Gas Permeability and Selectivity of Synthesized Diethanol Amine-Polysulfone / Polyvinylacetate Blend Membranes

The control of anthropogenic carbon dioxide release is one of the most challenging environmental problem faced by developing countries, as the interfering of atmospheric carbon dioxide level and climate revolutionize. An rising technology is the membrane gas separation, which is more dense, energy efficient and possibly more economical than past technologies, such as solvent absorption. Amine has a greater efficiency for removal of carbon dioxide. The blending technique not only provides improved chemical and thermal stability but is also efficient enough to improve the perm-selective properties with economical viability. In this study, research will be carried out to study the gas permeability behavior of glassy Polysulfone and Polyvinyl acetate rubbery polymeric blend membranes with diethanol amine. Polymeric amine blend membranes with different blending ratios were prepared in dimethyl acetamide solvent, flat sheet membrane were developed with enhance properties. We were studied PSU/PVAc blend with DEA amine using a gas permeability application for CO2 and CH4 at different feed pressures.


INTRODUCTION
The existence of CO 2 in natural gas decreasing its calorific value for incomplete combustion as well as environmental issues occur like its emission to atmosphere is increasing Global Warming and Green House Effects, need to be removed and increases the worth value.A wide study of gas transport properties for PSU has been conducted by Paul and co-workers (Barbari et al., 1988).One of the most extensively patented polymeric materials are polysulfones (Chiao, 1988;Bikson et al., 1985;Coplan et al., 1983;Rose, 1981a, b;Quentin, 1977;Quentin, 1973).They are regarded as amongst the most chemically and thermally robust thermoplastic polymers available; and polysulfones have been extensively applied to gas separation (Chiao, 1989;Bourganel, 1977;Graefe et al., 1975;Kawakami et al., 1991).Poly Vinyl Acetate (PVAc.) is an important polymer, exhibiting piezoelectric, pyro-electric and ferroelectric properties (Kroschwitz, 1989).The typical advantages of PVAc are flexibility, formability and low density.
Alkanolamines are widely used as the absorbents for CO 2 capture.Amine-containing chemical solvents are usually favored when the partial pressure of CO 2 within the feed gas is comparatively low or if once CO 2 is reduced to a very low concentration within the treated gas.Physical solvents are to be used at high CO 2 pressures within the feed gas and when deep CO 2 removal is not required.
Several researchers have investigated the chemistry of CO 2 -amine solutions over the years due to its important industrial application for CO 2 removal from gas streams.Table 1 shows the comparison of amines and membranes for CO 2 removal systems.
The overall reaction between CO 2 and secondary amines is: where, R represents the functional groups for DEA, R 1 = R 2 = -CH 2 CH 2 OH.The Dankwerts' zwitterions mechanism has recently become one of the most widely accepted mechanism for amine reaction with CO 2 (Blauwhoff et al., 1984;Versteeg and Van Swaaij, 1988;Versteeg et al., 1990;Versteeg and Oyevaar, 1989;Glasscock et al., 1991;Littel et al., 1992): Its mean: The amine solution has the potential to purify the natural gas having acid gas (Kerry, 2007).So, by blending a glassy polymer with different amine solutions, the separation ability is enhanced for CO 2 /CH 4 mixture.Amine has a natural attraction for both CO 2 and H 2 S, allowing this to be a very wellorganized and valuable removal process on the performance of polymeric membrane to study high selectivity and high permeability.

METHODOLOGY
Figure 4 relates to Table 4 and 5 and shows that the permeance of CO 2 and CH 4 for a pure PSU membrane was reduced with increased pressure.On the other hand, a pure PVAc membrane's CO 2 and CH 4 permeance rose with increased pressure.We observed that as the 10% DEA amine and percentage of PVAc increased in PSU, the permeability of both CO 2 and CH 4 also rose with pressure increases.
Figure 5 relates to Table 6 showing that pure PSU's selectivity for CO 2 /CH 4 rose with increased pressure.On the other hand, pure PVAc membrane's selectivity for CO 2 /CH 4 decreased with increasing pressure.As for our synthesized blended membranes, as 10% DEA amine and the percentage of PVAc increased in PSU, the membrane's selectivity also rose with increased feed pressure.
We therefore concluded that a pure PSU glassy polymeric membrane, a pure PVAc rubbery polymeric membrane and a polymeric amine membrane were not only completely miscible but also characteristically increased a blended membrane's permeance for CO 2 as feed pressures rose while also demonstrating increased selectivity.

CONCLUSION
Polymeric Amine Blend Membrane could be an advanced technique for gas separation.Blending of friendly environmental polysulfone, polyvinyl acetate with diethanol amine has proven to be an appropriate tool to produce novel materials with combined characteristics in having each improved application properties and low value benefits in material performance.In addition, as DEA amine was added we also observed remarkable improvement in the membrane's permeability and selectivity of/for CO 2 ; most likely due to soluble nature of CO 2 in DEA amine, indicating that the presence of amine enhanced carbon dioxide solubility across the membrane.Therefore, PSU/PVAc./DEApolymer blends may be considered a new, economical, high performance raw material suitable for the preparation of gas separation membranes for the separation of CO 2 from CH 4 with enhanced permeation and selectivity.In the future work we have a tendency to conjointly add the inorganic fillers like carbon molecular sieves; zeolites in blend which is further enhanced the polymeric amine blend membrane.Therefore, this will increase the economic process in gas trade.
Materials and membrane fabrication: Polysulfone (PSU) Udel® P-1800 having a glass transition Temperature (T g ) of 185°C was acquired from Solvay Advanced Polymers; L.L.C, U.S. PSU was in minced form.Polyvinyl Acetate (PVAc.)average M w ~100,000 by GPC, beads from Sigma Aldrich having a glass transition Temperature (T g ) 30°C.Diethanol amine and Dimethyl Acetamide (DMAc.)solvent with a purity of 99.99% was purchased from Merck.