Dual surfactants-assisted adsorption of lithium ions in liquid lithium resources on a superhydrophilic spinel-type H4Ti5O12 ion sieve

The industrial application scope of spinel-type titanium oxide ion sieves is limited by its low adsorption efficiency and regeneration performance. In this study, H4Ti5O12 (HTO-IV), a superhydrophilic spinel-type lithium ion sieve, was synthesized for the first time with the dual surfactants of CTAB and F127 to modulate the surface morphology and surface wettability of the raw material. The prepared HTO-IV lithium ion sieve was composed of ultrathin nanosheets assembled into microspheres and showed excellent surface hydrophilicity and an open hierarchical mesoporous structure, which allowed rapid ion exchange between Li+ and H+. Li+ adsorption rate exceeded 85 % within 30 min and its maximum theoretical adsorption capacity was 57.90 mg/g. The adsorption process of Li+ on HTO-IV followed a pseudo-second-order kinetic model and Langmuir adsorption isotherm model. HTO-IV also exhibited good adsorption selectivity towards Li+ in the presence of coexisting ions. Furthermore, the lithium adsorption ratio of the HTO-IV ion sieve remained at around 97 % even after five adsorption-desorption cycles, demonstrating excellent adsorption capacity and cycling stability. The study highlights the relationship between surface hydrophilicity and adsorption performance of the adsorbent.