1. Solvent Desorption: Uses solvents like ethanol or acetone to remove adsorbed dyes. Effective but solvent choice must avoid damaging the adsorbent.
2. pH Adjustment: Adjusting solution pH can reverse adsorption, especially for ionic dyes. Cost-effective and simple, but repeated cycles may affect adsorbent structure.
3. Thermal Regeneration: Heating to high temperatures removes contaminants. Suitable for stable adsorbents like activated carbon, but not ideal for hydrogels.
4. Microwave Regeneration: Fast and energy-efficient desorption using microwaves. Not suitable for heat-sensitive materials.
5. Electrochemical Regeneration: Uses electric current for controlled desorption. Efficient but requires specialized equipment.
6. Supercritical Fluid Regeneration: Highly effective and clean, but costly and complex.
Recommended for hydrogels: Use mild acid/base solutions for regeneration to preserve structure and maintain adsorption capacity.