목적: TFT-LCD의 제조공정에서 현상액으로 쓰여 배출되는 500 mg/L 이상의 TMAH 폐수를 효율적으로 제거하기 위해 UV/persulfate를 적용하여 TMAH의 산화반응 특성을 알아보았고 TMAH 산화반응에 미치는 영향인자에 따른 제거효율을 평가, 비교함으로써 최적의 처리조건을 도출하고자 하였다. 방법: 본 연구에서는 산화제 과황산염(persulfate)을 UV로 활성화하여 생성된 황산염 라디칼(SO₄<SUP>-·</SUP>)과 수산화 라디칼(OH<SUP>·</SUP>)을 발생시켜 TMAH를 산화반응을 유도하였고 산화반응에 대한 영향인자로 초기 pH, 산화제 농도, 초기 TMAH 농도 등을 조절하여 나타난 제거효율을 비교, 평가하여 처리조건을 최적화하였다. 결과 및 고찰 : UV/persulfate를 이용한 TMAH 산화반응에서 초기 pH (2, 7, 12), persulfate 주입량(0, 50, 100, 150, 200 mM), 초기 TMAH 농도(100, 300, 500, 700 mg/L)에 따른 제거효율을 비교하였다. UV/persulfate 적용 시 초기 pH 조절에 상관없이 90%에 가까운 처리효율을 보였으며 그 중 알칼리 조건일 때 제거율이 89%로 가장 높은 반응속도상수로 나타났다. 초기 pH에 따라 중간생성물의 생성 경향이 서로 다른 것으로 나타났다. Persulfate를 주입하지 않았을 때는 TMAH 농도변화가 거의 없었으며 persulfate 100 mM를 주입하였을 때 제거효율이 가장 높았으며 150 mM 주입하였을 때 오히려 효율이 낮게 나타났다. 또한 초기 TMAH 농도 100 mg/L일 때 150분 이내에 모두 감소하였고 초기 농도가 높아질수록 제거효율 및 반응속도상수가 낮아지는 경향을 보였다. 결론: 본 연구의 결과를 통해 UV/persulfate를 이용하여 750 mg/L TMAH 산화반응 시 초기 pH가 증가할수록 제거효율이 상승하고 persulfate 주입농도가 100 mM 일때 제거효율이 가장 높은 것으로 나타났다.
Objective : In order to efficiently remove TMAH from the wastewater generated by the TFT-LCD manufacturing process, the oxidation of TMAH was tested by applying an UV/persulfate. The optimum reaction conditions for high concentration TMAH oxidation were investigated by evaluating and comparing the removal efficiency according to the factors affecting TMAH oxidative degradation. Methods : In this study, TMAH was decomposed by sulfate radical (SO₄<SUP>-·</SUP>) and hydroxyl radical (OH<SUP>·</SUP>) generated from persulfate activated by UV. Factors affecting on the treatment efficiency were try to be optimized by comparing and evaluating the removal efficiency depending on the initial pH, oxidant concentration, and initial TMAH concentration. Results and Discussion : Depending on initial pH (2, 7, 12), persulfate addition (0, 50, 100, 150, 200 mM), initial TMAH concentration (100, 300, 500, 700 mg/L) degradation rates of TMAH were compared. When UV/persulfate was applied, the removal efficiency of TMAH was close to 90% regardless of the initial pH and, at initial pH 12, was the highest with 89%. It was confirmed that the generation pattern of intermediate formed were different depending on the initial pH. When the oxidizing agent was not added, there was little change in TMAH concentration. The removal efficiency was highest when 100 mM persulfate was added. However the efficiency was rather low when 150 mM persulfate was added. When the initial TMAH concentration was 100 mg/L, it was decreased within 150 minutes. As the initial concentration increased, the removal efficiency and reaction rate constant decreased. Conclusions : As a results, during the oxidation of 750 mg/L TMAH by using UV/persulfate, the removal efficiency was highest with initial pH 12 and 100 mM of persulfate addition.