본 연구에서는 막 축전식 탈이온 공정에 적용하기 위해 온도와 시간을 달리하여 술폰화 Poly(VDF-co-hexafluoropropylene) copolymers (PVDF-co-HFP)을 합성 후 캐스팅법에 의해 양이온교환막이 제조되었다. 술폰화 PVDF (SPVDF) 는 Fourier-transform infrared (FT-IR), 1H Nuclear magnetic resonance (1H NMR)를 통해 구조확인을 하였고, X-ray Photoelectron Spectroscopy (XPS)를 통해 화학조성에 대한 정량적 분석을 하였다. 막 성능은 함수율 및 이온교환용량과 전기 저항을 측정하였고. 60°C에서 7시간 술폰화한 SPVDF 멤브레인이 이온교환용량 0.89 meq/g, 함수율 21.5%, 전기저항 3.70 Ω ⋅cm2로 가장 우수하였다. 수중 이온제거 특성을 막 축전식 탈이온 방법(MCDI)으로 전압(0.9~1.5 V), 유속(10~40 mL/min)을 변수로 SPVDF의 탈염 특성을 확인하여 MCDI 공정에 적용가능 여부를 평가하였다. MCDI 충방전 시험 결과 최대 탈염제거 율은 62.5%이었다.

In this study, partially fluorinated cation exchange membranes were prepared by direct sulfonation of Poly(VDF-co-hexafluoropropylene) copolymers (PVDF-co-HFP) followed by a casting method for application in the Membrane capacitive deionization (MCDI). The structure of sulfonated PVDF-co-HFP (SPVDF) was confirmed by Fourier-transform infrared (FT-IR) and 1H Nuclear magnetic resonance (1H NMR) analysis. For quantitative analysis of the chemical composition, the X-ray Photoelectron Spectroscopy (XPS) was used. The membrane properties such as water uptake, ion exchange capacity and electrical resistance were measured. It was suggested that the optimum direct sulfonation condition of PVDF-co-HFP ion exchange membranes was 60°C and 7 hours for temperature and duration of sulfonation, respectively. The water uptake of the SPVDF ion exchange membrane was 21.5%. The ion exchange capacity and electrical resistance were 0.89 meq/g and 3.70 Ω⋅cm2, respectively. It was investigated that if it is feasible to apply these membranes in MCDI at various cell potentials (0.9~1.5 V) and initial flow rates (10~40 mL/min). In the MCDI process, the maximum salt removal rate was 62.5% in repeated absorption-desorption cycles.

1. 서 론
 2. 실 험
  2.1. 시약 및 재료
  2.2. PVDF 술폰화반응
  2.3. 양이온교환막 제조
  2.4. 구조확인
  2.5. 함수율과 수분함량 측정
  2.6. 이온교환용량 측정
  2.7. 전기저항 측정
  2.8. XPS 분석
  2.9. 축전식 탈염 특성 평가
 3. 결과 및 고찰
  3.1. 직접술폰화한 PVDF-co-HFP 구조확인
  3.2. XPS 분석
  3.3. 이온교환용량과 함수율 측정
  3.4. 전기적 특성 분석
  3.5. 막의 MCDI 공정 적용시험
 4. 결 론
 감 사
 Reference

• 강기원(충남대학교 바이오응용화학과) | Ki Won Kang
• 황택성(충남대학교 화학공학과) | Taek Sung Hwang Corresponding author