초순수 제조를 위한 역삼투 공정의 유기물 제거에 영향을 미치는 인자 분석

Abstract

Ultrapure water (UPW) is water containing nothing but water molecule (H2O). UPW is generally used for electricity businesses such as semiconductors, memories, and LCD displays. The two target pollutants for UPW production processes are ions and organic matters with low molecular weight. To obtain UPW quality (e.g., > 18.2 MΩㆍ㎝ as resistance and < 1 ppb as total organic carbon (TOC) concentration), dozens of unit processes such as ion exchange, ultraviolet (UV) oxidization, biological treatment, and membrane processes, should be combined optimally. Therefore it is very important to decrease the number of the unit processes by adapting a multi-functional unit process. Reverse Osmosis (RO) process can be one of the multi-functional units processes to remove ions and organic matters together and this is the reason why most of RO membrane manufacturers are developing RO membranes specialized to remove organic matters. In this study, we investigate factors affecting organic natter removal by RO membranes. Bench-scale experiments were carried out using 4-inches RO elements from several manufactures. Isopropyl alcohol (IPA, molecular weight=60) was used as a model organic matter. As a results, the removal of IPA increases as permeate flux increases, while the cross-flow velocity and IPA concentration do not have much effect on the removal. Interestingly, we found that high ion rejecting membranes showed worse organic matter removals than low ion rejecting membranes, which are specialized for organic matter removal.