232 results about "Potentiometric titration" patented technology

The invention relates to a method for on-line monitoring of the concentration of vanadium ions in an all-vanadium redox flow battery, which comprises the following steps: 1) Potential monitoring: installing a reference at the liquid inlets of the positive and negative liquid storage tanks of the all-vanadium redox flow battery The electrode and working electrode, the potential tester monitors the change of the positive electrode potential and the negative electrode potential of the all-vanadium redox flow battery in real time through the reference electrode and the working electrode connected with it. From the obtained test potential, the battery’s potential can be obtained according to the relevant potential calculation formula. Charge and discharge state; 2) Vanadium ion concentration monitoring: adopt potentiometric titration method, use titrant, and perform potentiometric titration by potentiometric titrator to obtain vanadium ion concentration. The advantages of the present invention are that the monitoring method is simple, convenient, easy to operate and control, has high accuracy, and will not pollute the electrolyte of the battery; not only the charging and discharging state of the battery can be monitored online, but also the positive and negative poles of the battery can be monitored regularly Changes in the concentration of vanadium ions in the electrolyte, and monitor whether the charge and discharge states of the positive and negative electrodes are consistent.

The invention discloses a small automatic titration device applied to an analysis instrument. The automatic titration device comprises a titration pool of which the bottom is provided with a unique liquid inlet and outlet opening, an electromagnetic stirring mechanism with a central through hole, an inlet and outlet liquid metering system, a fastening mechanism, a titration endpoint monitoring device and a control and calculation unit. The device can be applied to photometric titration and potentiometric titration, is easy to install and has relatively low cost. The invention also provides a method for titrating by using the automatic titration device and calculating the volume of consumed titrated liquid.

The invention relates to the monitoring technology of the state of charge (SOC) of electrolyte of a vanadium redox flow battery, in particular to an in-situ monitoring method of the SOC of the anode electrolyte of the battery. The method comprises the following steps: measuring the oxidation reduction potential value ORPa of the anode electrolyte of the vanadium redox flow battery; establishing a relation equation according to the principle that the ORPa value is in linear relation with SOCa (the SOC of the anode electrolyte) in an open interval (0,100%), and then performing temperature correction and temperature substitution on the equation to obtain an ORPa-SOCa relation equation which has universality on the temperature of the anode electrolyte; and comparing the SOCa value calculated by the equation with the SOCa value measured by a potentiometric titration method to obtain the error of less than plus or minus 1.50%, thus finally realizing in-situ monitoring of the SOC of the anode electrolyte.

A quantitative analysis method includes diluting lithium ion cell electrolyte in absolute ethyl alcohol or methyl alcohol, using MOH as titrant, applying automatic potentiometric titration, using (CoXV20) / (1000XM) to confirm titrimetric curve as Co referring to tritrant concentration, V referring to consumed tritrant volume ml, 20 referring to HF molecular weight and M referring to electrolyte weight, using potentiometric titrator to carry out second order derivation of titrimetric curve for cnofirming titrimetric end point.

The invention relates to a method for measuring the content of chloridion, in particular to a method for measuring the content of chloridion in wet flat liquid. The establishment of the method for measuring the content of chloridion in the wet flat liquid mainly adopts a calcination method to carbonize organic amine matters which restrict the chloridion, to form soluble inorganic matters, enables the chloridion to be dissociated, so that the content of the chloridion can be measured by a potentiometric titration method. The invention can accurately measure the content of chloridion in the wet flat liquid, provides an effective means for incoming quality control of the flat liquid, and avoids unqualified product being stored.

A substrate treating apparatus includes a circulating line having a treating tank for storing a phosphoric acid aqueous solution, a circulating pump for feeding the phosphoric acid aqueous solution, a heater for circulation for heating the phosphoric acid aqueous solution, a filter for filtering the phosphoric acid aqueous solution, the circulating line causing the phosphoric acid aqueous solution discharged from the treating tank to flow in order of the circulating pump, the heater for circulation and the filter, and returning the phosphoric acid aqueous solution from the filter to the treating tank. The apparatus also includes a branch pipe branching from the circulating line between the heater for circulation and the filter for extracting the phosphoric acid aqueous solution from the circulating line, and a concentration measuring station connected to the branch pipe for measuring silicon concentration in the phosphoric acid aqueous solution by potentiometry.

The invention discloses an on-line automatic potentiometric titration, comprising the processes of sampling, titrating and cleaning, and is characterized in that the sampling process is as following: firstly adding a sample into a provale cup by a peristaltic pump, overflowing the sample in the provale cup through an overfall at the bottom of the provale cup; and the titrating process is as follows: a linear stepper motor is used to push a piston pump titration device to dropwise add the titration agent into the provale cup. The on-line automatic potentiometric titration of the invention ensures very high sampling accuracy, ensures repeatability of quantitative sampling within 0.2%, and is not affected by the service time; as the transmission precision of the linear stepper motor can reach 0.0005mm / mm, the highest resolution ratio can reach 0.0015mm, the resolution of the dropwise adding volume can reach 0.0003ml, the invention greatly improves the accuracy of on-line automatic titration, and can meet the requirements of high-precision on-line automatic potentiometric titration.

The invention relates to an HPLC (High Performance Liquid Chromatography) method for simultaneously determining content of six organic acids in pinellia ternata. The method comprises the following steps: (1) preparing a sample solution; (2) preparing a comparison product solution; (3) determining by a high performance liquid chromatography: taking the comparison product solution and the sample solution and carrying out determination analysis under following chromatographic conditions: a chromatographic column is GL InterSustain-C18 (4.6mm*250mm, 5 microns), and a mobile phase is a phosphoric acid adjusted 0.03mol / L (NH4)H2PO4 buffering solution with the pH value of 2.0 and methanol; and the volume ratio is 97 to 3, the flow speed is 0.8mL / min, the column temperature is 30 DEG C and the detection wavelength is 210nm. Under the conditions of the method, oxalic acid, formic acid, malic acid, acetic acid, citric acid and succinic acid in pinellia ternata are effectively separated, and methodological results meet the analysis determination requirements. Compared with the traditional potentiometric titration method, the measurement for content of total organic acids is clear and objective by virtue of the HPLC method disclosed by the invention, and the content of the six organic acids in pinellia ternata can be effectively and rapidly determined and the quality of pinellia ternata can be comprehensively and accurately controlled.

The invention discloses a method for detecting content of bromine in fire retardant through automatic potentiometric titration, which comprises the steps of 1 utilizing nickel crucible to directly weigh a sample, adding emulsifier and potassium hydroxide solution or sodium hydroxide solution into the sample, and evenly infiltrating the mixture in advance; 2 after adding small amount of ground sodium carbonate on the surface of the sample to cover the sample, adding solid sodium hydroxide to cover the surface, covering a crucible cover on the crucible with gaps reserved; 3 slowly heating the sample on a pressure regulating electric stove and enabling the sample to fuse in alkali solution and absorb the alkali solution till no white powder solid exits in the crucible; 4 turning off the electric stove, enabling the test sample to cool down, adding water into the crucible till 1 / 2-1 / 3 of the height of the crucible, heating the water, enabling fusant to be completely melt in the water, transferring the mixture into a beaker, cleaning the nickel crucible and the cover and transferring cleaning solution into the beaker together; 5 metering the volume of the solution for standby measurement; and 6 utilizing the automatic potentiometric titrimetor, utilizing a silver / bromine iron selection electrode to serve as an indication electrode and utilizing silver nitrate (AgNO3) standard solution to titrate sample solution. The method for detecting the content of the bromine in the fire retardant through the automatic potentiometric titration has the advantages of being high in weighing accuracy, safe and reliable.

The invention provides a high-nickel ternary positive electrode material washing method. The method comprises the steps: weighing a certain amount of a lithium battery positive electrode material (NCM622), adding deionized water at a certain solid-liquid ratio, performing stirring for a time period, then performing the ultrasound treatment for a period of time, and then filtering the obtained solution to perform anti-burning for 5h in an oxygen environment under the temperature of 700 DEG C; adding 100g of deionized water to 5g of the powder obtained after drying, performing filtering after stirring, and finally testing the content of lithium carbonate and lithium hydroxide in the filtrate through a potentiometric titration method. The invention provides the water washing method for treating a high nickel ternary positive electrode material by using ultrasonic waves to reduce the residual alkali content on the surface of the material. The method has the advantages of simple process, convenient operation and high product safety.

The invention provides a fast and accurate method for measuring free acid concentration in acid liquid. An automatic potentiometric titrator is used to measure total acidity of the acid liquid. EDTA (ethylene diamine tetraacetic acid) which prevents iron ions, aluminum ions and the like from hydrolyzing is used as a screening agent to eliminate influence of hydrolysis of the iron ions, the aluminum ions and the like to free acid measurement. The defect that pH jump of the free acid is fully or partially covered during automatic potentionmetric titration is avoided. Jump of equivalent point is increased, and accuracy of the measurement is increased. An analysis result is automatically calculated according to an input formula. Operation time from analysis to result obtaining is shortened to less than 10 minutes. In addition, the method is low in sampling amount, fine in reproducibility, and accurate in analysis results. By the method, labor intensity of analysts is reduced, and labor productivity is emancipated.

The invention discloses a method for measuring content of chlorine in a mixed acid electrolyte through potentiometric titration. According to the method, the chlorine content of a to-be-measured solution is titrated by adopting a silver nitrate standard solution, a titration end point is judged according to change of electric potential in a titration process, and the content of chloride ions in a tested sample is calculated according to the volume of the consumed silver nitration solution. By means of sample dilution and addition of an appropriate amount of nitric acid in a sample processing process, on one hand, the influence of other acid radicals in the sample on the titration is eliminated; on the other hand, trivalent vanadium ions in the solution are oxidized into tetravalent vanadium ions through addition of nitric acid, so that complexing capacity between the vanadium ions and the chloride ions is reduced, and the reaction of titrating the chloride ions by silver nitrate is enabled to be more smooth and more stable. According to the chloride ion concentration obtained by the test, a chloride ion masking agent is added through calculation, and the content of trivalent vanadium and tetravalent vanadium in the solution is measured with a potassium permanganate-potentiometric titration method. The method effectively avoids disturbance of the chloride ions on the vanadium measurement process and is fast and accurate.

The invention discloses a detection method for chlorine ion content in lithium-ion battery electrolyte. A non-aqueous potentiometric titration method is adopted for detection. Non-aqueous silver nitrate standard solution is taken as titrant; a silver electrode is an indicating electrode and a glass electrode is a reference electrode; a detected sample is titrated to an end point by the non-aqueous silver nitrate standard solution; and the chlorine ion content in the sample can be obtained by calculation according to the size of the detected sample, the concentration of the silver nitrate standard solution and the titration volume. The method has the advantages of simplicity and rapidness in operation, low cost, low detection limit and high result precision.

The invention discloses a device and a method for continuously analyzing pH value, phenolphthalein end-point alkalinity, total alkalinity and chloridion concentration. The method comprises the following steps: a. using a standard acid liquid adding unit to perform alkalinity titration to a sample to be detected, and sequentially performing the alkalinity titration: phenolphthalein end-point alkalinity titration and total alkalinity titration, and respectively reading corresponding liquid volume values for titration in the titration end-point, calculating the phenolphthalein end-point alkalinity and the total alkalinity, wherein the initial pH value acquired by a pH electrode is the pH value of the sample to be detected; and b. performing chloridion potentiometric titration to the sample to be detected after the total alkalinity is completed, reading the liquid volume value for the titration when in the titration end-point and calculating the chloridion concentration. The device for continuously analyzing the pH value, the phenolphthalein end-point alkalinity, the total alkalinity and the chloridion concentration comprises a potentiometric titrimeter main machine with double electrode interfaces, the pH electrode (1), the standard acid liquid adding unit (2), a silver electrode (3), a silver nitrate standard liquid adding unit (4) and a control system. According to the invention, the detection time is greatly shortened, the working efficiency of the device is improved, and the sample consumption and the standard acid liquid consumption are saved.

An aqueous dispersion-type acrylic pressure-sensitive adhesive composition includes acrylic copolymer emulsion particles dispersed in an aqueous medium. The acrylic copolymer emulsion particles has a ratio (ANIN) / (ANSUR) of 1 or more, wherein (ANIN) is an amount of acid groups in the acrylic copolymer emulsion particles, and (ANSUR) is an amount of acid groups on the surfaces of the acrylic copolymer emulsion particles, (ANIN) and (ANSUR) being calculated from a titration curve of potentiometric titration performed by adding an inorganic base solution to an acidic sample dispersion solution containing the acrylic copolymer emulsion particles dispersed in ion exchange water. A pressure-sensitive adhesive tape which strongly adheres to an adherend and has excellent removability can be formed using the aqueous dispersion-type acrylic pressure-sensitive adhesive composition.

The invention discloses a determination method of chloride ion content of a copper electrolyte. The determination method comprises a, adding a silver nitrate standard solution with a concentration of 0.005-0.01mol / L into a reagent bottle of a potential analyzer, b, orderly adding a copper electrolyte and isopropanol into a beaker according to a volume ratio of 3-7: 1, adding water into the beaker until the mixed solution in the beaker has a volume of 50-60mL, inserting a silver composite electrode and a titrating head into the solution to be detected in the breaker, and controlling a stirring speed in a range of 620-630rpm, and c, dropwisely adding a silver nitrate standard solution into the breaker, recording a silver nitrate standard solution volume corresponding to titration consumption when potential jump is produced, and calculating chloride ion content of the copper electrolyte according to a formula. Through use of isopropanol in the solution to be detected, a potential jump point produced by potentiometric titration is obvious, determined potential is stable and repeatability is good so that accuracy and a precision of the calculated chloride ion content of the copper electrolyte are high, accurate and reliable guide data is provided for practical production for a copper mine enterprise and precious metal reliable recovery and electrolytic copper yield are guaranteed.

The invention discloses a method for detecting COD in sewage and reclaimed water. The detection mechanism, the water sampling amount and the addition amount of oxidant of the invention are the same asthe method of HJ 828-2017. A precious metal silver reagent is replaced by 4 kinds of metal ion sulfates with different catalytic activities and selectivity such as manganese sulfate, copper sulfate,potassium aluminum sulfate. The oxidizing property of potassium dichromate is reduced by using the reduction of acidity of sulfur-phosphorus mixed acid, the adsorption of phosphoric acid, and the presence of chromium potassium sulfate, and a large volume closed digestion is used to shorten the digestion time to 25 min, thereby achieving mercury-free to prevent the interference of chloride ions. Atthe same time, the reaction pressure is increased, the digestion temperature is increased to 165 DEG C, so that the oxidation efficiency is improved. The digestion / titration bottle is integrated, amanual indicator titration is replaced by a gold composite electrode potentiometric titration, and the COD in the water sample is calculated. The 5 kinds of metal ion sulfates of the method for detecting the COD in sewage and reclaimed water are non-toxic, easily available and cheap; the sample of the sulfur-phosphorus mixed acid large volume closed digestion has a good adaptability, the COD results are consistent with the method of HJ 828-2017, and the rapid determination and green determination of the COD are achieved.

The invention relates to a method for preparing vanadyl sulfate by using a failure vanadium cell electrolyte. The method comprises the following steps of (A) taking the failure vanadium cell electrolyte as a raw material, testing total vanadium concentration and average valence state of the failure electrolyte by a method of potentiometric titration or cheicaml titration for estimating electrolysis time, and simultaneously testing sulfate radical concentration of the failure electrolyte by a method of chemical deposition; (B) adjusting the vanadium concentration of the failure concentration to be 1-4moL / L, preferably 1.5-3.5moL / L and the sulfate radical concentration to be 2-8moL / L, preferably 3-7moL / L by adding vanadium pentoxide or sulfuric acid and water; (C) carrying out electrolysis on the electrolyte to tetravalence by using an electrolysis groove according to the electrolysis time estimated in the step (A), monitoring the electrolyte, and carrying out electrolysis to trivalent or pentavalent vanadium to obtain a vanadyl sulfate solution; and (D) carrying out evaporation or solvent-out crystallization on the vanadyl sulfate solution to obtain the vanadyl sulfate.

The invention provides a method for determining the content of iron in nickel-based high temperature alloy. The method comprises the following steps: 1, processing a nickel-based high temperature alloy sample with a hydrochloric acid-nitric acid-hydrofluoric acid mixed acid as a digestion agent, perchloric acid as an oxidant and ammonium hydroxide as a precipitating agent to obtain a sample digestion solution; and 2, determining the content of iron in the digestion solution through adopting a two jump potentiometric titration technology. The method for determining the content of iron in nickel-based high temperature alloy takes shorter time and less force than manual direct titration, is simple and feasible, uses two potential jumps to determine the end point without using the color abrupt change of an indicator, omits the reading of the titration result, eliminates system errors brought by the indicator and the end point reading, and improves the accuracy and precision of the determination result.

The invention relates to polyhydric alcohol value determination, in particular to a method for utilizing potentiometric titration method to measure a polyhydric alcohol acid value. The method comprises the steps of accurately weighing a polyhydric alcohol sample and utilizing an organic solvent without acid to dissolve the polyhydric alcohol sample, setting an acid value calculation formula for a potentiometric titrator, wherein an acid value AV is equal to (V1-V2)*C*56.1 / M; using a potassium hydroxide-alcoholic solution to titrate the sample, enabling the potentiometric titrator to automatically stop working when a terminal point is reached, and an acid value result is given. The polyhydric alcohol contains aromatic polyester polyol prepared by raw materials including polypropylene oxide ether polyhydric alcohol, phenyl anhydride polyester polyol and waste PET and the polyhydric alcohol which needs a special assistant in a production process and accordingly cannot normally develop color in acid value determination. The problem that a titration end point is unobvious in color development and inaccurate in titration result due to deep color of a detected material and other reasons can be solved through potentiometric titration, and the method is simple, and a determination result is accurate and reliable.

The invention discloses a potentiometric-titration-based method for detecting the doping amount of a modifying agent in modified asphalt. The method comprises the following steps of: preparing a modified asphalt solution with a known doping amount of modifying agent and a modified asphalt solution with an unknown and to-be-detected doping amount of modifying agent; adding unsaturated bond addition agent for treatment; then adding a potassium iodide solution for treatment; then performing oxidation-reduction titration with a sodium thiosulfate solution, and determining the volume of the consumed sodium thiosulfate solution through potentiometric titration; drawing a standard curve according to the volume of the consumed sodium thiosulfate solution in the modified asphalt solution with the known doping agent and the doping amount of the modifying agent; and calculating the doping amount of the modifying agent in the modified asphalt to be detected according to the volume of the consumed sodium thiosulfate solution in the modified asphalt solution with the doping agent to be detected, and the standard curve. The method can effectively overcome the influence of a dark background of asphalt and depositions generated during a titration process to conventional titration analysis, and quickly and accurately detect the doping amount of the modifying agent in the modified asphalt, thus guaranteeing the control on production and processing quality of modified asphalt.

The invention discloses a volumetric analysis method, in particular to a continuous potentiometric titration analysis method for micromolecule carboxylic acid and amino acid in aqueous solution. The weak jump is enhanced by converting the first derivative of a titration curve into a jump index by a curve of the jump index to titrant volume; the pH value of the solution is regulated below 2 by using a strong acid when in titration; then the titration is carried out by using standard alkali liquor; a first jump is generated when the solution is titrated to have the pH value of 3-3.5, which shows that the free strong acid is titrated; the titration continues until the pH value of carboxyl is 7.5-9.3 to generate a second jump; then the titration continues until the pH value of amino is 11-11.5 to generate a third jump; and the consumed standard alkali liquor between the two adjacent jumps respectively reflect the total amount of the free strong acid, the carboxylic acid and the amino acid. The method is simple and convenient to operate and rapid to determine and has reliable result and low analysis cost, can be popularized and applied to analyzing other complicated samples.

The present invention relates to electrochemical analysis technology and especially one automatic potentiometric titration capable of automatically judging end point. The titration process includes selecting titration mode, adding titrating agent, measuring present potential, calculating first order differential value, calcualting the volume of added titrating agent, judging the end point, endingthe titration, displaying the titration results and storing the titration curve. Meanwhile, the titration mode is selected in the computer, and the titration curve may be used as the titration mode for next similar titration analysis. The present invention has the advantages of fast titration speed, high precision, automatic titration process and simple operation process.

The invention discloses a chemical determination method for the contents of cobalt and manganese in a cobalt-manganese raw material. The method includes the steps that firstly, the cobalt-manganese raw material is titrated with EDTA, and the total concentration of cobalt and manganese in the raw material is obtained; then, manganese is removed through pretreatment, cobalt liquor is obtained, the concentration of cobalt is measured through a potentiometric titration method, and the concentration of manganese is obtained by conducting calculation through a difference method. The method is accurate in analysis, easy and convenient to implement and good in repeatability, and the error rate is smaller than 5%.

Provided are a flame retardant which is good in dispersibility in an organic polymeric material, and does not lower, even after mixed with an organic polymeric material, material properties thereof; a flame retardant composition; and a shaped body. The flame retardant of the present invention includes magnesium hydroxide particles subjected to a surface treatment, the particles satisfying the following (A) to (D): (A) an average particle size is 2 μm or less according to a laser diffraction method; (B) a BET specific surface area is 3 to 15 m2 / g; (C) a degree of mono-dispersion is 50% or more, the degree of mono-dispersion being represented by the following equation: Degree of mono-dispersion (%)=(average primary particle size [μm] of particles according to SEM observation / average particle size [μm] of particles according to laser diffraction method)×100; and, (D) just after 1 mL of a 0.1 M solution of nitric acid is dropwise added at a dropping rate of 0.1 mL / minute to a suspension obtained by adding 1.0 g of the flame retardant to 100 mL of an aqueous mixed solution containing 0.1% by weight of each of a wetting agent and an electrolyte, pH of the suspension is 9.0 or less according to a potentiometric titration.

The invention discloses a potentiometric titration determining method of boric acid in water-based adhesive. According to the potentiometric titration determining method, boric acid in a system is titrated with sodium hydroxide so as to adjust pH value of the system to a certain value; a mannitol saturated solution is added for complexing boric acid in the system and reducing pH value of the system; a second time of titration is carried out with sodium hydroxide, and when pH value of the system is increased to be equal to the pH value before complexing, the volume of sodium hydroxide consumed at the moment is recorded, and the boric acid content of the system is calculated further. The potentiometric titration determining method is capable of realizing continuous operation of manual titration and an automatic potentiometric titrator; operation is simple and rapid; and detection range is wide.

The invention discloses a potentiometric titration determination method of cemented sand gravel cement content, which comprises the following steps: (1) preparing at least three standard cemented sand gravel / cement mixtures with equal mass and different cement contents; (2) adding water into the standard cemented sand gravel / cement mixtures and diluting to obtain standard mortar mixed liquor; (3) adding a phenolphthalein indicator into clear liquid of the standard mortar mixed liquor, then titrating by using NH4CI aqueous solution till the clear liquid is colorless, recoding the titration quantity of the NH4CI aqueous solution and further obtaining a standard curve between the titration quantity of the NH4CI aqueous solution and the content of cement in the standard cemented sand gravel / cement mixtures; (4) taking the cemented sand gravel / cement mixtures to be detected, adding water and diluting to obtain mortar mixed liquor; and (5) adding the phenolphthalein indicator into clear liquid of the mortar mixed liquor, then titrating by using NH4CI aqueous solution till the clear liquid is colorless to obtain according to the standard curve. The potentiometric titration determination method has the advantages of simplicity in operation, easiness in implementation and short time consumption and is suitable for quickly determining the content of newly-mixed cemented sand gravel cement on site and controlling the construction quality of cemented sand gravel.

The invention discloses a method for modified asphalt separation evaluation based on modification agent mixing amount potentiometric titration quantitative analysis. The method comprises carrying out separation pipe heat storage tests on a sample to be detected for different time, taking one third of the sample at the top and one third of the sample at the bottom, respectively putting the parts into a sample box, accurately determining modification agent mixing amounts of the sample parts at the top and bottom by a potentiometric titration method, calculating a separation judgment index delta w, carrying out preliminary evaluation on a separation case of a modified asphalt sample to be detected, and carrying out accurate quantitative evaluation on a modified asphalt sample separation degree by a separation degree a. The method realizes fast and accurate evaluation of a modified asphalt separation case, accurately measures modification agent mixing amounts of the sample parts at the top and bottom after heat storage tests by the potentiometric titration method and directly represents a modified asphalt separation degree.

The invention relates to a measuring method for mineral oil acid value, implemented according to the following steps that: (1) petroleum ether and 99 percent ethanol aqueous solution are mixed according to the volume ratio of 1:1 to obtain mixed solvent; (2) KOH ethanol solution with the concentration being 0.05mol / L is prepared as volumetric solution; (3) according to the method of GB / T7304, the mixed solvent obtained in step (1) is measured by a potentiometric titrator to obtain a blank value; (4) a certain quantity of mineral oil sample, which is weighed out and is added in the mixed solvent, is stirred and heated to 45 to 55 DEG C, thereby ensuring that the mineral oil sample is completely dissolved in the mixed solvent; then, the mixture is cooled down; (5) according to the method of GB / T7304, 0.05molKOH / ethanol solution is used as volumetric solution to complete potentiometric titration on the potentiometric titrator; therefore, an end point can be judged by means of the potential jump on the potentiometric titration curve; finally, according to the volume of consumed volumetric solution, the total acid value of lubricating oil sample can be obtained through calculation.

The invention provides a method for analyzing morphological distribution of C5 raw materials and sulfide in fractions; the method comprises the steps: firstly, an ultraviolet fluorescence method is adopted to measure the total sulfur content of a sample; secondly, a potentiometric titration method is used for measuring the sulfur content of sulfide hydrogen and mercaptan in the sample; thirdly, the sample is washed by silver nitrate solution, the ultraviolet fluorescence method is adopted to measure the total sulfur content of the washed sample; finally, the sulfur content of alkyl sulfide is converted by a subtration method; and a Zn-HAc reduction method is used for measuring the sulfur content of disulfide in the washed sample. The invention has the advantages of good repeatability and high precision, effectively solves the problem that the analysis of the sulfide morphology of the C5 raw materials and the sulfide in fractions is difficult due to the complex morphological distribution thereof, and provides technical data support for analyzing the desulfuration, equipment corrosion and the influence of different sulfur morphologies on the production processes.