Supported Liquid Membrane-Based Pervaporation for VOC Removal from Water

Abstract

Supported liquid membrane pervaporation (SLMPV) is a pervaporation process for separating volatile organic compounds (VOCs) from their dilute aqueous solutions through a supported liquid membrane. It integrates simultaneous extraction of the VOCs from the aqueous solution with vacuum stripping of the VOCs from the organic phase in one membrane module. Using a liquid membrane consisting of nonvolatile hydrocarbons immobilized in the micropores of hydrophobic porous polypropylene hollow fibers with or without a plasma-polymerized ultrathin silicone membrane on the outside diameter of the fibers, trichloroethylene (TCE) was separated and concentrated from its aqueous solution at 25 °C and essentially atmospheric pressure. The feed TCE concentration was varied between 50 and 950 ppm; the permeate pressure range was 0.6-70 mmHg. A 78-fiber, 30-33-cm-long module can achieve as much as 98% removal of TCE. The hexadecane SLM is permselective for TCE: the experimental selectivity was 30 000, and the intrinsic selectivity could be as high as 2 × 10 5 , much higher than the values reportedly obtained by any solid membrane. The hexadecane SLM performance indicated long-term stability: about 30% decreases in both pervaporation flux and selectivity were observed in a run lasting 4 months. A mathematical model has been proposed to predict the exit concentration, permeation flux, and selectivity from the properties of the membrane and VOCs and the operating conditions.

Stable Liquid Membranes

“…These recent efforts have resulted in improving the stability of ILMs for gas separation tremendously; the ILMs formed were tested for a few months without any loss of stability or performance. Similarly, the approach of using non‐volatile solvents/carriers was equally successful in developing highly VOC‐selective ILMs for VOC removal from gas streams18 and aqueous streams 19. For example, trichloroethylene (TCE) was removed from aqueous streams using hexadecane immobilized liquid membrane in a membrane‐based pervaporation technique using an ultrathin silicone rubber‐coated microporous hollow fiber membrane.…”

“…For example, trichloroethylene (TCE) was removed from aqueous streams using hexadecane immobilized liquid membrane in a membrane‐based pervaporation technique using an ultrathin silicone rubber‐coated microporous hollow fiber membrane. The TCE and water fluxes were studied for a period of four months and were essentially stable 19…”

Synthesis of the novel symmetric buckypaper supported ionic liquid membrane for the dehydration of ethylene glycol by pervaporation

“…Numerous studies on the applications of SILM in pervaporation http for the separation of organic compounds from dilute aqueous solutions have been reported [8][9][10][11][12][13][14]. Although the use of SILM is always associated with an instability problem caused by the leaching of the liquid membrane from the porous support, particularly under high pressure or vacuum conditions, several methods have been proposed to overcome this limitation, and these include reimmobilisation of the liquid membrane [15], surface coating [16], and mixing with a base polymer to form a thin, stable film [17]. In addition, the use of a porous support with a smaller pore diameter would also help enhance the SILM stability [18,19].…”

Selective Removal of Dilute Benzene from Water by Various Cross‐Linked Poly(dimethylsiloxane) Membranes Containing tert‐Butylcalix[4]arene

“…Pervaporation is one of these membrane separation techniques, being noted as an advantageous method for the separation of azeotropes and volatile organic compound/water mixtures 5–8. Many studies have reported the removal of VOCs from water through various polymer membranes using pervaporation 9–12…”