79 results about "Back titration" patented technology

The invention provides a method for rapidly determining total iron in sulfur acid residue, which is as follows: reagent is used for analyzing in public and in a blank way volume difference of potassium dichromate standard titrimetric solution which is consumed by front and back titration, wherein the volume difference is blank valve (V0=V1-V2); milliliter quantity obtained by V1-V0 is used for calculating mass friction of total iron in sulfur acid residue test sample. The method overcomes shortcomings that the existing analytic method has poor accuracy, and a method of recycling and resolving sulfur acid residue test sample by alkali fusion or acid soluble is fussy, and has high energy consumption and the like. The method determining total iron in sulfur acid residue has the advantages of economy, environmental protection, simplicity, rapidness and accuracy.

The invention discloses a preparation method for nanometer yttrium oxide powder, belonging to the technical field of preparing superfine rare earth powder. The method comprises the steps of dropping yttrium-containing inorganic acid salt in alcohol-water mixed solution which contains a precipitant and a static stabilizing agent, then adding a surfactant after finishing dropping, stirring, aging and separating the reaction system to obtain precipitate, then carrying out cleaning and washing, vacuum drying and calcinating to the precipitate to obtain the nanometer yttrium oxide powder. According to the preparation method, by applying the back titration, alcohol-water mixture solution and surfactant, not only can yttrium ions be favorably separated out and crystallized, but also the particle size of the crystals and the specific surface area of the crystal particles can be better controlled, so that the prepared nanometer yttrium oxide powder has smaller particle size, narrow particle size distribution and larger specific surface area, thus further having higher sintering activity; the preparation method is simple in technology, short in synthesis route, easy to control, capable of remarkably improving the purity and yield of products, and suitable for industrial production.

The invention discloses a method for detecting quality of alkaloids in a Tibetan medicine herba aconiti tangutici and preparations thereof. The method comprises the steps of identification, check and content determination, wherein thin layer chromatography is adopted for identification and is characterized by taking a herba aconiti tangutici control medicine as the control and normal hexane-ethyl acetate-methanol-ammonia water as a developer; high performance liquid chromatography is adopted for check and is characterized by taking a mixed solution of an aconitine control substance, a hypaconitine control substance and a new aconitine control substance as the control, acetonitrile-tetrahydrofuran as a mobile phase A and an ammonium acetate water solution with glacial acetic acid as a mobile phase B to carry out gradient elution; high performance liquid chromatography is adopted for hordenine content determination and is characterized by taking a hordenine control substance as the control and an acetonitrile-potassium dihydrogen phosphate water solution as a mobile phase; and back titration is adopted for total alkaloid content determination. The method is stable and reliable, has strong specificity, can ensure the safety, effectiveness and quality controllability of the alkaloids in the Tibetan medicine herba aconiti tangutici and the preparations thereof, and has higher scientificity and application values.

The invention provides an automatic test method and instrument for modules of sodium silicate, so as to solve the problems that in the existing measuring method, naked eyes are adopted to judge the titration end point, the measuring precision is low, and the manual operation is adopted, back titration is required to be carried out on sodium hydroxide solution in the measuring process, and the test cycle is longer. In the invention, an electric potential signal collected by a pH electrode is adopted to replace the naked eyes to judge the titration end point, manual liquid-adding titration is replaced by accurate liquid-adding titration carried out by an accurate liquid-adding titration apparatus, a processor is adopted to control the titration process and processing data, and a magnetic force heating stirrer is adopted to heat and stir in the whole measuring process. The instrument in the invention consists of a liquid-adding titration unit, a reaction unit, a signal acquisition amplifying unit, a data processing unit and a result output unit. By utilizing the method and instrument provided by the invention, rapid and accurate measurement of modules of the sodium silicate is realized, and the labor intensity of experimenters is alleviated.

The invention discloses a method for quickly measuring sulfate radical content in a magnesium method desulfurization process. The method consists of the processes of filtration, constant volume determination, acidification, precipitation and back titration and comprises the following steps of: filtering a fetched sample by using filter paper; filling quantitative filtered clear solution with constant volume into a volumetric flask; filling proper constant volume clear solution in a beaker, and adding diluted hydrochloric acid of 1:1 concentration for acidifying; adding excessive barium chloride into the acidified clear solution to perform precipitation; filtering and fully washing the sediment, and titrating the total weight of barium, calcium and magnesium ions by using ethylene diamine tetraacetic acid (EDTA) coordination agent under the condition that chrome black T is used as an indicator; and meanwhile, calculating the content of the barium ions by measuring the total weight of the calcium and the magnesium so as to calculate the content of the sulfate radicals. The method has the advantages that: the control of solution concentration and measuring process conditions is accurate, the measurement of the content of the calcium and the magnesium is completed at the same time, and the preparation of barium and magnesium mixed solution is not needed; the accuracy of the sulfate radical detection is improved, and the detection time is shortened; and the method is suitable for quickly measuring the sulfate radical content in the debugging and operating process of a magnesium oxide method desulfurization system.

The invention provides a determination method of the content of cobalt in a lithium battery ternary positive electrode material, relates to a determination method of the content of cobalt in material with high manganese content, and in particular relates to a determination method of the content of cobalt in the lithium battery ternary positive electrode material. The method comprises the following steps: (1) accurately weighing moderate to-be-determined ternary positive electrode material, adding acid to dissolve and making up to volume; (2) adding perchloric acid-phosphoric acid to a certain amount of dissolved solution, heating till perchloric acid smoke emits, and adding a moderate masking agent to eliminate manganese interference; (3) performing back-titration on a potentiometric titrator by using a cobalt standard solution, drawing a differential curve and obtaining titration end point consumed volume according to a second-order differential method; and (4) computing to obtain the cobalt content in a sample according to a formula. According to the method provided by the invention, the manganese reducing operation is unnecessary, and the determination of the content of the cobalt in the sample containing manganese with the weight percent being not more than 40% cannot be influenced, the accuracy is high, the treatment process is simple and the method is easy to popularize.

The invention discloses a preparation process of a water-based fluorescent polyurethane compound. The preparation process includes the following steps that all components are dehydrated for use; dehydrated polypropylene glycol 2000 and dimethylolpropionic acid are added into a three-mouth flask and heated under protection of nitrogen gas, toluene diisocynate and acetone are dropwise added, then dibutyltin dilaurate is added, a reaction is conducted, and in the reaction process, back titration is conducted with di-n-butylamine; the temperature is lowered to 40-50 DEG C, triethylamine is added, and a reaction is conducted; the temperature is lowered to room temperature, triethylamine and ethidene diamine are added, emulsification and reduced pressure distillation are conducted, and the water-based fluorescent polyurethane compound is obtained. The prepared water-based fluorescent polyurethane compound is high in solid content, high in storage stability, high in fluorescence quantum yield and excellent in fluorescence property.

The invention provides a method for simultaneously determining Zr, Cu and Ni contents in Zr-Cu-Ni-Al amorphous alloy. The Zr, Cu and Ni are determined by using EDTA complexing back titration, the Zr, Cu, Ni and Al can be directly determined by using back titration in an acidic medium without interference according to a complexing stability constant; the Cu content and Ni content are determined by using the F- to shelter the Zr and Al under the acidity of pH 5-6, and the Ni content is determined by using thiorea to shelter the Cu, and the content of the Cu is obtained according to a computational formula. The contents of the Zr, Cu and Ni are determined in parallel through once sample preparation. The operation is free from electrolysis equipment, according to acidity ranges for EDTA complexing titration of different elements, the F- is used for sheltering the Zr and Al, and the thiorea is used for sheltering the Cu, so that the interference among the elements is eliminated, the titration end point sensitivity and the result accuracy are improved by using the back titration, and the content values of Zr, Cu and Ni can be fast and stably obtained.

The invention relates to the technical field of electrical equipment, and in particular relates to a method for judging a titration end point in an acidity test of an insulating medium, namely sulfur hexafluoride (SF6) gas, of electrical equipment. The judgment method comprises the following steps of: setting the titration end point; connecting an electrode; and performing back titration and liquid absorption. The method has the beneficial effects that as the end point is judged by a more accurate acidity meter, and the pH value of the acidity meter is set to be 5.0, the test end point is easy to judge, the precision of the acidity test for the SF6 gas is improved, and thus the method has significance to guarantee of safety operation of the electrical equipment. The method provided by the invention is easy to operate, the acidity value in the SF6 gas is accurately tested, and thus the safety operation of the electrical equipment can be reliably guaranteed.

The invention provides a method for detecting hydrogen sulfide (H2S), carbon dioxide (CO2) and hydrogen cyanide (HCN) in acid gas. The method comprises the following steps: combining a mixing solution of potassium hydroxide and a phenolphthalein indicator which are contained in different flasks in a volumetric flask; and adding pure water until reaching the scale, wherein potassium carbonate is generated by the CO2 adsorbed by the potassium hydroxide and reacts with calcium chloride to generate a calcium carbonate precipitation; the calcium carbonate precipitation is dissolved and titrated by using hydrochloric acid and a sodium hydroxide solution respectively, so that the content of the CO2 is obtained. The H2S adsorbed by the potassium hydroxide can generate potassium sulphide which reacts with a zinc acetate solution, so that a flocculent yellow precipitation is generated; an excess amount of standard iodine solution is added under the acid condition; the back titration is performed by using sodium thiosulfate; the content of the H2S is computed after blanking. After the HCN is adsorbed by potassium hydroxide, lead carbonate solid powder and a rhodanine indicator are added; the content of the HCN is computed after blanking. The method is rapid in detection speed and strong in operability; the precision and accuracy of the method can completely meet the requirement of a coking desulfurization and dehydrogenation process. Thus, the accurate detection data for the coking desulfurization and dehydrogenation process is provided.

The invention relates to a method for measuring the cadmium content in a waste nickel-cadmium battery, which comprises the steps of aqua regia solution sampling, iron and nickel removing, cadmium and cobalt amount measurement by a back titration method, cobalt content measurement by a conventional method, and the like, and finally the cadmium content is calculated by subtraction. The method has small error, accurate result and high precision, makes up the gap of measuring cadmium in the waste nickel-cadmium battery, and has an important meaning for healthily developing the waste nickel-cadmium battery recycling industry.

The invention provides a method for testing the content of aluminum ions in aluminum etching liquid. Automatic titration is carried out by automatic potentiometric titration apparatuses. The method includes carrying out thorough complexation on the aluminum ions in aluminum etching liquid samples by excessive EDTA-Na2 (ethylene diamine tetraacetic acid-Na2) solution by the aid of complexation reaction on EDTA-Na2 and the aluminum ions; carrying out back titration on excessive EDTA-Na2 by the aid of copper sulfate standard liquid; judging titration endpoints by the aid of sudden change of solution conductivity at the titration endpoints. The method has the advantages that test instruments are inexpensive as compared with flame atomic absorption spectrophometry and plasma emission spectrometry for testing the content of aluminum ions mainly by the aid of instruments, and the method is low in test cost; accurate and quick test results can be obtained by the method as compared with indicator color development back titration methods mainly by the aid of manual titration, and accordingly the method is a perfect scheme for monitoring the content of aluminum ions in aluminic acid in current laboratories and in an online manner.

The invention relates to a method for measuring contents of bismuth and lead ions in a tin lead bismuth alloy electroplating solution. According to the method, bismuth and thiourea react in 0.4 mol/L-1.2 mol/L of a nitric acid medium to generate a soluble yellow complex, interference of lead is eliminated with tartaric acid, interference of ferric ions is eliminated with ascorbic acid, and the content of bismuth in an electroplating solution is measured by a spectrophotometric method; and Sn<2+> is oxidized into Sn<4+> by the use of hydrogen peroxide in an acid solution, excessive EDTA-2Na complex bismuth, lead and the like are added, tin is screened with ammonium fluoride, a hexamethylenetetramine solution is added to adjust pH value of the solution to 5-6, xylenol orange is used as an indicator, back titration is carried out with a zinc standard titration solution, the content of lead in the electroplating solution is calculated according to the quantity of EDTA-2Na and the zinc standard titration solution, and determination of bismuth interference with lead is deducted during the calculation. The determination method is simpler, the detection process is faster, more convenient and more environmentally-friendly, expense cost is lower, and detection results are more accurate.

The invention discloses a method for determining a multi-component resultant in a multivariant anode material precursor based on an EDTA back titration-automatic titration method. Excessive EDTA standard solution is added to a prepared precursor sample solution to complex multi-component metal elements; in a boric acid-sodium borate buffer solution, an automatic titration device is utilized to dropwise add a Zn <2+> solution for back titration of the excessive EDTA; a zinc reagent serves as an indicator, the sudden change of the luminosity intensity is sensed by using a luminosity sensor with the light filter wavelength of 650 nm, and a terminal point is automatically judged; according to sample mass, the recorded volume and concentration of the EDTA standard solution and the volume and concentration of the consumed Zn <2+> solution, the multi-component resultant in a nickel and cobalt (manganese/aluminum and the like) multivariant anode material are calculated. The method can accurately, rapidly and stably detect the multi-component resultant in various types of multi-component precursors, is especially suitable for multi-batch testing in large-scale industrialized production and greatly improves automated detecting level and reliability in the field.

The invention discloses a method for analyzing cadmium chloride in an acid cyanide-free cadmium plating solution. The method includes the steps that a coordination agent in the acid cyanide-free cadmium plating solution is oxidized with ammonium persulfate under the strong acid condition so that cadmium ions can be released from coordination ions; iron ions are masked with ascorbic acid and aluminum ions are masked with triethanolamine under the condition that pH ranges from 9.5 to 10, an excess EDTA standard solution is added to coordinate with cadmium ions, eriochrome black T serves as an indicator, EDTA is subjected to back titration with a zinc sulfate standard solution, and the mass concentration of cadmium chloride in the plating solution is calculated with a minusing method. According to the method, in the testing process, sulfuric acid is added into the tested solution to make the tested solution have strong acidity, and then the coordination agent is completely oxidized with ammonium persulfate under the heating condition, so that interference of the coordination agent with cadmium chloride determination is eliminated. The method is accurate in determination result and superior to an existing method.

The invention discloses a preparation method of a high-capacity lithium-rich ternary positive electrode material. The method comprises the following steps of weighing a lithium salt, a manganese salt,a cobalt salt and a nickel salt according to a stoichiometric ratio in a general formula zLi2MnO3.(1-z)LiMO2 and dissolving the weighed salts into deionized water to form a mixed salt solution; dissolving a chelating agent into the deionized water to form a chelating agent solution; slowly dropwise adding the chelating agent solution into the mixed salt solution in a back titration manner and mixing evenly; and adding an alkaline solution to adjust the pH value of the solution, heating the solution into a sol form in water bath, carrying out spray drying and then putting a product into a muffle furnace for sintering according to a certain sintering curve to obtain the high-capacity lithium-rich ternary positive electrode material, wherein z is smaller than 1 and greater than 0, M is MnxNiyCo(1-x-y), x is smaller than 1 and greater than 0 and y is smaller than or equal to 0.6 and greater than 0. The high-capacity lithium-rich ternary positive electrode material is prepared by using a one-step sol method; the preparation method is simple, mild, environment-friendly and efficient; and the synthetic product has relatively high specific capacity and relatively good rate capability.

The invention provides a titration testing method for the content of nickel, cobalt and aluminum in a nickel-cobalt-aluminum ternary material or a precursor thereof. The titration testing method comprises the following steps: 1) dissolving a nickel-cobalt-aluminum ternary material or a precursor thereof to obtain a nickel-cobalt-aluminum solution; 2) determining the total amount of nickel, cobaltand aluminum ions by an EDTA back titration method; (3) precipitating by using a precipitator, filtering to remove aluminum ions, determining the total amount of nickel and cobalt ions by using EDTA titration filtrate, and calculating the difference value with the total amount of nickel, cobalt and aluminum ions to obtain the content of aluminum ions; 4) adding a proper oxidant and a complexing agent into the filtrate, shielding the cobalt ions in the filtrate, and titrating the content of nickel ions in the filtrate by using EDTA; and 5) calculating the difference between the measured nickelion content and the total amount of nickel and cobalt ions to obtain the cobalt ion content. The method provided by the invention has the advantages of small relative error of nickel, cobalt and aluminum contents in the test sample, high repeatability, economy and low test condition requirements, and is a test method suitable for work production.

The invention provides a method for testing content of titanium dioxide by a complexometric titration-back titration method. The method comprises the following steps of: (1) treating a sample; (2) optimizing an operation process, and reasonably adjusting the concentration of solution pH alkali; and (3) adding a buffer solution; and then calculating out the content of the titanium dioxide in the sample. By adopting the method provided by the invention, the acidity of the solution at the end point of titration can be controlled well, an indicator is ensured to change the color obviously, the precision of sample test is improved, and the relative deviation of the sample test result is less than 0.3%.

In the invention, a back titration and titer determination can be made using a back coulometric titration. When the iodine exists in a solution put in the titration flask with electrolytic electrodes, a back coulometric titration is performed to produce iodine ions from the iodine at the anode of the electrolytic electrodes. Where the solution is a dehydrated solvent including a Karl Fischer reagent for a volumetric titration, the titer can be determined by the back coulometric titration. Where the solution is anolyte in which the iodine remains after the coulometric titration in the coulometric titration method, the water content in the sample is found from the quantity of electricity consumed by the coulometric titration and the quantity of electricity consumed by the back coulometric titration. Where the solution is anolyte in which the iodine remains by adding Karl Fischer reagent in the volumetric titration method, the water in the sample put in the titration flask is found from the added amount of Karl Fischer reagent and the quantity of electricity consumed by the back coulometric titration.

The invention relates to a detection method for phosphate ester content in a powdery anti-caking agent. The method comprises the following concrete steps of: weighing m g of the powdery anti-caking agent, and placing the powdery anti-caking agent in a conical flask, adding concentrated sulfuric acid, then standing for 10 minutes, followed by heating until the powdery anti-caking agent is dissolved completely, adding concentrated nitric acid, the concentrated sulfuric acid and perchloric acid after the resulting solution is cooled, then carrying out heating until the solution presents white, followed by standing and cooling, adding a precipitation agent and standing for cooling, filtering the resulting solution through a sucking filtration apparatus, placing upper precipitation in a beaker, titrating the precipitation through a standard sodium hydroxide solution until the color of the precipitation turns from yellow to colorless, recording consumed volume of the sodium hydroxide solution, adding three drops of 10 g/L of phenolphthalein to the resulting solution, carrying out back titration through a standard hydrochloric acid solution until red color of the solution disappears, recording the consumed volume of the hydrochloric acid solution, calculating the phosphate ester content in the powdery anti-caking agent according to the consumed volume of the sodium hydroxide solution and the consumed volume of the hydrochloric acid solution. The method provided by the present invention is applicable for analysis of the phosphate ester content in various powdery anti-caking agents. In addition, the method has the following characteristics that: color error, calculating error, experiment error and the like are reduced.

The invention discloses a method for accurately determining starch gelatinization degree in pig feed. According to the method for accurately determining the starch gelatinization degree in pig feed, gelatinized starch is subjected to enzymolysis with beta-amylase, the gelatinized starch is quantitatively converted into reducing sugar, a quantitative iodine solution and the converted reducing sugarare subjected to a redox reaction, the remaining iodine solution is subjected to back titration with sodium thiosulfate, finally, the gelatinization degree of a sample of the pig feed is calculated on the basis of the consumption of sodium thiosulfate by the sample and a homologous and fully cured sample. Compared with the prior art, the method has the advantages that the detection result is accurate, the end point is easy to judge (from blue to colorless property), and besides, few reagents are used and the cost is low.

The invention relates to a method for utilizing ion exchange wastewater in a wastewater treatment process in phosphorus chemical industry, which comprises the following steps: collecting regenerated wastewater of an ion exchanger into a collecting tank; carrying out primary neutralization and primary settlement on acidic wastewater containing fluorine and phosphorus, extracting ion exchange wastewater from the collecting tank to substitute back titration acid according to fluorine, phosphorus and pH value of the slurry, and adding the ion exchange wastewater to the wastewater which is being treated to regulate the acidity until the consumption of alkaline solution by fluorine and phosphorus in the wastewater is basically equivalent to that of hydrogen ions, so that the pH value of the treated wastewater in phosphorus chemical industry is increased, thereby being beneficial to secondary treatment of wastewater; carrying out secondary neutralization and secondary settlement, and adding the ion exchange wastewater again, so that the acidity of the wastewater is further lowered, and the flocculation effect of the secondary settlement is good; and sending the treated wastewater, which meets the emission standard, into a clean water tank. The method provided by the invention recycles the ion exchange wastewater, lowers the amount of effluent wastewater, reduces the consumption of the back titration acid, and ensures the pH value of the effluent water to be qualified.

The invention discloses a method for measuring content of sodium tetraborate in a sintering promoting agent. The method is based on an acid base titration test, and comprises the following steps: dissolving a sample in water, heating, cooling, filtering, neutralizing the filtrate by using hydrochloric acid, heating and boiling to remove carbon dioxide, and filtering again; adding a paranitrophenol indicator into the filtrate, titrating until yellow color disappears by using a nitric acid standard titration solution, and adding glycerin to react with sodium tetraborate so as to generate glycerol borate; by taking phenolphthalein as an indicator, excessively titrating to become slight red by using sodium hydroxide; performing back titration on the excessive sodium hydroxide until the red color disappears by using the nitric acid standard titration solution, ending the operation, obtaining the consumption of the standard titration solution along with an accompanying blank experiment, and calculating to obtain the content of sodium tetraborate in the sample according to the volume difference of the consumed standard titration solution. The method has the characteristics of simplicity, convenience, rapidness, accuracy and reliability.

The invention provides a method for titrating primary amine content of natural protein fibers. The method comprises the following steps of: cleaning and drying the natural protein fibers, performing esterification reaction between the natural protein fibers and a coupling agent, reacting the esterified natural protein fibers with isocyanate, reacting di-n-butyl amine with excessive isocyanate, performing back titration on the di-n-butyl amine by using a standard hydrochloric acid solution, and calculating the primary amine content of the natural protein fibers according to a formula. The titrating method is simple, does not need additional complex conditions, and is sensitive and quick in measurement and high in precision.

A preparation method of cobalt oxide powder includes the following steps that A, during precipitating, an ammonium hydrogen carbonate solution is adopted as precipitator, a cobalt chloride solution is added in an ultrasonic atomization spraying mode with back titration, meanwhile, a surface active agent is added, and cobalt carbonate precipitate is obtained through a reaction, wherein the concentration of the cobalt chloride solution is 0.2 mol/L, and the concentration of the ammonium bicarbonate solution is 0.4 mol/L; B, during filtering and separating, the cobalt carbonate precipitate is filtered with water, then substances without a reaction are removed, then low-temperature drying is carried out for dewatering, and a cobalt oxide precursor is obtained; C, the cobalt oxide powder is obtained through thermal decomposition. The preparation method of the cobalt oxide powder is simple in technology, the pH is kept to be ranged from 7 to 8 during the reaction, and the generated cobalt oxide powder is high in purity and production efficiency and narrow in particle size distribution interval and does not contain impurity ions.

The invention particularly relates to a method for measuring the content of aluminum powder in titanium tetrachloride suspension liquid. The method includes the following steps that 1, the titanium tetrachloride suspension liquid is picked, slowly transferred to the bottom of a container containing ethyl alcohol samples, shaken to be uniform and filtered, and first sediment is obtained; 2, hydrochloric acid is added to the first sediment, nitric acid and perchloric acid are added after dissolution, heating and drying by distillation are conducted, then dissolution is conducted through hydrochloric acid, and a first solution is obtained; 3, after ferric salt is added to the first solution, the pH value is adjusted to 3-4, a buffering solution is added to adjust the pH value to 6-6.5, filtering is conducted, and second sediment is obtained; 4, hydrochloric acid is added to the second sediment, the pH value is adjusted to 9-12 after dissolution, and a second solution is obtained; 5, the second solution is boiled, cooled to the room temperature, subjected to constant volume and filtered, filtrate is picked, an EDTA back titration method is adopted to measure the content of aluminum in the second solution, and the content of aluminum powder in the suspension liquid is obtained through calculation. The method is high in both accuracy and recovery rate and has quite high practical value.

The present invention discloses a method for continuously determining the calcium content and the iron content in limestone powder. The method mainly comprises: separating impurities, determining iron in the filtrate by using an atomic absorption spectrometry method, adding excess EDTA, carrying out back titration on calcium in the filtrate with a CuSO4 standard solution, and finally respectively calculating the calcium content and the iron content in the sample. Compared with the method in the prior art, the method of the present invention has characteristics of simpleness, practicality and accurate and reliable result, and can meet the needs of daily analysis.