Chlorobenzenes in waterweeds from the Xijiang River (Guangdong section) of the Pearl River

The Xijiang River is the major source of water for about 4.5 millions of urban population and 28.7 millions of rural population. The water quality is very important for the health of the rural population. The concentration and distribution of chlorobenzenes （CBs） in both water and waterweeds collected from 4 stations in the Xijiang River （Gangdong section） of the Pearl River in April and November were determined. The result showed that nearly every congener of CBs was detected. The total contents of CBs （ZCBs） in the river water ranged from 111.1 to 360.0 ng/L in April and from 151.9 to 481.7 ng/L in November, respectively. The pollution level of CBs in the water in April was higher than that in November. The contents of ZCBs in waterweeds ranged from 13.53×10^2μg/g to 38.27×10^2μg/g dry weight （dw）. There was no significant difference between April and November in waterweeds. The distribution of CBs in roots, caulis, and leaves of Vallisneria spiralis L. showed different patterns. The leaves mainly contained low-molecular-weight CBs （DCBs）, whereas the roots accumulated more PCBs and HCBs. The average lgBCFlip （bioconcentration factor） of CBs ranged from 0.64 to 3.57 in the waterweeds. The spatial distribution character of CBs in the Xijiang River was： Fengkai County 〈 Yunan County 〈 Yun＇an County 〈 Gaoyao County according to the ZCBs, and the pollution deteriorated from the upstream to the downstream of the Xijiang River. Further analysis demonstrated that the discharge of waste containing CBs may be the main source of CBs pollution in the Xijiang River .

Electrokinetic movement of multiple chlorobenzenes in contaminated soils in the presence of β-cyclodextrin

This study investigated the electrokinetic （EK） behavior of multiple chlorobenzenes, including 1,2,3,4-tetrachlorobenzene （TeCB）, 1,2,4,5-tetrachlorobenzene （i-TeCB）, and 1,2,3-trichlorobenzene （TCB） in contaminated clayed soils. The effect of β-cyclodextrin （β- CD） on the EK removal of the chlorobenzenes was studied. The largest removal was obtained when Na2CO3/NaHCO3 buffer was used as anodic purging solution without β-CD. The removal efficiencies were related to the aqueous solubilities of chlorobenzenes. With the same cumulative electroosmotic flow, greater solubility led to higher removal efficiency. The addition of β-CD inhibited the EK removal efficiency of all chlorobenzenes. The inhibition increased with the increase of β-CD concentration. With the same β-CD concentration, the inhibition increased with the rise of electric potential. It was found that the inclusion compounds between β-CD and chlorobenzenzes were less soluble than chlorobenzenes. The formation of the less soluble inclusion compounds reduced the aqueous solubility of chlorobenzenes and led to the partial immobilization of the chlorobenzenes that desorbed from soil. It was feasible to use the EK technology to remove chlorobenzenes in contaminated soils using water as the anodic flushing solution. The addition of β-CD was not recommended for the EK removal of chlorobenzenes.

A Study on Side Reactions of Hydroxyethylation of 3-Nitro-4- chlorobenzenesulfinic Acid with Ethylene Oxide

The reaction of 3-nitro-4-chlorobenzenesulfinic acid and ethylene oxide to obtain 2-nitro-4-（β-hydroxyethylsulfonyl）chlorobenzene had been studied. Except hydroxyethylation on the sulfur atom of 3-nitro-4-chlorobenzenesulfinic acid to form the target product, 2-nitro-4-（β- hydroxyethylsulfonyl）chlorobenzene, there presented three kinds of side reactions： 1. Condensation and elimination of HCI to form biphenyl sulfone derivatives; 2. Addition to give bisulfonyl ethane derivative via vinyl sulfone; and 3. Hydroxylethylation on O-atom to produce hydroxylethylsulfinate due to the tautomerism of sulfinic acid.

Chlorobenzenes Contamination in Soils/Sediments at a Site of Decommissioned Plant in Central China

China is one of the most important producers and suppliers of the chlorobenzenes （CBs）, accounting for more than 50% of the world production. Although CBs contamination at the sites of chemical production factories is well-known, the knowledge on spatial distribution and contaminated degree of CBs are still limited. To better understand the occurrence of CBs, a total of 161 soil/sediment samples were collected from 36 sampling points within a 20 m deep from a site of decommissioned chlorobenzenes-producing factory in Wuhan City, Hubei Province, central China. The results showed that monochlorobenzene （MCB） is the predominant contaminants with the ∑CBs levels ranging from 0.05 to 8 600 mg/kg dry weight （dw） with a mean value of 384 mg/kg dw. The vertical distribution of CBs indicated that CBs may have clearly transported to deeper sections in the subsurface. Statistical analyses showed that there are no good correlations between the ∑CBs concentration with soil organic matter （SOM） content and the moisture content.

Chlorobenzenes and organochlorinated pesticides in vegetable soils from an industrial site, China

Organochlorinated compounds are ubiquitous contaminants in the environment, especially in industrial sites. The objective of the work was to investigate whether a vegetable field near an industrial site is safe for vegetable production. The residues of chlorobenzenes （CBs）, hexachlorocyclohexanes （HCHs） and dichlorodiphenyltrichloroethanes （DDTs） in a vegetable field which was near a chemical plant in China were characterized. Point estimate quotient was used for ecological risk assessment of the investigated site. The results showed that all CBs except monochlorobenzene （MCB） were detected in soils. The total concentrations of ∑ CBs ranged from 71.06 to 716.57 ng/g, with a mean concentration of 434.93 ng/g. The main components of CBs in soil samples were dichlorobenzenes （DCBs）, trichlorobenzenes （TCBs） and tetrachlorobenzenes （TeCBs）, while for single congeners, 1,2,4-TCB had the highest concentration, which ranged from 13.21 to 210.35 ng/g with a mean concentration of 111.89 ng/g. Residues of hexachlorobenzene （HCB） in soil samples ranged from 0.9 to 11.79 ng/g, significantly lower than ∑ DCB, ∑ TCB and ∑ TeCB. Concentrations of ∑ HCHs and ∑ DDTs in soils ranged from 11.32 to 55.24 ng/g and from 195.63 to 465.58 ng/g, respectively, of which the main components were α-HCH and p,p＇-dichlorodiphenyldichloroethylene （p,p＇-DDE）. Ecological risk assessment for the investigated site showed that the most potential risks were from TCBs and TeCBs, based on the hazard quotients. The higher residues of CBs and DDTs compared to the target values and the higher than 1 hazard quotients indicated that this area is not safe for vegetable production and thus soil remediation is needed.

Short-term toxic effects of chlorobenzenes on broadbean (Vicia faba) seedlings

The root growth, changes in superoxide dismutase (SOD, EC 1.15.1.1) activity,malonyldialdehyde (MDA) and total soluble protein level of broadbean (Vicia faba) seedlings were researched at different soil concentrations of chlorobenzene (CB), 1,2,4-trichlorobenzene (TCB) and hexachlorobenzene (HCB). The results showed that root growth of seedlings was growth was, however, restored to some extent although there was a delay in returning to the control level. The total soluble protein content in seedlings increased with TCB concentration and duration of exposure. Effect of TCB stress on SOD activity in seedlings displayed a significant were placed in clean tap water for 3 d following exposure to 5 d of TCB stress to clear tap water (P＜0.05). The experiments also revealed that a significant increase of MDA level in seedlings was a positive correlation between TCB concentration and MDA level. All the above results showed that SOD activity and MDA level of broadbean seedlings might be proposed as the biomarkers for short-term TCB contamination in soil. Compared to TCB, the toxicity of 50-1000 μg · g-1 CB or HCB in soil to broadbean seedlings was not observed after a 3 d exposure.

Effects of chronic and subtoxic chlorobenzenes on adrenocorticotrophic hormone release

Many environmental chemicals and pesticides have been found to alter neuroendocrine communication in exposed biological objects. The environmental loads have primary and secondary effects that can alter the homeostatic regulation potential. Since it is difficult to avoid human exposition, a potentially important area of research to develop in vivo and in vitro experimental models. In this context, the primary aim of this study was to demonstrate the effects of chlorobenzenes on adrenocorticotrophic hormone（ACTH） release. In our experimental study, male Wistar rats were exposed to 0.1, 1.0 and 10 μg/b.w.（body weight） kg of 1,2,4-trichlorobenzene and hexachlorobenzene（Cl B） mix via gastric tube for 30, 60 or 90 days. At the endpoints of the experiment blood samples were taken and animals were decapitated. Primary,monolayer adenohypophysis cell cultures were prepared by enzymatic and mechanical digestion. The ACTH hormone content in serum and supernatant media was measured by immuno-chemiluminescence assay. The Mg2＋-dependent ATPase activity was determined by modified method of Martin and Dotty. Significant differences were detected in the hormone release between the control and treated groups. The hormone release was enhanced characteristically in exposed groups depending upon the dose and duration of exposure. The Mg2＋-ATPase activity enhanced after chronic and subtoxic Cl B exposition. Light microscopy revealed that the adenohypophysis seemed to be more abundant. Results indicate that Wistar rats exposed to subtoxic Cl B have direct and indirect effects on hypothalamus–hypophysis–adrenal axis.

Effects of Protein on the Detection of Chlorobenzenes in Fish and Their Elimination by Modified QuEChERS Method

Molecular fluorescence spectrometry, resonance Rayleigh scattering and gas chromatography-mass spectroscopy（GC-MS） were used to study the effect of pure fish serum albumin（FSA） as the model protein on the extraction of three chlorobenzenes（CBs： 1,3-DCB, 1,2-DCB and 1,2,4-TCB; DCB=dichlorobenzene; TCB=trichlorobenzene） in fish samples. The results show that there was a strong binding effect between CB and FSA. In an aqueous solution of 90%（volume fraction） acetone, a slow but full protein denaturation might take place, which would cause the unfolding of protein and the releasing of CBs. Based on these results, a QuEChERS（quick, easy, cheap, effective, rugged and safe） method was modified by replacing the traditional acetonitrile with acetone aqueous solution in the present work. This modified QuEChERS method was applied in the determination of CBs in fish samples. The spiked recoveries and the limits of detection were 80.4%--118.3% and 2.4--7.3 ng/g, respectively. This paper proposes a new strategy by slowing down the protein denaturation and releasing bound organic compounds to enhance the extraction efficiency of CBs in fish samples.

Degradation of chlorobenzene by non-thermal plasma coupled with catalyst:influence of catalyst,interaction between plasma and catalyst

Non-thermal plasma(NTP)is considered to be a promising technology for the removal of volatile organic compounds;however,its application is limited by low CO_(2) selectivity and undesirable by-products.To overcome these issues,this paper discusses the degradation of chlorobenzene(CB)in systems of NTP coupled with catalysts,and the influence of catalyst locations in the NTP was investigated.In addition,the interaction between plasma and catalyst was also explored.The results indicated that the degradability of CB was remarkably improved through the combination of NTP with catalysts,and the formation of ozone was effectively inhibited.The degradation efficiency increased from 33.9%to 79.6%at 14 kV in the NTPcatalytic system,while the ozone concentration decreased from 437 to 237 mg m^(-3),and the degradation efficiency of in plasma catalysis(IPC)systems was superior to that of the post plasma catalysis system,while the inhibition ability of ozone exhibited an opposing trend.In the IPC system,the degradation efficiency was 87.7%at 14 k V,while the ozone concentration was151 mg m^(-3).Besides,the plasma did not destroy the pore structure and crystal structure of the catalyst,but affected the surface morphology and redox performance of the catalyst.Thus,NTP coupled catalytic system could improve the degradation performance of CB.Furthermore,the plasma discharge characteristics played a major role in the NTP synergistic catalytic degradation of CB.Finally,based on the experiment analysis results,the general reaction mechanism of CB degradation in an IPC reaction system was proposed.

Chlorobenzene degradation by electro-heterogeneous catalysis in aqueous solution:intermediates and reaction mechanism

This study was performed to investigate the variables that influence chlorobenzene (CB) degradation in aqueous solution by electro-heterogeneous catalysis.The effects of current density,pH,and electrolyte concentration on CB degradation were determined.The degradation effciency of CB was almost 100% with an initial CB concentration of 50 mg/L,current density 15 mA/cm2,initial pH 10,electrolyte concentration 0.1 mol/L,and temperature 25°C after 90 min of reaction.Under the same conditions,the degradation eff...

Biodegradation of Gaseous Chlorobenzene by White-rot Fungus Phanerochaete chrysosporium

Objective To evaluate the effect of white rot fungus Phanerochaete chrysosporium on removal of gaseous chlorobenzene. Methods Fungal mycelium mixed with a liquid medium was placed into airtight bottles. A certain amount of chlorobenzene was injected into the headspace of the bottles under different conditions. At a certain interval, the concentrations in the headspace were analyzed to evaluate the degradation of chlorobenzene by P. chrysosporium. Results The degradation effects of P. chrysosporium on chlorobenzene under different conditions were investigated. The difference in the optimum temperature for the growth of the fungi and chlorobenzene degradation was observed. The data indicated that a lower temperature （28℃） would promote the degradation of chlorobenzene than the optimum temperature for the growth of the fungi （37℃）. A low nitrogen source concentration （30 mg N/L） had a better effect on degrading chlorobenzene than a high nitrogen source concentration （higher than 100 mg N/L）. A high initial concentration （over 1100 mg/m3） of chlorobenzene showed an inhibiting effect on degradation by P chrysosporium. A maximum removal efficiency of 95% was achieved at the initial concentration of 550 mg/m3. Conclusion P. chrysosporium has a rather good ability to remove gaseous chlorobeuzene. A low nitrogen source concentration and a low temperature promote the removal of chlorobenzene by P. chrysosporium. However, a high initial chlorobenzene concentration can inhibit chlorobenzene degradation.

Catalytic Dechlorination of Chlorobenzene in Water by Pd/Fe System

Chlorobenzene was dechlorinated by Pd/Fe bimetallic system in water through catalytic reduction. The dechlorination rate increases with increase of bulk loading of Pd due to the increase of both the surface loading of the Pd and the total surface area. For conditions with 0.005% Pd/Fe, 45% dechlorination efficiency was achieved within 5 h. The dechlorinated reaction is believed to take place on the bimetal surface in a pseudo-first-order reaction, with the rate constant being 0.0043 min-1.

Catalytic dechlorination of chlorobenzene in water by Pd/Fe bimetallic system

Catalytic reductive dechlorination of monochlorobenzene(MCB) was carried out in the palladium/iron system. With low Pd loading(0 005%), 45% dechlorination efficiency was achieved within 5 h. Pd as catalyst accelerated the reductive dechlorination reaction. Dechlorination mechanism and kinetics were discussed. The reaction took place on the bimetal surface in a pseudo first order reaction, with the rate constant being 0 0071 min -1 ( K SA =8 0×10 -3 L/(m 2·h). The reduction product for MCB was benzene.

Heterogeneous Photocatalytic Mineralization of Chlorobenzene by Paratungstate-loaded Titania Catalysts in an Aqueous Medium

Paratungstate-loaded titania catalysts were prepared %via% the addition of a series of aqueous solutions of paratungstate(denoted as W_ 7) into an isopropanol solution of Ti[OCH(CH_ 3)_ 2]_ 4 by means of the sol-gel method. The catalysts were characterized by EDX, BET, FTIR, UV-Vis DRS, XRD and the results indicate that such paratungstate-loaded catalysts maintained their heptatungstate structure in the anatase titania matrix up to 400 ℃. The catalysts were tested for the heterogeneous photodegradation of chlorobenzene in aqueous media and showed a better catalytic activity than P-25 TiO_ 2 because paratungstate can prevent the recombination of the holes and electrons produced during irradiation. Moreover, the paratungstate-loaded titania catalysts can resist the disaggregation during the photoirradiation and can be easily recycled from the aqueous suspensions after reactions.

用表面活性剂提高生物滴滤床净化废气中氯苯的性能(英文)

A laboratory-scale trickling biofilter column, filled with Raschig rings and inoculated with Pseudomonas putida （ATCC 1785） was used to ＇purify chlorobenzene contained waste gases. Sodium dodecyl sulfonate （SDS） was used to enhance the performance of trickling biofilter. Purification performance of the trickling biofilter was examined for chiorobenzene inlet concentration of 1.20,-5.04 g/m^3 at different EBRTs between 76N153 s. Without SDS addition, with simultaneous increase in chlorobenzene inlet loading rate and gas flow rate, 100% removal efficiency was achieved at EBRT of 109 s and inlet loadings below 5120 mg/m^3. Addition of SDS to nutrient solution led to improvement of trickling biofilter purification performance. By introducing 25 mg/L SDS, the removal efficiency was increased by 21% and elimination capacity up to 234 g/（m^3.h） was achieved at chlorobenzene inlet loading of 241 g/（m^3.h）. Although SDS concentration experienced a low rate reduction after continuous nutrient solution recirculation, this result has period little influence on trickling biofilter＇s removal efficiency in monitoring period.

加氢脱氯在环境污染控制中的应用:负载及非负载型钯和镍催化剂性能的比较(英文)

Catalytic hydrodechlorination(HDC)is an innovative means of transforming chlorinated waste streams into a recyclable product. In this study,the gas phase HDC of chlorobenzene(CB)has been studied over bulk Pd and Ni and((8±1)wt%)Pd and Ni supported on activated carbon(AC),graphite,graphitic nanofibers(GNF),Al2O3,and SiO2.Catalyst activation was examined by temperature-programmed reduction(TPR)analysis and the activated catalysts characterized in terms of BET area,transmission electron microscopy,scanning electron microscopy,H2 chemisorption/temperature-programmed desorption,and X-ray diffraction measurements.Metal surface area(1-19 m 2 /g), TPR,and H2 uptake/release exhibited a dependence on both metal and support.The Pd system delivered specific HDC rates that were up to three orders of magnitude greater than that recorded for the Ni catalysts,a result that we link to the higher H2 diffusivity in Pd.HDC was 100%selective over Ni while Pd also produced cyclohexane(selectivity<4%)as a result of a combined HDC/hydrogenation.Bulk Pd outperformed carbon supported Pd but was less active than Pd on the oxide supports.In contrast,unsupported Ni presented no measurable activity when compared with supported Ni.The specific HDC rate was found to increase with decreasing metal surface area where spillover hydrogen served to enhance HDC performance.

Measurement and Correlation of Isobaric Vapor-Liquid Equilibrium of Three Binary Systems Containing Chlorobenzene at 50.00 and 101.33 kPa

Isobaric vapor-liquid equilibrium(VLE) data for three binary systems, chlorobenzene + N,N-dimethylformamide, chlorobenzene + furfural, and chlorobenzene + benzaldehyde, were measured at 50.00 and 101.33 kPa using a modified Rose-Williams still. Gas chromatography was used to analyze the compositions of the samples and no azeotropic behavior was found. All of the measured VLE values were checked by the semi-empirical method proposed by Herington and the point-to-point Van Ness test method modified by Fredenslund. The experimental data were correlated by using the Wilson, the non-random two-liquid and universal quasi-chemical activity coefficient models. The corresponding parameters for the three models were obtained.

Study on the Effect of Underground Temperature on the Adsorption Behavior of Chlorobenzene under Artificial Recharge Condition

[ Objective] The research aimed to study the effect of underground temperature on the adsorption behavior of chlorobenzene under artifi- cial recharge condition. [ Method] Based on the prior researches, combining actual condition of the artificial recharge test site, the adsorption be- havior of chlorobenzene under the background of artificial recharge was discussed. [ Reset ] The adsorption reaction of chlorobenzene correspon- ded with quasi-first-order and quasi-second-order kinetics equations at certain concentration. When temperature rose, reaction rate accelerated, and adsorption balance time shortened to 12 （0 ℃）, 10 （10 ℃） and 8 （20 ℃） h. The adsorption of chlorobenzene corresponded with isothermal adsorption model very well at different concentrations. When temperature ranged from 0 to 20 ℃, the adsorption amount of medium on chloroben- zene increased at equilibrium time. The maximal adsorption amounts calculated by Langmuir model were 20.747, 21. 505, 23.364 μg/g at 0, 10 and 20 ℃, respectively. [ Conclusion] The adsorption of chlorobenzene in aquifer medium was endothermic reaction, and the best season of artifi- cial recharne was in summer.

Carbon Dioxide Fixation Method for Electrosynthesis of Benzoic Acid from Chlorobenzene

Carbon dioxide fixation technique was developed as an alternative dechlorination method of chlorobenzenes. Electrolysis of chlorobenzene was carried out in a one-compartment cell fitted with an aluminium anode and a platinum cathode. Electrolysis in N, N-dimethylformamide （DMF） solution containing 0.1 M of tetrapropylammonium bromide （TPAB） at 0 ℃, 100 ml/min of CO2 flow rate and 120 mA/cm^2 of current density was found to be the optimum conditions of this electrocarboxylation, which gave 72% yield of benzoic acid from chlorobenzene. These conditions were then applied to 1,2-dichlorobenzene and 1,3-dichlorobenzene in order to convert them to their corrcsponding benzoic acids.