Fabrication of high-performance pervaporation composite membrane for alkaline wastewater reclamation

Pervaporation desalination has a unique advantage to recycle concentrated salt solutions. The merit can be applied to treat alkaline wastewater if the membrane has superior alkali-resistance. In this paper, we used polyethylene microfiltration membrane as the substrate and deposited a glutaraldehyde crosslinked sodium carboxymethylcellulose layer by spray-coating. Pervaporation flux of the composite membrane reached 35 +/- 2 kg.m(-2)h(-1) with a sodium chloride rejection of 99.9% +/- 0.1% when separating a 3.5 wt-% sodium chloride solution at 70 degrees C. The desalination performance was stable after soaking the membrane in a 20 wt-% NaOH solution at room temperature for 9 d and in a 10 wt-% NaOH solution at 60 degrees C for 80 h. Moreover, the membrane was stable in 4 wt-% sulfuric acid and a 500 mg.L-1 sodium hypochlorite solution. In a process of concentrating a NaOH solution from 5 to 10 wt-% at 60 degrees C, an average water flux of 23 kg.m(-2).h(-1) with a NaOH rejection over 99.98% was obtained.