• Title/Summary/Keyword: Molecular width

Search Result 3, Processing Time 0.059 seconds

Rejection Properties of Hydrophilic Solutes and Micro Organic Pollutants with a Hollow Fiber NF Membrane (중공사 나노여과 막분리를 이용한 친수성 용질과 미량 유기 오염물질의 배제 특성)

  • Jung, Yong-Jun;Min, Kyung-Sok
    • Journal of Korean Society on Water Environment
    • /
    • v.21 no.2
    • /
    • pp.205-210
    • /
    • 2005
  • There has been a growing interest in NF membrane for drinking water treatment, because it can remove simultaneously both hardness and hazardous micro pollutants such as pesticides and THM precursors. In this work, a hollow fiber NF membrane known as a composite membrane was employed for the rejection properties of both hydrophilic solutes and micro organic pollutants, where the former was used to evaluate the molecular sieving effect of this membrane and the latter was employed for the investigation of solute-membrane interaction as hydrophobic materials. This membrane effectively rejected the hydrophilic solutes and the permeation of them was mainly controlled by the molecular sieving effects such as molecular weight and molecular width. In the case of all micro organic pollutants, the rejections were varied from 42.2% for Simazine to 91.6% for Malathion, and the parameters related to the steric hindrance could significantly play an important role in the rejection. In the batch type adsorption experiments, all micro organic pollutants were entrapped mildly on the membrane in spite of lower degree compared with that of aromatic compounds, and they were correlated with log K.

Removal Mechanisms of BTEX Compounds by RO/NF Membrane Processes (RO/NF막 공정을 이용한 BTEX 물질의 제어 특성 평가)

  • Jang, Hyuewon;Park, Chanhyuk;Hong, Seungkwan;Yoon, Yeomin;Jung, Jin-Young;Chung, Yun-Chul
    • Journal of Korean Society on Water Environment
    • /
    • v.22 no.5
    • /
    • pp.926-932
    • /
    • 2006
  • A series of bench-scale membrane filtration experiments were performed to systematically investigate the removal mechanisms of reverse osmosis (RO) and nanofiltration (NF) membranes for BTEX (benzene, toluene, ethylene, xylene), trichloroethylene (TCE) and tetrachloroethylene (PCE). The molecular weight of these organic compounds ranged from 78 to 166 dalton. The rejection of organic compounds by RO/NF membranes varied significantly from 59.6 to 99.2% depending on solute and membrane types. Specifically, experimental results demonstrated that the removal efficiency of RO/NF membranes increased as solute molecular characteristics such as W/L (molecular width/length) ${\times}$ $M_W$ (molecular weight) and octanol-water partition coefficient increased. This observation suggested that the rejection of small organic compounds by RO/NF membranes was determined by the combined effect of physical (molecular size and shape) and chemical (hydrophobicity) properties.

Rejection Properties of Aromatic Pesticides by a Hollow Fiber NF Membrane (중공사 나노여과막을 이용한 방향족 농약의 배제 특성)

  • Jung, Yong-Jun;Kiso, Yoshiaki;Park, Soon-Gil;Kim, Jong-Yong;Min, Kyung-Sok
    • Journal of Korean Society on Water Environment
    • /
    • v.20 no.3
    • /
    • pp.296-300
    • /
    • 2004
  • The rejection properties of 6 aromatic pesticides were evaluated by a continuous flow system equipped with a hollow fiber NF membrane. Different from the separation experiment of batch cell, the rejection and the removal could be calculated exactly because the concentration of feed, permeate and retentate was separately obtained. The lowest and the highest rejection were found in carbaryl(54.8%) and methoxychlor(99.2%), respectively, and the removals were always shown higher than rejections. This may be caused by some reasons such as the solute adsorption on the membrane, the variation of feed concentration. Although molecular weight, molecular width regarded as solute characteristics and log P(n-octanol/water partition coefficient) as hydrophobicity could be applied to explain the rejection property, these factors should be considered together for better analysis. According to the higher relationship between log B(solute permeability) and molecular weight, it was revealed that the solute separation with this membrane was influenced more by molecular weight.