Study on the preparation of polyurethane foam and adsorption of gallium ions in gangue acid leach solution

Gallium is a strategic key metal, and its demand is increasing. Coal gangue is a kind of mine solid waste with huge reserves. Extracting gallium from coal gangue can realize high value-added utilization of solid waste. In this study, toluene-2,4-diisocyanate and polyether polyol were used to synthesize a new high-performance polyurethane foam adsorbent under triethanolamine catalytic. The feasibility of preparing polyurethane foams with different raw material ratios and the differences in their physicochemical properties were explored, and the optimal ratio of polyether polyol to toluene-2,4-diisocyanate was found to be 3.5. Adsorption tests of gallium ions in gangue acid leachate were carried out to determine the feasibility of adsorption of gallium by polyurethane foam in low gallium concentration solution, and the adsorption rate was 83.90% under the optimal conditions. The adsorption mechanism of polyurethane foam was revealed, indicating that Ga 3+ complexed with Cl - adsorbed on polyurethane groups (—COONH—), before adsorption need to use hydroxylamine hydrochloride to remove Fe 3+ in solution. The adsorption process can be described by pseudo-second-order kinetic model, conforms to Langmuir adsorption model, and belongs to the chemisorption. The reaction belongs to endothermic reaction. The foam still has good adsorption effect after multiple adsorptions, which opens up a new way for the recovery and utilization of gallium in coal gangue.