4-chlorobenzoic Acid Research Articles

Influence of organic carbon and metal oxide phases on sorption of 2,4,6-trichlorobenzoic acid under oxic and anoxic conditions.

Chlorobenzoic acids represent crucial recalcitrant metabolites in the environment; thus, the influence of soil components on the sorption of 2,4,6-trichlorobenzoic acid (TCB) under oxic and anoxic conditions was studied. The surficial physiognomies of untreated and isolated soil samples were studied using FTIR, XRD, specific surface area, and PZC determination. The roles of redox potential, dissolved organic carbon (DOC), and pH, particularly under anoxic condition, were appraised. Batch equilibrium adsorption studies on soils of variable Fe/Mn oxides and organic carbon showed that adsorption was low across all components (log Koc = 0.82-3.10 Lg(-1)). The sorption of 2,4,6-TCB was well described by the pseudo second-order kinetic model. The fluctuation of both redox potential and pH during anoxic experiment had a negative impact on the sorption, partitioning, and the oxidation of organic matter. Linear relationships were observed for Kd with both soil total organic carbon (TOC) and surface area (SA). The results showed the existence of DOC-mediated sorption of 2,4,6-TCB which seems to be enhanced at lower pH. The reductive dissolution, particularly of iron compounds, possibly impeded sorption of 2,4,6-TCB under anoxic condition. It could be inferred that habitats dominated by fluctuating oxygen concentrations are best suited for the development of environmental conditions capable of mineralizing 2,4,6-TCB and similar xenobiotics.

Study on enhanced ozonation degradation of para-chlorobenzoic acid by peroxymonosulfate in aqueous solution

Enhanced ozonation degradation of para-chlorobenzoic acid (pCBA) with the addition of peroxymonosulfate (PMS) was investigated in aqueous solution. The results demonstrated that the addition of PMS could accelerate the decomposition of O3 by 50 times compared to that of O3 alone, and the effect was comparable to that of hydrogen peroxide. The degradation of a typical organic contaminant pCBA, was significantly enhanced by the addition of O3/PMS. The mechanism behind the synergistic effect was preliminarily explored by the addition of hydroxyl and sulfate radical (SO4-) scavengers. The degradation of pCBA by O3/PMS could not be completely inhibited by tert-butanol, whereas it was inhibited by the addition of methanol, indicating that the effect of O3/PMS was primarily due to the production of a greater amount of SO4-. The addition of O3/PMS had a selective effect on various contaminants. The enhanced degradation of pCBA by O3/PMS was also observed in actual water samples, and provided some impetus for practical applications of the developed system.

폴리(페닐렌 설파이드)로 기능화된 다중벽 탄소나노튜브의 제조와 특성분석

Friedel-Crafts 직접 아실화 반응을 이용하여 <TEX>$P_2O_5$</TEX>/폴리인산 매질에서 다중벽 탄소나노튜브(MWNT)와 4-클로로벤조산(CBA)을 반응시켜 클로로벤조일(CB)기가 도입된 MWNT(c-MWNT)를 제조하였다. 이때 반응시키는 CBA양을 조절하여 염소원자 함량이 최대 5.3 wt%(CB기 함량 20.86 wt%)인 c-MWNT를 얻었다. 한편, 열가소성 엔지니어링 플라스틱 소재인 폴리(페닐렌 설파이드) (PPS)와 MWNT의 계면접착력을 증가시키기 위하여, 4-클로로벤젠티올(CBT)의 자기축합에 의한 PPS 중합시 c-MWNT를 함께 넣고 중합시킨 후 호모 PPS를 제거하여 MWNT-g-PPS를 얻었다. 이 MWNT-g-PPS의 열 및 표면 특성들을 분석하였으며, c-MWNT와 CBT가 반응하여 c-MWNT 표면에 PPS가 생성되었음을 확인하였다. 4-Chlorobenzoyl (CB) group-attached multi-walled carbon nanotube (c-MWNT) was prepared via a direct Friedel-Crafts acylation of MWNT with 4-chlorobenzoic acid (CBA) in a <TEX>$P_2O_5$</TEX>/poly(phosphoric acid) medium. c-MWNT with a maximum chlorine content of 5.3 wt% (CB group content of 20.9 wt%) was obtained by controlling the amount of CBA during the reaction. Using a self-condensation polymerization of 4-chlorobenzenethiol (CBT) to poly(phenylene sulfide) (PPS), MWNT-g-PPS was prepared by adding c-MWNT of chlorine content of 5.3 wt% during the self-polymerization of CBT and removing homo PPS after polymerization in order to increase the interfacial interaction between PPS and MWNT. Thermal and surface properties of the MWNT-g-PPS were characterized. The results showed that PPS was formed on the surface of c-MWNT by the condensation of c-MWNT and CBT.

Removal of Model Pollutants in Aqueous Solution by Gliding Arc Discharge. Part II: Modeling and Simulation Study

The aim of this work is the modeling of plasma-chemical reactions taking place between highly oxidizing gaseous species (·OH, ·NO and derivatives), generated by Gliding Arc Discharge in Humid Air (GAD-HA), and organic pollutants in aqueous solution. Theses pollutants were chosen on the base of their volatility at atmospheric and ambient conditions: 1-Heptanol (highly volatile), phenol (moderately volatile) and para-chlorobenzoic acid, pCBA (poorly volatile). The mass transfer model of diffusion-convection was coupled to a proposed kinetic model in order to describe the phenomenology of the electrical process. The mass transfer model was obtained independently by stripping toluene and phenol molecules. The simplified kinetic model was proposed with the main reactions in gas and liquid phases mentioned in the literature. The only adjustable parameter of the model was the ·OH concentration in the plasma plume. For a concentration of ·OH of 24 ppm in the plasma plume, the model gives results in agreement with experimental results for the three model pollutants tested. The coupling of the experimental results and the simulation study allowed us to: (1) confirm that the main removal mechanism is different according to the nature of the pollutant and depends on the pollutant properties (reactivity, volatility), (2) calculate [·OH], [ONOOH] and [NO 2 · ]. The results of this work can be used to assist experiences in the plasma engineering field.

Phototransformation pathways of the fungicide dimethomorph ((E,Z) 4-[3-(4-chlorophenyl)-3-(3,4-dimethoxyphenyl)-1-oxo-2-propenyl]morpholine), relevant to sunlit surface waters

Dimethomorph (DMM) is a widely used fungicide that shows low toxicity for birds and mammals but can be quite toxic to aquatic organisms. The persistence of DMM in surface waters is thus of high importance, and this work modelled its water half-life time due to photochemical processes. Depending on environmental conditions (e.g. water chemistry, depth, season), DMM lifetime could vary from a few days to a few months. For lifetimes of a few weeks or shorter, photochemistry would be an important pathway for DMM attenuation in surface waters. Such conditions could be reached in summer, in shallow water bodies with low dissolved organic carbon (DOC) and high nitrate and/or nitrite. The main pathways accounting for DMM photodegradation in environmental waters would be the reactions with OH and with the triplet states of chromophoric dissolved organic matter, 3CDOM* (under the hypothesis that 3CDOM* reactivity is well described by the triplet state of anthraquinone-2-sulphonate), while direct photolysis would be less important. The OH pathway would be favoured in low-DOC waters, while the opposite conditions would favour 3CDOM*. It was possible to detect and identify some intermediates formed upon reaction between DMM and 3CDOM*, namely N-formylmorpholine, 4-chloroacetophenone and 4-chlorobenzoic acid. The transformation of DMM into the detected compounds would not increase the acute toxicity of the fungicide towards mammals, and the acute effects for freshwater organisms could be decreased significantly.

Evaluation of the Catalytic Effect of the Ozone/Carbon Nanotube (O3/CNT) Process Using para-Chlorobenzoic Acid (pCBA)

The catalytic effects and mechanisms of the ozone/carbon nanotube (O3/CNT) process using para-chlorobenzoic acid (pCBA) were evaluated. To use pCBA as an O3-resistant OH• probe compound in a pure water system at pH 7, an adequate amount of scavenger was needed. During the O3/CNT process, a synergetic catalytic effect by OH• generation on the CNT surface could be evaluated in the condition of excess tert-butyl alcohol (TBA) concentration. The OH• radicals were generated and existed on both the bulk phase and CNT surface. The OH-ct values of the CNT surface and bulk phase in the O3/CNT process for 10 min were 2.1 × 10−5 and 2.5 × 10−5μ M·s, respectively. In modifying CNT evaluation, the catalytic effects were the most apparent in the following order: CNT treated with acid then heat (CNT-T), original untreated CNT (CNT-O), and CNT treated with an acid (CNT-A).

Aqueous meta-Chloronitrobenzene Degradation by Ozonation and Its Kinetics

The kinetics and degradation process of meta-Chloronitrobenzene by ozonation in aqueous solution were investigated. Compared to para-chlorobenzoic acid, the rate constant of meta-Chloronitrobenzene with O3 was 0.59 L/(mol·s), while that of the reaction with •OH was 2.07 × 109 L/(mol·s). The main intermediate products were chloronitrophenols and some carboxylic acids. Neither chlorophenols nor nitrophenols was detected. The five-day biochemical oxygen demand and chemical oxygen demand were determined. The ratio of the former to the latter was above 0.3 at 20 min. It was feasible to perform a continuous biotreatment step after 20 min of ozonation.

수산화라디칼 소모인자를 이용한 자외선/과산화수소공정의 효율적인 운전 조건도출

This study investigated a method to determine an efficient operating condition for the process. The OH radical scavenging factor is the most important factor to predict the removal efficiency of the target compound and determine the operating condition of the process. To rapidly and simply measure the scavenging factor, Rhodamine B (RhB) was selected as a probe compound. Its reliability was verified by comparing it with a typical probe compound (para-chlorobenzoic acid, pCBA); the difference between RhB and pCBA was only 1.1%. In a prediction test for the removal of Ibuprofen, the RhB method also shows a high reliability with an error rate of about 5% between the experimental result and the model prediction using the measured scavenging factor. In the monitoring result, the scavenging factor in the influent water of the pilot plant was changed up to 200% for about 8 months, suggesting that the required UV dose could be increased about 1.7 times to achieve 90% caffeine removal. These results show the importance of the scavenging factor measurement in the process, and the operating condition could simply be determined from the scavenging factor, absorbance, and information pertaining to the target compound.

Abraham model correlations for solute transfer into tributyl phosphate from both water and the gas phase

Solubilities are reported for acenaphthene, fluoranthene, benzil, 9-fluorenone, trans-stilbene, phenothiazine, 2-methylbenzoic acid, 3-methylbenzoic acid, 4-chlorobenzoic acid, 3-nitrobenzoic acid, 4-nitrobenzoic acid, 3,4-dichlorobenzoic acid, 3,5-dinitrobenzoic acid, 2-chloro-5-nitrobenzoic acid, and 4-chloro-3-nitrobenzoic acid dissolved in tributyl phosphate at 298 K. The experimental solubility data, combined with published infinite dilution activity coefficients and Henry’s law constants, are used to derive Abraham model correlations for predicting molar solubility ratios, gas-to-liquid partition coefficients, and water-to-liquid partition coefficients of organic solutes and inorganic gases dissolved in tributyl phosphate. The derived Abraham model equations describe the measured experimental values to within 0.15 log units or less.

Validated chromatographic methods for simultaneous determination of tolfenamic acid and its major impurities.

Two accurate, selective and precise chromatographic methods, namely thin-layer chromatography (TLC)-densitometric method and reversed phase high-performance liquid chromatography (RP-HPLC) method, were developed and validated for the simultaneous determination of tolfenamic acid (TOL) and its two major impurities, 2-chlorobenzoic acid (CBA) and 3-chloro-2-methylaniline (CMA), which are also reported to be its related substances. The developed TLC-densitometric method depended on separation and quantitation of the studied drugs on silica gel 60F254 TLC plates. Hexane:chloroform:acetone:acetic acid (75:25:20:0.1, v/v/v/v) was used as a developing system and the separated bands were UV-scanned at 240 nm. Linear relationships were obtained in the range of 10-100 µg band(-1) for the drug and in the range of 0.1-1 µg band(-1) for the studied impurities. The developed RP-HPLC depended on chromatographic separation of the studied drugs on a C18 column using 0.05 M KH2PO4 buffer (pH 3):acetonitrile (45:55, v/v) as a mobile phase delivered at constant flow rate of 1 mL min(-1) with UV detection at 230 nm. Calibration curves for TOL and the two impurities were constructed over the concentration ranges of 10-100 µg mL(-1) for TOL and 0.01-0.1 µg mL(-1) for both CBA and CMA. Factors affecting the developed methods have been studied and optimized. Further, methods validation has been carried out according to International Conference on Harmonization guidelines. The proposed methods were successfully applied for determination of the studied drug in its bulk powder and in pharmaceutical formulation. The methods showed no significant difference when compared with the reported RP-HPLC one. The developed methods have advantages of being more sensitive and specific than the published methods.

양이온성, 비이온성 및 혼합성 계면활성제에 의한&lt;br&gt;4-클로로벤조산의 가용화에 대한 연구

양이온성, 비이온성 및 혼합성 계면활성제에 의한&lt;br&gt;4-클로로벤조산의 가용화에 대한 연구

A new oxo centered basic p-chlorobenzoate bridging heterotrinuclear complex, [Cr2MnO(C7H4O2Cl)6(Py)3]C7H5O2Cl: Synthesis, X-ray crystal structure and theoretical DFT study

The direct reaction between p-chlorobenzoic acid and metal nitrate salts resulted in the formation of a novel heterometallic μ3-oxo trinuclear cluster with the formula [CrIII2MnIIO(C7H4O2Cl)6(Py)3]C7H5O2Cl (1), which has been characterized by elemental analysis, electronic and IR spectra, and single-crystal X-ray crystallography. The electronic spectrum of the complex exhibited two spin-allowed bands for CrIII in the regions 17900 and 22750cm−1, which could be assigned to the transitions from 4A2g(F) to 4T2g(F) and 4T1g(F), respectively. We have also examined the Cambridge Structural Database to investigate the abundance of this type of complex in terms of the trivalent/divalent metal ions and the hetero/homometallic nature of the trinuclear cluster. We have studied the relative stability of the different cluster situations, calculating the energetic costs of a series of metal substitution reactions by means of high level DFT calculations. Moreover, we have analyzed the effect of the p-chlorine substituent in benzoic acid, since the formation of halogen bonding interactions in the solid state are important in determining the crystal packing of 1.

Isolation and functional analysis of a glycolipid producing Rhodococcus sp. strain IITR03 with potential for degradation of 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (DDT)

A 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (DDT) degrading bacterium strain IITR03 producing trehalolipid was isolated and characterized from a pesticides contaminated soil. The strain IITR03 was identified as a member of the genus Rhodococcus based on polyphasic studies. Under aqueous culture conditions, the strain IITR03 degraded 282μM of DDT and could also utilize 10mM concentration each of 4-chlorobenzoic acid, 3-chlorobenzoic acid and benzoic acid as sole carbon and energy source. The catechol 1,2-dioxygenase enzyme activity resulted in conversion of catechol to form cis,cis-muconic acid. Cloning and sequencing of partial nucleotide sequence of catechol 1,2-dioxygenase gene (cat) from strain IITR03 revealed its similarity to catA gene present in Rhodococcus sp. strain Lin-2 (97% identity) and Rhodococcus strain AN22 (96% identity) degrading benzoate and aniline, respectively. The results suggest that the strain IITR03 could be useful for field bioremediation studies of DDT-residues and chlorinated aromatic compounds present in contaminated sites.

Optimizing the Biodegradation of 3,4-Dichlorobenzoic Acid by Corynebacterium jeikeium

Chlorinated benzoic acids (CBA) have been intentionally released to the environment due to their use in agriculture as herbicides or pesticides, or unintentionally because they are common metabolites in the aerobic transformation of many chlorinated pollutants. The biodegradation of 3,4-dichlorobenzoic acid compound was investigated by using Corynebacterium jeikeium bacteria, which was isolated from Petra wastewater plant in Jordan. 3,4-dichlorobenzoic acid compound (3,4-DCBA) was used as a sole carbon and energy source in minimal salt media (MSM). 3,4-DCBA was the most degradable compound among the Chlorobenzoic acid compounds tested by this bacteria. Different conditions such as substrate concentration, temperature, pH, agitation rate, carbon starvation and carbon adaptation were used to obtain optimal Biodegradation. The optimal conditions for the biodegradation were 3mM as substrate concentration and the culture conditions were also showed a significant impact on the ability of these cells to remove 3,4-DCBA. The optimum solution, temperature and agitation rate were 7.5, 37 °C and 150 rpm, respectively. Adaptation of the cells to 3,4-DCBA for 24 hr and 48 hr and cells starvation for 24 hr and 48 hr increased the initial degradation rate. The degradation ability was monitored through disappearance of the substrate from the medium and the measuring the accompanying chloride release. Corynebacterium jeikeium dioxygenases were physiologically induced by 3,4-DCBA compound. They were analyzed for both ortho or meta ring-cleavage of this aromatic compound. Only 1,2-dioxygenase activity was detected which mean that the cleavage is through the ortho pathway. This microorganism can be a valuable and promising candidate for use in the biotreatment of wastewater samples contaminated with 3,4-DCBA.

The effects of Fe–Mn oxide and TiO2/α-Al2O3 on the formation of disinfection by-products in catalytic ozonation

The catalytic activity of Fe–Mn oxide and TiO2/α-Al2O3 catalysts toward the ozonation of natural organic matter (NOM) and a model compound (p-chlorobenzoic acid, pCBA) was investigated in a heterogeneous catalytic ozonation process (HCOP). The monitored parameters in this study included pCBA, dissolved organic carbon (DOC), ultraviolet absorbance at 254 nm (UV254), trihalomethanes (THMs), and nine haloacetic acids (HAA9). The Fe–Mn oxide catalyst significantly enhanced the decomposition (kd) of dissolved ozone (O3) and promoted the formation of hydroxyl radicals in the HCOP to a greater extent than did the TiO2/α-Al2O3 catalyst. Both catalysts (Fe–Mn oxide and TiO2/α-Al2O3) used in the HCOP showed better performance with regard to removal efficiency of DOC and UV254 than adsorption and ozonation. Moreover, the Fe–Mn oxide catalyst had higher removal efficiencies for DOC and UV254 in both the HCOP and adsorption than those of the TiO2/α-Al2O3 catalyst. The removal efficiency associated with UV254 was significantly higher than that associated with DOC. The results show that the use of Fe–Mn oxide and TiO2/α-Al2O3 in catalytic ozonation could effectively remove the precursors of disinfection by-products (DBPs), resulting in the formation of fewer THMs and HAA9. In addition, biofiltration of the HCOP treated water can further increase the removal efficiency of DPB precursors, with the type of catalyst used being less important.

Investigation of supramolecular synthons and structural characterisation of aminopyridine-carboxylic acid derivatives.

BackgroundCo-crystal is a structurally homogeneous crystalline material that contains two or more neutral building blocks that are present in definite stoichiometric amounts. The main advantage of co-crystals is their ability to generate a variety of solid forms of a drug that have distinct physicochemical properties from the solid co-crystal components. In the present investigation, five co-crystals containing 2-amino-6-chloropyridine (AMPY) moiety were synthesized and characterized.ResultsThe crystal structure of 2-amino-6-chloropyridine (AMPY) (I), and the robustness of pyridine-acid supramolecular synthon were discussed in four stoichiometry co-crystals of AMPY…BA (II), AMPY…2ABA (III), AMPY…3CLBA (IV) and AMPY…4NBA (V). The abbreviated designations used are benzoic acid (BA), 2-aminobenzoic acid (2ABA), 3-chlorobenzoic acid (3CLBA) and 4-nitrobenzoic acid (4NBA). All the crystalline materials have been characterized by 1HNMR, 13CNMR, IR, photoluminescence, TEM analysis and X-ray diffraction. The supramolecular assembly of each co-crystal is analyzed and discussed.ConclusionsExtensive N---H · · · N/N---H · · · O/O---H · · · N hydrogen bonds are found in (I-V), featuring different supramolecular synthons. In the crystal structure, for compound (I), the 2-amino-6-chloropyridine molecules are linked together into centrosymmetric dimers by hydrogen bonds to form homosynthon, whereas for compounds (II-V), the carboxylic group of the respective acids (benzoic acid, 2-aminobenzoic acid, 3-chlorobenzoic acid and 4-nitrobenzoic acid) interacts with pyridine molecule in a linear fashion through a pair of N---H · · · O and O---H · · · N hydrogen bonds, generating cyclic hydrogen-bonded motifs with the graph-set notationR228, to form heterosynthon. In compound (II), another intermolecular N---H · · · O hydrogen bonds further link these heterosynthons into zig-zag chains. Whereas in compounds (IV) and (V), these heterosynthons are centrosymmetrically paired via N---H · · · O hydrogen bonds and each forms a complementary DADA [D = donor and A = acceptor] array of quadruple hydrogen bonds, with graph-set notation , and .

Iron Oxide Nanoparticle-Impregnated Alumina for Catalytic Ozonation of para-Chlorobenzoic Acid in Aqueous Solution

A granular media synthesized using iron oxide nanoparticle-coated alumina (IONA) has been demonstrated as an effective solid catalyst in the heterogeneous catalytic ozonation of para-chlorobenzoic acid (pCBA). TEM analysis showed that iron oxide nanoparticles with an average size of 5–20 nm were well-coated onto an alumina surface. It was determined that the iron oxide nanoparticle coating increased the specific surface area by 54 times and the functional group density by 1.5 times. During catalytic ozonation at acidic pH levels, it was clearly observed that IONA increased the degradation of pCBA (98 %) through effective hydroxyl radical formation compared to bare alumina (9 %) under continuous ozonation processes. In comparing the Rct value, which represents the ratio of ozone exposure to hydroxyl radical exposure, the Rct of IONA was approximately four times higher than for bare alumina. In addition, IONA showed good stability for catalytic ozonation of pCBA in the reusability tests.

Sensitive GC/MS determination of 15 isomers of chlorobenzoic acids in accelerated solvent extracts of soils historically contaminated with PCBs and validation of the entire method

Chlorobenzoic acids (CBAs) are the major metabolite of aerobic bacterial degradation of polychlorinated biphenyls (PCBs). A rapid and simple simultaneous derivatisation method has been developed for gas chromatography-mass spectrometry determination in historically PCB-contaminated soils for 15 isomers of mono-, di-, tri-, tetra-, and pentachlorobenzoic acids in CBA mixtures. Two derivatisation agents (diazomethane and methyl chloroformate) and various conditions were evaluated (temperature, time, solvents, catalysts) in terms of efficiency. The optimised derivatisation method with diazomethane and 1% methanol running 1 hour at 5°C was used for derivatisation of extracts of soils and river sediment from historically PCB-contaminated sites; the extracts were prepared using accelerated solvent extraction by a previously described method. Methylated CBAs were separated by gas chromatography using a system with two different common columns, DB-5 and DB-200, in series-coupled (tandem) arrangement and detected by EI-MS. A clean-up with a gel permeation chromatography was carried out to remove soil interfering matrix compounds as well as major portion of PCBs. The limits of quantification ranged between 1 and 10 ng g−1 of individual CBA in the soil. The procedure was applied to various soil samples from Lhenice (Czech Republic) highly contaminated with PCBs. CBAs were found in all tested soils and also in the river sediment. The most contaminated soil contained all CBAs representatives under the study with a total concentration of 3.1 µg g−1 of dry soil.

Biodegradation of chloroaromatic pollutants by bacterial consortium immobilized in polyurethene foam and other matrices

Chlorinated aromatic compounds are the major pollutants of the environment because of their extensive use and toxicity. A bacterial consortium isolated from Pulp and paper mill effluents was shown to degrade various chloroaromatic compounds as a sole source of carbon and energy. The bacterial consortium and Pseudomonas sp. AY762360 were immobilized in various matrices such as polyurethane foam (PUF), sodium alginate (SA), polyacrylamide and agar. The rate of degradation of 2-chlorobenzoic acid (2-CBA), 4-chlorobenzoic acid (4-CBA), 1,2-dichlorobenzene (1,2-DCB) and 1,4-dichlorobenzene (1,4-DCB) at a concentration of 0.2 and 0.6% by the immobilized cells of bacterial consortium in batches with shaken cultures were compared with that of freely suspended cells and immobilized cells of Pseudomonas sp. AY762360. There was complete degradation of these compounds by the PUF-immobilized bacterial consortium when compared to that by freely suspended cells, Pseudomonas sp. AY762360 immobilized in various matrices and the cells of bacterial consortium immobilized in polyacrylamide, SA and agar. The PUF-immobilized cells of bacterial consortium showed more tolerance to pH and temperature changes than freely suspended cells. Pseudomonas sp. AY762360, an isolate from the bacterial consortium, was shown to degrade 2-CBA through catechol by a meta-cleavage pathway. Thus these bacterial strains could potentially be useful in the bioremediation of chloroaromatics contaminated sites.

Liquid chromatography/mass spectrometry to study oxidative degradation of environmentally relevant pharmaceuticals by electrochemistry and ozonation

In this work, the potential of electrochemical oxidation as a tool for the rapid prediction of transformation products in water appearing after ozonation is investigated. These two approaches were compared by choosing the two environmentally relevant model compounds diclofenac and metoprolol and comparison of their transformation products after electrochemical oxidation and treatment with ozone. Within these two approaches, certain similarities were observed in the resulting chromatograms: Six transformation products of the electrochemical oxidation of metoprolol were also detected in the ozone samples. For diclofenac two transformation products matched. Additionally, five of the electrochemically generated oxidation products were reported in literature to occur after water treatment processes. The application of a boron-doped diamond working electrode for electrochemical oxidation allowed the generation of hydroxyl radicals, which was shown by spin trapping experiments with p-chlorobenzoic acid. This allowed the generation of certain transformation products previously not obtained by electrochemical oxidation. Concluding, the hyphenation of electrochemistry with liquid chromatography and mass spectrometry offers a useful tool in transformation studies.