic recollection and reuse without any significant loss of activity. Therefore, use of Fe3O4@AC-NH2@Cu-opa/H2O2 shows potential in an efficient method for the removal of phenolic compounds from wastewater.

Pollution characteristics and risk assessment of endocrine-disrupting chemicals in surface water of national (freshwater) aquatic germplasm resource reserves in Guangdong Province.

The distribution, composition, and risk assessment of 8 EDCs in the surface water of 14 national aquatic germplasm resource reserves (freshwater) were investigated during dry and wet seasons. Bisphenol A (BPA), nonylphenol (NP), and octylphenol (OP) were the main contributors of the 8 EDCs. The concentrations of phenolic pollutants in surface water during the dry season were higher than those in the wet season. However, no significant seasonal differences were found among the steroid hormones. According to the evaluation of estrogenic activity (EEQ > 1.0), E2 and EE2 were the main contributors to estrogenic activity. EDC mixtures posed a higher risk to crustaceans and fish (RQ > 1.0) and a moderate to high risk to algae (RQ > 0.1). Fish were the most sensitive aquatic organisms. In the study areas, EE2, E1, BPA, NP, and E2 had a higher risk than the other three compounds and should be controlled as a priority.

Site-scale groundwater pollution risk assessment using surrogate models and statistical analysis

Petroleum pollution in soil and groundwater has emerged as a significant environmental concern worldwide. As a sustainable and cost-effective in-situ remediation technique, Monitored Natural Attenuation (MNA) exhibits significant promise in addressing sites contaminated by petrochemicals. This study specifically targets a typical petrochemical-contaminated site in northern China and employs GMS software to establish a comprehensive physical model. The model relies on time-series monitoring data of phenol concentrations spanning from 2018 to 2020, effectively simulating both the leakage and natural attenuation of phenol. Within this study, the adsorption coefficient and maximum adsorption capacity emerge as the foremost influential factors shaping the outcomes of the model. Given the inherent heterogeneity of the site and the variability of hydrochemical conditions, parameters such as dispersion, porosity, and adsorption coefficient exhibit significant uncertainties. Consequently, relying on traditional deterministic models to predict the feasibility of MNA technology is not reliable. Therefore, this study employs machine learning (ML) methods to construct stochastic parameter models based on physical processes. The Random Forest Regression (RFR) algorithm, after trained, demonstrates strong alignment with numerical model output, exhibiting an average Nash-Sutcliffe Efficiency (NSE) >0.96. Using a stochastic approach, RFR iteratively computes phenol concentration across 6000 sets of parameters. Applying probability statistics, the model shows a notable reduction in the likelihood of phenol concentrations exceeding a threshold, dropping from 64.0% to 15.7% before and after natural attenuation. In parameter uncertainty, the stochastic model emphasizes natural attenuation's efficacy in mitigating phenol pollution risk (porosity being the most influential factor). This case study proposed a novel method to quickly assess the pollution risks at petrochemical sites under the influence of the uncertainty of pollutant transport and reaction parameters. The results can provide a reference for the pollution risk assessment at petrochemical sites, especially in sites with high stratigraphic heterogeneity or insufficient transport parameter data.

Adsorption and Kinetic study of priority organic pollutant phenol from aqueous waste using Activated carbon

Many organic compounds present in industrial and domestic wastewater are carcinogenic in nature. Removal of these organic compounds from waste waters has become a great challenge to waste water treatment technologies as many of them are non-biodegradable in nature. Adsorption on activated carbon has emerged as an efficient and economically viable technology for the removal of a broad spectrum of toxic organic compounds from domestic and industrial waste water. The adsorption of hazardous organic compounds on activated carbon has been the subject of research for the past three decades. In the present study, kinetic study for adsorption of some priority organic pollutants like phenol on activated carbon, was studied at laboratory scale. Series of experiments were carried out to determine kinetics for adsorbate, when present in aqueous solution as a single component. The commercially available bituminous coal based activated carbon Filtrasorb-400 was used as an adsorbent. A simplified interpretation of the kinetic data based on Langmuir theory has been used. The kinetics performed gives the adsorption equilibrium time. The adsorption and desorption rate constants were evaluated from the graph.

Revealing the degradation mechanisms of the hyper-tolerant bacterium Pseudomonas aeruginosa STV1713 under high phenol and 2,4-DCP-induced stress conditions through RNA-seq analysis.

The ability of bacteria to efficiently remove phenolic pollutants depends on their genetic makeup and environmental conditions. This study examined a novel strain, Pseudomonas aeruginosa STV1713, for degrading higher concentrations of phenol and 2,4-dichlorophenol. After optimization, a combination of degradation parameters, such as pH (7.0), temperature (32.5°C), and ammonium nitrate concentration (0.7g/L), was found to reduce degradation time while promoting cell growth. Under these optimal conditions, the bacterium effectively degraded up to 2000mg/L of phenol and 1400mg/L of 2,4-dichlorophenol, while maximum tolerance was observed till 2100mg/L and 1500mg/L, respectively. Metabolic profiling identified crucial metabolites in the ortho-degradation pathway during pollutant removal. Additionally, transcriptome analysis revealed that P. aeruginosa STV1713 utilizes different branches of the beta ketoadipate pathway for phenol and 2,4-DCP removal. Moreover, under high pollutant stress, the bacterium survived through differential gene expression in ribosome biogenesis, chemotaxis, membrane transport, and other pathways.

An efficient, recyclable and stable immobilized enzyme cascade catalytic system with visible-light driven for the removal of organic matter in water

A novel photo-enzyme composite catalyst based on modified carbon nitride was constructed and applied in the removal of antibiotics and phenolic pollutants in water. This composite catalyst (Cyt c/C/CN) has high catalytic activity and stability under acidic or alkaline conditions, which broadens the application range of cytochrome c (Cyt c). In addition, it has A high degradation rate and mineralized rate for sulfadiazine (SDZ) and bisphenol A (BPA). Among them, the degradation and total organic carbon (TOC) removal rate of SDZ were 65.53% and 40.44% respectively, which were much higher than that of pure CN (50.83% and 9.76%). Moreover, the degradation and TOC removal rate of BPA were 72.53% and 44.66%, which were 1.3 times and 2.5 times that of pure CN, respectively. The findings provide insights for designing photo-enzyme coupling systems to efficiently and at a high level remove sulfonamides antibiotics and phenolic agricultural organic pollutants in a simple step.

Extraction of Phenol as Pollutant from Aqueous Effluents Using Hydrophobic Deep Eutectic Solvents

Due to their toxicity and persistence in the environment, phenolic pollutants pose a serious threat to the ecosystem. In this work, the performance of hydrophobic deep eutectic solvents (HDESs) for phenol removal from aqueous effluents is thoroughly investigated using COSMO-RS screening followed by experimental validation. The screening results of 73 HDESs showed that the efficacy of phenol removal is significantly affected by chain length, functional groups, and aromaticity. Trioctylphosphine oxide (TOPO)-based HDESs were found to be the most effective HDESs for phenol elimination combined either with menthol (Men), 1-hexanol (Hex), Decanoic acid (DecA), or Thymol (Thy) all in 1:1 molar ratios. The better phenol elimination abilities of the selected HDESs were confirmed by experimental LLE data obtained at 298.15 K and 101 kPa. In fact, it has been found that there is a positive correlation between extraction efficiency and phenol content. For instance, at a phenol concentration of 7%, TOPO:Men had the highest extraction efficiency (96%). Moreover, the physicochemical properties of the selected HDESs, such as density, viscosity, FTIR, 1HNMR, and TGA, were also measured. The results showed their high thermal stability and low water solubility, which makes them suitable for phenol extraction applications. This study shows that HDESs are capable of removing phenolic contaminants from aqueous effluents in a sustainable and efficient manner and that the selected TOPO-based HDESs are of particular interest for further research and application in phenol removal.

On the mechanism and selectivity of a novel iodine/peracetic acid process for the efficient and rapid elimination of micropollutants

In recent years, halogen radical-based advanced oxidation processes (AOPs) have shown promise for metal-free, highly selective elimination of phenolic pollutants with high mineralization. This study explored a novel approach combing peracetic acid (PAA) and naturally available I− to efficiently remove bisphenol A (BPA) over a broad pH range (2–8). A dose of 500 μM PAA and 100 μM I− at a pH of 3 completely eliminated 43.8 µM of BPA within 10 min. Aside from I−, two more halogen ions, Cl− and Br−, could also enhance BPA elimination in the presence of PAA. Based on quenching experiments and density functional theory (DFT) thermodynamic calculations, only I− among the three halogen ions can react with PAA (primarily through the single electron transfer pathway) to generate •I, which efficiently removes BPA. The Cl− and Br− only contribute partially to the BPA removal, mainly through HOCl and HOBr following the oxygen atom transfer pathway. The water matrices had no noticeable influence on the I−/PAA process, and eliminating micropollutants with electron-rich groups from actual water samples remained effective. This work proposes an innovative and feasible technique for PAA-based AOPs and showcases its promising applicability for the treatment of phenolic contaminants in wastewater.

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.

Current status of phenolic pollution in urban lakes and its toxicity to cells – A case study of Xi’an, China

Current status of phenolic pollution in urban lakes and its toxicity to cells – A case study of Xi’an, China

Bacterial Nanocellulose/Copper as a Robust Laccase-Mimicking Bionanozyme for Catalytic Oxidation of Phenolic Pollutants.

Industrial effluents containing phenolic compounds are a major public health concern and thus require effective and robust remediation technologies. Although laccase-like nanozymes are generally recognized as being catalytically efficient in oxidizing phenols, their support materials often lack resilience in harsh environments. Herein, bacterial nanocellulose (BNC) was introduced as a sustainable, strong, biocompatible, and environmentally friendly biopolymer for the synthesis of a laccase-like nanozyme (BNC/Cu). A native bacterial strain that produces nanocellulose was isolated from black tea broth fermented for 1 month. The isolate that produced BNC was identified as Bacillus sp. strain T15, and it can metabolize hexoses, sucrose, and less expensive substrates, such as molasses. Further, BNC/Cu nanozyme was synthesized using the in situ reduction of copper on the BNC. Characterization of the nanozyme by scanning electron microscopy (SEM) and X-ray diffraction (XRD) confirmed the presence of the copper nanoparticles dispersed in the layered sheets of BNC. The laccase-mimetic activity was assessed using the chromogenic redox reaction between 2,4-dichlorophenol (2,4-DP) and 4-aminoantipyrine (4-AP) with characteristic absorption at 510 nm. Remarkably, BNC/Cu has 50.69% higher catalytic activity than the pristine Cu NPs, indicating that BNC served as an effective biomatrix to disperse Cu NPs. Also, the bionanozyme showed the highest specificity toward 2,4-DP with a Km of 0.187 mM, which was lower than that of natural laccase. The bionanozyme retained catalytic activity across a wider temperature range with optimum activity at 85 °C, maintaining 38% laccase activity after 11 days and 46.77% activity after the fourth cycle. The BNC/Cu bionanozyme could efficiently oxidize more than 70% of 1,4-dichlorophenol and phenol in 5 h. Thereby, the BNC/Cu bionanozyme is described here as having an efficient ability to mimic laccase in the oxidation of phenolic compounds that are commonly released into the environment by industry.

Food wastes clean water wastes: melon peel peroxidase isolation and immobilization onto magnetite nanoparticles for phenol removal

In this study, melon peel waste was utilized to isolate peroxidase enzyme through three-phase portioning (TPP) and subsequently immobilized onto magnetite nanoparticles for effective bioremediation of phenol pollutants from water. The optimization of TPP parameters ensured maximum activity recovery and enzyme purity. Magnetite nanoparticles were synthesized and used as a substrate for immobilizing the isolated peroxidase, achieving an activity recovery of 157% and a purification fold of 5.2. Protein homogeneity testing confirmed the purity of the peroxidase enzyme. The magnetite nanoparticles had an average diameter of 62 nm, and the immobilization efficiency reached 93% at pH 8 with an enzyme/nanoparticles v/v ratio of 1:9. The immobilized peroxidase demonstrated the ability to degrade 57% of phenol within 3 h and retained 30% relative activity even after five catalytic cycles. This immobilized melon peel peroxidase on magnetite nanoparticles proves to be a robust, enduring, and reusable biocatalyst with potential for various applications, especially in bioremediation processes.Graphical

Insights into synergistic metabolism of phenol and ammonium pollutants in treating coal gasification wastewater by algal-microbial fuel cell

The coexistence of phenol and ammonium induced mutual antagonism largely and hindered the application of biological treatment in coal gasification wastewater (CGW). A novel algal-microbial fuel cell (AMFC) was employed to separate and cleanse phenol and ammonium pollutants, and the insights into biological process were explored. Two types of AMFCs were developed to simultaneously remove phenol and ammonium from CGW, with cyanobacteria and green algal as the cathodes, respectively. The AMFC with Synechocystis cathode exhibited superior performance, removing COD and NH4+-N of 94.82 % and 20.16 %, about 1.12 and 1.06 times higher than the AFMC with Chlorella cathode. Meanwhile, the maximum power density of the AMFC with Synechocystis cathode was enhanced by 40.34 %. The conductive Synechocystis on the cathode and generated biomass on the anode might cooperate to facilitate extracellular electron transfer (EET), which consequently accelerated the separation and cooperative removal of phenol and ammonium in AMFC. By microbial community analysis, the microbiota in biofilm and generated biomass was respective keystone contributor to phenolic degradation and biomass transformation. Meanwhile, Chryseobacterium was the leading bacteria and might dominate both phenol degrading and the generated biomass formation.

Singlet oxygen is also involved in the formation of hypoiodous acid during the transformation of phenolic pollutants by peracetic acid in the presence of iodide

Peracetic acid (PAA) has been used as a disinfectant/oxidant in wastewater treatment. However, considering that the presence of iodide (I−) would induce the iodinated products in wastewater, the effect of I− on the transformation of phenolic pollutants by PAA was investigated. Herein, the presence of I− enhanced the transformation of phenolic pollutants (bisphenol S (BPS), bisphenol A (BPA), and p-hydroxybenzoic acid (p-HBA)) by PAA. Furthermore, hypoiodous acid (HOI) was reactive species in the PAA/I− system based on radical quenching experiments and electron spin resonance. In this system, PAA, together with 1O2 that was produced in PAA oxidized I− into HOI. Increasing PAA and I− dose promoted the transformation of phenolic pollutants but the promoting effect was less significant at higher dosage. The increase in H2O2 dose retarded the transformation of phenolic pollutants because of HOI being quenched by H2O2. In a wide range of pH (pH 4.0–10.0), the transformation of BPS, BPA, and p-HBA was pH-dependent and most effective at pH 7.0. The presence of chloride and bromide accelerated the transformation of phenolic pollutants by PAA/I− due to the formation of HOCl and HOBr. Furthermore, HOI substitution was the primary reaction pathway in the transformation of BPS, BPA, and p-HBA by PAA/I−. Finally, the transformation products of phenolic pollutants during the PAA/I− posed higher cytotoxicity compared to the parent pollutants. Overall, our findings improved the understanding of the chemical behavior of PAA in the presence of I− and suggested that the generation of iodinated products raised concerns for water safety.

Sustainable utilization of anthraquinone-rich Rheum officinale as electron shuttle in microbial fuel cell: Strategy for stimulating monohydric phenols degradation and bioelectricity generation

In an aim to completely degrade refractory phenolic compounds for effective wastewater treatment, a sustainable strategy using anthraquinone-rich herbal plant contents as electron shuttles is presented. This study is the first attempt of treating four different chemical structures of monohydric phenols, while simultaneously generate low-carbon electricity in a microbial fuel cell. An electron shuttle-mediated strategy was introduced to investigate the effect of electron shuttle against the degradation of phenolic pollutants and bioelectricity generation, by employing Rheum officinale extract as electron shuttle. Results revealed that there was a two-fold increase in chemical oxygen demand (COD) removal, degradation extent of phenol and cresol isomers, output voltage and power density of MFC, compared to the mediator-free MFC system. The degradation of phenol yielded higher COD removal, degradation efficiency, output voltage and power generation over cresol isomers, with and without the application of electron shuttle. A complete removal of COD and phenol, with output voltage of 620.06 mV and power density of 252.49 mW/m2 were obtained. Phenol outperformed cresol isomers with regard to its sole activating hydroxy (−OH) group, lower dipole moment and higher electronic conductivity (8.53 mS/cm). Conversely, meta-cresol exhibited the lowest removal efficiency and power generation, ascribed to greater inductive influence of methyl group in meta position on the dissociation energy of the − OH group. Moreover, detection of the phenolic intermediates by gas chromatograph-mass spectrometer analysis was conducted, and detailed degradation pathways were presented.

A highly efficient supported TiO2 photocatalyst for wastewater remediation in continuous flow

Although TiO2 materials have been extensively studied as photocatalysts, there is not any commercial TiO2-supported photocatalyst used for wastewater remediation. This fact set the goal to synthesize a new supported titanium dioxide photocatalyst which, besides being robust, also has a high reaction surface and a very efficient TiO2 shell thickness. Hence, we present a novel TiO2-supported photocatalyst composed of titania-covered glass wool (GW) fibers decorated with SiO2@TiO2 core-shell spheres. For optimizing the photocatalytic activity of this material, the surface of SiO2 microspheres, as well as, the highly mechanically resistant GW fibers, were covered by a robust titania layer of ca. 20–30 nm of thickness. This layer contains nanometric crystals, ca. 12 nm in size, linked to each other and to the surfaces of both SiO2 microspheres and GW. An exhaustive characterization of the physicochemical properties of this new SiO2-TiO2 composite was performed to confirm the SiOTi linkage and the anatase crystal phase. The photocatalytic activity was initially evaluated in batch through the photodegradation of Methylene Blue as a standard dye. Afterward, the addition of the new photocatalyst in a solid phase stationary (SPS) photoreactor coupled to a TOC detector allowed studying in situ the mineralization of the recalcitrant pollutant phenol under a continuous flow regime. Results revealed that the optimized TiO2 surface of the SiO2-TiO2 composite produced the complete mineralization of phenol in less than three minutes. Even more, it was demonstrated that this photocatalyst is suitable for the industrial scale-up of wastewater treatment because it does not leach titania, its reuse does not require filtration procedures, and it can be easily implemented in SPS photoreactors at plant scale. In this context, the new material could be a good starting point to prepare other supported photocatalysts for wastewater remediation.

Photocatalytic degradation of phenolic pollutants by Nanocomposites: A systematic review and pooled analysis

Photocatalytic degradation of phenolic pollutants by Nanocomposites: A systematic review and pooled analysis

The photocatalytic mineralization of phenolic wastewater via self-generation and -activation of H2O2 technology

Achieving efficient photocatalytic degradation and mineralization of phenolic pollutants under mild conditions is the key to solving the environmental crisis. Herein, a novel self-generation and -activation of H2O2 technology is achieved on graphitic carbon nitride (GCN)/anthraquinone-based covalent organic frameworks (TD-COF) heterojunction photocatalysts (CNTD-X). Some of the photogenerated electrons (e-) that migrate directionally to the surface of TD-COF could generate H2O2via oxygen reduction reaction (ORR) route, while the e- gathered around anthraquinone can reduce it to stable semi-quinone radicals, which can further release hydroxyl radical (·OH) through electron transfer with H2O2. The photogenerated holes (h+) gathered on the surface of GCN would provide important raw materials for ORR reaction through oxidation of water, and participate in the mineralization process of pollutants. With the ring opening of·OH and the oxidation of h+, this heterojunction system can achieve efficient phenolic pollutants removal. The optimal sample of CNTD-0.02 possesses an incredible phenol removal (99.4%) within 12 min under visible light irradiation (λ > 420 nm), and total organic carbon (TOC) analysis shows 81% phenol is converted into CO2 and H2O. The photo-degradation rate of CNTD-0.02 is about 204.2 and 26.8 times that of GCN and TD-COF, respectively. This novel photocatalytic strategy over CNTD-X could also be applied in other phenolic pollutants removal, and our work paves a new way for environmental remediation in clean and efficient technology.

Sulfur vacancies promoted highly efficient visible light photocatalytic degradation of antibiotic and phenolic pollutants over WS2/rGO heterostructure

Antibiotic and phenolic contaminations are severe and have become a significant source of worry in recent years. A multifunctional sulfur vacancy-induced WS2/rGO heterostructure was fabricated by a simple hydrothermal process for the photocatalytic degradation of antibiotic and phenolic compounds. The sulfur-based defects can reduce bandgap energies and enhance visible light absorption. The sulfur-enriched WS2/rGO heterostructure exhibited efficient photocatalytic activity towards Ciprofloxacin (CIP) and 4-Nitrophenol (4-NP) degradation under visible light illumination, and the deceptive rate constant is about 13 and 22 times higher than pristine WS2, and the removal efficiency was 16 and 13 times higher than pristine GO catalysts. The degradation efficiency and kinetic rate constants of 4-NP and CIP were 96.95 %, 92.30 %, and 0.113 min−1, 0.027 min−1, respectively. The excellent photocatalytic activity of WS2/rGO heterostructure was due to rGO acts as an electron mediator, and helps to accelerate charge separation and reduce the recombination rates. In addition, rGO improved the surface appearance of the heterostructure and provided more adsorption and reaction sites. The photocurrent measurement and time-resolved spectrum were used to investigate the photogenerated charge separation. Furthermore, the superoxide radical was the dominant reactive species of 4-NP and CIP degradation, as demonstrated by electron spin resonance and scavenger experiments. The possible degradation pathway and mechanism of 4-NP were proposed using liquid chromatography-mass spectroscopy.