Adsorption-responsive bionic photothermal ion pump for reversible seawater lithium extraction

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Lithium-ion sieve (LIS) technology shows promise for seawater lithium extraction, but faces challenges like performance degradation and dissolution after granulation.
• Low lithium ion (Li+) concentration in seawater and high sodium ion (Na+) interference limit the efficiency of existing LIS methods.

Purpose of the Study:

• To develop an enhanced and reversible Li+ extraction method for seawater using an innovative adsorption-responsive photothermal ion pump (APIP).
• To overcome the limitations of traditional LIS materials, focusing on stability, efficiency, and scalability for practical seawater lithium recovery.

Main Methods:

• An Albizia julibrissin-inspired APIP was created by integrating hydrogen manganese oxide (HMO) within an interpenetrating network hydrogel using in-situ crosslinking and ion-exchange.
• The APIP's adsorption-responsive swelling behavior and low free water characteristics were utilized to enhance Li+ adsorption and mitigate manganese dissolution.
• Solar irradiation was employed to leverage evaporative convection and photothermal effects, accelerating Li+ extraction kinetics.

Main Results:

• The APIP demonstrated a high Li+ extraction capacity of 34 mg g-1 HMO, outperforming HMO powders.
• The hydrogel matrix effectively reduced manganese dissolution, ensuring material stability.
• Solar irradiation boosted Li+ extraction kinetics by 2.9-fold due to photothermal effects and evaporative convection.

Conclusions:

• The developed APIP system effectively addresses the performance degradation and dissolution issues associated with traditional LIS materials.
• This technology offers a significant advancement in seawater lithium extraction, improving efficiency and stability for sustainable resource utilization.