Classification of sodium hypochlorite generators

A. Classification by electrolysis: non-diaphragm method and diaphragm(membrane) method.

1. Non-diaphragm method:

1.1. There is no ionic membrane between the cathode and anode electrodes, which produces a lower concentration sodium hypochlorite solution.

1.2. Application fields: used for One-Site on-site preparation, electrolysis of low-concentration brine (or seawater), in an electrolytic cell without a diaphragm, chloride ions are precipitated at the anode, OH- is precipitated at the cathode, and the precipitated chloride ions and OH- are mixed in an instant Sodium hypochlorite solution is formed, so there is almost no chlorine gas generated during the electrolysis process (because it is all absorbed by OH-), and the hydrogen gas produced as a by-product is diluted and discharged.

1.3. Features:

1.3.1. Because it uses no-diaphragm electrolysis, the anode uses DSA electrode, and the cathode is a pure titanium electrode plate, so the quality of the electrolyte is not high, and it can be used by dissolving salt in softened tap water (pickling cycle Up to 90 days), when the equipment is in the presence of seawater, seawater can be directly used as the electrolyte, but the pickling cycle will be shortened (usually 30 days, the cycle is related to the cleanliness of seawater).

1.3.2. On-site preparation, which solves the high cost and transportation safety problems of purchasing high-concentration sodium hypochlorite solution (above 10%) (sodium hypochlorite solution with more than 5% belongs to the catalog of "hazardous chemicals").

1.3.3. Can work at any time, prepare sodium hypochlorite solution on site, and will not be affected by the timely delivery of the solution supplier at the purchase cost.

1.3.4. The equipment is a general-purpose equipment with fully automatic operation and safe operation. It does not require a team of professional chemical engineers to manage and operate the equipment.

2. Ionic membrane electrolysis:

2.1. There is a cationic membrane between each group of anode and cathode to generate chlorine gas and caustic soda, and then use caustic soda to

The absorption tower absorbs chlorine gas to produce high-concentration sodium hypochlorite solution.

2.2. Application fields: special machinery for chlor-alkali chemical industry, used to produce chlorine gas and caustic soda products, or use caustic soda to absorb chlorine gas to produce high-concentration sodium hypochlorite solution.

2.3. Features:

2.3.1. Because cation membrane is used for cation separation, cations are highly susceptible to contamination, so refined brine must be used, and pure water (equipped with RO pure water machine) to dissolve high-purity salt particles will produce saturation. brine, and then the brine is subjected to primary brine refining and secondary brine refining to obtain refined high-purity saturated brine.

2.3.2. Chlorine gas is generated in the anode chamber, and caustic soda + hydrogen gas is generated in the cathode chamber.

2.3.3. The absorption tower at the back end of the electrolytic cell uses caustic soda to absorb chlorine gas to produce sodium hypochlorite solution.

2.3.4. It is necessary to adjust the pH value of the brine.

2.3.5. It is necessary to adjust the proportion of caustic soda and control the content of free alkali.

2.3.6. It needs to be installed in a specialized chemical factory, operated and managed by a professional chemical team.

2.3.7. Electrolysis of saturated brine produces high-concentration sodium hypochlorite solution for sale.

B. Classification by electrolyte: electrolytic brine and electrolytic seawater. 

1. Electrolyzed brine.

1.1. The membrane electrolysis method uses refined saturated brine as the electrolyte to produce a 10+% high-concentration sodium hypochlorite solution, which is used in chlor-alkali chemical plants.

1.2. The non-diaphragm method uses softened water to dissolve salt and dilute it into 3% dilute brine as electrolyte to produce 8000±10%ppm (0.8%) lower concentration sodium hypochlorite solution for on-site preparation.

2. Electrolysis of seawater.

2.1. Precisely filter the seawater, and then electrolyze it to produce 2000±10%ppm sodium hypochlorite solution by electrolysis without diaphragm, which only needs the cost of electricity and saves the cost of salt.

2.2. The finished product concentration of sodium hypochlorite solution is limited to about 2000ppm, and deep electrolysis cannot be carried out, otherwise iron, aluminum, magnesium, etc. in seawater will form chlorides, which will cause flocculation and eventually form sediments, which will make electrolytic cells, pipelines, etc. clogged.