Enhancing the recovery of water, lithium and cement material from concentrated seawater with membrane electrolysis-distillation process

Seawater represents a vast source for freshwater production and valuable resource recovery, particularly lithium (Li + ). However, the existence of divalent ions, including calcium (Ca 2+ ) and magnesium (Mg 2+ ), presents major difficulties, as they lead to scaling and obstruct Li + recovery in the direct contact membrane distillation (DCMD) process. In this study, a hybrid ultrafiltration (UF) membrane electrolysis-DCMD process is proposed to enhance water recovery and Li + enrichment while mitigating scaling. UF membrane electrolysis pretreatment demonstrated superior removal of Ca 2+ and Mg 2+ ions, achieving over 98 % removal efficiency without the use of direct chemical additives to seawater, compared to chemical precipitation and nanofiltration pretreatment. The integration of UF membrane electrolysis with DCMD increased water recovery from 73 % to 88 %. The process also achieved a 9–10 fold increase in Li + ion concentration, with the removal of Mg 2+ ions and the formation of alkaline conditions enabling efficient Li + recovery using manganese ion sieve nanomaterial. This staged approach demonstrates a promising pathway for comprehensive resource recovery, including freshwater, Li + and raw materials such as calcium and magnesium hydroxides for cement production. • Ultrafiltration (UF) membrane electrolysis removed 98 % Mg 2+ and Ca 2+ from seawater • Untreated seawater containing Ca 2+ was concentrated only 3.5 times by DCMD • UF membrane electrolysis-treated seawater was concentrated up to 9–10 times by DCMD • Li + increased 9–10 times in treated seawater, enhancing its recovery with HMO • Membrane electrolysis-distillation recovered water, Li + , and CaO (raw cement material).