Removal of cobalt ions from simulated radioactive wastewater by vacuum membrane distillation

The separation of cobalt ions (Co2+) by vacuum membrane distillation (VMD) process with commercial polypropylene hollow fibers membrane was investigated. The effect of operational parameters, including feed temperature (30-70 °C), permeate vacuum degree (0.10-0.98 atm) and feed flow rate (10.5-41.8 L/h), on the membrane flux was examined. The Pearson correlation analysis was employed to evaluate the significance of different operating parameters to the permeate flux. The results showed that permeate vacuum was the most significant to membrane flux (Pearson correlation coefficient = 0.621). The mass transfer mechanism during Co2+ separation was analyzed and Knudsen diffusion was proved to be the dominant mass transfer mechanism during VMD process. Dusty gas model could estimate the membrane flux well with average relative error of 5.21%. VMD method has shown its potential in the treatment of cobalt-containing wastewater.