Papers by Author: Zhi Yong Ji

Abstract: Based on preparing high purity powdered lithium ion-sieve precursor LiMn2O4, using lithium carbonate and manganese carbonate as raw materials, through roasting at high temperature of 800°C, laminar lithium ion-sieve precursor was prepared by commixing poly (vinyl chloride) (PVC) and powdered precursor in DMF (N, N-dimethylformamide) as solvent, and then powder and lithium ion-sieve flat sheet membrane was obtained through washing with HCl solution respectively. Their adsorption capacity and morphology was also characterized. The results show that both powdered lithium ion-sieve and laminar one have high adsorption capacity and selectivity for Li in solutions, and the effect of their retest is good. All these can provide a good foundation for the further study on lithium ion-sieve flat sheet membrane and lithium extraction from seawater.

Abstract: Potassium ionic sieve membrane was synthesized on porous α-Al2O3 tube support by the hydrothermal synthesis. The zeolite membranes were characterized by means of XRD and SEM. And the single-gas permeability through the membranes and selectivity to K+, Na+, Ca2+, Mg2+ were measured. The results show that the ideal separation factor is 3.68, which is close to Knudsen diffusion ratio 3.74 for H2/N2; the separation factors of the potassium ionic sieve membrane are , , respectively, indicating its high separation selectivity to potassium ion.

Abstract: Natural clinoptilolite collected from Chicheng of Hebei province in China, was treated with physical modification using sodium/ammonium salts, chemical modification using NaOH or NaAlO₂, and physicochemical modification using NaOH or NaAlO₂ and NaCl in order, respectively. And its adsorption capacity of NH₄⁺ in different conditions was investigated. The results show that modified clinoptilolite has the same crystal structure, and the clinoptilolite modified with NaOH or NaAlO₂ has good uptake of ammonia ion; the concentration of NaAlO₂ has apparent influence on the removal of ammonia nitrogen, and the perfect concentration is 0.1 mol/L and the uptake could reach 0.92 mmol/g in the 100 mg/L NH₄⁺ solution; the existence of K⁺、Na⁺、Ca²⁺、Mg²⁺ decreases the uptake of ammonia ion on clinoptilolite modified with 0.1 mol/L NaAlO₂.

Abstract: To meet increasing demand for lithium, it is very essential for exploiting the lithium resources dissolved in seawater, groundwater and brine. It’s prospected that extracting lithium from solution with lithium ion-sieve, that is, spinel lithium magnesium oxides. Preparing high effective lithium ion-sieve is the heart of the technology. Magnesium oxide (MnOOH), the precursor (Li1.6Mn1.6O4) and the lithium ion-sieve were prepared successively, and their structure and properties were characterized with AAS, XRD and SEM. The results show that fibrous MnOOH is synthesized via hydrothermal reaction of KMnO4 and ethanol at 120°C for 24 h, and brown Li1.6Mn1.6O4 with little impurity is prepared with the Li/Mn mole ratio 4 after hydrothermal reaction of MnOOH and 4 mol/L LiOH at 120°C for 24 h and roast 4 h at 400°C, then lithium ion-sieve is obtained after washing 24 h with 0.5 mol/L HCl solutions and its adsorption capacity for Li+ reaches 38.26 mg/g, which has considerable potentiality comparing to its theory value. All these suggested that synthesis of single phase Li1.6Mn1.6O4 should be essential for next study on extraction lithium with lithium ion-sieve from seawater, groundwater and brine.