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Title of the project

High flux antifouling nanofiltration membranes based on electrospun nanofibers with incorporated carbon nanotubes for treatment of textile industry wastewaters

Envisaged Program for funding / other sources for funding

Domain of interest

Abstract

(up to 500 words)

The high consumption of reactive dyes, mainly in the cotton industry, increases the environmental problems, due to their low degree of exhaustion (more than 60%). Traditional and advanced chemical, physical and biological dyes removal techniques appear to face several technical and economic limitations and were found to be inadequate because most textile dyes have complex aromatic molecular structures that resist degradation. Moreover, the amount of wastewater generated from the textiles industry is significant and sustainability of water resources is becoming an increasingly recognized issue. Therefore, not only the removal of the dye components is necessary, but also recovery and recycle of the water is desirable from a modern waste treatment plant. Recently reports are available for real textile wastewater treatment using membrane processes such as Ultrafiltration (UF), Nanofiltration (NF) and Reverse Osmosis (RO). UF is effective as single step treatment of secondary textile wastewater. On the other hand, NF and RO allow the separation of low molecular weight organic compounds and salts.

Nevertheless, many challenges still remain for the application of reverse osmosis membranes (SWRO), such as the high-energy consumption, rejection levels for salt and specific inorganic components such as boron, stabilization of the treated wastewater and fouling of the membranes. The NF permeate is usually colorless and low in total salinity. Its advantages over the well-established SWRO process include lower operating pressures and subsequently operating cost while maintaining a relatively high permeate flux and retention of multivalent ions.

Among the most innovative membranes combining high flux and mechanical strength, the thin-film composite (TFC) NF membranes are expected to be a key component in any water filtration technology in the future. However, the currently used materials (ceramics and specialized polymers) for membranes production, besides of being rather expensive, are not efficient for low molecular weight contaminants. The major objective of this project is the production of high flux/low pressure antifouling NF TCF membranes based on electrospun nanofibers with incorporated carbon nanotubes  (CNT) for textile wastewater treatment. The mid-layer for porosity and the thin-film layer for selectivity will be preferentially based in renewable biopolymers such as CS, CEPS, cellulose, cellulose acetate, polyhydroxyalkanoates and polylactide or in nontoxic synthetic polymers such as poly(ɛ-caprolactone) and poly(vinyl alcohol). The mid-layer will be produced by electrospinning to generate cost competitive nanofibrous membranes with appropriate physico-chemical properties. The ultrathin selective layer will be primarily produced by crosslinking coating but other techniques such as interfacial polymerization and electrospinning will be also studied. Incorporation of single walled (SWNT) and multi-walled (MWNT) carbon nanotubes (CNTs) with good dispersion and alignment into biopolymer nanofibres and thin layer are expected to improve the selectivity, flux, thermal conductivity, antifouling and mechanical properties of the membranes. Safe polymer matrixes and surfactants will be selected to avoid CNT bundling due to the van der Waals interactions between nanotubes that hinders the application for large-scale fabrication. Synthetic polymer such as PVDF or polyamide will be used for the non-woven support layer to provide mechanical strength.

Keywords (up to 5)

Nanofiltration, textile wastewaters, carbon nanotubes, electrospun, polymers

Envisaged partners sought

Contact data

(Name/Surname, Organization, email)

M. Teresa Amorim, University of Minho, mtamorim@det.uminho.pt