AmericanChemicalSociety.com

A new type of nanostructured polymeric membrane has been developed and utilized to effectively separate 1-butanol from water.  This separation is of interest in the emerging biofuels markets as butanol is compatible with existing infrastructure but is still an effective oxygenate. Using a "forced-assembly" method of solvent casting and crosslinking.

Vvinyl terminated diphenylsiloxane-dimethylsiloxane copolymers were prepared and tested. Swelling experiments revealed that the nanostructured membrane has significant sorption of pure butanol - swelling of ~125% was observed. Further, the pervaporation experiments revealed that these membranes have fantastic selectivity - a value of 117 for 1-butanol at the industrially relevant feed concentration of 1 wt%. Additionally, high flux of butanol was observed though these membrane materials. The high selectivity and flux were attributed to the presence of aromatic groups in the membrane material using a newly developed theory  which incoporates the formal arguments of the Onsager matrix in non-equilibrium thermodynamics coupled to an underlying free-energy derived from a multi-component extension of the Flory-Rehner theory for crosslinked polymers.