沉淀—胶溶法制备偏钛酸型锂离子交换剂研究

Study on H_2TiO_3-lithium Exchanger Synthesized by Precipitation-peptization Method

报道一种制备Li_2TiO_3的新方法—无机沉淀胶溶法。以硫酸氧钛为钛源、乙酸锂为锂源、过氧化氢为络合剂,经沉淀-胶溶制备钛-锂溶胶体系,再经干燥、煅烧、酸洗制备偏钛酸型锂吸附剂。采用FTIR、TG-DSC、XRD、SEM、ICP、Zetasizer Nano及旋转式黏度计等测试、表征手段,考察了各制备条件对溶胶体系稳定性、干凝胶及Li_2TiO_3显微结构特性及性能的影响。结果表明:乙酸锂为锂源,体系pH值为7,Ti^(4+)浓度为0.2 mol/L,经陈化24h,可得到黏度为7.3 m Pa·s,Zeta电位为-29.5 m V的稳定溶胶体系。红外光谱分析表明干凝胶中含过氧键;干凝胶较佳煅烧温度和煅烧时间分别为750℃、2 h,制备得到β-Li_2TiO_3,;将β-Li_2TiO_3用0.2 mol/L盐酸溶液进行酸洗制备得到偏钛酸型锂吸附剂H_2TiO_3,锂的酸洗率为85.31%,锂的再吸附容量为27.15 mg/g。

A novel inorganic precipitation-peptization method was proposed to synthesize Li_2TiO_3 in this work.TiOSO_4 and CH3COOLi were employed as lithium and titanium sources respectively,and H_2O_2 was used as complexing agent resulted in titanium-lithium sol system via precipitation-peptization method,and then H_2TiO_3-lithium adsorbent was obtained by drying,calcining,treating with hydrochloric acid successively. The effects of preparation conditions on the stability of the sol system,the morphology and properties of the xerogel and Li_2TiO_3 were investigated by FTIR,TG-DSC,XRD,SEM,ICP,Zetasizer Nano and rotary viscosimeter. The research results indicated that a stable sol system with viscosity 7. 3 m Pa·s and the Zeta potentials(-29. 5m V) could be prepared after aged 24 hours under the conditions of using CH_3COOLi as lithium source,the value of p H about 7,Ti4 +concentration 0. 2 mol/L. The complex peroxide exist in this system can be proved through analyzing the bonding of the xerogel by infrared spectrum. Better calcining temperature and time of the dry gel was 750 ℃,2 h respectively,and β-Li_2TiO_3 was obtained under this condition. β-Li_2TiO_3 was further treated with hydrochloric acid( 0. 2 mol/L) to obtain H_2TiO_3-lithium absorbent,and finally the Li+drawn out ratio from β-Li_2TiO_3 reaches 85. 31%,the adsorption capacity comes up to 27. 15 mg/g.