Microcoulometric titratorIt is a "zero equilibrium" closed-loop negative feedback system composed of a Coulomb amplifier, a titration cell, and a suitable electrolysis system, based on the principle of microcoulometric titration technology. The collection of bias voltage data and the control of cracking furnace temperature are executed by a microcontroller, which is connected to a computer through serial communication to achieve automatic control of the entire system.

⑴ Working principle of sulfur

When the system is in equilibrium, a constant concentration of I3- is maintained in the titration cell. When SO2 enters the titration cell, it reacts with I3- ions: I3-+SO2+H2O → SO3+2H++3I-

The concentration of I3- in the electrolytic cell decreases, and the measuring electrode pair senses this change. The signal of the change is input into the Coulomb amplifier, which then outputs a corresponding current to the electrolytic electrode pair. The electrolysis anode generates I3-, which is consumed by SO2, until the original I3- ion concentration is restored: 3I - → I3-+2e. The amount of electricity consumed during electrolysis can be measured, and the total sulfur content in the sample can be obtained according to Faraday's law of electrolysis.

⑵ Working principle of chlorine

When the system is in equilibrium, a constant concentration of Ag+is maintained in the titration cell After the sample is cracked, organic chlorine is converted into chloride ions, which are then carried into the titration cell by the carrier gas to react with silver ions: Ag++Cl - → AgCl

The concentration of silver ions in the titration cell decreases, and the indicator electrode pair indicates the change in this signal. The signal of this change is input into the Coulomb amplifier, which then outputs a corresponding current to the electrolytic electrode pair. The electrolytic anode generates Ag+ions consumed by Cl - until the original concentration of Ag+ions is restored. The amount of electricity consumed during the generation of Ag+ions can be measured, and the total chlorine content in the sample can be determined according to Faraday's law of electrolysis.

Electrolytic cell maintenance:

It should be stored in a cool and air free place, and the chlorine electrolysis cell must be strictly protected from light;

The electrolytic cell should always maintain a certain amount of electrolyte and keep the platinum plate below the liquid level;

Do not pull the reference electrode and ensure that its reference electrode arm is free of bubbles;

Electrolyte should be prepared regularly and kept fresh;

Do not allow the washing solution or acetone to seep into the reference side arm during cleaning, otherwise the entire electrolytic cell needs to be reinstalled