Toluene recovery from simulated gas effluent using POMS membrane separation technique

Membrane with polyoctylmethyl siloxane (POMS) separation layer, in flat and spiral wound module, was tested to remove toluene from air by applying vacuum pressure at the permeate side of the membrane. Effect of vacuum pressure (0.02–0.1 MPa), feed flow rate (0.6–3.0 × 10−2 m3/h, linear velocity across the membrane at 4.3–21.5 m3/(m2 h)) and toluene concentration (1500–4000 mg/m3, common for industrial effluents) on removal efficiency of the flat membrane module was determined. Under similar feed concentration and vacuum pressure, a higher toluene removal efficiency was obtained using the spiral wound membrane module than using the flat membrane, when flow rates in spiral wound unit ranged 0.15–0.27 m3/h (linear velocities across the membrane at 2.0–3.15 m3/(m2 h), much lower than in flat membrane). Under 0.09 MPa vacuum, toluene removal in spiral wound unit ranged between 70 and 84%. The removal percentage of toluene did not change much when its concentration increased in feed. This result shows that the membrane used to recover toluene in effluent stream can achieve high removal efficiency.