Mass transfer process in nonporous tubular membrane for extraction of phenol with caustic stripping solution

Mass extraction process of phenol from aqueous solution to a caustic solution through nonporous silicone rubber membrane was investigated. The effects of liquid flow status, pH of stripping solution, initial phenol concentration, transmembrane pressure, and system temperature on mass transfer coefficient were discussed. Based upon the resistance-in-series model, the overall mass transfer coefficient (OMTC) across membrane was calculated. The experiment results showed OMTCs presented logarithmic relation to the Reynolds number, while the changes of flow status had little effect on OMTCs at the higher Reynolds numbers (Re-t>86.5 and Re-s>2000), which indicated that mass transfer of phenol was dominated by membrane resistance for nonporous membrane system (3.72x10(-7)m.s(-1)). The presence of transmembrane pressure went against permeability of phenol. Moreover, OMTC was linearly proportional to the initial phenol concentration in the range of 5,000-7,500 mg.l(-1), and reached a plateau value at higher phenol initial concentration. OMTC was directly proportionate to the temperature in this process. Mass transfer of phenol through nonporous membrane was scarcely affected by pH value of the stripping solution.