Electrolytic chlorine dioxide generator

Composition of an Electrolytic Chlorine Dioxide Generator

The electrolytic chlorine dioxide generator consists of two main components: an electrical control cabinet and an electrolytic cell.

Electrical control cabinet

The electrical control cabinet is a regulated constant-current power supply cabinet. It comprises AC power input terminals, an AC contactor, a main transformer, a thyristor rectifier assembly with its temperature sensor, positive and negative output terminals, and a computer-controlled integrated circuit board (including power supply board, main control board, proportional‑control board, display board, etc.), as well as an operator panel and a cabinet enclosure.

Electrolytic cell

The electrolyzer is designed as an integrated bipolar structure, comprising a brine chamber, an anode compartment, a cathode compartment, DC busbars, and a piping system. The brine chamber houses a salt‑dissolving tank; the anode compartment contains two anode plates, two neutral plates, and cooling water pipes; and the cathode compartment accommodates two cathode plates and cooling pipes. A partition and a brine circulation channel are provided between the brine chamber and the anode compartment, while a diaphragm separates the anode and cathode compartments. The DC busbars consist of positive and negative terminals. The piping system includes a main tap‑water supply line, inlet lines for the brine chamber, the cathode compartment, and the cooling water system, an automatic alkali‑drain line for the cathode compartment equipped with a solenoid valve, a chlorine dioxide disinfectant absorption line, effluent discharge lines for both the anode and cathode compartments, a gravity‑driven alkali‑drain line from the cathode compartment, a hydrogen‑gas vent line, and a water‑jet device, as well as a disinfectant‑output line, among others.

The electrolyzer’s cell body, as well as the brine chamber, anode compartment, and cathode compartment, are all fabricated by welding PVC panels. The anode is a multi‑element coated titanium mesh, the neutral plate is also a coated titanium mesh, the cathode is made of stainless steel, the diaphragm is constructed from a newly developed polytetrafluoroethylene material, the cooling water pipes are titanium tubing, and all fittings are made of UPVC. With outstanding performance across all components and meticulous manufacturing, the entire system boasts a long service life.

Working Principle of an Electrolytic Chlorine Dioxide Generator

1. Required raw materials

This generator uses coarse-grained table salt (NaCl) as its feedstock. It also requires the addition of distilled water (H₂O) and connection to an AC power supply (single-phase 220 V or three-phase 380 V).

2. Electrolysis process

First, coarse‑grained sodium chloride (NaCl) is loaded into the salt tank, and fresh water is added to dissolve it into a saturated brine, which then circulates automatically into the anode chamber. Simultaneously, fresh water is introduced into the cathode chamber. Next, the power switch is closed to energize the system, and the control cabinet supplies direct current to both the anode and cathode of the electrolytic cell. In the anode chamber, four gases—chlorine dioxide (ClO₂), ozone (O₃), chlorine (Cl₂), and hydrogen peroxide (H₂O₂)—are generated; these are collected by the absorption pipeline and, under the negative pressure created by the ejector, drawn out and mixed with water to form a disinfectant solution. The solution is then conveyed via the dosing pipeline to the water body requiring treatment for disinfection. Meanwhile, in the cathode chamber, hydrogen gas (H₂) and a sodium hydroxide (NaOH) solution are produced. The hydrogen gas is discharged outdoors through the hydrogen vent line, while the NaOH alkaline solution, after intermittent addition of fresh water for dilution, is allowed to flow out naturally through the alkali discharge line.

3. Basic principles of electrolysis:

Electrolysis takes place in the anode compartment and the cathode compartment. Under the influence of an electric current, relatively complex electrochemical reactions occur in both compartments: in the anode compartment, four gases—ClO₂, O₃, Cl₂, and H₂O₂—are produced, while in the cathode compartment, H₂ and NaOH are generated. The corresponding reaction equations are as follows:

4NaCl + 16H2O == 2ClO2 + 2O3 + Cl2 + H2O2 + 12H2 + 4NaOH

4. The function of chlorine dioxide composite disinfectant

During the electrolysis process, four gases—ClO₂, O₃, Cl₂, and H₂O₂—are generated in the anode compartment, forming a composite chlorine dioxide disinfectant. Each of these—ClO₂, O₃, Cl₂, and H₂O₂—is a powerful oxidizing agent; moreover, their synergistic effects further enhance the disinfectant’s broad‑spectrum bactericidal and virucidal activity as well as its high oxidation capacity. It not only rapidly inactivates both nonpathogenic and pathogenic microorganisms but also deactivates algae and zooplankton in water, while virtually eliminating the formation of trihalomethanes and other organohalogen compounds. In addition, it can oxidatively degrade certain organic contaminants in water—for example, by undergoing redox reactions with phenolic compounds to suppress the formation of chlorophenols and reduce unpleasant odors—and can transform 3,4‑benz[a]pyrene into a noncarcinogenic quinone‑type structure. Furthermore, it can oxidize or reduce various reductive anions (such as S²⁻, SO₃²⁻, CN⁻, NO₂⁻, etc.) and metal ions (including Fe²⁺, Mn²⁺, Ni²⁺, etc.), achieving effective removal.

Mechanism of chlorine dioxide disinfection: It primarily works by penetrating bacterial cells, oxidizing nucleic acids (RNA or DNA), thereby inhibiting bacterial biosynthesis and leading to cell death, or by suppressing protein synthesis to disrupt bacterial growth.

Application Scope of Electrolytic Chlorine Dioxide Generators

1. Disinfection and sterilization of wastewater from hospitals, outpatient clinics, and health centers;

2. Disinfection of drinking water in municipal and rural waterworks, industrial and mining facilities, military units, railways, highways, and other self-supplied water systems;

3. Disinfection of secondary water supply systems in high-rise buildings such as office buildings, residential buildings, hotels, and guesthouses;

4. Disinfection of swimming pool water;

5. Disinfection and algaecide treatment for industrial circulating cooling water and reclaimed water.

6. Cyanide removal treatment for cyanide-containing wastewater;

7. Papermaking and textile bleaching processes.