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The content and species of oxygen functional groups are significant factors influencing the electrochemical supercapacitor performance of graphene electrodes.

The continuously increasing demand for lithium has made it one of the strategic metals, rendering its exploitation of critical importance. Natural α-spodumene is still the primary resource of lithium extraction. The traditional process for the treatment of α-spodumene generates immense quantities of waste residue and needs a high-temperature heat treatment, leading to high energy consumption. In addition to lithium, α-spodumene is rich in aluminum and silicon, and thus it is a potential raw material for zeolite synthesis. Herein, a novel process was developed for the clean and efficient extraction of lithium from α-spodumene coupled with the synthesis of hydroxysodalite zeolite. By hydrothermal alkaline treatment, α-spodumene was converted into hydroxysodalite; the lithium in α-spodumene was released into the solution and subsequently recovered by precipitation with Na2CO3. A lithium extraction efficiency of 95.8% was obtained under optimum conditions: temperature of 250 °C, NaOH concentration of 600 g/L, liquid/solid ratio of 5:1, stirring speed of 500 rpm, and reaction time of 2 h. In addition, the influences of various factors on the composition and textural properties of the product were analyzed using XRD, SEM, TG, N2 adsorption/desorption, and FTIR.

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