Mass Transfer Characteristics Of Membrane Extraction Of Aromatic Acid Aqueous Solution Using Silicone Rubber Membrane

Membrane osmosis extraction is a new extraction separation technology, which combined membrane separation with liquid-liquid extraction. In this study, three kinds of aromatic acid wastewater (benzoic acid, p-hydroxy benzoic acid, p-nitrobenzioc acid) were chosen as model compounds of aromatic acid. One kind of membrane process system was constructed by homogeneous nonporous silicone rubber membrane. Osmosis extraction of different operating conditions was studied on total mass transfer coefficient (Kov).A new membrane extraction technology with spiral wound and single tubular silicone rubber membrane and alkaline stripping solution were combined into membrane extraction used for treatment of aromatic acid wastewater. The use of spiral wound membrane recycle reactor extraction benzoic acid aqueous solution achieved preferable effect. The use of single tubular mass exchanger extraction aromatic acid aqueous solution was operated by circulating cross-flow mode. Based upon the resistance-in-series model, the effects of aromatic acid initial concentration, liquid flow status on the surface of membrane, stripping solution pH, and system temperature, different kinds of salt ion strength and different kinds of acid were discussed. The experiment results indicated that when Res≥853and Ref>26, Kov was dominated by membrane resistance; Kov value increased with the increasing of the stripping solution pH level; Kov was direct proportion to the temperature in this process, the different kinds of salt ion and acid in the wastewater could change the distribution coefficient of the three kinds of aromatic acid between two phase to effect on Kov.As for the mass transfer character of inside and outside of membrane, based upon the model, the experimental data measured Kov of aromatic acid. On this basis, the document and the project that is commonly used the the numerical model expression in total mass transfer coefficient and mass transfer of membrane flux were found out.On this basis, mass transfer characteristics of three kinds of aromatic acid were compared. Selected three kinds of aromatic acids are low volatile substances, the membrance resistance was determinant of affecting Kov. Based upon the resestance-in-series model, Kov of aromatic acid were increased with the increasing of pH and the system temperature. The salinity (NaCl and Na2SO4) had an obvious enhancement on Kov, the role of Na2SO4was better than NaCl. When the ionic strength was up to160g/L,Kov of the Na2SO4than NaCl improved a magnitude. All of selected factors, the comparison results of the three substances on Kov:benzoic acid>p-hydroxy benzoic acid>p-nitrobenzioc acid.