Electrophoretic Deposition and Fixing of Functional Mineral Fine Powder-Examination of the Technique to Prepare a Throw-in Type Environmental Cleaning Module -

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Environmental pollution is still a serious problem in the society in these days. There is a possibility that some natural minerals can be used to clean the environment because they have large surface area for adsorbing various chemicals and/or superior ion-exchange ability. In order to remove harmful materials from the environment with high efficiency, the electrophoretic deposition (EPD) and fixing of various functional mineral powders on porous substrate to prepare a throw-in type environmental cleaner was investigated ; such deposited materials can be exposed to a large amount of polluted natural water rapidly. We studied : (1)the fixing of a natural zeolite (clinoptilolite, yielded in Akita prefecture, Japan) ~fine powder by a solid-liquid chemical reaction, (2)the effect of the chemical composition of reacting materials with the natural zeolite in the reaction (1), and (3)the EPD of opal-CT fine powder, which is difficult to be deposited by a normal EPD process. In the experiments, mineral powders finely ground with a planetary potmill around <1μm were used. As a result of the studies, the following results have been cleared : (1)the natural zeolite (clinoptilolite) fine particles can be grew and fixed each other by a solid-liquid chemical reaction using Na_2O-Al_2O_3-SiO_2-H_2O reacting materials in the reaction at 90℃ for longer than 24 h, (2)the clinoptilolite particle was changed into various zeolite by changing the composition (mainly in the ratio SiO_2/Al_2O_3) of the reacting material, and (3)very fine opal-CT powder can be deposited on an electrode by the co-deposition with a soda-lime glass powder with larger particle size which can be deposited easily by the EPD. As stated above, the the possibility of the preparation of a high-performance adsorbing material prepared from natural minerals was proved in this study.