Development of a grafted fibrous metal adsorbent functioning in highly concentrated alkaline solution

Ueki, Yuji; Hoshina, Hiroyuki; Saiki, Seiichi; Seko, Noriaki

no journal, , 

Highly concentrated alkaline solutions such as 48% NaOH and 48% KOH were used as surface etchants for Si wafer. These strong-alkaline solutions contain ppb-level of Cu ions as an impurity. This Cu ion caused poor production yield of the Si wafers, because many small pits on the Si wafer surface were created by Cu impurities. Therefore, the development of the novel metal adsorbent which can function even under a strong-alkaline condition ( pH 15) is desired earnestly. We developed a fibrous metal adsorbent which can function at a pH range from 3 to 15. This fibrous metal adsorbent was synthesized by radiation-induced emulsion grafting of glycidyl methacrylate onto a nonwoven polyethylene fabric and subsequent amination with 2,2'-iminodiethanol (IDE). It was found that two IDE groups captured one Cu ion, and the Cu adsorption capacity at pH 15.0 was 0.41 mmol/g-adsorbent. Although this capacity was equivalent to one third of the maximum value (capacity: 1.3 mmol/g, pH 5.7), the fibrous metal adsorbent exhibited practically sufficient metal adsorption capacity even under a strong-alkaline condition.