Kunio Fujiwara

The synthesis of a new type adsorbent for the removal of toxic gas by radiation-induced graft polymerization

Abstract A new type of adsorbent containing sulfulic acid group for the removal of ammonia gas was synthesized by radiation-induced graft polymerization of styrene onto fibrous and nonwoven type polypropylene followed by sulufonation with chlorosulfonic acid. The rate of the adsorption of ammonia gas by H-type adsorbent is independent of the ion-exchange capacity. The amount of ammonia gas adsorbed by the chemical adsorption was dependent on the ion-exchange capacity of H-type fibrous adsorbent and was kept constant value in spite of the equilibrium pressure of ammonia gas. Cu(II)- and Ni(II)-types fibrous adsorbent were prepared by the ion exchange reaction of Na-type fibrous adsorbent with metal nitrate solutions. Although, the rate of adsorption of ammonia gas by metal-type fibrous adsorbent is lower than that of H-type adsorbent, the amount of ammonia gas adsorbed increase compared to H-type adsorbent with the same ion exchange capacity. It was related to the highest coordination number of metal ion. The ratio of the number of ammonia molecules adsorbed chemically and the number of metal ion adsorbed in fibrous adsorbent was 4 for Cu-type and 6 for Ni-type fibrous adsorbent, respectivelly.

Purification of Trace Amount of Metal Impurity from Ultra Pure Water Using Membrane Purifier/Filter

Introduction Manufacturing processes for microelectronics devices, and silicon wafers get exposed to high-purity water more frequently than any other chemicals. The ultra pure water (UPW) produced at the central water system in a fab is of extremely high purity, with each critical metal concentration typically below 1 parts per trillion (ppt). However, it is difficult to maintain such high purity out of the central system during distribution to points of use for wafer cleaning. In the FEOL and BEOL wet cleaning processes, UPW wafer rinsing tools are designed to process many wafers in short period of time in order to reduce cost of ownership. The processes require high flow rate of UPW and need to be fed with the highest purity level all the time. We have reported the effectiveness of metal purifier/filter cartridge assembled from ion exchange membrane prepared from radiation induced graft polymerization method.[1] The advantage of using the membrane purifier device at point of use was also reported.[2] In this paper, consideration the practical conditions such as multiple metal contamination and colloidal impurity in UPW, the effect on the performance, and impact on microelectronics devices manufacturing are discussed.