In this work, a mathematical model has been developed for vacuum membrane distillation incorporating molecular diffusion–Knudsen diffusion–Poiseuille flow and validated with the experimental data. The feed-side membrane surface temperature used in mathematical model was estimated by computational fluid dynamics modeling. The effects of different operating parameters such as feed flow rate, feed bulk temperature, inlet concentration, and permeate-side pressure on water flux and salt rejection have been studied using PTFE membrane. It has been shown that with variation in feed flow rate from 0.5 to 2 lpm, the permeate flux increased from 20.1 to 25.6 kg/m² h. Similarly, with increase in feed bulk temperature from 40 to 60°C, the permeate flux increased from 2.10 to 26.6 kg/m² h. The permeate flux showed the variation from 17.8 to 19.5 kg/m² h on decreasing permeate pressure from 7 to 5.5 kPa. No significant effect of feed salt concentration was observed on permeate flux. More than 99% rejection was obtained at the feed salt concentration of 40,000 ppm of NaCl. Few runs were also carried out by taking multi-ion feed (Ca⁺⁺, Mg⁺⁺, Na⁺, K⁺, Cl⁻, , Fe⁺⁺, , F⁻) equivalent to that in ground water; in which case also more than 99% rejection was obtained.

In this study, the extraction of phenol from an aqueous solution with the help of an emulsion liquid membrane (ELM) has been carried out. This membrane has the edge over the conventional separation processes in selectivity, efficiency, and feasibility. Certain factors such as surfactant, carrier, and diluent play an essential role in membrane synthesis. In our case, Span 80 (sorbitan monooleate) was taken as a surfactant, kerosene as a diluent, and Aliquat 336 and Isodecanol as carriers. Under different optimum operating conditions, it was found that external-to-membrane phase ratio, surfactant concentration, carrier concentration, agitation speed, time of extraction, membrane-to-internal phase ratio, and solute concentration were the significant parameters. At optimum conditions, 89.52% phenol removal has been recorded. The percentage removal changes with time, and it was seen that it tends to remain constant after a while. The experiment was also carried out in two stages, taking into account the higher concentration of phenol from around 1,000 ppm to a lower concentration of around 100 ppm. It was observed that the final concentration of phenol after the two-stage process had been reduced to around 7–10 ppm.