水熱条件下での2八面体型スメクタイトによるリチウム吸着

概要

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Six dioctahedral smectites were tested as a Li+ adsorbent in Li+ diluted solution (10,30,and 50 mg/l under hydrothermal conditions of 100,150,and 200℃. Layer charge of these smectites arises mainly by Mg^<2+> for Al^<3+> substitution in the octahedral sheet and balanced by the interlayer cations, which are dominantly Na^+ and Ca^<2+> ions with various ratios. After the hydrothermal treatment, smectites were examined by X-ray powder diffraction (XRD) and the amount of adsorbed Li+ were detemined by chemical analysis. The hydrothermal reaction reaches adsorption equilibrium within 24 h above 150℃. The amount of Li+ adsorbed on the smectites increased with hydrothermal temperature and reached about 50% of cation exchange capacity at 200℃ for 24 h (sample HH). Because reduced charge phase was recognized in the XRD patterns of treated smectites and its peak intensity increased with the temperature, it is presumed that the Li+ ions at least partly penetrated into the octahedral sheet of smectite. Ca^<2+>, which are usually contained in geothermal brine with the concentration of almost the same order of Li+ ion, and Mg^<2+> hindered the Li^+ adsorption on smectites exponentially because of the ion selectivity on the silicate surface. Dioctahedral smectites are therefore effective as a Li^+ adsorbent if they are applied on the geothermal brine with low Ca^<2+> and Mg^<2+> contents
日本粘土学会の論文
1988-09-01