Page 40 - Technology Compendium

CSIR-IMMT/EXM - 11

Production of sodium hydroxide and sulphuric acid from sodium sulphate effluent

Advantages / Salient Technical Features
• The sodium sulphate (Na SO )effluent is split into
4
2
sodium hydroxide (NaOH) and sulphuric acid ( H SO )
2
4
• 25 % NaOH and 5 % H SO can be produced from
2
4
effluent containing 5-20% Na SO
2
4
• Energy consumption is in the range of 5-6 kWh/kg
NaOH
• NaOH and H SO produced can be recycled back into
4
2
the hydrometallurgical or chemical process.
Problem being addressed
• Processing Na2SO4 effluent
• Reduction in Effluent Discharge
• Recovery of valuable chemicals
• Recycling

Environmental Considerations (if any)
• Solves environmental issue of sodium sulphate
effluent disposal

Major Raw Materials to be Utilized Commercialization Status
• Consumables (3-5 yrs life): • Prototype cell provided to HWB, Mumbai
• Cation exchange membranes
• Anion exchange membranes Techno-economics
• MMO coated electrodes • Revenue 45-65 Rs /kg >> Cost of production
Rs 30-35 Rs/kg sodium hydroxide
IPR Status / Details (India/Abroad)
• Production of valuable NaOH and H2SO4 Technology Package
• Process know-how, Basic Engineering
Application/Uses Package, detailed electro-membrane cell
• Defence, High temperature resistant alloys, Steel, design
Light bulb, Electronics, Machinery, etc.

Scale of Development
• Bench scale of 1-10 kg/h sodium sulphate feed.
(Current TRL Level : 06)

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