Degradation Of Pentachlorophenol Research Articles

Pentachlorophenol degradation in the heterogeneous catalytic ozonation process using Al2O3 as a catalyst agent

Pentachlorophenol degradation in the heterogeneous catalytic ozonation process using Al2O3 as a catalyst agent

Electrochemical Sensing and Photoelectrodegradation of Pentachlorophenol using Co‐, Mn‐ and Zn‐Porphyrins

AbstractIn this work, we present Zn, CoII, and MnIII metalated meso‐tetra‐[4‐(methylthio) phenyl] porphyrin ([Zn(TMtPP)], [CoII(TMtPP], and [MnIII(TMtPP)Cl]) as electrocatalysts and photoelectrocatalysts for electrochemical detection and photoelectrocatalytic degradation of pentachlorophenol (PCP). The complexes were characterized using UV‐visible spectroscopy, mass spectroscopy, and elemental analysis. Proton nuclear magnetic resonance (1H NMR) studies were only conducted for the Zn derivative. The electrochemical detection of PCP was carried out using cyclic voltammetry and chronoamperometry. [CoII(TMtPP)] showed better detection limit. For photoelectrocatalytic (PEC) degradation studies of PCP, linear sweep voltammetry and UV‐visible spectra were employed. [Zn(TMtPP)] showed better removal efficiency. The main species responsible for the PEC degradation were found to be superoxide radicals (⋅O2) and electron holes (h+).

Degradation of Pentachlorophenol by CTAB-Modified Ni/Fe Bimetallic Nanoparticles in the Soil Solution

Degradation of Pentachlorophenol by CTAB-Modified Ni/Fe Bimetallic Nanoparticles in the Soil Solution

Pentachlorophenol degradation by activated sludge with phenol and glucose as growth substrates

Pentachlorophenol degradation by activated sludge with phenol and glucose as growth substrates

Nghiên cứu phân hủy pentaclophenol trong nước bằng hệ oxy hóa percarbonic acid

In this work, the degradation of a persistent organic pollutant, pentachlorophenol (PCP) by a green oxydation system based on peroxymonocarbonate (HCO4-) was studied. Different factors including pH, HCO3- concentration, metal ion catalyst, temperature, and UV irradiation were investigated for their effects on PCP degradation. The results showed that among five tested metal ions (Co2+, Ni2+, Fe2+, Cu2+, Mn2+), Co2+ gave the best catalytic activity. The optimum degradation of PCP was obtained at the concentration of HCO3- and H2O2 of 10 mM and 25 mM, respectively, catalyzed by the presence of 0.1 mg/L Co2+ ion at the intrinsic pH value of the system (8÷10). Moreover, UV irradiation remarkably enhanced the radical formation in the oxydation system, which led to higher degradation efficiencies. The results of COD and TOC removal and LC/MS/LS analysis clearly revealed the potential of complete mineralization of PCP by the oxydation system H2O2/HCO3-/Co2+/UV.

Insights into oxidation of pentachlorophenol (PCP) by low-dose ferrate(VI) catalyzed with α-Fe2O3 nanoparticles

In this study, the catalytic performance of α-Fe2O3 nanoparticles (nα-Fe2O3) in the low-dose ferrate (Fe(VI)) system was systematically studied through the degradation of pentachlorophenol (PCP). Based on the established quadratic functions between nα-Fe2O3 amount and observed pseudo first-order rate constant (kobs), two linear correlation equations were offered to predict the optimum catalyst dosage and the maximum kobs at an applied Fe(VI) amount. Moreover, characterization and cycling experiments showed that nα-Fe2O3 has good stability and recyclability. According to the results of reactive species identification and quenching experiment and galvanic oxidation process, the catalytic mechanism was proposed that Fe(III) on the surface of nα-Fe2O3 may react with Fe(VI) to enhance the generation of highly reactive Fe(IV)/Fe(V) species, which rapidly extracted a single electron from PCP molecule for its further reaction. Besides, two possible PCP degradation pathways, i.e., single oxygen transfer mediated hydroxylation and single electron transfer initiated polymerization were proposed. The formation of coupling products that are prone to precipition and separation was largely improved. This study proved that nα-Fe2O3 can effectively catalyze PCP removal at low-dose Fe(VI), which provides some support for the application of Fe(VI) oxidation technology in water treatment in the context of low-carbon emissions.

Pentachlorophenol degradation in the heterogeneous catalytic o zonation process using Al2O3as a catalyst agent

In this study, the catalytic ozonation of pentachlorophenol (PCP) in the presence of aluminum oxide (Al2O3) and the formation of byproducts during ozonationhas been studied. Results showed that catalytic ozonation in the presence of Al2O3 can substantially enhance PCP degradation efficiency compared with the using only ozonation process. The influences of severalenvironmental parameters including pH of the solution, initial PCP concentration, dosage of Al2O3 and dissolved ozone concentration were also investigated. The highest degradation efficiency of PCP was achieved at conditions: pH 8, 1.87 g/LAl2O3, and 0.49 g/L dissolved ozone concentration. The catalytic activity of Al2O3 was linked to highly hydroxylated surface. The surface hydroxyl groups on Al2O3 were the active places during catalytic ozonation. According to the drastic changes in the color of solution during ozonationin this study and results of some previous researches, formation of the intermediate reaction products during ozonationwas verified.Free chloride ion released, which was favored at slightly alkaline solution, was also followed in catalytic ozonation process.

Pentachlorophenol degradation in the heterogeneous catalytic o zonation process using Al2O3as a catalyst agent

In this study, the catalytic ozonation of pentachlorophenol (PCP) in the presence of aluminum oxide (Al2O3) and the formation of byproducts during ozonation has been studied. Results showed that catalytic ozonation in the presence of Al2O3 can substantially enhance PCP degradation efficiency compared with the using only ozonation process. The influences of several environmental parameters including pH of the solution, initial PCP concentration, dosage of Al2O3 and dissolved ozone concentration were also investigated. The highest degradation efficiency of PCP was achieved at conditions: pH 8, 1.87 g/LAl2O3, and 0.49 g/L dissolved ozone concentration. The catalytic activity of Al2O3 was linked to highly hydroxylase surface. The surface hydroxyl groups on Al2O3 were the active places during catalytic ozonation. According to the drastic changes in the color of solution during ozonation this study and results of some previous researches, formation of the intermediate reaction products during ozonation was verified. Free chloride ion released, which was favored at slightly alkaline solution, was also followed in catalytic ozonation process.

Compost-derived humic acid impacts on the biodechlorination of pentachlorophenol in high organic matter paddy soil

The long-term accumulation of pentachlorophenol (PCP) has adversely affected the paddy soil ecosystem. PCP reductive dechlorination under anaerobic conditions is an efficient pathway for PCP degradation. This process is affected by the content of organic matter and the iron mineral composition of the soil. Our previous study analyzed the effects of compost-derived Humic acids (HAs) on reductive dechlorination of PCP in a paddy soil system under Fe-reducing conditions. The effects and mechanisms of high organic matter and compost-derived HAs in promoting PCP dechlorination need further investigation. This study examined paddy soils with high organic matter content in Heilongjiang Province. PCP reductive dechlorination in this system was studied using HAs from three stages of municipal solid waste compost as soil supplements. The results showed that natural HA and microorganisms could promote the dechlorination and transformation of PCP in the paddy soil system. After removing humic acid, the detected concentrations of PCP in paddy soil and solid-liquid interface were 1.84 and 9.67 times of those in the original soil experiment, respectively. The concentration of low chlorine products decreased significantly in the sterilized group. Compost-derived HAs from different stage were also presented various effect on PCP reductive dichlorination. Furthermore, the synergistic effect between natural HA and compost-derived HAs would limit the electron donating capacity of compost-derived HAs in the paddy soil with high organic matter. Organic matter in soil has an important influence on pollutant fate. Late-stage HA were more effective in promoting PCP degradation than early-and middle-stage HAs. The research provided a comprehensive and meticulous analyses of the effects of compost-derived HAs on PCP bio-dechlorination in paddy soil with high organic matter.

Spent-coffee grounds-derived biochar-supported heterogeneous photocatalyst: a performance evaluation and mechanistic approach for the degradation of pentachlorophenol

A detailed description of the CGBT nanocomposite synthesis and photocatalytic mechanism for pentachlorophenol.

Advanced oxidative degradation of pentachlorophenol from aqueous media by Taguchi analysis: comparison of dithionite/persulfate and UV/persulfate processes

Advanced oxidative degradation of pentachlorophenol from aqueous media by Taguchi analysis: comparison of dithionite/persulfate and UV/persulfate processes

Complete pentachlorophenol biodegradation in a dual-working electrode bioelectrochemical system: Performance and functional microorganism identification

Bioelectrochemical system (BES) can effectively promote the reductive dechlorination of chlorophenols (CPs). However, the complete degradation of CPs with sequential dechlorination and mineralization processes has rarely achieved from the BES. Here, a dual-working electrode BES was constructed and applied for the complete degradation of pentachlorophenol (PCP). Combined with DNA-stable isotope probing (DNA-SIP), the biofilms attached on the anodic and cathodic electrode in the BES were analyzed to explore the dechlorinating and mineralizing microorganisms. Results showed that PCP removal efficiency in the dual-working BES (84% for 21 days) was 4.1 and 4.7 times higher than those of conventional BESs with a single anodic or cathodic working electrode, respectively. Based on DNA-SIP and high-throughput sequencing analysis, the cathodic working electrode harbored the potential dechlorinators (Comamonas, Pseudomonas, Methylobacillus, and Dechlorosoma), and the anodic working enriched the potential intermediate mineralizing bacteria (Comamonas, Stenotrophomonas, and Geobacter), indicating that PCP could be completely degraded under the synergetic effect of these functional microorganisms. Besides, the potential autotrophic functional bacteria that might be involved in the PCP dechlorination were also identified by SIP labeled with 13C-NaHCO3. Our results proved that the dual-working BES could accelerate the complete degradation of PCP and enrich separately the functional microbial consortium for the PCP dechlorination and mineralization, which has broad potential for bioelectrochemical techniques in the treatment of wastewater contaminated with CPs or other halogenated organic compounds.

Enhanced Exciton Effect and Singlet Oxygen Generation Triggered by Tunable Oxygen Vacancies on Bi2MoO6 for Efficient Photocatalytic Degradation of Sodium Pentachlorophenol.

Construction of the tunable oxygen vacancies (OVs) is widely utilized to accelerate molecular oxygen activation for boosting photocatalytic performance. Herein, the in-situ introduction of OVs on Bi2MoO6 was accomplished using a calcination treatment in an H2/Ar atmosphere. The introduced OVs can not only facilitate carrier separation, but also strengthen the exciton effect, which accelerates singlet oxygen generation through the energy transfer process. Superior carrier separation and abundant singlet oxygen played a crucial role in favoring photocatalytic NaPCP degradation. The optimal BMO-001-300 sample exhibited the fastest NaPCP degradation rate of 0.033 min-1, about 3.8 times higher than that of the pristine Bi2MoO6. NaPCP was effectively degraded and mineralized mainly through dechlorination, dehydroxylation and benzene ring opening. The present work will shed light on the construction and roles of OVs in semiconductor-based photocatalysis and provide a novel insight into ROS-mediated photocatalytic degradation.

Insight into the degradation mechanism of peroxyacetic acid for pentachlorophenol by thermal activation in soil system

In this study, inorganic and organic radicals generated from a thermally activated peroxyacetic acid (PAA) system were used to degrade pentachlorophenol (PCP) in contaminated soils. In addition, the effects of various operating parameters on PCP removal were fully considered, including reaction temperature, PAA dosage, initial pH and natural organic matter (NOM). The experimental results showed that PCP was more easily degraded under the conditions that temperature was higher than 40 °C and near neutral pH, and PAA dosage was more than 750 mM/kg. In contrast, humic acid (HA) exhibited a significant inhibitory impact on PCP degradation. The results from the chemical quenching and electron para-magnetic resonance (EPR) experiments further indicated that in the PAA system, HO• has much better degradation ability for PCP than 1 O 2 . Moreover, the degradation of PCP was dominated by R-O• radicals, including CH 3 C(O)O• and CH 3 C(O)OO•. Besides, the potential degradation pathways of PCP by PAA system were investigated, based on the degradation intermediates and the density functional theory (DFT) calculation. The present study results indicated that the combined process of PAA and heat treatment has a significantly high efficiency in the degradation of chlorobenzenes in soils. This study is the first to use thermally activated PAA for soil remediation without the use of other chemicals as activators, and provides a novel, efficient and economical technique for the remediation of actual chlorinated hydrocarbon contaminated sites. • PCP can be efficiently degraded through thermal activation PAA in soil systems. • Higher temperature, near neutral pH, and higher PAA dose were more beneficial for degrading PCP. • HA shows an inhibitive effect on PCP decomposition. • R-O• dominated PCP degradation.

Optimizing rapid pentachlorophenol biodegradation using response surface methodology

Pentachlorophenol (PCP) is one of the most toxic pollutants in the environment during modern industrial processes. Statistical experimental designs based on biological methods optimized the PCP biodegradation by Bacillus mucilaginosus and Pseudomonas plecoglossicida. Four factors were selected for PCP removal; glucose, ferric ammonium citrate, PCP concentration, and incubation period. PBD and CCD were performed to recognize the maximum PCP biodegradation. The maximum PCP biodegradation in PBD by B. mucilaginosus was obtained at glucose, 0.5 (g/l); ferric ammonium citrate, 0.5 (g/l); PCP concentration, 300 (mg/l) and incubation period, 3 (days) while the maximum conditions by P. plecoglossicida were glucose, 0.5 (g/l); ferric ammonium citrate, 0.5 (g/l); PCP concentration, 100 (mg/l) and incubation period, 3 (days). In addition, CCD predicted the optimum predicted degradation of PCP (100%) by the two selected strains using glucose (1.0 g/l), ferric ammonium citrate (0.059 mg/l), PCP concentration (350 mg/l), and 2-days for B. mucilaginosus. While glucose (0.276 g), ferric ammonium citrate (0.047 mg/l) and 2-days were optimal conditions for P. plecoglossicida. P. plecoglossicida.and B. mucilaginosus could degrade more than 72% and 61% of PCP when these isolates were grown under a high concentration of PCP (300 and 350 mg L−1) in a mineral salt medium, respectively.

Zn/N co-doped TiO2 Nanotubes for Enhancement of Photocatalytic Degradation of Pentachlorophenol

Zn/N co-doped TiO2 Nanotubes for Enhancement of Photocatalytic Degradation of Pentachlorophenol

Fenton-Mediated Chlorophenol Degradation by Iron-Reducing Compounds Isolated from Endophytic Fungi in Atacama Puna Plateau Lecanicillium ATA01

Low-molecular-mass iron-reducing compounds (IRCs) were produced by entomopathogenic endophytic fungi Lecanicillium sp. ATA01 in liquid cultures. The extracellular hydrophilic extract contained three IRCs formed by peptides, iron and phenolate structures with molecular masses of 1207, 567 and 550 Da. These compounds were able to chelate and mediate the reduction of Fe+3 to Fe+2 and oxidized recalcitrant lignin-model substrates such as veratryl alcohol (VA), 2,6-dimethoxyphenol (DMP), and 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid (ABTS) with or without hydrogen peroxide. Besides, IRCs can promote the degradation of chlorophenols. The maximal degradation of p-chlorophenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol, and pentachlorophenol was conducted at optimal degradation conditions for IRCs (pH 3.5, iron 100 mM, and H2O2 10 mM). Furthermore, Fenton-like reactions using the synthetic iron chelates DTPA and EDTA and free Fe+2 and Fe+3 were also carried out in order to compare with the reaction mediated by IRCs. The ferric IRCs displayed the ability to enhance the hydroxylation of chlorophenols as a part of a degradation mechanism of the IRC-assisted Fenton reaction. The complexed iron was more efficient than free iron in the Fenton-like reaction, and between them, the fungal chelates were more efficient than the synthetic mill chelates.

Degradation of pentachlorophenol in peroxymonosulfate/heat system: Kinetics, mechanism, and theoretical calculations

In this work, we systematically investigated the transformation of pentachlorophenol (PCP) in the heat-activated peroxymonosulfate (PMS) system. The degradation efficiency of PCP increased with initial PMS concentration, temperature and pH. The calculated % reaction stoichiometric efficiency (RSE) reached up to 92.2%. SO42− was found to promote the degradation of PCP, because it significantly enhanced the generation of HO• and SO4•− as confirmed by EPR experiments. According to the radical quenching tests, SO4•− was the dominant reactive radical for PCP degradation. A total of 10 intermediates were identified, and hydroxylation, sulfate addition, dechlorination and oligomerization were speculated as main reaction pathways. Then, possible reactions between reactive radicals and substrate were calculated at the m062x/land2dz level to interpret the mechanisms of different reactions. It was found that ionic PCP had lower activation energy than molecular PCP, and hence showed higher reactivity towards SO4•− and HO• in the course of radical addition reaction. As for the coupling reaction, SO4•− more likely to react with ionic PCP to generate phenoxy radicals than HO•, due to the negative Gibbs free energy change. Meanwhile, the abstraction of an Cl atom by HO• was confirmed to be the first step for the formation of dechlorination products. In addition, toxicity evaluation by ECOSAR and TEST programs illustrated that the toxicity of reaction products was all lower than that of PCP. Findings of this work demonstrated the feasibility of this PMS/heat method for effective removal of PCP in contaminated waters.

Effects of compost-derived humic acid on the bio-dechlorination of pentachlorophenol in high iron content paddy soil

Pentachlorophenol (PCP) is a common residual organic pollutant in paddy soil, and its harmful effects on soil ecosystems have been confirmed. Humic acid (HA) could act as an electron shuttle to promote the reductive dechlorination of PCP under anaerobic conditions. Humic-like substances produced by composting of kitchen waste were able to facilitate the reductive dechlorination of PCP during Fe(III) oxide reduction by iron-reducing bacteria. However, the effects of compost-derived HAs on reductive dechlorination of PCP in a paddy soil system with a high iron content have not been fully confirmed. The characteristics of HAs from different stages of composting during bio-dechlorination of PCP were still unclear. The functional components of compost-derived HAs, which are responsible for reductive dechlorination of PCP in different stages of composting, also need further investigation. In this study, we conducted a series of experiments on the Guangdong paddy soil system with high iron content (17.5 mg kg−1) to investigate the reductive dechlorination of PCP by HA in the early, middle, and later stages of food waste composting. The results showed that the middle- and late-stages of compost-derived HAs all promoted reductive dechlorination of PCP in the paddy system, but it was opposite in the early-stage. Significant differences were also presented in the components of HAs from different stages of composting. The early-stage compost-derived HAs contain numerous easy degradable components, it would inhibit the dechlorination of PCP by the changes of microbial metabolism in paddy soil. Compost-derived HAs in the middle composting stage showed the best reductive dechlorination effects on PCP. The reason might be that the compost-derived HAs in the middle composting stage could act both as electron donors and transfers. The electron transfer capacities (ETC) of middle-stage compost-derived HAs were significantly higher than those in the early and later composting stages. Compared with the natural HAs in the soil system, compost-derived HAs contained more chlorinated products with lower toxicities after the PCP degradation. This result mainly contributed to the detoxification and mineralization of PCP in the soil. These findings clarified the effects of compost-derived HAs on PCP bio-dechlorination in paddy soil with high iron content, identifying the optimal phase of compost-derived HA and providing a theoretical basis for the utilization of kitchen waste composting as a resource of HA.

Mineralization, kinetics, and degradation pathway of pentachlorophenol degradation from aqueous media via persulfate/dithionite process

The applicability of the dithionite/persulfate (DTN/PS) process for the degradation of pentachlorophenol (PCP) as an organic contaminant from aqueous solutions was investigated. Effective operational parameters, including the initial PCP concentration (25, 50, 100, and 150 mg/L), PS concentration (5, 10, 15, and 20 mg/L), DTN concentration (2.5, 5, 7, and 10 mg/L), solution pH (5, 7, 9, and 11), and reaction time (3, 5, 7, and 10 min) were investigated. To identify the influences of experimental factors involved in PCP degradation, an experimental design based on an orthogonal array was proposed using the Taguchi method. Based on the results, 97.28% of the PCP was removed at the optimal conditions (initial concentration of 25 mg/L, Na-PS (sodium persulfate) concentration of 20 mg/L, Na-DTN (sodium dithionite) concentration of 10 mg/L, pH of 11, and reaction time of 10 min) in the DTN/PS process. Moreover, COD and TOC removal rates were 75.2% and 41% in the DTN/PS process, respectively. An analysis of variance (ANOVA) indicated that PS is the most effective agent in removing PCP in the DTN/PS process. The compounds of phenol, 3,4-dichlorophenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol, oxalic acid, propionic acid, tetrachloro-o-benzoquinone, and butanedioic acid were identified as intermediates.