Recovery of lithium using H4Mn3.5Ti1.5O12/reduced graphene oxide/polyacrylamide composite hydrogel from brine by Ads-ESIX process

Abstract

Powdery Li+-imprinted manganese oxides adsorbent was widely used to the recovery of Li+, but there are some difficulties, such as poor stability in acid solution, inconvenience of operation and separation. In this work, a useful hydrogel composite based H4Mn3.5Ti1.5O12/reduced graphene oxide/polyacrylamide (HMTO-rGO/PAM) was fabricated by thermal initiation method with promising stable, conductive and selective properties. The resulting materials were characterized by field emission scanning electron microscope, infrared absorption spectrum, X-ray diffraction, X-ray photoelectron spectroscopy and electrochemical techniques. The recovery of Li+ was investigated using HMTO-rGO/PAM from brine by a separated two-stage sorption statically and electrically switched ion exchange desorption process. The adsorption capacity of 51.5 mg·g−1 could be achieved with an initial Li+ concentration of 200 mg·L−1 in pH 10, at 45 °C for 12 h. Li+ ions could be quickly desorbed by cyclic voltammetry (CV) in pH 3, 0.1 mol·L−1 HCl/NH4Cl accompanying the exchange of Li+ and H+(NH4+) and the transfer of LMTO-rGO/PAM to HMTO-rGO/PAM.