Abstract: A novel and efficient electrochemical method is disclosed for the recovery of lithium value from an aqueous solution containing lithium ions in a relatively low concentration together with ions of various kinds of other metallic impurity elements. The method comprises electrochemical selective adsorption of lithium ions from the aqueous solution on to a specific working electrode by applying a DC voltage of a relatively low DC voltage of 0.1-0.4 volt versus a saturated calomel electrode to the working electrode as the cathode opposed to a counterelectrode as the anode and then desorption of the lithium ions therefrom by applying a DC voltage of 0.7-1.2 volts versus a saturated calomel electrode to the lithium-bearing working electrode as the anode opposed to a counterelectrode as the cathode in an aqueous desorption medium containing an electrolyte such as a lithium salt.

Abstract: A highly sensitive and reliable electrochemical method is proposed for the determination of the lithium ion concentration in an aqueous medium, e.g., blood of a patient suffering depression and administrated with a lithium-containing medicament, by measuring the electromotive force between the medium and a powdery non-selective electrode, which is a non-stoichiometric composite oxide of lithium and manganese of the formula Li.sub.x Mn.sub.2 O.sub.4, x being a positive number smaller than 1, prepared by partially leaching lithium ions out of a spinel-type lithium manganate LiMn.sub.2 O.sub.4 with an acid, dipped in the medium. The ion-selective electrode can be in the form of a thin film or coating layer on an electrode element. This film or layer can be formed of a polymeric resin as a binder for the powdery composite oxide.

Abstract: The invention provides an adsorbent for lithium in an aqueous medium capable of adsorbing the lithium value even when the concentration of lithium in the aqueous medium is very low as in natural sea water so as to give an adsorbed amount of lithium on the adsorbent comparable to the content in some low-grade lithium ores. The inventive adsorbent is prepared by the steps comprising (a) impregnating a manganese compound with an alkali, e.g. sodium and potassium, or akaline earth, e.g.