Adsorption of Ionic Liquids from Aqueous Streams on Activated Carbon

Adsorption methodology is a fast, economic, non-destructive, and universal technology for water purification and adsorbent recycling. The development of low-cost activated carbons (ACs) has led to the growth of scientific interest in this area. This chapter propounds a guideline for the efficient treatment of ionic liquids (ILs) at low concentrations (<5 mmol L−1) from aqueous solution based on the adsorption onto ACs. Relevant features of adsorption phenomena and successfully applied theoretical models are described with a focus on process design to improve the recovery of both hydrophobic and hydrophilic ILs. The structural and chemical properties of the inexpensive AC adsorbent required to enhance the adsorption thermodynamics and kinetics depending on the IL’s nature are reported in batch and fixed-bed operations. Available procedures for the regeneration of AC after being the adsorbent re-used in successive sorption–desorption cycles and the efficient recovery of IL with high purity are discussed. Adsorption of ILs onto ACs is highlighted as an affordable and versatile technology for wastewater treatment, providing suitable recovery of ILs with remarkably different chemical structures. AC adsorbent is demonstrated to be efficiently regenerated in successive sorption–desorption cycles for continuous treatment of aqueous streams.