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PubMedDate not supplied

Rapid determination of nineteen chlorophenols in wood, paper, cardboard, fruits, and fruit juices by gas chromatography/mass spectrometry.

Although the use of pentachlorophenol (PCP) is prohibited in most countries, it is still widely found in the wood of pallets, containers, crates and in cardboard, paper, etc. Such material may contain not only PCP but other chlorophenols as well. Wooden crates and cardboard boxes are often used to store and transport fresh fruits. Consequently, chlorophenols present in the wood may contaminate the stored fruits by migration. To ascertain that packaging, storage material, and fruit raw materials are free from chlorophenol residues, we developed a rapid and sensitive method for the detection of 19 chlorophenols by gas chromatography/mass spectrometry (GC/MS). The test portions are directly extracted and acetylated in a solution of sodium carbonate in the presence of acetic anhydride and hexane. The hexane layer is analyzed, without further purification, by GC/MS in the selective-ion monitoring mode. The method allows the analysis of >40 samples/day with detection limits of <20 microg/kg for chlorophenols in wood, cardboard, and paper, and <2 microg/kg for chlorophenols in fruits. Typical recoveries of all chlorophenols were 94% from paper, 115% from cardboard, 51% from wood (depending on the size of the chips or shavings), and 93% from fruit puree.

Beverages↗

PubMed2003

Reaction mechanism of 3-chlorophenol with OH, H in aqueous solution.

The reaction mechanism of 3-chlorophenol with OH, H in aqueous solution was studied by transient technology. The 3-chlorophenol aqueous solutions have been saturated with air or N2 previously. Under alkaline condition, the reaction of OH radical with 3-chlorophenol produces 3-chlorinated phenoxyl radical, with the absorption peaks at 400 nm and 417 nm. Under neutral condition, the reaction of OH radical with 3-chlorophenol produces OH-adduct with the maximal absorption at about 340 nm. And in acid solution, the reaction of H with 3-chlorophenol produces H-adduct with the maximal absorption at about 320 nm. 3-chlorophenol is compared with 4-and 2-chlorophenols from the free radical pathways. The results show that the positions of chlorine on the aromatic ring strongly influence the dehalogenation and degradation process.

Absorption↗

PubMed2003

Identification of electrical degradation products of 4-chlorophenol in water.

The electrical decomposition of 4-chlorophenol in water was examined with iridium dioxide doped on atitanium electrode. A number of electrical degradation products of 4-chlorophenol, such as hydroquinone and chlorohydroquinone via the addition of hydroxyl radicals, and dichlorophenol through addition of chlorine radical, were observed as major products. Moreover, hydroxylated chlorobiphenylethers, hydroxylated dibenzo-p-dioxin/furans and hydroxylated chlorobiphenyls formed by a dimerization process during the electrolysis process of 4-chlorophenol were also observed. On the other hand, benzoquinone, muconic acid and aldehyde derivatives that were further oxidative products of hydroquinone formed by photocatalysis process, were not observed. The electrical decomposition products of 4-chlorophenol were trimethylsilylated and then identified by gas chromatography-mass spectrometry. The degradation rate of 4-chlorophenol in water by iridium oxide electrode was measured against the electrical process duration. After iridium electrical process for 120 min, about 50% of 4-chlorophenol was converted into a number of products through oxidation processes. On the basis of the identified products, the degradation pathways of 4-chlorophenol under electrolysis process were proposed.

Journal Article↗

PubMed2000

Occupational exposure to chlorophenol and the risk of nasal and nasopharyngeal cancers among U.S. men aged 30 to 60.

BACKGROUND: Elevated rates of nasal and nasopharyngeal cancers have been associated with wood-related occupational exposures, including chlorophenols, formaldehyde, and wood dust. METHODS: Occupational information was obtained from 43 nasal carcinoma cases, 92 nasopharyngeal carcinoma cases, and 1909 controls, by interview. Exact conditional logistic regression was used to evaluate the association of these cancers with chlorophenol exposure, estimated from a review of verbatim responses. RESULTS: Both nasal and nasopharyngeal cancers were significantly associated with estimated duration of chlorophenol exposure. For nasopharyngeal cancer, elevated risk was observed among those who held jobs assigned medium or high intensity chlorophenol exposure (n(exposed)=18, OR=1.94, 95% CI=1.03-3.50) and among those with 10+ years in jobs assigned high intensity with high certainty (n(exposed)=3, OR=9.07, 95% CI=1.41-42. 9). Controlling for estimated formaldehyde and wood dust exposure did not alter these findings, as much of the estimated chlorophenol exposure was among machinists. CONCLUSIONS: These findings support the hypothesis that occupational exposure to chlorophenol is a risk factor for nasal and nasopharyngeal cancer, although the role of machining-related exposures warrants further assessment.

Adult↗

PubMed1987

Urinary chlorophenols in sawmill workers.

The concentration of urinary chlorophenol was assayed for 230 sawmill workers. Information on the work tasks was obtained through questionnaires from occupational health centres. The workers were divided into three groups on the basis of the type of exposure: (1) those with skin absorption as the main route, (2) those with skin and respiratory route of equal importance and (3) those with respiratory tract as the main route. The concentrations of urinary chlorophenol were higher in workers with skin absorption as the main route (median concentration: 7.8 mumol l-1; range 0.1 to 210.9 mumol l-1) than in those with both routes of equal importance (1.4 mumol l-1; range 0.1 to 47.8 mumol l-1, P less than 0.001) or in those with mainly respiratory route (0.9 mumol l-1; range 0.1 to 13.3 mumol l-1, P less than 0.001). The urinary chlorophenol concentration was below 15 mumol l-1 in all workers with the lungs as the main absorption route. In nine out of 112 workers whose main absorption route was the skin, the urinary chlorophenol values were above 50 mumol l-1. Six were loaders when the through-dipping method was used. In two of them urinary chlorophenol concentrations were as high as 170.8 and 210.9 mumol l-1. These results emphasize the need to develop and use simple methods of protection against skin contact with chlorophenols.

Administration, Inhalation↗

PubMed1994

Environmental monitoring of bleached kraft pulp mill chlorophenolic compounds in a northern Canadian river system.

The environmental transport of pulp mill effluent compounds and the exposure of two fish species has been monitored by parallel analyses of effluent, water column and suspended sediment samples, and fish bile and muscle. Compounds analyzed included over 20 chlorophenolic compounds and 12 fatty and resin acids. The concentration of chlorophenols varied with seasonal river flows and mill process changes such as the substitution of chlorine dioxide (ClO2) for chlorine gas (Cl2) in the bleach plant. At 100% (ClO2) substitution, the effluent and the water column concentrations of most chlorophenolics approached the analytical detection limits of 0.1-1 parts per billion. Chlorophenolic and fatty/resin acid compounds were detected in the bile of both mountain whitefish (Prosopium williamsoni) and longnose sucker (Catostomus catostomus), but were rarely detected in fillets. Fish bile concentrations were observed in an apparent spatial gradient as far as 230 km downstream of the mill. A depuration experiment with fish held in uncontaminated water for eight days indicated a rapid decrease in chlorophenol levels. These observations corroborate previous investigations that chlorophenolic compounds are rapidly excreted and can be used as sensitive markers for recent exposure to mill effluents.

Alberta↗

PubMed2004

Acclimation of anaerobic sludge degrading chlorophenols and the biodegradation kinetics during acclimation period.

The acclimation of sludge from Hangzhou citrate factory and Hangzhou municipal wastewater treatment plant for degradation dechlorination of chlorophenols (CPs) compounds, and its biodegradation kinetics were studied in batch process with or without addition of sucrose. Three monochlorophenols (2-CP; 3-CP; 4-CP) and pentachlorophenol (PCP) were concurrently fed to different bioreactors. The parameters that were monitored included biogas production, biogas composition and chemical oxygen demand (COD). The results showed that acclimation with chlorophenol can increase the degradation activity of anaerobic sludge and degradation rate of chlorophenolic compounds, and reduce the lag time. Degradation dechlorination activity of the acclimated sludge strongly depended on sludge source, microorganism population and chlorophenol congener. 2-CP was more easily acclimated than 3-CP and 4-CP. Among the four tested compounds, 4-CP was the most difficult to be acclimated. The observed degradation rate with presence of sucrose was higher than that with absence of sucrose, suggesting that addition of the external carbon source can stimulate the formation of acclimated sludge which could effectively degrade chlorophenols. Kinetic equations of biodegradation of chlorophenols were also presented in this paper.

Anaerobiosis↗

PubMed2003

A kinetic study of 3-chlorophenol enhanced hydroxyl radical generation during ozonation.

Hydroxyl (OH) radical is proposed as an important factor in the ozonation of water. In the present study, the enhancing effect of 3-chlorophenol on OH radical generation was mathematically evaluated using electron spin resonance (ESR)/spin-trapping technique. OH radical was trapped with a 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) as a stable adduct, DMPO-OH. The initial velocity of DMPO-OH generation in ozonated water containing 3-chlorophenol was quantitatively measured using a combined system of ESR spectroscopy with stopped-flow apparatus which was controlled by home-made software. The initial velocity of DMPO-OH generation increased as a function of the concentration of ozone and the more effectively of 3-chlorophenol concentration. The relation among ozone concentration, amount of 3-chlorophenol and the initial velocity (nu(0)) of DMPO-OH generation was mathematically analyzed and the following equation was obtained, nu(0) (10(-6)M/s)=[9.7 x [3-chlorophenol (10(-9)M)] + 0.0005]exp(57 x [ozone (10(-9)M)]). The equation fitted very well with the experimental results, and the correlation coefficient was larger than 0.99. The equation for the enhancing effect by 3-chlorophenol should provide useful information to optimize the condition in ozone treatment process of water containing phenolic pollutants.

Chlorophenols↗

PubMed2004

Biosorption of phenol and chlorophenols by acclimated residential biomass under bioremediation conditions in a sandy aquifer.

Phenol and chlorophenols are common environmental contaminants. The fate and transport of these chemicals must be sufficiently understood to predict detrimental environmental impacts and to develop technically and economically appropriate remedial action to minimise environmental degradation. In order to gain a better understanding of the many mechanisms influencing the fate of phenol and chlorophenols in a sandy aquifer, we conducted biosorption experiments with biomass collected from a simulated aquifer polluted by consecutive accidental spills of phenol, 2-monochlorophenol, 2,4,6-trichlorophenol and pentachlorophenol under continuous bioremediation conditions following a closed-loop configuration during 180 days. A comparative study of the biosorption capacity of phenol and chlorophenols characterised by different physicochemical properties, at different pHs in the range of 6.0+/-0.1 to 9.0+/-0.1 showed the following: (i) the biosorption of phenol and chlorophenols on resident biomass was rapid (equilibrium reached in less than 2h); (ii) the experimental data followed the Freundlich isotherm; (iii) changes in pH from 6.0+/-0.1 to 9.0+/-0.1 resulted in a decrease in the equilibrium biosorption capacity (qeq); (iv) both Freundlich parameters (KF, n) should be used together as predictive parameters in mathematical models to simulate the fate of phenol and chlorophenols in the aquifer; (v) qeq of phenol and chlorophenols investigated in this study were satisfactorily correlated to their hydrophobicity (Kow) with a correlation factor 0.98. In addition, available data from other reported studies fell in the same correlation curve. The results of the present study should be introduced in mathematical models developed to predict the effect of biomass fate and transport of contaminants in aquifers during bioremediation conditions.

Adsorption↗

PubMed2006

Electrochemical determination of 2-chlorophenol using an acetylene black film modified glassy carbon electrode.

Herein, an insoluble acetylene black (AB) was dispersed into water in the presence of a special kind of surfactant: dihexadecyl hydrogen phosphate (DHP), resulting in a homogeneous and stable AB-DHP suspension. Thus, a novel AB-DHP composite film coated glassy carbon electrode (GCE) was fabricated via coating technology. Additionally, the electrochemical behaviors of 2-chlorophenol at bare GCE, DHP-modifed GCE, and AB-DHP modified GCE were investigated, respectively. Compared with the unmodified and DHP-coated GCE, the AB-DHP film-modified GCE significantly enhances the oxidation peak current of 2-chlorophenol, and thus greatly improves its determining sensitivity, suggesting that this new modified electrode has great potential in the determination of trace level of 2-chlorophenol. All the experimental conditions, which affect the electrochemical response of 2-chlorophenol, were studied. Finally, a sensitive and simple voltammetric method with a good linear relationship in the range 2.0 x 10(-7)-4.0 x 10(-5) mol/L, was developed. The detection limit of 2-chlorophenol was 5.0 x 10(-8) mol/L for 2 min accumulation (S/N = 3). This electrode was successfully applied to detect 2-chlorophenol in water samples.

Acetylene↗

PubMed2002

Oxidation of chlorophenols in soil at natural pH by catalyzed hydrogen peroxide: the effect of soil organic matter.

This investigation reports on the effects of soil organic matter (SOM) during the oxidation of chlorophenols with Fe2+-catalyzed H2O2 (Fenton oxidation) system. The soil pH was 7.1 and was not altered. Sorption experiments of soil pre-treated under various oxidation conditions were performed. Concentrations of organic matter in the liquid phase and soil before and after oxidation were analyzed. The results were correlated to the observation in batch Fenton oxidation tests. They showed that the oxidation of chlorophenols at natural soil pH depended on the dose of H2O2 and Fe2+. The soil organic content did not vary significantly after various Fenton treatments, while the sorption of chlorophenols was 10-25% less by the oxidation. The concentration of chlorophenols in the liquid phase exhibited a "decrease and rebound" phenomenon in the batch Fenton oxidation tests. It appeared that the oxidation of SOM resulted in the release of sorbed chlorophenols which were then oxidized by the excess H2O2. An "oxidation-desorption-oxidation" scheme was proposed to describe one of the interaction mechanisms among the oxidant, SOM, and chlorophenols during oxidation.

Adsorption↗

PubMed2003

Biotreatability and kinetics of UASB reactor to mixtures of chlorophenol pollutants.

In most natural ecosystems heterotrophic microorganisms encounter complex mixtures of carbon sources, each of which is present at a concentration of few micrograms per litre. This study examined the biotreatability and kinetics of an upflow anaerobic sludge blanket (UASB) reactor to complex mixtures of chlorophenols encountered in environmental conditions using on-line and off-line experimental studies. Results indicate that (1) steady-state concentration was quite lower (98.3 mg L(-1)) with complex mixture of chlorophenols than steady-state concentration achieved when only 2.4 dichlorophenol (124 mg L(-1)) was studied alone on the same reactor; (2) that toxic effects of chlorophenols increase with increasing concentrations of toxicant. (Onset of the inhibitory effect occurred at a lower concentration in multi-substrate than in single substrate utilization): (3) addition of alternative utilizable substrate can mitigate toxic effects and enhance degradation; (4) the relative concentration of substrate was critical in determining utilization patterns. HPLC analysis of off-line experimental samples resulted in a steady-state treatment efficiency of 68% for COD, 36% for 2-chlorophenol, 40.5% for 4-chlorophenol, 70.7% for 2,4-dichlorophenol, 53.2% for 2,4,6-trichlorophenol and 42% for pentachlorophenol in presence of glucose. Kinetic constant in terms of Vmax and Ks were determined. Ks for the five chlorophenols ranged between 0.016 and 0.117 kg m(-3) day(-1) while Vmax range between 0.056 and 0.244 kg m(-3) day(-1).

Bacteria, Anaerobic↗

PubMed2002

Development of an enzyme-linked immunosorbent assay for screening contamination by chlorophenols in environmental waters.

The development of an immunoassay for screening contamination by chlorophenols is presented. Two haptens were synthesized and conjugated to immunizing proteins to raise rabbit polyclonal antibodies. The antibody-coated format (direct) gave better sensitivity than the conjugate-coated format (indirect) if 2,4,6-trichlorophenol is used as target analyte. The measurement range was 86.4 microg l(-1) to 0.7 microg l(-1), with an average I50 of 7.8 microg l(-1) and a detection limit of 0.2 microg l(-1). The assay detects the presence of trichloropyridinol and other chlorophenols such as di-, tetra- and pentachlorophenols constituting thus a suitable tool for the early warning of the presence of such family contaminants. The optimized method permits the detection of the most important chlorophenols in a fast and reproducible way using no more than one antibody and a single assay. The results achieved with water samples spiked with different chlorophenols fit with a multiple linear regression model when expressing the total concentration of chlorophenols as equivalent of 2,4,6-trichlorophenol (P < 0.01), demonstrating the usefulness of the assay as a screening tool to detect contamination by chlorophenols.

Animals↗

PubMed2003

Enzymatic degradation of p-chlorophenol in a two-phase flow microchannel system.

Enzymatic degradation of p-chlorophenol was carried out in a two-phase flow in a microchannel (100 microm width, 25 microm depth) fabricated on a glass plate (70 mm x 38 mm). This is the first report on the enzymatic reaction in a two-phase flow on a microfluidic device. The surface of the microchannel was partially modified with octadecylsilane groups to be hydrophobic, thus allowing clear phase separation at the end-junction of the microchannel. The enzyme (laccase), which is surface active, was solubilized in a succinic aqueous buffer and the substrate (p-chlorophenol) was in isooctane. The degradation of p-chlorophenol occurred mainly at the aqueous-organic interface in the microchannel. We investigated the effects of flow velocity and microchannel shape on the enzymatic degradation of p-chlorophenol. Assuming that diffusion of the substrate (p-chlorophenol) is the rate-limiting step in the enzymatic degradation of p-chlorophenol in the microchannel, we proposed a simple theoretical model for the degradation in the microchannel. The calculated degradation values agreed well with the experimental data.

Algorithms↗

PubMed2001

Use of green fluorescent protein and luciferase biomarkers to monitor survival and activity of Arthrobacter chlorophenolicus A6 cells during degradation of 4-chlorophenol in soil.

The recently isolated novel species Arthrobacter chlorophenolicus A6 is capable of growth on and degradation of high concentrations of 4-chlorophenol (up to 350 microg ml(-1)) as the sole carbon and energy source. This strain shows promise for bioremediation of environmental sites contaminated with high levels of chlorophenols. In this study, green fluorescent protein (gfp) or luciferase (luc) genes were used as biomarkers for monitoring cell number and activity, respectively, during degradation of 4-chlorophenol by A. chlorophenolicus cells. The individual marked strains, Arthrobacter chlorophenolicus A6L (luc-tagged) and Arthrobacter chlorophenolicus A6G (gfp-tagged), were monitored during degradation of 250 microg ml(-1) 4-chlorophenol in pure culture and 175 microg g(-1) 4-chlorophenol in soil microcosms. Both gene-tagged strains were capable of cleaning up the contaminated soil during 9 d incubation. During the bioremediation experiments, the luc-tagged cells were monitored using luminometry and the gfp-tagged cells using flow cytometry, in addition to selective plate counting for both strains. The cells remained at high population levels in the soil (evidenced by GFP-fluorescent cell counts) and the A. chlorophenolicus A6L population was metabolically active (evidenced by luciferase activity measurements). These results demonstrate that the Arthrobacter chlorophenolicus A6 inoculum is effective for cleaning-up soil containing high concentrations of 4-chlorophenol.

Arthrobacter↗

PubMed2003

Ferrioxalate-mediated photodegradation and mineralization of 4-chlorophenol.

INTENTION, GOAL, SCOPE, BACKGROUND: Advanced oxidation processes are powerful methods which are capable of transforming refractory, nonbiodegradable and/or toxic organic compounds into harmless end products such as carbon dioxide and water. However, one commen problem of all advanced oxidation processes is the high demand of electrical energy for ultraviolet lamps, which causes high operational costs. Minimization of the required irradiation time, and therefore the energy consumption, by optimization of other reaction conditions such as catalyst-oxidant type and concentration, pH, temperature, pollutant/oxidant ratio etc., therefore continues to gain importance. OBJECTIVE: The main objective of this study was the minimization of the required irradiation time through optimization of the use of a newly patented catalyst, ferrioxalate, and also to compare the performance of this catalyst with the performance of other AOPs. METHODS: Oxidation of 4-chlorophenol by photo-Fenton process using potassium ferrioxalate as a mediator was studied in a lab scale photoreactor. The influence of parameters such as hydrogen peroxide and ferrioxalate concentrations, initial pH, power-output, oxalate/iron ratio and different iron sources was evaluated. An upflow photoreactor equipped with a 1000 Watt high-pressure mercury vapour lamp and operating in a recirculation mode was used during photodegradation experiments. The extent of the reduction of 4-chlorophenol, Total Organic Carbon and Chemical Oxygen Demand was used to evaluate the photodegradation reaction. RESULTS AND DISCUSSION: The optimum pH range observed was found to be 2.7-3. The efficiency of 4-chlorophenol oxidation increased with increasing concentrations of hydrogen peroxide and ferrioxalate, reaching a plateau after the addition of 10 and 0.072 mM of those reagents, respectively. Using an Oxalate/iron ratio of 12 was 18% less efficient than using a ratio of 3:1. The efficiency increased with increasing radiation power. However, this increase was not linear. The UV/ferrioxalate/H2O2 process, by which complete mineralization of 100 mg l(-1) 4-chlorophenol was achieved in 20 min of total reaction time, was the most efficient process among the alternatives applied. CONCLUSIONS: The use of ferrioxalate as the catalyst was found to be more efficient than the use of Fe(II) and Fe(III) iron species. It was possible to completely mineralize 4-chlorophenol. RECOMMENDATION AND OUTLOOK: The results of this study demonstrate that the ferrioxalate-mediated degradation of 4-chlorophenol requires less irradiation times than other advanced oxidation processes. There are mainly 19 phenol isomers and other toxic and nonbiodegradable organic compounds. We recommend that similar studies should be performed on many such compounds in order to attain a clear understanding of the performance of this catalyst. Because of its light sensitivity, this catalyst should be used immediately after its preparation. The use of low pressure mercury vapour lamps in this process should also be considered, since low power outputs may be enough for the process.

Chlorophenols↗

PubMed2002

Kinetic studies on UV-photodegradation of some chlorophenols using TiO2 catalyst.

A number of chlorophenols, namely 2-chlorophenol, 2,4,-dichlorophenol and 2,4,6-trichlorophenol, were decomposed in aqueous solution by using TiO2 as photoactivated catalyst under UV radiation emitted by a 125W medium pressure Hg lamp in an immersion well-type quartz photoreactor. The organic-bound chlorine was converted into the environmentally harmless inorganic chloride. For catalyst doses between 0.1 and 0.5gl(-1) the reaction mechanisms are elucidated. The corresponding rate constants were obtained by periodically measuring the remaining chlorophenol, and converted chloride in solution. A theoretical model for the degradation pathway is proposed expressing the rate as a linear function of the concentrations of chlorophenol and catalyst. Aside from the model-calculated values, the pseudo-first order rate constants for a rough approximation of chlorophenols degradation as well as the kinetic parameters of Langmuir-Hinshelwood type decomposition are compared. The photodegradation rate of chlorophenols followed the order: C13 x Ph > Cl2 x Ph > Cl x Ph.

Chlorophenols↗

PubMedDate not supplied

[Inhibition of bacterial bioluminescence by chlorophenols].

Photobacteria were used as a test object for rapid monitoring of ecotoxicants. Specific inhibitory effects of phenol and its chlorinated derivatives (2-chlorophenol, 2,3-dichlorophenol, pentachlorophenol, 2,4-dichlorophenoxyacetic acid, and 2,4,5-trichlorophenoxyacetic acid) on bioluminescence and respiration of intact cells, as well as on the emission activity of the bioluminescence system and luciferase itself, were studied. The toxic effect on the photobacterial cells was found to increase as the number of chlorine atoms in the chlorophenol molecule increases. However, this trend was not observed in cell-free systems (purified luciferase or the protein fraction of a cell-free extract treated with (NH)4SO4 at 40-75% saturation). Bacterial cells have a higher threshold sensitivity to chlorophenols in comparison to the sensitivity of the bioluminescence enzyme system or luciferase. Neutral phenols inhibit luciferase by competing with decanal, whereas a mixed mechanism of inhibition with this substrate is typical of phenoxyacetic acids. With respect to FMNH2, all chlorophenols tested in this work were uncompetitive inhibitors. Oxygen uptake by photobacteria was shown to be insensitive to chlorophenols, at least within the concentration range that was effective in bioluminescence inhibition. The results of this study suggest that bacterial bioluminescence system is not the primary target of the chlorophenol-induced effect on photobacteria.

Bacteria↗