Lithium extraction process from low grade Na+/K+ brines dependent on high layer charge layered double hydroxides
Bingchun Sheng, Haiping Su, Jianguo Yu, Sen Lin
Abstract
To meet the rigorous separation demand for lithium in monovalent ion systems, high layer charge layered double hydroxides (H-LDHs) were used to extract lithium resource from Na + /K + brines dependent on a stronger Li + adsorption effect than conventional Li/Al-LDHs. Adsorption kinetics , isotherms and selectivity of H-LDHs were thoroughly investigated and it was found that H-LDHs had a high selectivity to Li + , and could extract the low concentration Li + in 3 M Na + /K + brines in <30 min. Additionally, the effects of desorption temperature and initial Li + concentration in the eluent were explored in detail. It could be clearly seen that the Li + desorption rate was increased with less Li + in the eluent and higher desorption temperature, and the Li/Al molar ratios of H-LDHs dramatically decreased after desorption as the initial Li + concentration in the eluent was lower than 100 mg/L. Under optimal conditions, the Li + adsorption capacities of H-LDHs always maintained >4.0 mg/g in 10 adsorption-desorption cycles, reflecting a great stability on the adsorption performance and the crystal structure. These experimental results confirmed great potential application prospects of H-LDHs in lithium extraction from Na + /K + brines.