Absorption of nitrogen dioxide by PVDF hollow fiber membranes in a G–L contactor

Microporous asymmetric PVDF hollow fiber membranes were prepared from commercially available polyvinylidenefluoride and N,N-dimethylacetamide (DMAc) by the dry-jet wet phase inversion process. Lithium chloride and water were used as additives. Mean pores size and effective surface porosity were evaluated by the gas permeation method. The membrane morphology was examined with help of scanning electron microscope. PVDF hydrophobic membranes were tested for the absorption of NO2. A series of experiments were performed in a countercurrent mode of operation with gas in the shell side and liquid in the fiber lumen of the module to examine the effect of various operating variables such as module stages, gas and liquid flow rate, concentration of inlet NO2 gas, concentration of absorbent, and nature of absorbent on the NO2 removal efficiency using PVDF HF membranes. The absorption efficiency of aqueous solutions of various chemicals such as Na2SO3, Na2CO3, NaHCO3 and NaOH has been compared and Na2SO3 was found to be the most promising absorbent among them.