The Relationship Between Organics Structural Characteristic And Its Extraction Efficiency In The Methyl Silicone Rubber Membrane

The molecular structure of organics contained information, which determines physical and chemical properties. Thus, there is a link between the structure and properties of organics. Molecular structure characterization (MSC) is a method that use structure parameters to quantitative description the properties of molecules.Membrane permeation extraction is a new extraction separation technology, which is developed rapidly in recent years. Non-porous silicone rubber membrane with selective extraction ability for organic matter is used in this technology which is applied in effective separation and recovery of target organic. In recent, at home and abroad, researches on this technique are often for a single component of organic wastewater. And researches involve many process conditions. But have less study on silicone rubber membrane for selective extraction of organic matter.In this paper, methyl silicone rubber membrane as a separation medium, three kinds of pollutants were selected as research subjects which commonly found in organic wastewater. And ten kinds of structural parameters were selected to quantitative description the properties of molecules. By analyzing the relationship between structural parameters and the extraction efficiency of organic matter in the methyl silicone rubber membrane, the effect of structural properties was investigated. And the main factors which effect on the extraction efficiency was identified in order to provide the basis for methyl silicone rubber membrane selective extraction of different pollutants from organic wastewater.The results show that the ability of methyl silicone rubber membrane selective extraction for organic matter is closely related to the structural properties of the organic matter itself. The hydrophobic property of organic matter is the main factor in the methyl silicon rubber membrane extraction behavior. More hydrophobic, more easily extracted into methyl silicone rubber membrane for aniline, phenols and low molecular weight organic acids. Analysis from the perspective of the structural parameters, octanol/water coefficient(1gP) and solubility(S) of organic matters are the main parameters affecting the extraction efficiency. With the increase of octanol/water coefficient or decrease of solubility, the extraction rate of organic matters in the methyl silicone rubber membrane is gradually increased. But the permeation experiments show that the transmittance first increase and then decrease with the increase of octanol/water partition coefficient. The most advantages are 1gP=1.14 (aniline), 1gP= 1.54 (phenols) and 1gP= 1.87(organic acids). The molecular size of organics also has influence on the permeation extraction efficiency, but not the main factor. For substances that can be extracted, adjust the pH of the solution to make the molecular content in aqueous solution increases referring to the acid dissociation constant, which play an important role in improving the extraction rate. In addition, after mixing the driving force of organic substance decreased compared to the single, and there have the extraction competition mechanism between different organics, the extraction rate and permeability of mixture decreased compared to a single substance. Finally,the multiple stepwise regression method was used to establish the regression model of structure parameters and the extraction rate/transmittance.The results showed that four structural parameters (octanol/water partition coefficient,the largest atom net positive charge,acid dissociation constant, molar volume)have effect on extraction efficiency.Transmittance primarily mainly was affected by octanol/water partition coefficient and molecular polarizability.