| Abstract: | Hydrazine and glycerol are two widely utilized solvents in the chemical industry, which form aqueous solutions during various stages of their production or application. Distillation of these aqueous solutions is either hazardous due to the explosive nature of hydrazine or energy intensive in case of the high boiling glycerol. The focus of this study was to develop and compare alternative safe and economical methods such as Pervaporation (PV) and Membrane Distillation (MD) for separation of water from these solvents. PV experiments using the indigenously developed thin film composite (TFC) Pebax membrane revealed a high selectivity of 107 at a reasonable flux of 0.05 kg/m2 h for a typical hydrazine hydrate feed composition of 64 wt.% N2H4. For glycerol-water mixtures, MD through a microporous, hydrophobic polytetrafluoroethylene (PTFE) membrane gave better flux (0.1 kg/m2 h) than PV through the Pebax membrane. Interestingly, both membrane types exhibited a selectivity of infinity throughout the range of feed composition (10–90% glycerol) studied due to poor volatility of glycerol. The effect of operating parameters such as permeate pressure (0.5–10 mmHg) and feed temperature (37–100°C) on MD performance for glycerol-water separation was evaluated. The membranes were characterized by scanning electron microscopy (SEM) and sorption experiments to explain the observed results. |
