Showing papers on "Potassium dichromate published in 2012"

Photocatalytic reduction of hexavalent chromium in aqueous solutions with zinc oxide nanoparticles and hydrogen peroxide

Abstract: Photocatalytic reduction of Cr(VI) to Cr(III) in aqueous solutions under UV irradiation and ZnO semiconductor catalyst was investigated using potassium dichromate as a model compound. The effects of pH, catalyst dose (0.05−0.15 g/dm), Cr(VI) initial concentration (0.1−15 mg/dm) and hydrogen peroxide concentration on photocatalytic reduction of Cr(VI) were investigated. The reduction rate of chromium was more favorable in acidic solution. Hydrogen peroxide was added as a reduction reagent for enhancement of the photoreduction. The process of photoreduction of Cr(VI) approximately followed first-order kinetics. Drinking water samples and wastewater were collected and photocatalytically treated for reduction of Cr(VI).

Stool sample storage conditions for the preservation of Giardia intestinalis DNA

Abstract: Stool is chemically complex and the extraction of DNA from stool samples is extremely difficult. Haemoglobin breakdown products, such as bilirubin, bile acids and mineral ions, that are present in the stool samples, can inhibit DNA amplification and cause molecular assays to produce false-negative results. Therefore, stool storage conditions are highly important for the diagnosis of intestinal parasites and other microorganisms through molecular approaches. In the current study, stool samples that were positive for Giardia intestinalis were collected from five different patients. Each sample was stored using one out of six different storage conditions [room temperature (RT), +4oC, -20oC, 70% alcohol, 10% formaldehyde or 2.5% potassium dichromate] for DNA extraction procedures at one, two, three and four weeks. A modified QIAamp Stool Mini Kit procedure was used to isolate the DNA from stored samples. After DNA isolation, polymerase chain reaction (PCR) amplification was performed using primers that target the β-giardin gene. A G. intestinalis-specific 384 bp band was obtained from all of the cyst-containing stool samples that were stored at RT, +4oC and -20oC and in 70% alcohol and 2.5% potassium dichromate; however, this band was not produced by samples that had been stored in 10% formaldehyde. Moreover, for the stool samples containing trophozoites, the same G. intestinalis-specific band was only obtained from the samples that were stored in 2.5% potassium dichromate for up to one month. As a result, it appears evident that the most suitable storage condition for stool samples to permit the isolation of G. intestinalis DNA is in 2.5% potassium dichromate; under these conditions, stool samples may be stored for one month.

In situ Carica papaya stem matrix and Fusarium oxysporum (NCBT-156) mediated bioremediation of chromium

Abstract: Removal of heavy metal chromium was carried out using the fungus Fusarium oxysporum NCBT-156 strain isolated from soil of leather tanning effluent in in situ condition using potassium dichromate solution with 10 per cent Czapek-dox liquid medium. Biosorbent matrix was developed using Carica papaya plant dry stem to colonize the fungal strain to facilitate bioabsorption process. Bioabsorption of chromium was by metabolically mediated intracellular accumulation process. Maximum efficiency of chromium removal by biosorption upto 90 per cent was achieved at the end of 5th day of incubation (120 h of contact time) for 100 and 200 ppm concentration, upto 80 per cent for 300 and 400 ppm, and upto 65 per cent for 500 ppm to 1000 ppm concentrations with pH ranging from 5.8, 5.6, 5.5, 5.4 and 5.2, respectively for 100, 200, 300, 400, 500-1000 ppm concentration. SDS-PAGE protein profile showed significant difference in 34 kDa protein band after chromium absorption by the fungus. FTIR spectroscopic analysis revealed that the main functional groups involved in the uptake of chromium by F. oxysporium strain were carbonyl, carboxyl, amino and hydroxyl groups.

Antibacterial activity of Cr2O3 nanoparticles against E.coli; Reduction of chromate ions by Arachis hypogaea leaves

Abstract: Chromium oxide nanoparticles (NPs) were rapidly synthesized by reduction of potassium dichromate solution with Arachis hypogaea leaf extract containing reducing sugars which act as reducing agent. The results indicated that the aldehyde groups present in the plant extract played an important role in the formation of Cr2O3 nanoparticles. The purification process of the Cr2O3 product does not require expensive methods, since a solid product is obtained from a reaction in liquid phase. The antibacterial effect of Cr2O3 nanoparticles against Escherichia coli was investigated as a model for Gram-negative bacteria. Bacteriological tests were performed in Potato Dextrose Agar (PDA) medium on solid agar plates and in liquid systems supplemented with different concentrations of nanosized Cr2O3 particles. These particles were shown to be an effective bactericide. The resulting Cr2O3 nanoparticles were characterized by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), UV-VIS absorption and Fouriertransform infrared (FTIR) spectroscopy.

Genotoxic and Mutagenic Assessment of Hexavalent Chromium in Fish Following In Vivo Chronic Exposure

Abstract: Chromium is a well-documented carcinogen. To evaluate the genotoxic potential of hexavalent chromium on an aquatic bio-system, freshwater murrel fish (Channa punctatus) were exposed to potassium dichromate. The 96-h LC50 for potassium dichromate was 61.80 mg/L for the test fish in a static system. On the basis of the 96-h LC50, fish were exposed to sublethal concentrations of the test chemical. Fish exposed to the test chemical were sampled on days 1, 7, 14, 21, and 28 post-exposure and blood and gill cells were collected. Significantly (p < .05) higher DNA damage in both lymphocyte and gillcells and micronuclei formation in whole blood was observed at different test concentrations and sampling times of the test chemical as compared to control fish. The mean% tail DNA in the comet tail assay showed a concentration-dependent increase and the maximum% tail DNA was observed on day 7 of exposure in both cells. A similar trend was also observed in micronuclei induction in blood with maximum induction ...

Effect of Potassium Dichromate on the Survival and Reproduction of Daphnia magna

Abstract: An attempt was made to evaluate chronic effect of Potassium dichromate on Daphnia magna, semi-statically. Based on the results of an acute immobilisation study (48 hour EC50), the test item concentrations of 0.03, 0.05, 0.1, 0.2 and 0.4 mg/L of Potassium dichromate was selected for the chronic investigation. During the study, physico-chemical parameters of M4 medium were recorded and maintained within the range as stated in the OECD guideline no.211 and the validity criteria were met during the study. Based on the results, the EC50 of Potassium dichromate (based on % inhibition of reproduction) was determined as 0.19 mg/L with 95% confidence limits of 0.16 0.22 mg/L. The NOEC and LOEC were determined as 0.05 and 0.1 mg/L. Based on number of offspring reproduced, the NOEC and LOEC were determined as 0.03 and 0.05 mg/L, respectively. Based on survival of parental animal, the EC50 of Potassium dichromate was determined as 0.20 mg/L with 95% confidence limits of 0.15 0.24 mg/L. The NOEC and LOEC were determined as 0.1 and 0.2 mg/L, respectively. There is no published data available in the public domain for chronic effect of Potassium dichromate to Daphnia magna. The data on Potassium dichromate is an important prerequisite for test laboratories because it is used as reference test item for acute and reproduction studies to validate the test. Hence, an attempt was made to generate data for the Potassium dichromate under laboratory conditions.

Comparison of three electrochemical end-point detection methods to assay potassium dichromate by coulometric titration

Abstract: Coulometric titrations with three electrochemical end-point detection methods were performed to assay potassium dichromate as a standard for oxidation–reduction titration. The assay as an oxidizing agent was carried out with ferrous ions produced by electrolytically reducing ferric ions. Three end-point detection methods were employed and compared with each other: constant potential amperometry, potentiometry, and constant voltage biamperometry (a dead-stop method). The last one was found to provide high accuracy in the coulometric titration of potassium dichromate. Solution form samples were also measured to confirm the possible existence of chromium(III) in potassium dichromate by both coulometric titration and ion-exchange chromatography with inductively coupled plasma time-of-flight mass spectrometry.

Caffeic Acid Inhibits Chromium(VI)-Induced Oxidative Stress and Changes in Brush Border Membrane Enzymes in Rat Intestine

Abstract: We have previously shown that a single oral dose of potassium dichromate results in a decrease in the activities of several brush border membrane enzymes, produces oxidative stress, and alters the activities of several antioxidant enzymes in the small intestine of rats. In the present study, we have investigated the effect of treatment with the dietary antioxidant caffeic acid on potassium dichromate-induced biochemical changes in the rat intestine. Adult male Wistar rats were randomly divided into four groups: control, potassium dichromate alone, caffeic acid alone, and potassium dichromate + caffeic acid. Administration of a single oral dose of potassium dichromate alone (100 mg/kg body mass) led to a decrease in the activities of brush border membrane enzymes, increase in lipid peroxidation, decrease in sulfhydryl groups, and changes in the activities of several antioxidant enzymes. Two oral doses of caffeic acid (each of 250 mg/kg body mass) greatly attenuated the potassium dichromate-induced changes in all these parameters, but the administration of caffeic acid alone had no effect. Thus, caffeic acid is an effective agent in reducing the effects of potassium dichromate on the intestine and could prove to be useful in alleviating the toxicity of chromium(VI) compounds.

Metal Deposition Methods

Abstract: The Italian scientist Camillo Golgi was the €rst to use a mixture of potassium dichromate and silver nitrate to stain tissue samples in 1873. Pierre Aubert was allegedly the €rst to use silver nitrate to detect latent prints as far back as 1877 [1]. With regard to processing porous items, the silver nitrate technique was used almost exclusively in the early twentieth century until being supplemented by ninhydrin in 1954. Silver nitrate solutions typically varied between 3% and 10% w/v, although Cuthbertson reported that 1% w/v was the optimum concentration [2]. Although aqueous silver nitrate solutions were commonly used, an alcohol-based formulation had the advantage of drying faster. Olsen reported thatCONTENTS3.1 Silver Nitrate 55 3.2 Physical Developer 58

Acute sensitivity to Nitokra sp benthic copepod to potassium dichromate and ammonia chloride

Abstract: The present study assesses acute toxicity of non-ionized ammonia and potassium dichromate using the estuarine benthic copepod Nitokra sp from laboratory cultures. Bioassays with non-ionized ammonia sensitivity were carried out, and the mean. Bioassays with non-ionized ammonia sensitivity were carried out, and the mean of LC(I)50-96h was 1.7 mg.L-1. – LC(I)50-96h was 1.7 mg.L-1. Potassium dichromate was used as reference substance in two distinct periods of exposure and the mean LC(I)50-48h and LC(I)50-96h values were 55.61 mg.L-1and 21.70 mg.L-1, respectively. The organism showed sensitivity to the toxic agents used and good reproducibility of results, indispensable factors for use in ecotoxicological assays. Keywords: bioassay, acute sensitivity test, potassium dichromate, ammonium chlorinate, estuarine copepod

Reagent and method for determining chemical oxygen demand of high-chloride wastewater

Abstract: The invention discloses a reagent and a method for determining the chemical oxygen demand of high-chloride wastewater. The reagent consists of a reagent A and a reagent B, wherein the reagent A comprises 20 to 40 mass percent of potassium dichromate, 20 to 50 mass percent of aluminum potassium sulfate, and 10 to 60 mass percent of ammonium molybdate; and the reagent B comprises 20 to 40 mass percent of silver sulfate, 10 to 20 mass percent of bismuth nitrate, 10 to 20 mass percent of chromium potassium sulfate, and 20 to 60 mass percent of mercury sulfate. The method comprises the steps of: during the determination, sequentially adding the reagent A and the reagent B into a water sample, placing the obtained solution into a digestion device for digestion, cooling the obtained product, andthen performing colorimetric determination. The reagent and the method are suitable for wastewater with the chloride ion concentration of between 1,000 and 10,000mg/L; and the reagent has the characteristics of accurate formula proportion, accurate and reliable determined data, short determination time, simple determination steps, convenient operation and the like; and the method can perform batch determination.

High-efficiency iron rust conversion agent

Abstract: The utility model relates to a high-efficiency iron rust conversion agent, and belongs to the field of an antirust paint The iron rust conversion agent comprises the following raw materials by weight: 01-10% of zinc oxide, 20-40% of phosphoric acid, 05-15% of dichromate, 05-10% of phosphate, 01-10% of corrosion inhibitor, and 50-70% of solvent, wherein the dichromate is potassium dichromate or sodium dichromate; the phosphate is sodium phosphate or potassium phosphate; the corrosion inhibitor is urotropine or urea; and the solvent is water or ethanol The preparation method comprises the steps as follows: sequentially adding the solvent, the phosphoric acid, the dichromate, the phosphate, the corrosion inhibitor and the zinc oxide to a glass cup under persistently stirring according to the mass ratio, and dissolving for 10-20 min The production method bases on the dissolving of the solid reactants in the phosphoric acid solution The phosphorized film formed by iron rust conversion has the effects of preventing rust and fixing remnant rust, and the formed phosphorized layer protective film is long-acting, and stable in atmospheric environment, lubricating oil and organic solvent, has high adhesion, can be used as a primer, has dielectric properties, and can prevent electro-chemical corrosion on the metal surface

Morphological features of the organs of the immune system in conditions of exposure to chromium and benzene

Abstract: Morphological features of the thymus, spleen and lymph nodes on the 45th--and 90th day of oral exposure to benzene, potassium dichromate and their mixtures were studied in 40 Wistar rats. A strong trend to a decrease in the activity of T lymphocytes has been established. Apoptotic thymocytes and lymphocytes in the T-dependent areas of spleen and lymph nodes have been revealed.

Light and Scanning Electron Microscopic Studies on Chromium-Induced Anemia in a Murine Model

Abstract: Blood hemoglobin level, hematocrit value and erythrocyte count were reduced by 17.5, 17.4 and 15.9%, respectively, as compared to the controls, in Swiss mice treated intraperitoneally with hexavalent chromium (4 mg of potassium dichromate per Kg for 5 day per week) for 2 weeks. Echinocytic transformation of 33.8% erythrocytes, as revealed by both light and scanning electron microscopy, indicated the anemia to be hemolytic in nature. Leucopenia was apparent after 2 weeks (mean leucocyte count: 4.91 thousand c mm−1), but not 1 week of treatment (mean count: 6.43 thousand c mm−1), However, cytochemical studies indicated that chromium did not interfere with iron utilization for hemoglobin synthesis and also, did not cause denaturation of already synthesized hemoglobin. The study hints to the necessity of periodic monitoring of blood in workers of chromium-dependent tanneries of Kolkata, India.

Comparative studies on corrosion behaviour of sealed aluminium with cerium salt under bidirectional pulse electric field

Abstract: A new cerium salt sealing method for anodic film on aluminium alloy using pulse electric field was introduced in this paper, and the corrosion behaviours of the sealed aluminium were comparatively studied in neutral, acidic and alkaline NaCl solutions by means of polarisation curve and electrochemical impedance spectroscopy measurements. The results show that the corrosion resistance of anodic film sealed with the method is better than that sealed with boiling water and potassium dichromate. The sealing mechanism of Ce salt under bidirectional pulse electric field was also proposed. Owing to its low energy consumption and low toxicity, this method could be an alternative to potassium dichromate or boiling water sealing.

Isolation of chromium resistant Bacillus sp. MRKV and reduction of hexavalent chromium potassium dichromate

Abstract: The ability of Bacillus sp. MRKV isolated from tannery effluent which shows resistant towards hexavalent chromium potassium dichromate (K2Cr2O7) was evaluated in this study. The bacterial strain was assayed for its reducing ability towards K2Cr2O7. The study revealed that the isolated strain has the ability to reduce the hexavalent chromium and the optimal conditions required for the chromium reduction was also evaluated. The observations infer that the bacterial strains can be exploited for bioremediation of hexavalent chromium containing wastes, as they seem to have a great potential to reduce the toxic hexavalent form to a less toxic trivalent form.

Method for determining total iron by titanium trichloride

Abstract: The invention belongs to the technical field of methods for determining total iron and particularly relates to a method for determining total iron by titanium trichloride. The invention aims to solve the technical problems and provide the method for determining the total iron by the titanium trichloride, which has simple and convenient process without discharging toxic substances. The method for determining the total iron by the titanium trichloride comprises the following steps: (1) melting a sample and then leaching the smelt sample by acid; (2) by adopting sodium tungstate as an indicator, adding the titanium trichloride into the leached solution until tungsten blue is generated, and dropping potassium dichromate solution until the blue is disappearer; and (3) by adopting sodium diphenylamine sulfonate as an indicator, performing titration with potassium dichromate standard solution, and calculating the content of the total iron according to consumption volume of the potassium dichromate standard solution. The method for titration of the total iron by the titanium trichloride has the advantages of more accurate measuring result, higher qualified rate and less analytical error.

Fire extinguishing agent composition for solid-aerosol automatic extinguisher and manufacturing method thereof

Abstract: PURPOSE: A fire extinguishing composition for a solid aerosol fire extinguisher system and a preparation method thereof are provided to improve stability against external shocks or vibration. CONSTITUTION: A fire extinguishing composition for a solid aerosol fire extinguisher system comprises 60-90 wt% of potassium nitrate, 1-10 wt% of potassium permanganate, 1-10 wt% of flammable metal powder, and 5-25 wt% of epoxy resin. The flammable metal powder is selected from magnesium, aluminum, titanium, zirconium, potassium, zinc, cesium, and lithium. An oxidant is selected from a group consisting of potassium perchlorate, potassium carbonate, potassium nitrite, potassium dichromate, potassium citrate, potassium bicarbonate, sodium nitrate, sodium bicarbonate, ammonium nitrate, ammonium perchlorate, barium nitrate, and cesium nitrate.

Method and device for testing content of sulfur in iron ore

Abstract: The invention relates to a method testing content of sulfur in iron ore, which comprises the steps of: enabling air to pass through a concentrated sulfuric acid liquid I with a concentration range of 96-98 percent and a concentrated sulfuric acid liquid II with a concentration range of 96-98 percent, wherein 5-8g of potassium dichromate is dissolved in the concentrated sulfuric acid liquid II; then reacting with sulfur under high temperature to generate a sulfur dioxide gas; absorbing the sulfur dioxide gas with acidic starch and titrating with a potassium iodate standard solution; and figuring out the mass fraction of the sulfur according to the volume of the consumed potassium iodate standard solution. Compared with the prior art, the invention has the advantages that air passes throughthe concentrated sulfuric acid and the potassium dichromate-sulfuric acid, water vapor and carbon dioxide in air can be effectively removed, air is convenient for taking and has low cost, oxygen is much expensive relative to air, air is used as a gas source, and safety factor of air is improved relative to oxygen as the gas source.

Superconducting fluid special for vacuum superconducting heating and preparation method thereof

Abstract: The invention discloses superconducting fluid special for vacuum superconducting heating and a preparation method thereof; the superconducting fluid comprises distilled water, potassium dichromate, ethylene glycol, anhydrous ethanol, sodium hydroxide, calcium chloride, and cobalt nitrate, wherein the weight proportion of all the components is as follows: 68.33 percent of distilled water; 1.95 percent potassium dichromate; 9.76 percent of glycol; 19.52 percent of anhydrous ethanol; 0.30 percent of sodium hydroxide; 0.04 percent of calcium chloride; and 0.10 percent of cobalt nitrate; the preparation method of the superconducting fluid special for vacuum superconducting heating is as follows: first heating the distilled water to 60 to 90 DEG C by weight proportion and then pouring into the potassium dichromate, stirring uniformly and adding with sodium hydroxide, adding with anhydrouse thanol to be stirred uniformly and then adding with glycol to stay still for 30min, and adding with calcium chloride and cobalt nitrate to be stirred uniformly to prepare the superconducting fluid; and the invention has the benefits of simple preparation, low cost, high-temperature cooling, anti-cold and anti-frost, no toxin and no taste, long service life and wide scope of application.

Evaluation of the stability of iron(II) solutions by precise coulometric titration with electrogenerated cerium(IV).

Abstract: An iron(II) solution is often used as a reducing agent in titrimetry and standardized with cerium(IV) or potassium dichromate. Such an iron(II) standard solution is needed for not only titrimetric analyses, but also instrumental ones. Iron(II) is unstable even in a highly acidic solution, mainly due to air-oxidation; therefore, its standardization is required before use. In the present study, the concentration of an iron(II) solution was accurately determined by coulometric titration with electrogenerated cerium(IV), and also by gravimetric titration with a standard potassium dichromate; new useful information concerning the stability of iron(II) solutions in aqueous sulfuric acid was obtained. The current efficiency of the coulometric titration with electrogenerated cerium(IV) was not very high; however, it was found that the titration efficiency was sufficient to assay an iron(II) solution.

Application of brominating agents and potassium dichromate for the spectrophotometric determination of captopril in pharmaceutical formulations

Abstract: Three simple and sensitive spectrophotometric methods were developed for the estimation of captopril (CAPT) in pure form or in tablet formulations. The three methods are based on the reactivity of the thiol group. The first two methods (A and B) are based on the oxidation of CAPT by bromate/bromide mixture of known concentration in acid medium. In method A, the determination of the residual bromine is based on its ability to bleach the methylene blue dye and measuring the absorbance at 664 nm. Method B involves treating the unreacted bromine with a measured excess of iron(II) and the remaining iron(II) is complexed with 2,2 � -dipyridyl and the increase in absorbance is measured at 523 nm. Method C involves the addition of a known excess amount of potassium dichromate in acidic medium, followed by the estimation of unreacted amount of dichromate by reacting with excess of iron(II). The resulting iron(III) is complexed with thiocyanate and the absorbance is measured at 478 nm. In all the methods, the amount of oxidant reacted corresponds to the drug content. The different experimental parameters affecting the development and stability of the color product are carefully studied and optimized. After validation, the proposed methods were successfully applied to assay of CAPT in its commercial tablets. No interference was observed from common additives found in pharmaceutical preparations. The results were statistically compared with those of a reference method by applying Student's t- and F-test.

Zinc PVA versus potassium dichromate for preservation of microsporidian spores of human origin.

Abstract: Microsporidia are emerging opportunistic parasites. Preservation of the biological properties of microsporidian spores is often required in research work. The present study compared two preservatives; zinc polyvinyl alcohol (zinc PVA) and potassium dichromate solutions for preservation of microsporidian spores separated from human faecal samples. After 0, 1, 2 and 4 months of storage, morphological features and staining characters of the spores were assessed by light microscopy in modified trichrome-stained smears and their viability percentages were calculated using acridine orange/ethidium bromide mixture. Also, spore infectivity was evaluated by faecal spore shedding and intestinal spore load in mice orally inoculated with the preserved spores. Results revealed that morphological features, staining characters and viability of the spores were maintained in both solutions throughout the study period. Spore infectivity was completely preserved in zinc PVA solution but showed significant reduction in potassium dichromate solution at the fourth month of the preservation duration.

Zinc oxide nanoparticles for the photocatalytic reduction of hexavalent chromium in wastewater under sunlight

Abstract: Common sources of chromium in wastewater are leather industries, electroplating, electronic, and timber. Hexavalent chromium is more toxic and carcinogenic than trivalent chromium. Photocatalytic reduction of Cr (VI) to Cr (III) in an aqueous medium under tropical sunlight and nanosized ZnO semiconductor catalyst has been investigated using potassiumdichromate as the model compound. Methanol was added as a hole- scavenger for enhancement of the photo-reduction. Effects of the process parameters such as nano-ZnO loading (0 to 0.6g/L), initial concentration of substrate solution (10 to 50mg/L), pH(4-9) and methanol-dosing (0 – 1.75mol/ L) have been investigated. The initial rate of the photochemical method was found to be independent of the concentration of potassium dichromate as well as concentration of methanol above an optimum value. A probable mechanism for the entire reaction and the corresponding kinetic model have been proposed for the photo reduction and proved by experimental results. Another rate equation based on the LHHW model compares well with the mechanistic rate equation.

Investigating Concrete Steel Rebar Degradation Using Some Selected Inhibitors in Marine and Microbial Media

Abstract: Potential monitoring investigations were conducted on concrete steel rebar samples premixed with selected inhibitors accompanied by fixed amount of sodium chloride salt and partially immersed in sulphuric acid and sodium chloride solution. Varying concentration of potassium dichromate, potassium chromate and sodium nitrite inhibitors were used individually and synergistically in this study. The potential readings were taken in accordance with ASTM C 876 through the open circuit potential corrosion monitoring technique. Suppressive quality and dependability of the inhibitor was then assessed by the Weibull probability density distribution as an extreme value statistical modeling approach to study performance effectiveness and forecast the most effective inhibitor concentration in each media. Inhibitor effect on the compressive strengths of the reinforced concrete samples was also examined and reported. Results showed that 0.15M potassium chromate inhibitor had the best overall and individual performance in its inhibiting ability in the H2SO4 medium, while 0.68M sodium nitrite admixture was predicted as showing the lowest probability of corrosion risk in NaCl medium. Also, the best synergistic performance was shown by sample admixed with 0.06M K2Cr2O7, 0.15M K2CrO4 and 0.27M NaNO2 partially immersed in the NaCl medium. The compressive strength of concrete sample admixed with 0.03M K2Cr2O7 and 0.10M K2CrO4 was the highest amongst samples admixed with inhibitor in both media, though the control sample partially immersed in the NaCl medium had the highest overall compressive strength value.

Low-temperature External-heat Potassium Dichromate Oxidation-photo-colorimetric Method for Determination of Organic Carbon in Dewatering Sludge

Abstract: According to the principle of low-temperature external-heat potassium dichromate oxidation-photo-colorimetric method,organic carbon(OC) of sludge was determined in the municipal sewage plant.The results showed that absorbance of 0.005~0.04 g dry sludge was in the standard curve;relative standard deviation of the twelve parallel sludges OC results was 0.66%-the precision was well,and fiducially interval range of their population mean was smaller-the accuracy was also well.

Research on the recovery of protein from surimi wash water of hairtail trichiurus haumela by natural algae flocculant sodium alginate

Abstract: To obtain the optimum conditions of sodium alginate flocculants used for the recovery of protein from surimi wash water of hairtail Trichiurus haumela,the methods of sodium alginate flocculants,biuret and potassium dichromate oxidation were adopted.Results showed that the optimum recovery conditions of sodium alginate were as follows:sodium alginate 1.11mg/ml;protein concentration of surimi wash water 16.54mg/ml;pH 4.6;temperature 4℃;time 20min.Under the above condition,protein recovery ratio and removal ratio of COD was 86.68% and 58.67%,respectively.The removal effect of protein from surimi wash water was obvious by adding sodium alginate.