Dichromate Concentration Research Articles

Optimizing Cr(VI) reduction to Cr(III) using Pd-CNTs nanocatalyst: kinetic Monte Carlo simulation and experimental design insights

In this investigation, we explored the kinetics of Cr(VI) reduction to Cr(III) on carbon nanotube decorated with palladium (Pd-CNTs) nanocatalyst, using formic acid as the reducing agent. This study has been bone utilizing kinetic Monte Carlo simulation and experimental design methods. The mechanism and kinetic parameters of this reaction are provided. The effect various factors such as reaction time, pH level, dichromate (Cr2O72−) concentration, and formic acid concentration on Cr(VI) reduction was studied. Concentrations of HCOOH and Cr2O72− were identified as the crucial variables, while the HCOOH concentration has the most significant impact. Positive influences on Cr(VI) reduction were observed with increasing pH level and HCOOH concentration. Reaction time positively affects on Cr(VI) reduction efficiency. However, the concentration of Cr2O72− showed an increasing effect up to a threshold, negatively impacting the efficiency. The optimal conditions (Reaction time = 60 min, pH = 4.5, [Cr2O72−] = 5.05 × 10−3 M, and [HCOOH] = 0.95 M) for Cr(VI) reduction. At optimal conditions, the Cr(VI) reduction efficiency was obtained to be 100%.

Behaviors and Mechanisms of Adsorption of MB and Cr(VI) by Geopolymer Microspheres under Single and Binary Systems.

Geopolymers show great potential in complex wastewater treatment to improve water quality. In this work, general geopolymers, porous geopolymers and geopolymer microspheres were prepared by the suspension curing method using three solid waste products, coal gangue, fly ash and blast furnace slag. The microstructure, morphology and surface functional groups of the geopolymers were studied by SEM, XRD, XRF, MIP, FTIR and XPS. It was found that the geopolymers possess good adsorption capacities for both organic and inorganic pollutants. With methylene blue and potassium dichromate as the representative pollutants, in order to obtain the best removal rate, the effects of the adsorbent type, dosage of adsorbent, concentration of methylene blue and potassium dichromate and pH on the adsorption process were studied in detail. The results showed that the adsorption efficiency of the geopolymers for methylene blue and potassium dichromate was in the order of general geopolymers < porous geopolymers < geopolymer microspheres, and the removal rates were up to 94.56% and 79.46%, respectively. Additionally, the competitive adsorption of methylene blue and potassium dichromate in a binary system was also studied. The mechanism study showed that the adsorption of methylene blue was mainly through pore diffusion, hydrogen bond formation and electrostatic adsorption, and the adsorption of potassium dichromate was mainly through pore diffusion and redox reaction. These findings demonstrate the potential of geopolymer microspheres in adsorbing organic and inorganic pollutants, and, through five cycles of experiments, it is demonstrated that MGP exhibits excellent recyclability.

Identifying applicability viscoelastic systems in the context of improving well casing processe

The object of research in this study is viscoelastic systems used as spacer systems in well casing during drilling. Polymer network-metal ion systems display distinctive properties, facilitating effective well coverage through their normal stresses. The primary problem addressed in this research was optimizing viscoelastic system composition for well casing. Researchers sought the ideal sodium dichromate concentration to maximize viscosity in polyacrylamide-based spacer fluids. This optimization is crucial for enhancing casing cementing quality, especially in challenging geological conditions. Utilizing a precise HAAKE MARS III rheometer, various tests, including shear, oscillatory, frequency, creep, and recovery tests, were performed to assess viscoelastic system rheology. Obtained results of optimal deformation interval for a solution with sodium bichromate is 40 Pa and aluminum sulfate, the yield strength was equal to 110 Pa. This research optimized cross-linker concentration, increasing spacer system viscosity. This enhancement improves well cementing efficiency and allows for operation in challenging geological conditions. The precise rheometer unveiled previously unexplored rheological characteristics. The optimized viscoelastic spacer fluid is invaluable in well casing, especially in challenging geological settings. This research guides the design of process fluids, enhancing casing cementing quality, and improving drilling efficiency and safety. Engineers and researchers can leverage the rheological data for informed decisions and better field performance

Potential of sodium dichromate and sodium silicate to control in vitro growth of Bacillus cereus, a metal corrosion-causing bacterium

Abstract. Ciawi Y, Inabuy FS, Teriyani NM, Ramona Y. 2023. Potential of sodium dichromate and sodium silicate to control in vitro growth of Bacillus cereus, a metal corrosion-causing bacterium. Biodiversitas 24: 1530-1537. The maintenance cost of metal-based objects in industrial and construction sectors has been found to significantly increase due to corrosion. Most corrosion is caused by metal oxidation, and about 2% of this corrosion is induced by microbial activity (MIC). The main objectives of this research were to isolate, and identify corrosion-causing bacteria, and to find out the optimum concentration of sodium dichromate and sodium silicate to control their growth in vitro. These compounds have been used to protect the metal surface from corrosion caused by non-microbial-induced corrosion. Three different bacterial isolates were obtained in this study and the black colony (the predominant isolate) was further investigated in the determination of their optimum inhibitory concentrations. Application of sodium dichromate and sodium silicate at the rates of 0.1% w/v and 2% w/v, respectively were found to be optimum to inhibit the in vitro growth of this black bacterial isolate in our study. The predominant isolate found in our study was identified as Bacillus cereus, following the alignment of its 16s rDNA sequence with those deposited at the GenBank (NCBI). Additionally, Enterobacter asburiae was also found on the surface of corroded water tanks.

New machine learning-based automatic high-throughput video tracking system for assessing water toxicity using Daphnia Magna locomotory responses

Daphnia magna is an important organism in ecotoxicity studies because it is sensitive to toxic substances and easy to culture in laboratory conditions. Its locomotory responses as a biomarker are highlighted in many studies. Over the last several years, multiple high-throughput video tracking systems have been developed to measure the locomotory responses of Daphnia magna. These high-throughput systems, used for high-speed analysis of multiple organisms, are essential for efficiently testing ecotoxicity. However, existing systems are lacking in speed and accuracy. Specifically, speed is affected in the biomarker detection stage. This study aimed to develop a faster and better high-throughput video tracking system using machine learning methods. The video tracking system consisted of a constant temperature module, natural pseudo-light, multi-flow cell, and an imaging camera for recording videos. To measure Daphnia magna movements, we developed a tracking algorithm for automatic background subtraction using k-means clustering, Daphnia classification using machine learning methods (random forest and support vector machine), and tracking each Daphnia magna location using the simple online real-time tracking algorithm. The proposed tracking system with random forest performed the best in terms of identification (ID) precision, ID recall, ID F1 measure, and ID switches, with scores of 79.64%, 80.63%, 78.73%, and 16, respectively. Moreover, it was faster than existing tracking systems such as Lolitrack and Ctrax. We conducted an experiment to observe the impact of toxicants on behavioral responses. Toxicity was measured manually in the laboratory and automatically using the high-throughput video tracking system. The median effective concentration of Potassium dichromate measured in the laboratory and using the device was 1.519 and 1.414, respectively. Both measurements conformed to the guideline provided by the Environmental Protection Agency of the United States; therefore, our method can be used for water quality monitoring. Finally, we observed Daphnia magna behavioral responses in different concentrations after 0, 12, 18, and 24 h and found that there was a difference in movement according to the concentration at all hours.

Optimization of Zinc and Germanium Recovery Process from Zinc Oxide Dust by Response Surface Methodology

AbstractBased on the problems existing in the existing process, the ultrasonic field enhanced potassium dichromate atmospheric leaching of zinc and germanium in zinc oxide dust was studied, and three main factors (liquid‐solid ratio, leaching temperature and potassium dichromate concentration) were optimized by the Box‐Behnken design (BBD) model. XRD, ICP‐OES, EPMA and SEM results show that the occurrence state of Ge is highly correlated with ZnS. Promoting the dissolution of ZnS is the basis for improving the leaching rates of Zn and Ge. Finally, under the conditions of liquid‐solid ratio of 7 mL/g, leaching temperature of 90 °C and potassium dichromate concentration of 19.16 g/L, the leaching rates of zinc and germanium were 99.968 % and 90.395 %, respectively. The error between the prediction results of the quadratic model and the experimental results is small, and the correlation coefficients are greater than 0.99, indicating that the model is credible.

Purge and trap in-tube colorimetric detection method for the determination of ethanol in alcoholic and non-alcoholic beverages

• Purge and trape coupled with smartphone-based detection were for the first time introduced for ethanol analysis. • Improvements in mass transfer efficiency were achieved with low reagent consumption. • The methodology showed good reproducibility with low operational costs. • The workflow is easily performed and it is suitable for low-source countries. • A low limit of detection (0.05 %v/v) was achieved. A simple and cost-effective analytical approach based on the combination of purge and trap technique coupling with smartphone-based image analysis was developed for the sensitive detection of ethanol. Herein, the dichromate solution was used as the detection reagent to determine the ethanol concentration in alcoholic beverages. The ethanol from the sample solution was purged by the airstream and then trapped into a 1-mL Eppendorf tube containing the detection reagent. During the process, ethanol is oxidized by dichromate reagent to form ethanoic acid, and the orange color of the dichromate ion is started to become darker after one minute. The color image of the Eppendorf tube was taken by smartphone in a controlled-light box and then analyzed by the laptop ImageJ software. Experimental parameters affecting the method sensitivity, such as extraction time, stirring rate, and dichromate concentration, were studied. Under the optimal conditions, the calibration curve was linear for the ethanol concentrations ranging from 0.15 and 3.0 %v/v (R 2 >0.993). The limit of detection of 0.05 %v/v was obtained. The intra- and inter-assay results (RSD%) were less than 1.0% and 2.0%, respectively. The developed approach has been successfully applied to determine ethanol percentage in beverage samples (alcoholic beer, brandy, and non-alcoholic beer), with relative recoveries ranging from 86-112%. Finally, the accuracy was assessed by comparison of the results obtained by our method and the UV-Vis spectrophotometric method, which agreed at the 95% confidence level.

Bioaccumulation of Heavy Metals in Some Tissues of Fish, Clarias batrachus Exposed to Sub-lethal Concentration of Nickel Sulphate and Potassium Dichromate

Bioaccumulation of Heavy Metals in Some Tissues of Fish, Clarias batrachus Exposed to Sub-lethal Concentration of Nickel Sulphate and Potassium Dichromate

Enhanced biogeogenic controls on dichromate speciation in subsoil containment.

In general, lab-based Cr (VI) reduction studies do not often corroborate the prevailing biogeochemical controls for on-site pollution abatement. To promulgate its importance, herein, we investigate the existing biogeogenic parameters of a contaminated site to attenuate the underground Cr (VI) toxicity. This study significantly assesses the speciation of dichromate by biogenic agents that are inherent and self-sustaining to treat the contaminated soil. Herein, a group of bacteria exposed to high concentrations of chromium (≥3500mg/L) plays a vital role as an enhanced biogeogenic control for the detoxification of toxic Cr (VI). All identified bacteria were screened based on their ability to differentiate from extracellular speciation and harvested in a Cr (VI)-enriched molasses to achieve dichromate concentrations as low as 0.05mg/L in 168h. Under low O2 condition, the bacterial growth rate and doubling time were monitored to establish the half-life period of Cr (VI) for adequate containment treatment. Furthermore, to understand the soil decontamination, Cr (VI) reactive transport was demonstrated to facilitate the contaminant reduction under both saturated and unsaturated groundwater conditions. Herein, Cr (VI) speciation to Cr (III) by the influence of abiogenic factors are unlikely or less probable as studied in existing geogenic conditions. Moreover, the evidence of biogenic reduction of Cr (VI) in microcosm suggests its effectiveness in enhanced detoxification of Cr (VI) up to≤0.1mg/L, within the reaction period of 144h and 192h, for saturated and unsaturated flow conditions, respectively.

Development of a reference material for the composition of 0.1 m potassium dichromate solution. Certified reference material GSO 10992-2017

This paper describes key stages in the development and investigation of a high-precision certified reference material (CRM) for the composition of potassium dichromate solution. The proposed reference material (RM) exhibits metrological traceability to the units of the International System of Units (SI). Not requiring additional preparation before use, the CRM is convenient for use as a titrant in redox titration. The metrological characteristics of the developed CRM were determined by the direct primary method of coulomet-ric titration using the State Primary Standard GET 176. The interval of permissible certified values of the molar concentration of potassium dichromate in the CRM under study is found to vary from 0.098 mol/dm 3 to 0.102 mol/ dm 3 . The relative expanded uncertainty (k = 2) of the certified value ofpotassium dichromate molar concentration is calculated to be 0.024 %, with relative standard uncertainties caused by long-term and short-term instability each being equal to 0.0044 %. The shelf life of the developed CRM is found to be 1 year, provided that storage conditions are ensured. A procedure for measuring the molar concentration ofpotassium dichromate is described, along with the equipment used. A comprehensive uncertainty budget for the measurements is assembled. The developed CRM is included into the State Register of Certified Reference Materials under the number GSO 10992-2017. The CRM can be used for transferring the mass (molar) concentration unit of a component to RMs and chemical reagents via oxidation-reduction reactions; the verification and calibration of measuring instruments (MI), as well as control of metrological characteristics during MI trials including type approval; MI graduation; validation of measurement procedures; control of measurement results when determining the mass (molar) fraction and mass (molar) concentration of components in liquid and solid substances and materials.

Gelation behavior as a function of concentration of sodium thiosulfate for PAM gels cross-linked with chromium

Existing reducing agents for cross-linking polymers are expensive and toxic and mostly limited for water shut off applications. A gelation study was performed on a safer, cheaper, more soluble, and short-lived gel by cross-linking polyacrylamide and chromium as a cross-linking agent using a rheometer and bead-pack porous media. The effect of concentration of sodium thiosulfate as the reducing agent was investigated to determine conditions for optimum yield strength and the gelation time and behavior which has never been published before. For a fixed minimum concentration (for the gel to form) of polyacrylamide and sodium dichromate, the gel yield strength vs. sodium thiosulfate concentration showed a somewhat bell-shaped curve initially increasing, reaching a peak at 2000 ppm, and then starting to decrease. The gelation formed by sodium thiosulfate was comparatively weak and short lived as compared to the ones formed by other reducing agents. Gel started to form instantaneously, reached a peak in 2 h, began to decrease, and then stabilized at 40 cp. The mobility reduction trends were similar to the yield strength curve. The short-lived gel could be useful to improve the waterflood mobility ratio far away from the wellbore without compromising on ease of injectivity.

Reduction–Oxidation of Chromium Ions in Aqueous Solution by Treatment with Atmospheric-Pressure Direct-Current Discharge in Argon

Kinetic features of the oxidation–reduction processes of chromium ions in a potassium dichromate aqueous solution subjected to treatment in argon atmospheric-pressure dc discharge have been investigated in the discharge current range of 20–80 mA and the dichromate concentration range of 0.1–0.5 mmol/L. The solution served as the discharge cathode. It has been revealed that the discharge treatment stimulates the reduction reactions of Cr6+ to Cr3+ ions and the reverse reactions of oxidation of Cr3+ to Cr6+ ions; i.e., the oxidation–reduction reactions are reversible. The limiting degree of reduction of Cr6+ ions has been found to depend on the discharge current and the initial concentration of the solution. The apparent rate constants of oxidation and reduction have been determined, and the energy efficiency of the process has been evaluated. The data are compared with the results obtained earlier for a discharge in air.

Highly sensitive SERS determination of chromium(VI) in water based on carbimazole functionalized alginate-protected silver nanoparticles

An easily manipulated method was developed to synthesize silver nanoparticles (AgNPs) by using sodium alginate (SA) to perform the dual role of reducing and protecting agent. Using SA-protected AgNPs as substrates, a simple and ultra-sensitive surface-enhanced Raman scattering (SERS) method was established for the determination of Cr(VI) in water. The method is based on redox reaction of carbimazole with Cr(VI). In the presence of Cr(VI), the SERS signal of carbimazole decreases with the increase of dichromate concentration, so as to achieve the purpose of indirect determination of Cr(VI). The volume of AgNPs, the acidity of the system and the concentration of NaCl solution were optimized. Under optimum conditions, a good linearity (r = 0.993) in the range of 1.71–171 × 10−9 mol L−1 was obtained and the limits of detection (LOD) is 1.01 × 10−9 mol L-1. The method was applied to the determination of Cr(VI) in water, with recoveries between 97.9–104.0% and with relative standard deviations of <4.0% (n = 5).

The impact of kraft pulping effluent on egg survival and hatching success in two species of Clupeiformes (Teleostei).

The anchoveta (Engraulis ringens) and sardine (Strangomera bentincki) are coastal pelagic species with important spawning areas off the coast of Chile. The discharge of secondary-treated effluents from a kraft pulp plant near one of these spawning areas has raised environmental concerns. Therefore, effluent effects on the development of anchoveta and sardine eggs were assessed by in vitro exposure. Eggs were sampled between 2007 and 2010 off Talcahuano, Chile. Subsequent toxicity tests (96h duration, 12°C) were performed using increasing effluent concentrations, a filtered seawater control, and two potassium dichromate concentrations (to verify consistent embryonic sensitivity). Egg mortality and hatching success were evaluated. For anchoveta, mortality (9.9 ± 7.1%) did not significantly differ among groups in five toxicity tests except the final toxicity test that showed significant differences in mortality (5.6% control vs 27.8% in 100% effluent). For sardines, no differences in mortality existed between the effluent dilutions (2.6 ± 3.6%) and control (6.3 ± 3.9%). Notably, anchoveta egg survival and hatching success rates were inconsistent, i.e., the highest rates of hatching failure occurred on the same sampling date with the highest rates of survival for the 100% effluent group (72%). In conclusion, the obtained results indicate that (i) anchoveta egg mortality and hatching failure increase only under 100% effluent exposure, coinciding with decreased egg quality near the end of spawning season and (ii) high effluent dilutions not significantly increase sardine and anchoveta egg mortalities. Nevertheless, the recorded adverse effects to the hatching process should be studied in greater detail, particularly considering interspecific variability and the complexity of reproductive processes, especially during early development.

Effect of Lattice Structure of Bismuth Sesquioxide on the Electrochemical Energy Storage Characteristics

Bismuth sesquioxide (Bi2O3) exists in different polymorphs such as monoclinic α phase, tetragonal β phase, face centered cubic (fcc) δ phase, and body centered cubic (bcc) γ phase. The stable phase at room temperature is α- phase, and at temperatures between 729-824 °C the δ phase is stable. Other phases are metastable which transform from the δ phase during the cooling cycle. The metastable phases can be stabilized at room temperature either by doping with aliovalent cations in the Bi2O3 lattice or by controlling the synthesis parameters. Bi2O3 polymorphs are used in several engineering applications such as electrode materials for sensors, photocatalysts, and solid state electrolytes for fuel cells. Furthermore, Bi2O3 is a building block for advanced ferroelectric, and multiferroic materials. Our modeling calculations suggest that β-Bi2O3 could show auxetic behavior in certain crystallographic planes. Bi2O3 has been investigated as a potential supercapacitor electrode material because of its promising theoretical specific capacitance (1370 F/g). Depending on the morphology and the matrix in which a composite structure was formed, the reported capacity varied from 94 – 332 F/g [[1], [2]]. Most of the investigations focused on the morphology of the Bi2O3 or the composite structure of the electrode. The investigated material was either alpha [[3]] or delta phase [[4]], but no particular attention was given to the crystal structure. The effect of the lattice structure of the Bi2O3 on the energy storage properties was not investigated in detail to the best of our knowledge. A recent report focused on the engineered lattice defects to enhance the capacitance [4]. In this presentation, the results of electrochemical energy storage behavior of Bi2O3 electrodes prepared in the form of pure α-phase, a mixture of α+β, β-phase, and δ by electrodeposition will be reported. The α-Bi2O3 thin film specimens were electrodeposited on to ITO-coated glass surfaces under galvanostatic condition at +5 mA/cm2 in a 100 ml solution containing 0.1 M bismuth nitrate, 0.2 M tartaric acid, and NaOH to adjust the pH to 12.0 at room temperature. In order to obtain β-Bi2O3 deposition, 0.05 M of Na2Cr2O7 was added to the solution used for electrodepositing the α-phase and the electrodeposition was carried out under galvanostatic condition at 45 °C. Thin film electrodeposits with mixed α+β phases were obtained by varying the dichromate concentration in the electrolyte. The δ-Bi2O3 was obtained by using a pH:14 solution containing bismuth salt on to a fcc lattice substrate (austenitic stainless steel) at 65 °C, following a similar procedure reported by Helfen et al. [[5]]. Cyclic voltammetry, and galvanostatic charge-discharge experiments were carried out on the thin film Bi2O3 specimens in 0.5 M LiCl + 0.1 M NaOH solution at room temperature. The β-Bi2O3 specimens showed significantly higher specific capacitance than the α-Bi2O3. The electrochemical behavior of different phases will be discussed based on the impedance spectroscopy, and Mott-Schottky results before and after charge-discharge cycles. [1] S. X. Wang, C. C. Jin, W. J. Qian, J. Alloys Compd. 2014, 615, 12 [2] M. Ciszewski, A. Mianowski, P. Szatkowski, G. Nawrat, J. Adamek, Ionics 2015, 21, 557. [3] S.T. Senthilkumar, R. Kalai Selvan, M. Ulaganathan, J.S. Melo, Electrochimica Acta 115 (2014) 518– 524 [4] R. Liu, L. Ma, G. Niu, X.-L. Li, E. Li, Y.Bai, G. Yuan, Adv. Funct. Mater. 2017, 27, 1701635 [5] A. Helfen et al., Solid State Ionics 176 (2005) 629–633

Flow Injection Amperometric System Coupled with a Well-Plate for Fast Screening of Total Antioxidant Capacity

ABSTRACTA flow injection (FI) system with an amperometric detection in combination with a 96-well-plate has been developed for high throughput screening of total antioxidant capacity. It is based on the reaction between dichromate and antioxidants Chromium reducing antioxidant capacity (CHROMAC) assay. Antioxidant reduces dichromate leading to a decrease of dichromate concentration, in which reacts further with triiodide reagent. The slow reaction between antioxidant and dichromate takes place in parallel in a 96-well microplate, with the reaction time sufficiently long to reach steady state conditions. Microliter volumes of the remaining dichromate solution were manually injected into the FI amperometric system. Reaction with iodide in acidic medium produces triiodide which undergoes electrochemical reduction on a glassy carbon working electrode at 200 mV versus a Ag/AgCl reference electrode. The decrease of electrical current was directly proportional to the antioxidant capacity. The optimum conditions have been achieved as follow: 160 mg L−1 of potassium dichromate, pH of dichromate solution of 2.82, 0.005 mol L−1 of potassium iodide, 0.20 mol L−1 of hydrochloric acid, and 3.0 mL min−1 total flow rate. The developed method was applied for the determination of total antioxidant capacity of tea and herbal infusions and fruit juice samples. The results obtained indicated that the developed method had good correlation with the batch CHROMAC spectrophotometric method and 1,1-diphenyl-2-picrylhydrazyl scavenging assay. The proposed method provides fast and high throughput analysis, convenient operation, and low consumption of chemical reagents and samples.

Current efficiency of individual electrodes in the sodium chlorate process: a pilot plant study

Current efficiency in the sodium chlorate process is a key issue in the evaluation of the power consumption. A pilot cell unit for executing the sodium chlorate process was constructed to study the current efficiency of the anode and cathode separately. The effects of sodium dichromate and sodium sulphate concentrations and the electrolyte temperature on the anode and cathode current efficiencies were studied. Corrosion products formed on the mild steel cathodes after their removal from the cell were characterised using X-ray diffraction and infrared spectroscopy. The results show that the cathodic current efficiency increases with increasing dichromate concentrations in the electrolyte until approximately 5 g dm−3 is reached. At this optimum concentration of dichromate, the presence of sulphate ions decreases the cathodic current efficiency. For moderate increases in temperature, the cathodic current efficiency increases, but oxygen evolution is promoted, and the power consumption also increases. Surface characterisation of the electrodes after their exposure to air shows two primary types of behaviour, depending on the process parameters. At low dichromate concentrations, amorphous corrosion layers are formed, while at higher concentrations, reduced forms of iron hydroxides, i.e., “green rust”, are identified. Although the electrodes were positioned at the open circuit potential for 40 min before their removal from the cell, chromium remains on the cathode surface. This result might explain the corrosion-inhibiting effect of the addition of chromate to the electrolyte. The results from this study can be used to optimise operating procedures in real plants, decrease the energy consumption and minimise the environmental impact of these processes.Graphical

The catalyzing effect of chromate in the chlorate formation reaction

Electrolyte used in the manufacturing process of sodium chlorate contains chromate primarily to inhibit cathodic loss reactions. Chromate also accelerates the chlorate formation reaction which reduces the concentration of hypochlorite species in the chlorate cell leading to enhanced anodic current yield, reduced risk of oxygen explosions and reduced cost for the purification of the cell gas.Laboratory scale trials show that the rate of chlorate formation can be described as an ‘uncatalyzed’ third order reaction with respect to hypochlorite species and a parallel chromate catalyzed reaction of apparent reaction order 2.2. Validation is presented based on data from electrolysis trials in pilot plant and bench scale at technically relevant conditions. If the dichromate concentration is increased from 0 to 5g/L, more than 50% of the chlorate may be formed via the chromate catalyzed path and the apparent reaction order changes from 3 to about 2.4. The kinetic effect of the chromate species also lowers the optimum reaction pH below that of the uncatalyzed reaction. Furthermore, anionic hypochlorite does not seem to be necessary to generate chlorate via the chromate catalyzed path.Other hypochlorite consuming reactions such as anodic and homogeneous oxygen formation as well as cathodic reduction and desorption of chlorine species in the cell gas only have a marginal effect on the hypochlorite concentration in the chlorate cell.

Toxic effects of potassium dichromate on loach fin cell lines with different ploidies in vitro

PDF HTML阅读 XML下载 导出引用 引用提醒 重铬酸钾对不同倍性泥鳅鳍细胞系的毒性效应 DOI: 作者: 作者单位: 1. 大连海洋大学 辽宁省海洋生物资源恢复与生境修复重点实验室, 辽宁 大连 116023;2. 大连海洋大学 农业部北方海水增养殖重点实验室, 辽宁 大连 116023 作者简介: 吴迪(1991-),女,硕士,专业方向为海洋生物学.E-mail:15842623565@163.com 通讯作者: 中图分类号: X171 基金项目: 国家自然科学基金项目（31272650）. Toxic effects of potassium dichromate on loach fin cell lines with different ploidies in vitro Author: Affiliation: 1. Key Laboratory of Marine Bio-resource Restoration and Habitat Reparation in Liaoning Province, Dalian Ocean University, Dalian 116023, China;2. Key Laboratory of Mariculture, Ministry of Agriculture;Dalian Ocean University, Dalian 116023, China Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:以二倍体和三倍体泥鳅（）鳍细胞系（DIMF和TRMF）为实验材料，研究了重铬酸钾对细胞的氧化损伤、微核形成以及金属硫蛋白表达情况的影响，旨在多角度探讨重铬酸钾对细胞系的毒性效应，建立适合监测其污染情况的指标。采用MTT法测定了细胞的半数抑制浓度；使用试剂盒测定了3种主要抗氧化酶活性；吉姆萨染色后观察了细胞微核的变化，并通过实时定量PCR方法测定了金属硫蛋白的表达情况。结果表明，24 h急性毒性实验两种细胞系的半抑制浓度分别为（25.3±1.2）μmol/L、（27.9±0.6）μmol/L，DIMF对重铬酸钾的敏感性要高于TRMF。当重铬酸钾浓度为0~30 μmol/L时，二个细胞系的超氧化物歧化酶（SOD）活性随染毒浓度升高而升高。当重铬酸钾浓度为0~20 μmol/L时，谷胱甘肽过氧化物酶（GSH-Px）活性逐渐升高，浓度为30~40 μmol/L时，其活力开始下降。两种细胞系的谷胱甘肽S转移酶（GST）活性随重铬酸钾浓度增大逐渐降低。二倍体细胞系氧化酶活性均低于三倍体。微核试验显示，重铬酸钾可引起细胞核损伤，形成微核。当重铬酸钾浓度为40 μmol/L时，DIMF、TRMF微核率达到最大，分别为7.33‰和8.00‰，DIMF微核率要低于TRMF。实时定量PCR结果显示，对照组金属硫蛋白（<0.01）。 Abstract:Waste water discharge containing chromium can lead to chromium polluted regional water. Because of the accumulation and enrichment of chromium, fish and other aquatic organisms can be injured seriously in polluted water, and chromium can cause toxic effects or death in humans if ingested. Chromium mainly refers to Cr6+, which exists as a noncatalytic form or as potassium dichromate. Fish, such as loach and carp, are commonly used to detect chromium, but few reports have used fish cell lines. Previous studies have revealed that cells cultured are homogeneous, respond quickly, and are convenient to use. In this study, loach fin cell lines established from diploids and triploids (DIMF and TRMF) were used to assess the toxic effects of potassium dichromate . The purpose of this study was to establish suitable indicators to monitor chromium pollution. The concentration that inhibited 50% of the cells (IC50) was determined using the thiazolyl blue (MTT) method, the activities of three main antioxidants were tested with kits, the changes in cell nuclei were observed after Giemsa staining, and expression of the metallothionein () gene was measured by real-time polymerase chain reaction (PCR) analysis. The results showed that the 24-h IC50 values of DIMF and TRMF were (25.3±1.2) mol/L and (27.9±0.6) μmol/L, respectively; the sensitivity of DIMF to potassium dichromate was higher than that of TRMF, and the sensitivities of the two cell lines were higher than those of loach in vivo. Superoxide dismutase (SOD) activities in the two cell lines increased as the potassium dichromate concentration was increased from 0 to 30 μmol/L. Glutathione peroxidase (GSH-Px) activities increased in the two cell lines as the potassium dichromate concentration was increased from 0 to 20 μmol/L; however, GSH-Px activities decreased when concentration was 30-40 μmol/L. Glutathione S-transferase (GST) activities in the two cell lines decreased gradually as the potassium dichromate concentration was increased. Overall, the enzymatic activities of DIMF were lower than those of TRMF. Potassium dichromate caused nuclear damage and micronuclei formed. The maximum rates of micronuclear formation in DIMF and TRMF were 7.33‰ and 8.00‰, respectively when the potassium dichromate concentration was 40 μmol/L. The rate of micronuclear formation was lower in DIMF than that in TRMF. The real-time PCR results showed that MT gene expression in the control group was very low, but increased significantly in response to potassium dichromate stress (<0.01). MT gene expression was maximal in response to 30 μmol/L potassium dichromate and was 49.9-and 50.7-times higher than that of the control group, respectively. However, the difference between DIMF and TRMF was not significant. 参考文献 相似文献 引证文献

Effect of plasma treatment and grafting of β-cyclodextrin on color properties of wool fabric dyed with Shrimp shell extract

The aim of this study was to evaluate the effect of low temperature plasma (LTP) treatment and grafting of beta-cyclodextrin (β-CD) on dyeing and fastness properties of wool fabrics using natural dye extracted from shrimp shell. Aluminum sulfate, iron sulfate, tin chloride, copper sulfate, and sodium dichromate were used as mordant and the dyeing of samples was conducted after the pre-mordanting process. Scanning electron microscopy and Fourier transform infrared spectroscopy (FTIR) were used to study the morphological and chemical changes of the fibers. Also, the antimicrobial properties of fabrics were quantitatively evaluated against Staphylococcus aureus according to AATCC 100-1993 test method. The results showed using of sodium dichromate as mordant could be attained to green shade after dyeing fabrics. The color difference and color strength of samples were improved by increasing the sodium dichromate concentration and β-CD in the after-treatment process. FTIR analysis indicated a significant increase in the absorption peak of hydroxyl group after grafting of β-CD on LTP-treated samples. Antimicrobial results of samples indicated that LTP-treated fabric demonstrated no antimicrobial behavior, while the dyed and β-CD-grafted sample possessed significant reduction in the number of bacteria. Moreover, the β-CD-treated samples showed very good to excellent light and washing fastness properties.