Why reuse spent adsorbents? The latest challenges and limitations

Area of Science:

• Environmental Science
• Materials Science
• Chemical Engineering

Background:

• Inconsistent data representation in adsorbent studies hinders comparison.
• Adsorbent disposal poses environmental risks, necessitating regeneration and reuse.
• Desorption and regeneration are as crucial as adsorption for sustainable applications.

Purpose of the Study:

• To review and compare the desorption and regeneration abilities of various adsorbents.
• To analyze influencing parameters, advantages, and disadvantages of different regeneration methods.
• To evaluate the recovery efficiency and reusability of adsorbents.

Main Methods:

• Categorization of adsorbents into graphene, carbon nanotubes, activated carbon compounds, and clays/polymers.
• Examination of desorption media/eluants and process conditions (pH, dose, concentration).
• Evaluation of adsorption capacity, removal effectiveness, and reusability.

Main Results:

• Graphene adsorbents show the highest adsorption capacity (108–>480 mg/g), followed by activated carbon (34–>384 mg/g).
• Carbon nanotubes and polymer adsorbents exhibit lower and more variable capacities.
• Most adsorbents demonstrate high removal effectiveness (71%–99%) and reusability.

Conclusions:

• Adsorbent regeneration and desorption are vital for environmental sustainability.
• Graphene and activated carbon are promising materials for efficient and reusable adsorption.
• Adsorbents generally show high reusability, fitting the pseudo-second order kinetic model.