Toluene–Water Removal from Synthetic Water Using Air Gap Membrane Distillation

In this study, poly-tetra-fluoro-ethylene (PTFE) microporous hydrophobic membrane of pore size 0.22 µm and thickness 175 µm was used in AGMD module. The effect of different operational parameters such as feed temperature (40–60 °C), air gap width (3–11 mm), feed flow rate (1–5 L/min), feed concentration (1000 ppm), and cooling water temperature (8–12 °C) on total permeate flux and selectivity was studied. It was observed that the permeate flux increases exponentially from 2.88 kg/(m2h) to 4.65 kg/(m2h) on increasing the feed bulk temperature from 40 to 60 °C at 3 mm air gap width. However, it increases linearly on increasing the feed bulk temperature at 11 mm air gap. The separation factor in terms of selectivity of toluene is increased from 40 to 60.8 on increasing the feed temperature from 40 to 60 °C at 3 mm air gap width. Moreover, selectivity of toluene is found to be greater than 1 indicated easier and effective separation of toluene using air gap membrane distillation. The membrane fouling phenomena was also studied in this work and understood using scanning electron microscopy images. The permeate and retentate of toluene concentration was measured using UV–Visible spectrophotometer at 264 nm.