Electrolysis process and equipment for producing standard hydrogen sulphideThe present invention relates to a kind of electrolytic process and produce the method and apparatus of standard cure hydrogen.
When scale of correcting gas analytical instrument etc. utilized standard gas on a small scale, the work of preparing calibrating gas was very important.Because hydrogen sulfide has reactive behavior and the intensive adsorptivity, corrodibility of height, the hydrogen sulfide of accurate preparation standard is difficulty and trouble especially, prolonged preservation is more impossible, and therefore, it is significant to develop the simple and practical device of producing the normal concentration hydrogen sulfide.
Permeation tube method commonly used produces standard hydrogen sulphide.It is pure liquid hydrogen sulfide to be contained in materials such as tetrafluoroethylene make in the stainless steel tube of cap, and hydrogen sulfide just constantly oozes out from cap.The speed of oozing out is relevant with temperature, needs accurately control permeation tube envrionment temperature, and feeds carrier gas with certain speed.Permeation tube method produces standard hydrogen sulphide required equipment complexity, operation inconvenience such as adjusting concentration, and duration of service is short, transportation and use trouble.
Japanese Patent is clear to have provided the method that a kind of suspension electrolysis method prepares hydrogen sulfide on a small scale with 55-2765, electrolyzer is divided into cathode compartment and anolyte compartment with barrier film, allow the sulphur powder constantly suspend in the acidic solution in this cathode compartment, when electric current passes through this electrolyzer, chemical reaction is carried out on surface at suspension sulphur powder, just produces hydrogen sulfide in the cathode compartment.This method is adsorbed on the sulphur powder with CuS and plays katalysis.The suspension electrolysis method needs to separate cathode compartment and anolyte compartment with barrier film, and the constantly stirring of sulphur powder, thereby the electrolyser construction complexity of using, electrode is insecure, and electrolysis time is long, and needs preelectrolysis, operation inconvenience, current efficiency is low, and its efficient is obviously descended the degradation shortcoming with the increase of pond electric current.The hydrogen sulfide of this method preparation can not be as known normal concentration hydrogen sulfide.
The present invention provides a kind of method and apparatus of electrolytic process preparation standard hydrogen sulfide, under certain cathode current density, can obtain the normal concentration hydrogen sulfide of 100% current efficiency.Concentration is accurate, and regulation range is wide, select easily and temperature independent, and the time that reaches steady concentration after the beginning electrolysis is short, and when not using, negative electrode can be placed on dry director's phase and preserve.
The present invention proposes with a kind of insoluble metallic sulfide Ag2S makes electrolysis cathode.Electrolyzer is made by glass, and its structure exports (2), cathode compartment and Ag by carrier gas inlet (1), gas as shown in Figure 12S negative electrode (3), anolyte compartment and platinum filament anode (4), standard ground (5) and base (6) are formed, and cathode compartment and below, anolyte compartment have a connecting pipe that two utmost point chambers are communicated with.Rare H packs in the electrolyzer2SO4Or rare H3PO4Electrolytic solution, electrolytic solution can flow between cathode compartment and anolyte compartment, when the input constant current, Ag2Silver in the S negative electrode is reduced into argent, discharges sulfonium ion, and its reaction is Ag2S+2e → 2Ag+S-, sulfonium ion enters and changes hydrogen sulfide in the acid electrolyte into, when allowing carrier gas pass through electrolytic solution with certain speed, just can obtain certain density standard cure hydrogen.
H2SO4Or H3PO4In the 0.05-1M scope, can both reach above-mentioned electrolysis effectiveness.When selecting H for use2SO4The time, do not allow too high concentration, because vitriol oil meeting and hydrogen sulfide react; Because of consumption acids in the process of electrolysis generation hydrogen sulfide, low excessively acid concentration can increase the number of times of changing electrolytic solution again.
Work as Ag2The current density of S cathode surface is 0.008-8 milliampere/centimetre2The time, the amount that produces hydrogen sulfide is directly proportional with Faradaic current, and in certain limit of error, obtain the normal concentration hydrogen sulfide of 100% current efficiency, the stability of its sum of errors Faradaic current is relevant, temperature independent, therefore, need require to select for use the constant current source of different current stability,s according to difference.
It is relevant with the size of Faradaic current to reach the time of stablizing concentration of hydrogen sulfide, and electric current is big more, and it is short more to reach stable time.
Ag2The preparation method of S negative electrode has: silver-colored rod is placed in the 1M sodium sulfide solution as anode, and platinum filament carries out electrolysis as negative electrode, can plate one deck Ag on silver-colored rod2S; Also can be Ag2S powder and silver powder mix, and compressing tablet becomes electrode; Also can be with Ag2The S powder smelting is shaped to electrode.The Ag that melt-forming is made2S negative electrode firm and durable is a kind of ideal method.
Embodiment:
Use electrolyzer shown in the accompanying drawing 1 and the constant current source shown in the accompanying drawing 2.In the accompanying drawing 2, (7) are electrolyzer.It is the H of 0.5M that electrolytic solution is selected concentration for use3PO4, the Ag of use φ 5 * 10 melt-formings2During the S negative electrode, feed constant current, after stable, the current efficiency that records is as shown in the table:
From last table as seen, the hydrogen sulfide amount that records is directly proportional with Faradaic current, and consistent with the hydrogen sulfide that produces in theory.Work as Ag2The current density of S cathode surface is not more than 8 milliamperes/centimeter2The time, in certain limit of error, obtain 100% current efficiency.
As the Ag that uses φ 3 * 10 melt-formings2During the S negative electrode, record same result, all temperature independent.
It is relevant with the size of Faradaic current to reach the time of stablizing concentration of hydrogen sulfide.When electric current greater than 0.2 MAH, can reach the hydrogen sulfide of steady concentration after 10 minutes; When electric current greater than 1 MAH, just can reach steady concentration in 1 minute; When electric current during, need 30-60 minute less than 50 microamperes.For shortening reaches time of steady concentration, can separate with large-current electric earlier, be transferred to required Faradaic current then.
Faradaic current 0.05 0.1 0.2 0.5 1.0 2.0 4.0 6.0 8.0 10.0
(milliampere)
Produce in theory
Hydrogen sulfide amount 0.58 1.06 2.13 5.29 10.57 21.1 42.3 63.3 84.4 105.7
(little Grams Per Minute)
The sulfuration that records
Hydrogen amount 0.57 1.06 2.16 5.35 10.57 21.4 42.3 63.5 85.2 105.2
(little Grams Per Minute)
Current efficiency 98.3 100 101 101 101 101 100 100 101 99.5
（%）