A New Method Based on a Zero Gap Electrolysis Cell for Producing Bleach: Concept Validation.

Area of Science:

• Electrochemistry
• Chemical Engineering
• Materials Science

Background:

• Commercial bleach production relies on sodium hypochlorite, often derived from chlorine-soda processes.
• Existing smaller-scale electrolysis methods for bleach production are limited by hypochlorite ion degradation.
• Current methods yield low-concentration bleach (0.3-1 wt% active chlorine).

Purpose of the Study:

• To develop a new electrolysis process for producing higher concentration sodium hypochlorite bleach (up to 3.6% active chlorine).
• To investigate the use of a three-compartment zero-gap electrolysis cell with various membrane types.
• To optimize operating conditions for efficient bleach synthesis.

Main Methods:

• Utilized a three-compartment zero-gap electrolysis cell with ion-exchange or porous membranes.
• Generated hypochlorous acid (HClO) in the anode compartment by maintaining pH between 4.5 and 5.5.
• Produced caustic soda in the cathode compartment and used brine in the central compartment.
• Neutralized synthesized hypochlorous acid with sodium hydroxide (NaOH) to form bleach.

Main Results:

• Achieved bleach with active chlorine content close to 1.8 wt%.
• Evaluated performance based on membrane properties, durability, and electrochemical conditions.
• Identified optimal membrane couples and operating parameters for enhanced bleach production.

Conclusions:

• The developed three-compartment electrolysis process shows potential for producing higher concentration sodium hypochlorite bleach.
• Membrane selection and electrochemical conditions are critical factors for optimizing the process.
• Further research can refine the process for industrial application and higher yields.