各種ゼオライト鉱物による廃水中の重金属除去

抄録

Experimental studies have been conducted on the removal of heavy metal ions from waste water by using natural zeolite which have large adsorptivity and ion exchange capacity.
Since the mineralogical properties and compositions depend on the occurrence of zeolite, the relations among the properties, the compositions and adsorptivity of heavy metal ions were investigated. Bisides, the influence of NH⁺₄ and CN^-ions in the waste water was discussed. The results obtained are summerized as follows.
(1) The zeolite contents in tuff had no relation with the molar ratio of Si0₂ /Al₂0₃ and X-ray intensity of zeolite, but had a strong positive corelation with Na₂0 and K₂0 contents. The alkali contents showed a important relationship for the adsorptivity of metal ions.
(2) Adsorptive capacity of heavy metal ions increased in order of Pb> Cr> Cu≥Cd≥Zn> Ni in spite of the kinds of zeolite tuffs such as mordenite and clinoptilolite. This tendency corresponds to the order of hydroionic radius.
(3) The adsorption rate of heavy metal ions except Pb²⁺ and Cr²⁺ decreased in the presence of NH⁺₄ ion in the solution.Especially, adsorptivity of Ni²⁺ ion decreased with increasing CN^-ion content due to the formation of complex anion with CN^-.