Shale gas produced water is produced in a large amount as a result of hydraulic fracturing in the shale gas development process. The median concentration of lithium in Marcellus shale gas produced water is 95 mg/L, and it is about 500 times higher than the lithium concentration in seawater. Lithium is one of the valuable metals which is mainly used in batteries for electric devices. The demand and cost of lithium have rapidly increased in the last several years due to the growing market of electric cars. Therefore, it would be economical if lithium can be recovered from shale gas produced water. This study aims to recover lithium ions selectively from the shale gas produced water by a combination of precipitation and adsorption. H2TiO3 was synthesized and used as lithium adsorbent for synthetic produced water. Lithium adsorption in the shale gas produced water initially showed poor adsorption capacity due to the pH decrease during the ion exchange reaction of the adsorbent. For this reason, pH buffer was applied in the produced water and showed better adsorption capacity. However, divalent cations such as barium or calcium adheres to the H2TiO3 surface, which hinders the lithium ions adsorption to the surface of adsorbent. Therefore, a precipitation technique using sodium carbonate was applied to remove divalent cations prior to the lithium adsorption. Up to 99% of calcium, barium and strontium ions were removed after the precipitation, and the solution pH was kept high so the adsorption could be conducted without using a pH buffer. The desorption test result showed that the lithium ions had been selectively recovered from the synthetic shale gas produced water through precipitation-adsorption process and the maximum adsorption capacity of lithium was about 25 mg/g.

Lithium recovery form shale gas produced water using precipitation and adsorption method

254th National Meeting (2017)

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