Carbon dioxide stripping from diethanolamine solution through porous surface modified PVDF hollow fiber membrane contactor

Abstract

Porous asymmetric polyvinylidene fluoride (PVDF) hollow fiber membrane were fabricated via a phase-inversion method using surface modifying macromolecules (SMM) (1wt%) as the additive in the spinning dope. Distilled water and tap water were used as internal and external coagulation bath, respectively. The membranes were characterized in terms of gas permeation, wetting resistance, overall porosity, contact angle and collapsing pressure. CO2 stripping from diethanolamine (DEA) solutions was conducted through the gas-liquid membrane contactor. The effect of some operating conditions such as gas and liquid velocities, DEA concentration and rich solution temperature on the CO2 stripping flux and efficiency were investigated. By increasing liquid flow rate to 200ml.min-1, the maximum CO2 stripping efficiency of almost 82% was achieved. In addition, an increase in the liquid flow rate resulted in a significant increase of CO2 stripping flux. By increasing the liquid flow rate from 50 to 200mlmin-1, the CO2 flux increased by 900%. By increasing the gas velocity the CO2 desorption flux increased but this changing was negligible. The effect of rich solution temperature was investigated and the results showed that the CO2 desorption flux increased with increasing the solution temperature from 80 to 90°C. The results of DEA concentration enhancement on the CO2 desorption flux showed that the CO2 stripping flux increased drastically with enrichment of the DEA concentration from 1.0 to 3.0 (moll-1). Therefore, the higher stripping efficiency can be achieved by applying the higher liquid flow rate, temperature and DEA concentration in the absorbent liquid in the membrane contactor module.