Preparation, characterization and adsorptive properties of foam-type lithium adsorbent

Spinel lithium manganese oxide (LMO) foam was prepared by a polyurethane template method. The LMO foam was then treated with an HCl solution to extract lithium from the LMO, resulting in a lithium adsorbent of spinel manganese oxide (MO) foam. The investigations on structure, morphology, composition and Li+ adsorption properties of the MO foam were carried out by thermogravimetric analysis (DTG), X-ray diffractometer (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), energy dispersive spectrometry (EDS), N2 adsorption–desorption tests and atomic absorption spectrophotometer (AAS). The results show that the MO foam consists of the lithium ion-sieve of MO and oxygen-containing cross-linked pitch. The pitch works as the binder and support to closely bond MO together into a homogeneous three-dimensionally interpenetrating network. The MO foam presents meso-/macroporous structure which allows free passage of the solution. Li+ adsorption experiments confirm that the MO foam shows selectivity for Li+ in the presence of Na+, K+ and Mg2+. It exhibits considerable Li+ adsorption capacities of 8.73, 3.83 and 1.49 mg(Li+)/g(MO foam) in LiOH solution, LiCl buffer solution and lithium-enriched salt lake brine, respectively. This makes the MO foam a promising inorganic lithium adsorbent. The MO foam after Li+ adsorption can generally maintain its structure and morphology, but the combination of the pitch support and the MO particles becomes loose. The efforts to enhance the overall performances of the MO foam are still underway.