desorptionoxidation

Desorption-oxidation is a remediation approach that combines desorption of adsorbed contaminants from solid matrices with subsequent oxidation of the desorbed material. In this sequential process, pollutants that are strongly bound to soils, sediments, or sorbents are first released into a liquid phase and then oxidized to less harmful products, ideally mineralized to carbon dioxide and water.

Desorption is achieved by altering solvent conditions, such as pH, salinity, or temperature, or by adding surfactants or flushing liquids to desorb contaminants. Oxidation follows, using chemical oxidants (for example hydrogen peroxide in advanced oxidation processes, ozone, permanganate, or persulfate) or catalytic systems (metal oxides, activated carbon surfaces) that promote breakdown of the desorbed compounds. The process can be carried out ex-situ, where contaminated solids are treated away from their original location, or in-situ, where oxidants are injected into the contaminated zone and contaminants are flushed out for oxidation.

Applications include soil and sediment remediation of organic pollutants, groundwater treatment, and the regeneration of spent sorbents such as activated carbon by destroying adsorbed organics. It is used for compounds that are difficult to oxidize while bound and for protecting aquifers from recontamination.

Advantages of desorption-oxidation include the ability to target strongly adsorbed contaminants, potential reductions in energy use compared with thermal destruction, and the possibility of integrating with existing soil washing or adsorption-based treatments. Limitations include incomplete desorption limiting overall removal efficiency, formation of oxidation byproducts, management of oxidant dosing and contact time, and costs associated with reagents and reactors. The approach is related to advanced oxidation processes and other adsorbent-based remediation strategies.