Preparation of light-responsive polyacrylamide/carboxymethyl chitosan composite aerogel and its adsorption...

As an essential material for manufacturing lithium batteries, the demand of lithium is increasing, which means novel extracting method from various lithium-containing solutions is necessary. Spiropyran molecules undergo a photoisomerization reaction under light, transitioning from a closed-ring form (colorless) to an open-ring form (colored), generating multiple coordination sites to form coordination bonds with metal ions. In this paper, a polyacrylamide/carboxymethyl chitosan composite aerogel grafted with photoresponsive spiropyragroups (Fe₃O₄/CNTs@PAM/CS-SP), used for extracting lithium from solutions, was prepared by dual cross-linking and vacuum freeze-drying. Batch adsorption experimental results showed that the incorporation of Fe₃O₄ nanoparticles further enhances its adsorption capability, as it enables rapid separation of the aerogel from water using an external magnetic field and also improves the adsorption efficiency due to its magnetic properties. The aerogel exhibits good adsorption capacity in the pH range of 9-12 and shows selectivity for Li in simulated brine, achieving a maximum adsorption capacity of 176.5 mg/g at 35 °C and a Li concentration of 1 g/L. The preparation of this aerogel offers a novel and effective approach to creating environmentally friendly adsorbents, providing a new method for extracting lithium from lithium-containing solutions.