Study On Mass Transfer Characteristics Of Acrylic Acid In Ion-exchange Membranes And Its Effect On Bipolar Membrane Electrodialysis

Bipolar membrane electrodialysis process was used to recover acrylic acid and sodiumhydroxide from butyl acrylate wastewater. The process could also reduce the concentrationsof toxic pollutants and salts in the wastewater, reducing the difficulty of wastewater treatment,and showed broad application potential. This study investigated the mass transfercharacteristics of acrylic acid within the anion exchange membranes and bipolar membrane,and established the mass transfer model of the bipolar membrane electrodialysis. Throughmathematical simulation， the influence of acrylic molecular mass transfer on bipolarmembrane electrodialysis process was evaluated, and the operating conditions was optimized.Main conclusions are as follows:Mass transfer coefficient of acrylic acrylic in the anion exchange membrane JAM-I-10,ACM homogeneous membrane and FBM bipolar membrane is influenced greatly bytemperature, while it is little influenced by acrylic acid concentration. When the acrylic acidconcentration of acid cell was between0.5and4.0mol/L, the average mass transfercoefficients of acrylic acid in JAM-I-10, ACM homogeneous membrane and FBM bipolarmembrane at20℃were1.28×10^-2dm/h,8.45×10^-4dm/h and2.91×10^-5dm/h （alkaline cell isNaOH）, respectively. At temperatures between15and30℃, the mass transfer coefficients ofacrylic acid in JAM-I-10, ACM homogeneous membrane and FBM bipolar membraneincrease with the rise of temperature, following Arrhenius equation. When the temperature isabove20℃, the mass transfer coefficient changes more significantly with the temperature.Three-compartment bipolar membrane electrodialysis mass transfer model was establishedand verified with experiment data. The results indicated that the mass transfer of acrylic acidmolecular in the ion exchange membrane had important influence on the bipolar membraneelectrodialysis process. This influence can be simulated through the mass transfer model.The results of mathematical simulation of bipolar membrane electrodialysis process ofbutuyl acrylate wastewater indicate that the initial volume ratio of salt and acid cell solution,the salt cell solution initial concentration, temperature, type of ion exchange membrane andcurrent density all have significant influence on the electrodialysis process. The followingmeasures including maintaining temperature below20℃, appropriate increaseing initialvolume ratio of salt and acid cell solution, increasing salt cell solution initial concentrationand current density, using low-mass-transfer-coefficient anion exchange membrane, can raisethe acrylic acid concentration in the acid cell. Current efficiency of the process increased withthe increase of current density, while decreased with the increase of the initial volume ratioand temperatue.