Vol.9 No.3 2017

Research paper : Development of HASClay® as a high-performance adsorption material (M. Suzuki et al.)−157−Synthesiology - English edition Vol.9 No.3 (2017) condensation prevention properties, and fungicidal properties, but problems of condensation began to develop as highly airtight buildings were constructed. Corresponding air conditioning facilities became necessary, but from the perspective of energy savings and facility management, humidity controlling building materials were developed to give humidity control functions to the materials themselves. Allophane was used as such a humidity controlling building material. Allophane dehumidifies when the humidity increases, and humidifies when the humidity decreases, and is capable of maintaining the humidity range in which people can live comfortably. The successful development of humidity controlling tiles using allophane was conducted jointly with a company.[9] These humidity controlling tiles with allophane are used in the building of AIST Chubu.2.3 Development of imogoliteImogolite is composed of naturally existing nanotubes. Since the amount existing in nature is extremely small, it was necessary to synthesize it. The synthesis was already done by Farmer et al. in 1977, but it was conducted in dilute concentration. We succeeded in synthesizing at higher concentration of about 10 times the conventional method, by adding a desalination procedure to the processes.[10] Even using this method, only a few grams could be recovered by dehydrating 1 L of the solution, and it was one digit less compared to general clay synthetic products in terms of production efciency. On the other hand, when imogolite was evaluated as a heat exchange adsorbent for adsorption heat pump using hydration heat measurement, it was found that it had excellent capacity even by reuse at 40 ºC,[11] but we were unable to conduct a practical evaluation.3 History of the development of new adsorbents (2005–present)3.1 Breakaway from imogoliteAfter completing the synthesis and evaluation of imogolite as a heat storage agent by 2003, we looked at various applications for use as nanotubes, and started activities for realizing practical use and pioneering new usages.The first foothold was a research commission from the Shingijutsu Kyokai (New Technology Association) that was subcontracted by the Japan Science and Technology Agency (JST) in 2004. The “Imogolite Synthesis and Application Technology Workshop” was set up, and investigations were done in the fields of environmental technologies, energy savings, and living environment. We also set up the “Imogolite Workshop” at AIST Chubu in 2006, and obtained opportunities to participate in exhibitions and others at the International Nanotechnology Exhibition and Conference (Nano Tech), and were able to hear voices from companies.We found that the elds of application of imogolite included Fig. 3 Structural models of allophane and imogolite (Left: allophane[5], right: imogolite[6])Fig. 4 TEM photographs of allophane and imogolite (Left: allophane[7], right: imogolite[7])20 nm10 nmOHOAlSiOHOAlSi

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