Concentrations Of Carbon Tetrachloride Research Articles

Sensing volatile organic compounds with CVD graphene: insights from quartz crystal microbalance and surface plasmon resonance studies

This study explores the sensing capabilities of chemical vapor deposition (CVD)-grown graphene in detecting volatile organic compounds (VOCs) through quartz crystal microbalance (QCM) and surface plasmon resonance (SPR) techniques. Two distinct sensing devices were developed, each tailored for QCM and SPR transducing mechanisms, utilizing CVD graphene as the sensing element. The sensors demonstrated consistent and reproducible responses when exposed to various concentrations of dichloromethane, chloroform, carbon tetrachloride, benzene, toluene, and m-xylene. Notably, both sensors exhibited unparalleled sensitivity to dichloromethane, with the graphene-coated SPR sensor displaying a sensitivity value of 294 × 10−3 ppm−1 and a limit of detection (LOD) value of 10.62 ppm. Additionally, the SPR sensor showcased remarkably swift response and recovery times, both under 3 sec. Results indicate that the adsorption of VOC molecules on the CVD graphene surface increases with the rising dipole moments and vapor pressure values of the molecules. The utilization of CVD graphene in both sensing approaches demonstrates good reproducibility in detecting ultralow concentrations of VOCs at room temperature.

Metformin modulates autophagic pathway in renal fibrosis induced by carbon tetrachloride in adult male albino rats

ABSTRACT Backgrounds Chronic kidney disease (CKD) is a global public health problem. All progressive chronic kidney disease (CKD) is characterized by tubulointerstitial fibrosis. Exposure to high concentrations of carbon tetrachloride (including vapor) can destroy the kidneys. Autophagy played an important role in maintaining the homeostasis of organs. Impaired autophagy was frequently associated with renal damage and fibrosis. Recent data suggests that metformin protects against a variety of kidney disorders. Aim To investigate the protective role of metformin on carbon tetrachloride induced renal damage via autophagy pathway. Materials and Methods Forty adult male albino rats were divided into four equal groups (10 rats, each); Group 1: control group. Group 2: olive oil group received olive oil 1.5 mg/kg twice weekly S.C for 12 weeks. Group 3: The ccl4 group, the rats were received ccl4 1.5 mg/kg twice weekly S.C for 12 weeks. Group 4: CCL4 and Metformin group received concomitant treatment of CCL4, 1.5 mg/kg twice weekly S.C and 100 mg/kg/day Metformin orally for 12 weeks. After sacrifice, kidneys were taken from all animal groups and processed for light and electron microscopy, immunological studies and biochemical tests. Statistical analysis was done. Results Administration of ccl4 resulted in histopathological changes in the kidney tissue in the form of areas of tissue destruction, inflammatory cell infiltration, congestion and fibrosis. Ultrastructurally, irregular thickening of GBM was observed. Improvement was noticed with concomitant treatment of ccl4 with metformin. Conclusion Metformin administration can modulate histological and biochemical effects in the renal tissue induced by of ccl4.

Impact of dietary supplementation with chokeberry (Aronia melanocarpa, Michx.) on tetrachloride-induced liver injury in Wistar rats: Hematological and biochemical implication.

In the current study, we assessed the hematological/biochemical alterations, histopathological changes in the liver, and blood cell disorders in Wistar rats exposed to a toxic concentration of carbon tetrachloride (CCl4 ) and the potential protective effect of a 30-day oral extract of chokeberry (Aronia melanocarpa, AM). The concentration of AM (3.38 mg/kg) obtained by quantitative purification from AM fruit showed the highest antioxidant activity (AOA) in vitro and was used for oral ingestion. In addition to high AOA, high values of total phenols (85.334 mg/g), total phenolic acid (606.95 mg/g), total flavonids (22.10 mg/g), and total anthocyanins (11.01 mg/g) were recorded in chokeberry extract. CCl4 treatment caused serious liver injury, hepatocyte and blood cell impairment. AM extract given to rats before CCl4 application had a moderate hepatoprotective effect in comparison to after CCl4 application. White blood count and leukocytes were significantly altered by CCl4, however, the protective role of AM in leukocyte disorders was not established. A high number of microcytes, stomatocytes, anisocytes, and hemolyzed erythrocytes during CCl4 exposure was reduced by AM extract. Flower erythrocytes in the AM + CCl4 group were recorded. Supplementation with chokeberry extract without CCl4 caused hyperproteinemia and hyperalbuminemia. Although the results indicate a weak protective role for AM, it is nevertheless important for improved erythropoiesis and regulation of the development of anemia. The hepatoprotective role of AM was moderate, and the immune response was not proven. Daily consumption of chokeberry extract can improve health. However, the results of our study showed that the ingestion of AM extract at this dose with the highest AOA would have more effective effects if the supplementation were significantly increased.

Self-diffusion of aromatic compounds in the carbon tetrachloride – acetone binary system. NMR experiment and MD simulation

In this work, we studied the influence of the structure of molecules of aromatic compounds (methylparaben (MP), propylparaben (PP), syringic acid (SA), gallic acid (GA), protocatechualdehide (PAL), p-coumaric acid (p-CA), and caffeic acid (CA)) on their molecular association and self-diffusion in the binary carbon tetrachloride – acetone solvent. The self-diffusion coefficients of PAL, SA, and GA in the binary carbon tetrachloride – acetone‑d6 solvent were measured by the pulsed gradient spin-echo nuclear magnetic resonance (PGSE NMR) method at temperatures of 288, 298, and 308 K. The data obtained at 298 K were also compared with the data on the self-diffusion coefficients of MP, PP, CFA, and p-CA in the binary solvent available in the literature. According to the presented data, the self-diffusion coefficients of all the substances under consideration become greater with an increase in the acetone‑d6 concentration and decrease in the MP > PAL > PP > p-CA > SA > CA > GA series of compounds. Quantitative assessment of the degree of influence of molecular association on solute self-diffusion was carried out within the framework of a method based on the ratio of the self-diffusion coefficient of a solute to the self-diffusion coefficient of its monomers. The study shows that the degree of influence of molecular association of the solute on its self-diffusion is determined by the number and type of active functional groups in the structure of the solute molecules (MP < PP < PAL < SA < p-CA < CA < GA), but does not depend on the composition of the binary solvent. According to the results of molecular dynamics (MD) simulation, this effect correlates with the increase in the degree of self-association of solutes and decrease in the degree of solute – acetone heteroassociation observed when the carbon tetrachloride concentration becomes higher. This effect is also responsible for the similar concentration dependencies of the self-diffusion coefficients of active and inert compounds.

Volatile Organic Compound Emissions from Disinfectant Usage in the Home and Office.

Volatile Organic Compound Emissions from Disinfectant Usage in the Home and Office.

Chromatographic determination of organohalogen compounds in swimming pool water

The purpose of the work was to search for a sorbent with good selective properties for water purification. For this purpose, we determined the organohalogen compounds in the water of a swimming pool. A method of gas-liquid chromatography was used, using packed and capillary chromatographic columns. To concentrate the impurities of the organohalogen compounds, an automatic vapour-phase dispenser was used. This established that the swimming pool water, taken in the evening, had a complex composition of components, including 33 organohalogens, which have different toxicities for the human body. These are classed as belonging to the first and second groups of hazards. Identification of the individual component composition was carried out by determining the relative retention times of the test compounds and standard samples of the organohalogen compounds dissolved in methanol. Out of the entire range of the organohalogen compounds contained in the swimming pool water it was determined that the highest concentration of chloroform was 0.024 mg/dm3 and the highest concentration of carbon tetrachloride was 0.018 mg/dm3. The total content of organohalogen substances in the swimming pool water was 0.370 mg/dm3, which increases the risk of human diseases while the swimming pool is in operation. It is proposed to clean the water in the swimming pools from toxic impurities by an adsorption method using rocks containing zeolite from the Tatar-Shatrashan deposit, which are characterized by a sufficiently high sorption capacity in relation to the organohalogen compounds.

Combretum dolichopentalum extract normalized biochemical and haematological parameters in carbon tetrachloride (CCL4) intoxicated rats

Background: The ethanol extract of Combretum dolichopentalum (EECD) is employed in Nigeria to stabilize the uterus after parturition. The ability of EECD to confer protection on rats destabilized by moderate concentrations of carbon tetrachloride (CCl4) was evaluated. Methods: Fifty rats were assigned to 5 groups of 10 rats each. The experimental animals after acclimatization were handled accordingly: Groups 1 and 2 respectively were maintained on food and water only throughout the study. Group 3, 4, and group 5 were pre-treated with 250 mg/kg and 500 mg/kg body weight of EECD and 50 mg/kg of silymarin for 28 respectively. All groups except group 1 were intoxicated to 0.2 ml/kg body weight of CCl4, administered via an intraperitoneal route on day 29. Serum pipetted from the blood of the rats after cardiac puncture was assayed for antioxidant enzymes, lipid peroxidation product and serum iron, zinc and biocarbonate. Haematological analysis was also conducted. Results: Administration of CCl4 at 0.2 ml/kg b.w slightly increased the oxidizing species as indicated in the concentration of malondialdehyde in the rats while reducing the antioxidant enzymes; it increased the Iron and zinc concentrations and also the haematological parameters except for the white blood cells. However, this was corrected by pre-treatment with the EECD dosedependently. Conclusion: These characteristics portends that the crude ethanol extract of C. dolichopentalum could be employed to correct minor oxidative perturbation induced by CCl4 intoxication

Enhanced dechlorination of carbon tetrachloride by Ni-doped zero-valent iron nanoparticles @ magnetic Fe3O4 (Ni4/Fe@Fe3O4) nanocomposites

A bimetallic nanocomposite, named as Ni4/Fe@Fe3O4, which was prepared via loading Fe/Ni bimetallic onto magnetite (Fe3O4), was applied to the reductive dechlorination of carbon tetrachloride (CT) for the first time and was identified by scanning electron microscopy (SEM), X‐ray energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) to explore its structure and properties. The effects of the Ni loading (weight ratio of Fe/Ni), CT concentration, initial solution pH, temperature and Ni4/Fe@Fe3O4 dosage on the reaction system were studied. The experimental results showed that the nanoscale Ni/Fe@Fe3O4 bimetallic particles with a mass ratio of 4% of Ni/Fe exhibited excellent performance for CT degradation. The removal efficiency of CT can reach 96.3% within 35 min with only 0.2 g/L of Ni4/Fe@Fe3O4. The degradation kinetics of CT by Ni4/Fe@Fe3O4 nanocomposites was conformed to the pseudo first-order kinetics and the activation energies (Ea) was 25.87 kJ/mol. Moreover, Ni4/Fe@Fe3O4 presented good reusability and stability after four cycles. Based on the detection results of CT degradation products by gas chromatography (GC), a possible degradation mechanism was discussed, which can be divided into the following ways: (1) Migration and adsorption of CT molecules. (2) Direct reductive dechlorination of CT molecules by nano zero-valent iron (nZVI). (3) Reduction dechlorination of CT by Fe2+ released by Ni4/Fe@Fe3O4. (4) Ni0 might induce the conversion of H2 to active atomic hydrogen (·H) to degrade chloromethane. These results exhibited that Ni4/Fe@Fe3O4 will be a nanocomposite with great application potential for CT degradation from aqueous solutions.

Disorders of lipid and carbohydrate metabolism in children consuming drinking water of a non-normative quality

Clinical and laboratory investigation of violations of lipid and carbohydrate metabolism in children consuming drinking water of non-normative quality on content of organochlorine compounds. Children with elevated blood concentrations of chloroform and carbon tetrachloride, endocrine pathology are diagnosed 2.1 times more likely, the relative risk of developing obesity (E66.0) and excess supply (E67.8) is by 2.7 times higher than in the comparison group. There was found a causal relationship between the development of overweight children with a high content of chloroform in blood. Negative effects of organochlorines (chloroform, carbon tetrachloride) manifested by dysfunction of the hypothalamic-adrenal and pituitary-thyroid system, the activation offree radical oxidation and the accumulation ofperoxidation products, overvoltage and resource depletion of antioxidant defense, and violation of neurotransmitter processes was found to be followed by dysregulation offat and carbohydrate exchange. There were identified markers of disorders of lipid and carbohydrate metabolism in the conditions of exposure to chloroform and carbon tetrachloride.

Application of nanoencapsulated silymarin to improve its antioxidant and hepatoprotective activities against carbon tetrachloride-induced oxidative stress in broiler chickens

The objective of this study was to evaluate antioxidant and hepatoprotective activities of nanoencapsulated silymarin (NES) against carbon tetrachloride-induced oxidative stress in broiler chickens. An in vitro study was conducted using a 20 kHz ultrasound with 62.5% amplitude to produce NES, stabilized by alginate for controlled release of its bioactive compounds in simulated gastrointestinal tract of broiler chickens. Results showed that sonication reduced the size of particles from 657.5 to 169.1 nm and polydispersity index from 0.60 to 0.31.Simulated gastrointestinal digestion in vitro indicated that NES was more resistant to gastric fluid compared to intestinal fluid. An animal model study was designed to investigate the antioxidant and hepatoprotective effects of NES on broiler chickens subjected to carbon tetrachloride-mediated oxidative stress. A total of 640 one-day-old mail broiler chickens were randomly assigned to 8 treatments with 4 replicate cages of 20 broiler chickens per cage as 2 × 2 × 2 factorial arrangement of treatments in a completely randomized design, including 2 concentrations of silymarin (0 and 100 mg/kg of body weight), NES (0 and 100 mg/kg of body weight), and carbon tetrachloride (0 and 1 mL/kg of body weight). All broiler chickens were fed a common diet throughout the study. From d 21, broiler chickens of control group received saline (intraperitoneally), while other treatment groups received silymarin (orally), carbon tetrachloride (intraperitoneally), and NES (orally). On d 42, 2 broiler chickens per replicate cage were euthanized for blood and tissue sampling. The interactions of silymarin × carbon tetrachloride (P = 0.003) and NES × carbon tetrachloride (P = 0.001) improved protein metabolism and lipid oxidative stability (P = 0.001). Combination of NES and carbon tetrachloride decreased serum content of alanine aminotransferase (P = 0.001), whereas combination of silymarin and carbon tetrachloride and NES increased (P = 0.02) its serum content as compared to broiler chickens that received none of those treatments. Carbon tetrachloride down-regulated (P = 0.03) the expression of superoxide dismutase 1, while silymarin, NES, and combination of silymarin and NES up-regulated its expression (P = 0.03). In contrast to carbon tetrachloride (P = 0.001), NES down-regulated (P = 0.03) heat shock protein 47 as compared with broiler chickens that received none of those treatments. In conclusion, NES has potential to mitigate the oxidative stress-induced hepatotoxicity in broiler chickens through modulation of oxidative stress biomarkers and expression of superoxide dismutase 1 and heat shock protein 47 genes.

Three‐Dimensional Ordered Structures of Metal‐Organic Frameworks for Carbon Tetrachloride Sensing and Comparative Study

AbstractThree‐dimensional (3D) ordered structure of PS@ZIF‐8 and FT‐ZIF‐8 was prepared by self‐assembly method. The 3D ordered structure of PS@ZIF‐8 and FT‐ZIF‐8 were used to investigate the sensing characteristics for carbon tetrachloride in real time, and the two structures exhibited good response to carbon tetrachloride. It was found that the response time required to reach the maximum reflection peak only 2 s for FT‐ZIF‐8, and the shift of the reflection peak from about 825 nm to 836 nm of about 31 nm for PS@ZIF‐8. The relationship of the shift peak position with different concentration of carbon tetrachloride was demonstrated to be linear. Moreover, The fabricated 3D ordered structures exhibited high long‐term, repeatability and stability, which are beneficial for practical applications.

Ameliorative effect of Combretum dolichopentalum in CCl4- induced oxidative stress

The study evaluated the ability of the ethanol extract of Combretum dolichopentalum (EECD) to offer protection on rats perturbed by relatively low concentrations of carbon tetrachloride (CCl4). Five groups of 10 rats each were treated thus: Group 1 and group 2 constituting the normal and positive control group were maintained on food and water throughout the study. Group 3, 4, and 5 received 250, 500 mg/kg body weight of EECD and 50 mg/kg of silymarin for 28 days respectively. All groups except group 1 were exposed to 0.2 ml/kg body weight of CCl4 intraperitonealy on day 29. Serums from the rats were assayed for antioxidant and liver specific enzyme. Lipid profile and peroxidation product as well as antioxidant molecules were determined to check the oxidative as well as the liver status of the test organism. Standard biochemical methods were employed for the assay and results were subject to statistical analysis using one way ANOVA. Administration of CCl4 at 0.2 ml/kg b.w slightly altered the redox status of the rats; however, pre-treatment with the ethanol extract of C. dolichopentalum dose dependently stabilized the altered perturbation. This potential indicates that the crude EECD could be employed to correct minor oxidative imbalances as a result of CCl4 intoxication, C. dolichopentalum has been reported to possess a wide array of bioactive phytochemicals, and also reported not to present significant side effects when administered. Thus C. dolichopentalum could be a pharmacological tool needed to offer protection on liver during toxic assault from accidentally ingested toxicants such as carbon tetrachloride.

Methanol-enhanced degradation of carbon tetrachloride by alkaline activation of persulfate: Kinetic model

Carbon tetrachloride (CT), a chlorinated organic compound widely used in the chemical industry during the 20th century, is nowadays a ubiquitous contaminant in groundwater and in situ technologies for its destruction are required. In this work, the degradation of CT by the alkaline activation of persulfate (PS) has been studied. Among the pool of radical species generated (hydroxyl radicals, sulfate radicals and superoxide radicals), O2∙− resulted to be the only species responsible for CT abatement. It has been found that the presence of other solvents less polar than water (hydrogen peroxide, acetone, propanol and methanol) improves CT degradation. Among them, methanol was selected as the most adequate co-solvent, leading to the complete elimination of CT (100 mg L−1, 24 h) with a moderate unproductive consumption of the oxidant. The degradation of CT increased proportionally with the concentration of this solvent (from 0.1 to 10 g L−1). The ratio NaOH:PS (from 1 to 8) did not affect the degradation of CT when working with a constant concentration of PS and highly alkaline conditions were maintained. The removal rate of CT increased as the concentration of PS increased (from 20 to 60 g L−1), while the conversion of this pollutant did not depend on its initial concentration (from 10 to 100 mg L−1). A kinetic model that considers the concentration of PS, MeOH and CT and can predict the concentration of CT with reaction time at different operating conditions, has been developed from the experimental data.

FEM Analysis of Sezawa Mode SAW Sensor for VOC Based on CMOS Compatible AlN/SiO₂/Si Multilayer Structure.

A Finite Element Method (FEM) simulation study is conducted, aiming to scrutinize the sensitivity of Sezawa wave mode in a multilayer AlN/SiO2/Si Surface Acoustic Wave (SAW) sensor to low concentrations of Volatile Organic Compounds (VOCs), that is, trichloromethane, trichloroethylene, carbon tetrachloride and tetrachloroethene. A Complimentary Metal-Oxide Semiconductor (CMOS) compatible AlN/SiO2/Si based multilayer SAW resonator structure is taken into account for this purpose. In this study, first, the influence of AlN and SiO2 layers’ thicknesses over phase velocities and electromechanical coupling coefficients (k2) of two SAW modes (i.e., Rayleigh and Sezawa) is analyzed and the optimal thicknesses of AlN and SiO2 layers are opted for best propagation characteristics. Next, the study is further extended to analyze the mass loading effect on resonance frequencies of SAW modes by coating a thin Polyisobutylene (PIB) polymer film over the AlN surface. Finally, the sensitivity of the two SAW modes is examined for VOCs. This study concluded that the sensitivity of Sezawa wave mode for 1 ppm of selected volatile organic gases is twice that of the Rayleigh wave mode.

Degradation of Carbon Tetrachloride by nanoscale Zero‐Valent Iron @ magnetic Fe3O4: Impact of reaction condition, Kinetics, Thermodynamics and Mechanism

Nano‐scale zero‐valent Iron (nZVI) attached on the Fe3O4 nanoparticles were prepared and creatively applied in the reductive dechlorination of Carbon Tetrachloride (CT). The characterization results of the synthesized composite indicated a main component of nZVI particles assembled on the surface of Fe3O4 with a layer of iron‐oxide film on the periphery, of which the dispersibility was better and the specific surface area was larger. The effects of different reaction conditions like temperature, initial pH values, Fe0@Fe3O4 dosage and initial CT concentrations on the removal of CT were evaluated. Under the optimum conditions, the Fe0@Fe3O4 composites showed a CT removal efficiency of 89.1% in 60 min, which was much greater than that of nZVI (61.7%) and Fe3O4 particles (14.3%). The removal process obeyed the pseudo‐first‐order kinetic model. Synergy effects of the constituents in the composite which can promote the relative rates of mass transfer to reactive sites were proposed to be existed and the magnetism of Fe3O4 could help to overcome the aggregation and surface passivation problem of nZVI. Thus, Fe0@Fe3O4 nanoparticles in our study can effectively complete the reductive dechlorination of CT and an improved nZVI catalyst is provided for the remediation of chlorinated organic compounds.

Study on the Law of Carbon Tetrachloride Migration in Groundwater System

Carbon tetrachloride (CCl 4 ) has a lot of toxic effects on the human body. According to our survey, the pollution of carbon tetrachloride in groundwater in the eastern part of Jinan City is serious. In this study, 40 sampling points were selected in the study area of 100km 2 , and carbon tetrachloride was detected in all sampling. The highest sampling point concentration as high as 20.87μ g / L . The concentration of carbon tetrachloride detected in 40 sampling points ranged from 1.68 to 20.87 μ g / L, and most of them exceeded the standard value of 2 μ g / L. In order to control the carbon tetrachloride pollution, a solute transport model was established by GMS software to predict the carbon tetrachloride pollution in the study area in the next 15 years. The results show that the concentration of carbon tetrachloride in the groundwater system will decrease to a certain extent, but there is still a considerable distance from the national standard, and the pollutants have tendency to migrate to the southeast and northwest.

Enhanced reductive degradation of carbon tetrachloride by carbon dioxide radical anion-based sodium percarbonate/Fe(II)/formic acid system in aqueous solution

The performance of sodium percarbonate (SPC) activated with ferrous ion (Fe(II)) with the addition of formic acid (FA) to stimulate the degradation of carbon tetrachloride (CT) was investigated. Results showed that CTcould be entirely reduced within 15 min in the system at a variety of SPC/Fe(II)/FA/CT molar ratios in experimental level. Scavenging tests indicated that carbon dioxide radical anion (CO2∙–) was the dominant reactive oxygen species responsible for CT degradation. CT degradation rate, to a large extent, increased with increasing dosages of chemical agents and the optimal molar ratio of SPC/Fe(II)/FA/CT was set as 60/60/60/1. The initial concentration of CT can hardly affect the CT removal, while CT degradation was favorable in the pH range of 3.0–9.0, but apparently inhibited at pH 12. Cl– and HCO 3 - of high concentration showed negative impact on CT removal. Cl– released from CTwas detected and the results confirmed nearly complete mineralization of CT. CT degradation was proposed by reductive C-Cl bond splitting. This study demonstrated that SPC activated with Fe(II) with the addition of FA may be promising technique for CT remediation in contaminated groundwater.

Simultaneous anaerobic transformation of carbon tetrachloride to carbon dioxide and tetrachloroethene to ethene in a continuous flow column

The simultaneous anaerobic transformation of tetrachloroethene (PCE) and carbon tetrachloride (CT) was evaluated in a continuous flow column. The column was packed with quartz sand and bioaugmented with the Evanite culture (EV) that is capable of transforming PCE to ethene. Azizian and Semprini (2016) reported that PCE and CT could be simultaneously transformed in the column, with PCE (0.1mM) transformed mainly to ethene and CT (0.015mM) to chloroform (CF) (20%) and an unknown transformation product, likely carbon dioxide (CO2). The fermentation of propionate, formed from lactate fermentation, was inhibited after the transformation of CT, likely from the exposure to CF. Reported here is the second phase of that study where a second bioaugmentation of the EV culture was made to reintroduce a lactate and propionate fermenting population to the column. Effective lactate and propionate fermentation were restored with a H2 concentration of ~25nM maintained in the column effluent. PCE (0.1mM) was effectively transformed to ethene (~98%) and vinyl chloride (VC) (~2%). Unlabeled CT (0.015 to 0.03mM) was completely transformed with a transient build-up of CF and chloromethane (CM), which were subsequently removed below their detection limits. A series of transient tests were initiated through the addition of carbon-13 labeled CT (13CT), with concentrations gradually increased from 0.03 to 0.10mM. GC–MS analysis of the column effluent showed that 13C labeled CO2 (13CO2) was formed, ranging from 82 to 93% of the 13CT transformed, with the transient increases in 13CO2 associated with the increased concentration of 13CT. A modified COD analysis indicated a lesser amount of 13CT (18%) was transformed to soluble products, while 13CO2 represented 82% the 13CT transformed. In a final transient test, the influent lactate concentration was decreased from 1.1 to 0.67mM. The transformation of both CT and PCE changed dramatically. Only 59% of the 13CT was transformed, primarily to CF. 13CO2 concentrations gradually decreased to background levels, indicating CO2 was no longer a transformation product. PCE transformation resulted in the following percentage of products formed: cDCE (60%), VC (36%), and ethene (4%). Incomplete propionate fermentation was also observed, consistent with the build-up of CF and the decrease in H2 concentrations to approximately 2nM. The results clearly demonstrate that high concentrations of CT were transformed to CO2, and effective PCE dehalogenation to ethene was maintained when excess lactate was fed and propionate was effectively fermented. However, when the lactate concentration was reduced, both PCE and CT transformation and propionate fermentation were negatively impacted.

树叶提取液制备纳米零价铁及处理含四氯化碳废水的研究

利用紫叶小檗树叶提取液绿色制备的纳米零价铁。采用正交试验探究紫叶小檗树叶提取液最佳提取条件，结果表明，提取因素的重要性依次为浸提温度 > 固液比 > 浸提时间 > 乙醇浓度。最佳试验组合为浸提温度50℃、乙醇和树叶的液固比为60:1 mL/g、浸提时间为30 min、乙醇浓度为40%。采用XRD、SEM、TEM及FT-IR对紫叶小檗树叶提取液和合成的纳米零价铁进行了分析表征。以四氯化碳废水为目标吸附物，检测合成的纳米零价铁对四氯化碳的吸附还原性能。考察了初始浓度、pH和投加量对吸附还原性能的影响。结果表明：当pH和投加量一定时，初始浓度为4 mg/L时，反应时间110 min时，合成的纳米零价铁对四氯化碳的降解率最高为98.19%。当四氯化碳初始浓度和零价铁的投加量不变的条件下，pH = 6.1，反应110 min时，降解率为99.6%。当四氯化碳初始浓度和pH一定时，投加量为0.12 g/L，降解率为97.89%。该还原反应符合一级反应动力学模型。 Nano zero-valent iron was synthesized by green methods based on purple leaf barberry leaves extract as a reducing agent and stabilizer. In order to explore the best extraction conditions of the purple leaf barberry leaves extract, we used orthogonal test. The results showed that the contributions of the factors to the polyphenols extracting could be list in descending order as follows: extraction temperature > solid-liquid ratio > extraction time > ethanol concentration. In addition, the best extracting conditions were temperature of 50˚C, ethanol and liquid solid ratio of leaves was 60:1 ml/g and leaching time was 30 min and ethanol concentration was 40%. Purple leaf barberry leaves extract and synthesis nano zero valent iron were analyzed and characterized by XRD, SEM, TEM and FTIR. Green synthesis of nano zero-valent iron adsorption performance was detected, by aiming at carbon tetrachloride adsorption. The influences of adsorption performance by the initial concentration, pH and dosing quantity were investigated. The result show that under the constant as pH and additive quantity, initial concentration of 4 mg/L, 110 min degradation reaction rate effect was 98.19%. When the initial concentration of carbon tetrachloride and zero-valent iron dosing quantity invariable condition, the optimum condition for pH is 6.1, the reaction of 110 min, the degradation rate was 99.6%. When carbon tetrachloride under the constant initial concentration and pH, the best dosing quantity is 0.12 g/L, the degradation rate is 97.89%. This reduction reaction is in line with the first order reaction kinetics model.

Fabrication of bimetallic Ag/Fe immobilized on modified biochar for removal of carbon tetrachloride

As an effective conventional absorbent, biochar exhibited limited adsorption ability toward small hydrophobic molecules. To enhance the adsorption capacity, a novel adsorbent was prepared by immobilizing nanoscale zero-valent iron onto modified biochar (MB) and then the elemental silver was attached to the surface of iron (Ag/Fe/MB). It's noted that spherical Ag/Fe nanoparticles with diameter of 51nm were highly dispersed on the surface of MB. As the typical hydrophobic contaminant, carbon tetrachloride was selected for examining the removal efficiency of the adsorbent. The removal efficiencies of carbon tetrachloride by original biochar (OB), Ag/Fe, Ag/Fe/OB and Ag/Fe/MB were fully investigated. It's found that Ag/Fe/MB showed higher carbon tetrachloride removal efficiency, which is about 5.5 times higher than that of the OB sample due to utilizing the merits of high adsorption and reduction. Thermodynamic parameters revealed that the removal of carbon tetrachloride by Ag/Fe/MB was a spontaneous and exothermic process, which was affected by solution pH, initial carbon tetrachloride concentration and temperature. The novel Ag/Fe/MB composites provided a promising material for carbon tetrachloride removal from effluent.