No abstract

Dehydration of widely used organic solvents such as acetic acid (AA) and isobutanol (IB) is challenging tasks, which form close boiling mixtures with water. Sodium alginate (SA) thin film composite membranes were prepared and crosslinked with 2,4-toluene diisocyanate (TDI) and glutaraldehyde for dehydration of IB and AA/water mixtures through pervaporation (PV). The crosslinked and uncrosslinked SA composite membranes were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction, thermogravimetric analysis, scanning electron microscopy, and universal testing machine for intermolecular interactions, crystalline nature, thermal stability, surface morphology, and tensile strength, respectively. At a feed composition of 98 wt % IB and 95 wt % AA aqueous solutions, the TDI crosslinked SA composite membrane exhibited separation factors of 3229 and 708 with reasonable fluxes of 0.021 and 0.012 kg m 22 h 21 , respectively. The results obtained in the study for IB and AA systems were compared with other SA membranes reported in the literature. The membranes appeared to have potential for commercial PV ability to dehydrate the solvents up to desirable purity levels (>99%) and feasibility of preparing them in a composite form which would enable scale-up into modular configurations.

A route for the fabrication of porous inorganic hollow fibers with high surface‐area‐to‐volume ratio that avoids harmful solvents is presented. The approach is based on bio‐ionic gelation of an aqueous mixture of inorganic particles and sodium alginate during wet spinning. In a subsequent thermal treatment, the bio‐organic material is removed and the inorganic particles are sintered. The method is applicable to the fabrication of various inorganic fibers, including metals and ceramics. The route completely avoids the use of organic solvents, such as N‐methyl‐2‐pyrrolidone, and additives associated with the currently used fiber fabrication methods. In addition, it inherently avoids the manifestation of so‐called macro voids and allows the facile incorporation of additional metal oxides in the inorganic hollow fibers.

This work concerns the intensification of membrane processes by coupling the Joule effect with two membrane processes: pervaporation and sweeping gas membrane distillation. For this purpose, conducting metallic hollow fibers impregnated or coated with polydimethyl siloxane were simultaneously used as membrane and heating electric resistance. The application of an electrical potential resulted in an enhancement of 40% of the water vapor permeate flux in sweep gas membrane distillation. However, the flux enhancement is the result not only of the heating on the membrane vicinity but also on the enhancement of the feed temperature. In the case of pervaporation of aqueous ethanol solutions (20%), the direct heating of fibers allowed improving by 100% the ethanol permeate flux while increasing the process selectivity.