A kind of method of content of hydrochloric acid in Accurate Determining iron chloride etchant solution
Technical field
The invention belongs to chemical analysis technology field, relate to the technology of content of hydrochloric acid in a kind of Accurate Determining iron chloride and hydrochloric acid mixed solution, particularly to the determination techniques of content of hydrochloric acid in the higher iron chloride etchant solution of iron content.
Background technology
Ferric chloride solution is used for the process of surface treatment before circuit board, stainless etching and inter process, metallographic, fluoroscopic examination, and main component in solution is iron chloride and hydrochloric acid, is widely used.
At present, the assay method of content of hydrochloric acid in special iron chloride etchant solution is not all had in GB and navigation mark.The method that can inquire is mainly industrial chlorinations iron Free Acid, wherein relate to the precipitation of ferric ion, filtration, divide steps such as getting, and method is applied to specialized equipment-potentiometric titrimeter.
The assay method related in foreign trade standard is phenolphthalein indicator, standard solution of sodium hydroxide direct titration, wherein ferric existence causes terminal to be difficult to differentiate, along with the consumption of the hydrochloric acid in solution, ferric ion is constantly hydrolyzed, and produces ferric hydroxide reddish-brown precipitation, mixes with Phenol Red color contamination during terminal, during titration, color change is not sharp, judges to have an impact to titration end-point.
Also certain methods is had to utilize total chloridion to deduct the chlorion of suitable iron chloride content, thus calculate content of hydrochloric acid, only effective to new soln analysis, but along with composition transfer each in solution, measurement result departs from actual content far away, along with component in solution change after solution puts into production a period of time, become no longer applicable, even complete failure.
Through update search do not find special for iron chloride etchant solution in the assay method of content of hydrochloric acid.Inquiry ferric chloride solution, relevant has " a kind of crystallization is separated the nickel ion in ferric trichloride with extraction ".The patent No.: CN200410017133.Inquiry hydrochloric acid solution, the patent No. that relevant is the method for separation of iron " from the hydrochloric acid solution of chloride containing iron optionally ": the nickel ion that CN201210153853. Patents content relates in ferric trichloride detects, and the assay method of iron in the hydrochloric acid solution of chloride containing iron, and do not relate to the method for content of hydrochloric acid in iron chloride etchant solution.
Summary of the invention
The technical problem to be solved in the present invention: the object of the invention is to provide the method for content of hydrochloric acid in a kind of Accurate Determining iron chloride etchant solution, easy and simple to handle, process is simple, titration end-point sudden change obviously, and accuracy is high, by ferric ion in solution and impurity effect little.
Technical scheme of the present invention: a kind of method of content of hydrochloric acid in Accurate Determining iron chloride etchant solution, comprising:
(1) with distilled water diluting iron chloride etchant solution, the dilution of iron chloride etchant solution is obtained;
(2) with pipette, extract above-mentioned dilution, obtain a point dilution for the iron chloride etchant solution taken out, the reality of the front solution of record dilution is divided and is got volume V
0;
(3) in the dilution point to get, add ascorbic acid solution successively, then add distilled water, obtain ferric ion to be reduced to the+dilution of the iron chloride etchant solution of divalent;
(4) to ferric ion be reduced to+dilution of the iron chloride etchant solution of divalent in, with dropper add 10 bromine potassium phenol green-methyl red indicator, be titrated to solution just to green with standard solution of sodium hydroxide, obtain the dilution of titration iron chloride etchant solution completely, record titration value V
1;
(5) replace the dilution of iron chloride etchant solution in addition with distilled water, repeat step (2) to step (4), as blank assay, record titration value V2;
(6) content of hydrochloric acid in solution is obtained according to following formula:
Described formula is:
Wherein, V
1---the volume ml of the standard solution of sodium hydroxide that titration iron chloride etchant solution consumes;
V
2---the volume ml of the standard solution of sodium hydroxide that titration blank solution consumes;
V
0---divide the volume ml getting iron chloride etchant solution;
The concentration mol/L of C---standard solution of sodium hydroxide;
Iron chloride content g/L in iron chloride etchant solution before ρ FeCl3---dilutes.
Beneficial effect of the present invention: utilize ascorbic acid reduction Fe3+ in method, eliminate the impact that+3 valency ferric ions react acid base titration.Selected indicator indicating range is narrow, and titration end-point is obvious, and result is accurate.Designed by formula, exclusion process introduces deviation, makes result of calculation truly reasonable.The terminal acidity of the method can avoid the impact of hydrolysis reaction on titration end-point introducing impurity in solution use procedure.
Embodiment
Technical scheme of the present invention comprises:
(1) with distilled water diluting iron chloride etchant solution, the dilution of iron chloride etchant solution is obtained;
(2) with pipette, extract above-mentioned dilution, obtain a point dilution for the iron chloride etchant solution taken out, the reality of the front solution of record dilution is divided and is got volume V
0;
(3) in the dilution point to get, add ascorbic acid solution successively, then add distilled water, obtain ferric ion to be reduced to the+dilution of the iron chloride etchant solution of divalent;
(4) to ferric ion be reduced to+dilution of the iron chloride etchant solution of divalent in, with dropper add 10 bromine potassium phenol green-methyl red indicator, be titrated to solution just to green with standard solution of sodium hydroxide, obtain the dilution of titration iron chloride etchant solution completely, record titration value V
1;
(5) replace the dilution of iron chloride etchant solution in addition with distilled water, repeat step (2) to step (4), as blank assay, record titration value V2;
(6) content of hydrochloric acid in solution is obtained according to following formula:
Described formula is:
Wherein, V
1---the volume ml of the standard solution of sodium hydroxide that titration iron chloride etchant solution consumes;
V
2---the volume ml of the standard solution of sodium hydroxide that titration blank solution consumes;
V
0---divide the volume ml getting iron chloride etchant solution;
The concentration mol/L of C---standard solution of sodium hydroxide;
Iron chloride content g/L in iron chloride etchant solution before ρ FeCl3---dilutes.
Below by embodiment, the invention will be further described:
Embodiment one
The present embodiment is the method measuring content of hydrochloric acid in high temperature alloy etchant solution, and solution technique condition is HCl91g/L-126g/L, FeCl3242g/L-300g/L, comprises the following steps:
Step 101, accurately draws 10.00 milliliters of high temperature alloy etchant solutions with transfer pipet, is placed in 100 milliliters of volumetric flasks, with distilled water diluting to scale, shakes up.Obtain the dilution of high temperature alloy etchant solution.
Step 102, accurately draws above-mentioned dilution 10.00 milliliters with transfer pipet, is placed in 250 milliliters of triangular flasks.Obtain a point dilution for the high temperature alloy etchant solution taken out.
Step 103, in the dilution dividing the high temperature alloy etchant solution got in 250 milliliters of triangular flasks, adds 5.00 milliliters of ascorbic acid solutions successively, then adds distilled water 50 milliliters.Obtain ferric ion to be reduced to the+dilution of the high temperature alloy etchant solution of divalent.
Step 104, to ferric ion be reduced to+dilution of the high temperature alloy etchant solution of divalent in, with dropper add 10 bromine potassium phenol green-methyl red indicator, be titrated to solution just to green with standard solution of sodium hydroxide.Obtain the dilution of titration high temperature alloy etchant solution completely.
Step 105, replace the dilution of high temperature alloy etchant solution in addition with 5mL distilled water, the same above-mentioned steps of all the other test procedures (102)-step (104), as blank assay.
Step 106, according to content of hydrochloric acid in formulae discovery high temperature alloy etchant solution:
In formula, the volume ml of the standard solution of sodium hydroxide that V1---titration high temperature alloy etchant solution consumes;
The volume ml of the standard solution of sodium hydroxide that V2---titration blank solution consumes;
V0---divides the volume ml getting high temperature alloy etchant solution;
The concentration mol/L of C---standard solution of sodium hydroxide;
Iron chloride content g/L in iron chloride etchant solution before ρ FeCl3---dilutes.
HCl=115g/L is obtained according to formulae discovery
Embodiment two
The present embodiment is the method measuring content of hydrochloric acid in the brilliant rotten solution of stainless steel metallographic, and solution technique condition is HCl66g/L-76g/L, FeCl33g/L-7g/L, comprises the following steps:
Step 201, accurately draws the brilliant rotten solution of 10.00 milliliters of stainless steel metallographics with transfer pipet, is placed in 100 milliliters of volumetric flasks, with distilled water diluting to scale, shakes up.Obtain the dilution of the brilliant rotten solution of stainless steel metallographic.
Step 202, accurately draws above-mentioned dilution 10.00 milliliters with transfer pipet, is placed in 250 milliliters of triangular flasks.Obtain the dilution of the brilliant rotten solution of point stainless steel metallographic taken out.
Step 203, in the dilution dividing the brilliant rotten solution of the stainless steel metallographic got in 250 milliliters of triangular flasks, adds 5.00 milliliters of ascorbic acid solutions successively, then adds distilled water 50 milliliters.Obtain ferric ion to be reduced to the+dilution of the brilliant rotten solution of the stainless steel metallographic of divalent.
Step 204, to ferric ion be reduced to+dilution of the brilliant rotten solution of the stainless steel metallographic of divalent in, with dropper add 10 bromine potassium phenol green-methyl red indicator, be titrated to solution just to green with standard solution of sodium hydroxide.Obtain the dilution of the titration brilliant rotten solution of stainless steel metallographic completely.
Step 205, replace the dilution of the brilliant rotten solution of stainless steel metallographic in addition with 5mL distilled water, the same above-mentioned steps of all the other test procedures (202)-step (204), as blank assay.
Step 206, according to content of hydrochloric acid in the brilliant rotten solution of formulae discovery stainless steel metallographic:
In formula, the volume ml of the standard solution of sodium hydroxide of the brilliant rotten solution consumption of V1---titration stainless steel metallographic;
The volume ml of the standard solution of sodium hydroxide that V2---titration blank solution consumes;
V0---divides the volume ml getting the brilliant rotten solution of stainless steel metallographic;
The concentration mol/L of C---standard solution of sodium hydroxide;
Iron chloride content g/L in iron chloride etchant solution before ρ FeCl3---dilutes.
HCl=71g/L is obtained according to formulae discovery.
It is+divalent that the present invention adds ascorbic acid by+3 valency Fe3+ reduction, and before titration end-point, iron exists in the form of an ion, can not participate in the drop reaction of soda acid;
Select bromcresol green-methyl red to be indicator, indicator mutational range is narrow, and directing terminal accurately, obviously;
In computing formula, consider the H+ generated in reduced iron process, ascorbic acid is monoacid in acid base titration process, but in oxidation-reduction process, discharge 2 H+, be equivalent to dibasic acid, designed by formula, according to Chlorine in Solution iron content, calculate and reduce, obtain true acid number;
Indicator color change terminal is PH5.1, and the PH initial range that ferrous iron generates precipitation is about 6, and the nickel usually existed in production, manganese, copper plasma also not by the impact of alkalimetric titration, measure, need not consider the interference of hydrolysis reaction under this acidity;
Experimentation carries out ascorbic acid blank titration, if ascorbic acid enough just can, without the need to carrying out the demarcation of ascorbic acid normal concentration, and by Synchronization Analysis, better can grasp terminal change.
As can be seen from these aspects above, this method is saved time, impact on acidity assaying when the step of reduced iron eliminates analysis, when the selection of indicator makes titration, end point mutation is clearly effective, by producing the calculating of H+ content to iron chloride reduction in formula, make acid content more accurate, method application is more extensive.