NOVEL RESIN-BASED ULTRAPURIFICATION SYSTEM FOR REPROCESSING IPA IN THE SEMICONDUCTOR INDUSTRY

There is an urgent need for the development of energy-efficient recycl ing and ultrapurification processes for 2-propanol solvent wastes gene rated from the semiconductor industry. In this paper, experimental res ults are presented that set the stage for the development of efficient resin-based closed-loop recycling systems for 2-propanol drying appli cations in the semiconductor industry. The process employs ion exchang e resins to reduce cations and anions to low and sub-part-per-billion levels. Batch adsorption experiments were carried out in 2-propanol to determine the adsorption isotherms of various ions on commercially av ailable ion exchange resins. The results indicate that ion exchange re sins indeed have both high affinity and capacity for ions in the relat ively nonpolar 2-propanol solvent. Under dynamic flow conditions, colu mns of appropriate column diameter and length packed with the resins w ere indeed capable of reducing ionic impurities to low parts-per-billi on levels. In fact, long-term experiments indicate that these systems can generate ultrapure 2-propanol from relatively large volumes of sol vent waste. In addition to the ionic impurities, it is necessary to re move water and organic contaminants from the solvent. Columns packed w ith activated carbon and molecular sieves were shown to be efficacious in removing organic and water impurities, respectively, from 2-propan ol to low levels required for semiconductor applications.