Phenol Degradation Research Articles

Green Synthesis of ZnO and Black TiO2 Materials and Their Application in Photodegradation of Organic Pollutants.

ZnO and black TiO2 have been selected as the most efficient materials for organic pollution abatement due to their increased efficiency when compared to other materials. However, the concept of green chemistry makes it desirable to design green synthesis approaches for their production. In this study, black TiO2 was synthesized using an environmentally safe synthetic technique with glycerol as a reductant. ZnO was prepared by using ionic-liquid-based microwave-assisted extracts of Polygonum minus. To investigate the materials' potential to photodegrade organic pollutants, methylene blue (MB) and phenol were chosen as model organic pollutants. Both materials were found to exhibit spherical morphologies and a mesoporous structure and were efficient absorbers of visible light. ZnO exhibited electron-hole pair recombination lower than that of black TiO2. Black TiO2 was discovered to be an anatase phase, whereas ZnO was found to have a hexagonal wurtzite structure. In contrast to black TiO2, which had a surface area of 239.99 m2/g and a particle size of 28 nm, ZnO had a surface area of 353.11 m2/g and a particle size of 32 nm. With a degradation time of 60 min, ZnO was able to eliminate 97.50% of the 40 mg/L MB. Black TiO2, on the other hand, could reduce 90.0% of the same amount of MB in 60 min. When tested for phenol degradation, ZnO and black TiO2 activities were reduced by nearly 15 and 25%, respectively. A detailed examination of both ZnO and black TiO2 materials revealed that ZnO has more potential and versatility for the degradation of organic pollutants under visible light irradiation.

Insights into the activation of peroxymonosulfate by ZIF-L@ZIF-67 derived CoCN catalyst for highly effective removal of phenol in the presence of chloride ions

A novel catalyst with cobalt and nitrogen-codoped porous carbon matrix (CoCN-900) was successfully prepared, characterized and applied for activating peroxymonosulfate (PMS) to remove phenol in aqueous solution. The CoCN-900 material exhibited superior performance in activating PMS for phenol degradation and could completely remove phenol within 60 min. Radical quenching tests and electron paramagnetic resonance (EPR) analysis showed that 1O2 and SO4•– played a major role in the phenol removal process over the CoCN-900/PMS system. In addition, the influences of catalyst/PMS dose, initial phenol concentration, reaction temperature, natural organic matter and coexisting anions on phenol degradation were systematically investigated. Particularly, it was found that the chloride ions (Cl–) had a significant accelerative effect, increasing the phenol degradation rate from 0.142 to 0.600 min−1. In the presence of Cl–, the phenol degradation efficiency was primarily ascribed to the effects of 1O2 and O2•–, which were significantly different from those in the absence of Cl–. Meanwhile, Cl– could also accelerate the deactivation of the catalyst. Findings in this study provided new insight for the fabrication of high-performance zeolitic imidazolate frameworks (ZIFs)-derived carbon materials and evaluating the influences of anions on the degradation of phenolic contaminants in PMS-based advanced oxidation processes (AOPs).

NaOH and temperature-induced formation of Bi-based BixOyBrz photocatalyst for phenol degradation

In this work, Bi-based BixOyBrz photocatalyst including BiOBr, Bi2O3/Bi4O5Br2, BiOBr/Bi4O5Br2 and Bi4O5Br2 were successfully prepared by adding NaOH and controlling reaction temperature. BiOBr/Bi4O5Br2 composite displayed excellent photocatalytic activity for phenol degradation compared with other Bi-based BixOyBrz photocatalyst. Toxicity experiments suggested that low environmental toxicity of BiOBr/Bi4O5Br2 composite for the growth state of Sudangrass seeds and Mung bean seeds. A BiOBr/Bi4O5Br2 S-scheme heterojunction was proposed to explain the photocatalytic degradation mechanism.

Ion exchange synthesis of copper-based hydroxyapatite for the catalytic degradation of phenol

Abstract Hydroxyapatite (HAP) is a material renowned for its exceptional capabilities in adsorbing and exchanging heavy metal ions, making it a widely employed substance within the environmental domain. This study aims to present a novel material, namely copper–HAP (Cu–HAP), which was synthesized via an ion exchange method. The resulting material underwent comprehensive characterization using scanning electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, and Brunauer–Emmett–Teller (BET) analysis. Subsequently, based on the principle of the Fenton-like oxidation reaction, the material was used for the degradation of phenol. The outcomes of the investigation revealed that the optimal preparation conditions for the catalyst were achieved at a temperature of 40 °C, a pH value of 5, and a relative dosage of Cu–HAP at 100 mg/g. Under the reaction conditions of a catalyst dosage of 2 g/L, a 30% hydrogen peroxide concentration of 30 mM, a phenol concentration of 20 mg/L, a pH value of 6, a temperature of 40 °C, and the degradation rate of phenol impressively reached 98.12%. Furthermore, the degradation rate remained at 42.31% even after five consecutive cycles, indicating the promising potential of Cu–HAP in the treatment of recalcitrant organic compounds within this field.

Ascorbic acid enhanced CuFe2O4-catalyzed heterogeneous photo-Fenton-like degradation of phenol

CuFe2O4 particles were synthesized using the sol-gel self-combustion method and characterized for their compositional surface morphology and crystal structure. When compared to the photo-Fenton system without ascorbic acid (AA), the presence of AA significantly enhanced the catalytic degradation of phenol using CuFe2O4. The highest catalytic degradation efficiency was achieved at an AA concentration of 1 mmol/L, resulting in up to 98.6 % elimination of phenol in just 40 min. The reaction rate was found to be 31.7 times higher than that of the system without AA. The mechanism of AA enhancement in the CuFe2O4 photo-Fenton system was further investigated. Two key factors were found to contribute to the enhancing mechanism of AA introduction in the CuFe2O4 photo-Fenton system. Firstly, AA promoted the Cu/Fe redox cycle on the catalyst surface, leading to a more efficient generation of reactive species that are responsible for phenol degradation. Secondly, AA accelerated the leaching of metal ions from the catalyst surface, facilitating the homogenous Fenton effect. The Cu/Fe bimetallic cycle system offers new perspectives on effective Fenton catalyst design and provides crucial insights for reductant-enhanced photo-Fenton activation.

Purification and characterization of catechol 1,2-dioxygenase (EC 1.13.11.1; catechol-oxygen 1,2-oxidoreductase; C12O) using the local isolate of phenol-degrading Pseudomonas putida.

The purpose of the present study was to purify and characterize the catechol 1,2-dioxygenase (EC 1.13.11.1; catechol-oxygen 1,2-oxidoreductase; C12O) enzyme from the local isolate of Pseudomonas putida. This enzyme catalyzes the initial reaction in the ortho-pathway for phenol degradation in various gram-negative bacteria, including the genus of Pseudomonas. Pseudomonads are commonly used in the biodegradation of xenobiotics due to their versatility in degrading a wide range of chemical compounds. Eighty-nine soil samples were taken from the contaminated soil of the Midland Refineries Company (MRC) of Al-Daura refinery area at Baghdad from April to August 2021. The samples were grown in a mineral salt medium containing 250mg per L of phenol to test their ability to biodegrade phenol. The pH was adjusted to 8.0 at 30°C using a shaking incubator for 24-48h. A number of 62 (69.6%) isolates of the total number were able to degrade phenol efficiently. The findings of the VITEK system and the housekeeping gene 16S rDNA confirmed that out of the positive isolates for phenol degradation, 36 from 62 (58.06%) were identified as Pseudomonas spp. isolates. Those isolates were distributed as P. aeruginosa 30 (83.3%) and P. putida 6 (16.6%). The enzyme production capabilities of the isolates were evaluated, and the highest activity was 2.39 U per mg for the isolate No. 15 which it was identified as P. putida. The previous isolate was selected for enzyme production, purification, and characterization. The enzyme was purified using ion exchange and gel filtration chromatography, with a combined yield of 36.12% and purification fold of 15.42 folds. Using a gel filtration column, the enzyme's molar mass was calculated to be 69kDa after purification. The purified enzyme was stable at 35°C and a pH of 6.0.

Sustainable and effective catalytic particles for electrocatalytic combustion of refractory organic matter

The development of ultra-efficient, sustainable, and easily accessible catalytic particle (CP) is a useful strategy for hydroxyl radical generation in the three-dimensional electrolytic system (3D ECs). Herein, a crystalline fused CP composed of coal gangue, activated sludge, and iron sludge, were synthesized for refractory organic matter electrocatalytic combustion in a boron-doped diamond (BDD) 3D ECs. A rough and SnO2 semiconductor metal oxide pellet-anchored continuous interface was created through a one-pot calcination method. In determination of the CP agglomeration mechanism, XRD and XPS results displayed that discrete component of SiO2, Al2O3, and Na2O were transformed into a homogeneous quartz albite NaAlSi3O8 phase, and SnO2-Sb2O5 components formed and spread in the whole ball structure during high-temperature molding process. The newly designed CP exhibited incomparable phenol degradation capacity. The dichromate oxidizability (CODCr) removal efficiency of phenolic wastewater increased 14.3 % compared to the commercial active carbon packed system. The electrocatalytic oxidation capacity of CP was evaluated comprehensively under various working condition, e. g. different cathodes, present or absent of Cl- and persulfate agents, and with or without microbubble coupling. Our experimental results showed that considerable CODCr removal efficiency of 86.3 % was obtained with microbubble coupling oxidation using cell voltage 6.0 V and treating time 120 mins. Besides these, the designed CP presented outstanding stability, and CODCr removal efficiency slightly decreased 7.1 % after 10 cycle repetitions. The use of solid waste as the main material for CPs production not only realizes harmless treatment of solid wastes but also improve the 3D ECs significantly.

Isolation and Characterization of Phenol degrading Bacteria from Wastewater

Out of 30 bacterial isolates from wastewater were checked for growth on a minimal salt medium amended with different concentrations of phenol by flask culture technique. The eight most tolerant bacterial strains to the higher concentrations of phenol, designated as W2, W5, W9, W12, W14, W15, W19 and W29, were investigated for their ability to grow and degrade phenol. Among the eight higher phenol degrading isolates, W15 can tolerate up to 1000 ppm of phenol concentrations and grow and degrade 94% of phenol within 72 hrs. The optimum temperature and pH condition were 37C◦ and 7, respectively. The yeast extract is the best organic nitrogen source, while ammonium chloride is the best inorganic nitrogen source for the growth and degradation of phenol.

Effect of Aloe vera gel coating on organoleptic and nutritional quality of minimally processed carrot.

Demand for fresh vegetables has led to development studies in postharvest area mainly focused on minimizing and look for alternatives to chemical additives for food preservation. The use of natural derived edible coatings emerges as a promising alternative for maintaining quality of vegetables. The objective of this study was to evaluate the effect of Aloe vera gel in minimally processed carrot during postharvest storage. Samples with different degrees of processing were immersed in Aloe vera gel, packaged polyolefin bags, and stored in refrigerated chambers at 5 °C for 12 days. Different organoleptic and quality parameters were evaluated. In general, the samples treated with Aloe vera gel showed less quality loss and a lower increment in the bleaching index. Moreover, sensory analysis allowed to establish that carrots processed in slices and shredded and coated with the gel had a more flavorful taste and higher moisture content. Aloe vera treatment did not influence the microbiological growth of bacteria and fungi during storage. Regarding nutritional quality, the treated samples showed a higher accumulation or lower degradation of phenols, flavonoids, and carotenoids, probably generating in this way, a higher antioxidant capacity in these samples. Finally, Aloe vera gel treatment did not influence sugar dynamics in any of the samples. It can be concluded that the treatment with Aloe vera gel allows maintaining a better organoleptic and nutritional quality of carrots with different degrees of processing during refrigerated storage.

Preparation and catalytic degradation of phenol achieved by utilizing pH and Upper Critical Solution Temperature dual responsive intelligent enzyme catalysts

Phenolic compounds are toxic substances that exert harmful effects on all living organisms. Irrigation farmland with phenolic wastewater can result in reduced crop yields or even crop failure, while consuming phenolic wastewater has a strong carcinogenic effect. Horseradish peroxidase (HRP), a heme-containing peroxidase, is capable of catalyzing the oxidative conversion and coupling reaction of phenols in sewage to form polymerization products in the presence of hydrogen peroxide (H2O2). However, free HRP can only function within a relatively narrow range of temperature and pH conditions, and its excellent water solubility makes it difficult to recover, thereby significantly increasing the cost of enzyme utilization. The immobilized enzyme was prepared by incorporating HRP and self-synthesized UCST (Upper Critical Solution Temperature) and pH dual responsive polymer P(NAGA-b-AA-b-VBA). The loading capacity of HRP reached 295 mg/g while maintaining the UCST performance. Compared to the free enzyme, the immobilized enzyme exhibited enhanced pH stability, thermal stability and storage stability. In laboratory experiments as well as actual water samples, the immobilized enzyme achieved phenol degradation rates of 90.4% and 88.4% respectively, within 1 h. After five cycles, the immobilized enzyme retained 80.1% catalytic activity with a recovery rate of 84.5%. Furthermore, it was demonstrated that the biological toxicity of the reaction product was significantly lower than that of simulated pollutant phenol.

Hybrid TiO2/Carbon quantum dots heterojunction photoanodes for solar photoelectrocatalytic wastewater treatment

The modification of titanium dioxide (TiO2) is a strategy to maximize the utilization of sunlight. Carbon quantum dots (CQDs) are carbon nanomaterials with outstanding optical and electronic properties that are suitable for that purpose. In this work, three types of hybrid TiO2/CQD photoelectrodes were synthesized following different methods: 1) deposition of a CQD layer on top of TiO2 (labelled as TiO2-CQD); 2) deposition of a TiO2 layer on top of CQDs (labelled as CQD-TiO2) and; 3) deposition of a mixed CQD + TiO2 layer (labelled as CQD + TiO2). The photoelectrodes were investigated for the photoelectrocatalytic degradation of phenol as model pollutant under simulated solar light and TiO2-CQD showed the highest apparent reaction rate constant of kapp = 0.0117 min−1 with 40% of TOC removal in 6 h of treatment. CQDs were found to enhance photon absorption in the visible region of the electromagnetic spectrum and in turn phenol degradation by promoting the separation of photogenerated charge carriers through electron transfer via the Ti–O–C bonds formed at the TiO2-CQD interface. Finally, the performance of the TiO2-CQD photoanode was evaluated for the treatment of real wastewater from the membrane fabrication sector, confirming its photoelectrocatalytic efficiency under solar radiation with 93% of TOC removal in 8 h of treatment and kapp = 0.0058 min−1.

A three-dimensional in-situ self-electrolysis system based on Ni3(HITP)2/graphene-based composite aerogel particle electrodes for efficient deep removal of phenol from coking wastewater

Herein, a Ni3(HITP)2/graphene-based composite aerogel (Ni3(HITP)2/GA) particle electrode is developed for the oxidation removal of phenol with three-dimensional electrode technology. The as-constructed three-dimensional electrode system possesses high in-situ self-electrolysis capacity and achieves highly efficient degradation of phenol, completely removed within 15 min with a decomposition rate constant of 0.3283 min−1. Ni3(HITP)2 in Ni3(HITP)2/GA and the tetradentate Ni–N2O2 coordination bond generated at the composite interface produce H2O2 highly selectively via the 2e- ORR pathway. The graphene layer converts H2O2 into •OH by using the 1e- of Ni3(HITP)2 excitation and the microelectrode action of the particle electrode. Furthermore, the simultaneous generation of •OH and O2•- in the system greatly reduces the dependence on acidic environment and broadens the scope of utilization. The present work provides a new strategy for the efficient construction of particle electrodes in 3D electrode systems, which allows their potential application in the purification of coking wastewater.

Polyphenols Cause Structure Dependent Effects on the Metabolic Profile of Human Hepatocarcinogenic Cells.

Although many beneficial health effects are attributed to polyphenols their influence on the human metabolome has not been elucidated yet. The ubiquitous occurrence of polyphenols in the human diet demands comprehensive knowledge about physiological and toxicological effects of these compounds on human cells. The human hepatocarcinogenic cell line HepG2 is used to elucidate the effects of 13 polyphenols and three respective phenolic degradation products on the human metabolome using HPLC-MS/MS. To investigate structure-activity-relationships, structurally related examples of polyphenols from different compound classes are selected. The analysis of catechins points toward a relation between the degree of hydroxylation and the extent of metabolic effects particularly on the urea cycle and the pentose phosphate pathway (PPP). A correlation between the modulation of the PPP and the stability of the compounds is demonstrated, which may be caused by reactive oxygen species (ROS). The incubation of flavones and alkenylbenzenes demonstrates reduced activity of methoxylated compounds and no impact of the B-ring position. In general, polyphenols induce a multitude of metabolic effects, for example, on energy metabolism, PPP, and urea cycle. These metabolic alterations may be related to the widely reported bioactivity of these compounds such as the anticarcinogenic effects.

Facile Synthesis of TiO2 with a Narrow Bandgap and Low Valence Band for Efficient Visible-Light Photocatalytic Degradation of Various Phenols

Facile Synthesis of TiO₂ with a Narrow Bandgap and Low Valence Band for Efficient Visible-Light Photocatalytic Degradation of Various Phenols

Preparation of SnO2-Sb/attapulgite (AP) clay particulate electrode for efficient phenol electrochemical oxidation.

A novel SnO2-Sb/AP (attapulgite) particle electrode was prepared for three-dimensional electrocatalytic oxidation (3D/EO) of organic pollutants using a co-sintering method. The electrochemical properties and micromorphology were determined using polarization, cyclic voltammetry (CV), and field emission scanning electron microscope (FE-SEM), and compared with activated carbon (AC), AP, and TiO2/AP particle electrodes. Besides, their potential application in the electrochemical degradation of phenol was investigated. The SnO2-Sb/AP particle electrode exhibited higher electrochemical activity than other particle electrodes due to its large number of active sites, low transfer coefficient (α, 0.12), and high-volt ampere charge (q*, 1.18 C·cm-2). The electrochemical CODCr degradation efficiency (100%) of phenol on SnO2-Sb/AP particle electrodes is much higher than for other particle electrodes. Moreover, an excellent stability of the SnO2-Sb/AP particle electrode is also verified by repeated experiments. These results indicate that the SnO2-Sb/AP particle electrodes broaden the application area of clays and are expected to be a promising method for 3D/EO.

Peruvian carrot chips obtained by microwave and microwave-vacuum drying

Peruvian carrot is a root from South America. Despite its nice taste and health-promoting effects, commercialization of Peruvian carrot is restricted due to its short shelf life and post-harvest losses. This study aimed to obtain Peruvian carrot chips at different drying processes. The comparison with convective drying at 70 °C (CD-70) showed that the microwave (MW) and microwave vacuum (MWV) technologies improved the quality of the chips (at 100, 250, and 400 W). It was found that a shortening in the drying time caused by the microwave power level partially controlled the textural collapse and crispness, besides reducing hardness and shrinkage characteristics and preserving β-carotene content. However, it also promoted phenolic compound degradation and color changes. The vacuum application in microwave drying (MWV) maintained the physical improvement observed in MW besides aiding in preserving phenolic compounds, β-carotene, and color changes. The results suggested that MWV-100 drying of Peruvian carrots was able to produce chips with suitable physical and nutritional quality.

Photodegrading hazardous pollutants using black TiO2 materials with different morphology and estimation of energy requirement

Black TiO2 materials were synthesized with different morphologies, including nanoparticles (NPs) and nanonails (NNs), and their performance for the photodegradation of hazardous phenols from model palm oil mill wastewater (TPOME) was compared. For the first time, the black TiO2 NNs were prepared by hydrothermal processing, followed by HCl treatment of the TiO2 NPs that had already been produced using an improved glycerol-assisted precipitation method. Four phenolic compounds (phenol, caffeic acid, ferulic acid, and gallic acid) were combined to represent the model wastewater based on their relative concentrations in actual TPOME. The TiO2 NNs outperformed the TiO2 NPs in the photocatalytic degradation of phenols due to their improved properties, including higher visible light absorption and surface area and lower bandgap and rate of electrons and holes recombination. The removal rate and energy requirements of the TiO2 NNs were also impactful. The TiO2 NNs degraded more than 99% of individual phenols in 210 min and 84.22% of the total phenols in 270 min with the least amount of electrical energy used (96.36 kW/m3), the lowest cost of treatment of a unit volume of model TPOME, and the highest removal rate constant.

Modification of Electro-Fenton Process with Granular Activated Carbon for Phenol Degradation – Optimization by Response Surface Methodology

Modification of Electro-Fenton Process with Granular Activated Carbon for Phenol Degradation – Optimization by Response Surface Methodology

Synergistic Impact of Biochar Nanorods on the Performance of Polyacrylamide Matrix: UV-assisted Degradation of Phenol and Biological Activity

Synergistic Impact of Biochar Nanorods on the Performance of Polyacrylamide Matrix: UV-assisted Degradation of Phenol and Biological Activity

Dual metabolic pathways co-determine the efficient aerobic biodegradation of phenol in Cupriavidus nantongensis X1

Phenol, as an important chemical raw material, often exists in wastewater from chemical plants and pollutes soil and groundwater. Aerobic biodegradation is a promising method for remediation of phenolic wastewater. In this study, degradation characteristics and mechanisms of phenol in Cupriavidus nantongensis X1 were explored. Strain X1 could completely degrade 1.5 mM phenol within 32 h and use it as the sole carbon source for growth. The optimal degradation temperature and pH for phenol by strain X1 were 30 °C and 7.0. The detection of 3-oxoadipate and 4-hydroxy-2-oxopentanoate indicated that dual metabolic pathways coexist in strain X1 for phenol degradation, ortho- and meta-pathway. Genome and transcriptome sequencing revealed the whole gene clusters for phenol biomineralization, in which C12O and C23O were key enzymes in two metabolic pathways. The ribosome proteins were also involved in the regulation of phenol degradation. Meanwhile, the degradation activities of enzyme C23O was 188-fold higher than that of C12O in vitro, which indicated that the meta-pathway was more efficient than ortho-pathway for catechol degradation in strain X1. This study provides an efficient strain resource for phenol degradation, and the discovery of dual metabolic pathways provides new insight into the aerobic biological metabolism and bioremediation of phenol.