Co-Deacidification and Dechlorination of Aqueous/Gaseous Streams by Mineral Dissolution (Case No. 2022-173)

Summary

UCLA researchers have developed a method and composition for simultaneous deacidification and dechlorination of acidic aqueous solutions (including brines or electrolyte streams enriched in free-chlorine species), using mineral or rock solids containing low-valent metals to neutralize acidity and remove chlorine contaminants.

Background

Electrolytic processes and industrial streams (e.g., seawater electrolysis or chlorine-rich wastewater) often produce solutions with low pH and high levels of free chlorine (e.g., Cl₂, ClO⁻, HOCl). These streams are corrosive, hazardous, difficult to treat, and costly to neutralize or dechlorinate using standard methods (e.g. adding alkali, activated carbon). There is a need for simpler, lower-cost, more sustainable methods that can treat such streams efficiently, ideally in one step.

Innovation

The technology uses solid minerals or rock materials, especially mafic or ultramafic minerals (such as olivine, serpentine, basalt), that contain low-valent metal species (e.g. Fe⁰, Fe²⁺, Mn⁰, Ni⁰ etc.), along with silicate, carbonate, oxide, hydroxide, or oxyhydroxide forms. These are contacted with acidic aqueous solutions that contain free-chlorine species. The mineral solids both neutralize the acidity (raising pH toward neutral or alkaline) and act reductively to convert free-chlorine species to chloride (Cl⁻), thereby dechlorinating. Operational parameters—solid type, particle size, solid-to-liquid ratio, mixing or agitation, contact time, reactor design (batch or continuous)—are tuned to achieve desired performance.

Advantages

Treats both low pH (acid) and free-chlorine species in one step.
Uses naturally abundant or cheap minerals/rocks rather than expensive chemicals or activated carbon.
Potential to avoid or reduce use of harsh alkalis or high-carbon-footprint materials.
Solid particles of wide size range possible; materials like olivine or basalt are scalable.
Flexible reactor configurations (batch or continuous); adjustable loading and contact times.
Produces dechlorinated brine solutions with neutral to alkaline pH, safer for handling or disposal.

Potential Applications

Treatment of industrial acid/chlorine contaminated wastewater or effluents.
Treatment of electrolyte streams from seawater electrolysis or chlorine-evolving electrolyzers.
Brine or saltwater streams that accumulate free chlorine (e.g., desalination, cooling towers).
Environmental remediation where acid rock drainage or chlorine exposure occurs.
Pre-treatment or polishing steps in water reuse, mining, or chemical processes.