Improved structural stability and adsorption capacity of adsorbent material Li1.6Mn1.6O4 via facile surface fluorination

Preparation of HMn2O4 lithium-ion sieves with low manganese dissolution loss for improved cycling stability

Manganese-based lithium-ion sieves have become some of the promising adsorbents for extracting Li+ from brines. However, manganese dissolution loss (MDL) severely impairs the stability and cyclicity of ion sieves. A novel ozone eluent was first developed to extract Li+ from lithium manganese oxides, which decreased MDL decreased from 5.89% to 0.11%, and after ten regeneration cycles, the adsorption capacity retained 85.39% of the initial value, which was better than 55.15% when only hydrochloric acid (HCl) was used as the eluent. Based on these phenomena, the mechanism for the O3 lowering of MDL was investigated. First, the catalytic decomposition reaction of O3 competed with the disproportionation reaction, and the involvement of O3 inhibited the occurrence of the disproportionation reaction. Additionally, the presence of O3 and reactive oxygen species provided a preferential electron acceptor compared to Mn3+ during the migration of electrons from the bulk phase to the surface. In this study, MDL was greatly reduced with a very simple strategy, and the cycling stability of the adsorbent was improved.

Ni-Al layered double hydroxide-coupled layered mesoporous titanium dioxide (Ni-Al LDH/LM-TiO2) composites with integrated adsorption-photocatalysis performance

Nickel aluminum layered double hydroxides (Ni-Al LDHs) and layered mesoporous titanium dioxide (LM-TiO₂) were prepared via a simple precipitation process and novel precipitation-peptization method, respectively, and Ni-Al LDH-coupled LM-TiO₂ (Ni-Al LDH/LM-TiO₂) composites with dual adsorption and photodegradation properties were obtained via the hydrothermal approach. The adsorption and photocatalytic properties were investigated in detail with methyl orange as the target, and the coupling mechanism was systematically studied. The sample with the best performance was recovered after photocatalytic degradation, which was labeled as 11% Ni-Al LDH/LM TiO₂(ST), and characterization and stability studies were carried out. The results showed that Ni-Al LDHs showed good adsorption for pollutants. Ni-Al LDH coupling enhanced the absorption of UV and visible light, and the transmission and separation of photogenerated carriers were also significantly promoted, which was conducive to improving the photocatalytic activity. After treatment in the dark for 30 min, the adsorption of methyl orange by 11% Ni-Al LDHs/LM-TiO₂ reached 55.18%. Under illumination for 30 min, the decolorization rate of methyl orange solution reached 87.54%, and the composites also showed an excellent recycling performance and stability.