Electrospinning Preparation of Functionalized Chitosan Mixed-Matrix Fibrous Membranes for Efficient Separation of Inorganic and Organic Species from Water

The separation or removal of inorganic and organic species is often encountered in either product purification in chemical/biochemical engineering processes or water and wastewater treatment processes. The common techniques for the separation of inorganic oxyoanions, for example, would be coagulation, flocculation, precipitation, adsorption, ion exchange, nanofiltration and reverse osmosis. It is accepted that adsorption and ion exchange are the most efficient and economic among these methods. For the removal of inorganic cations, ion exchange, nanofiltration, and reverse osmosis could be applied. For instance, chelating technique is an important one for removing dissolved ions for the aqueous solutions, and has been widely applied to separate, concentrate, and remove inorganic cations. This is because the chelating resins contain donor atoms such as O, S, P, and particularly N, which reveal excellent adsorption (coordination) ability towards cations. Conventional adsorbents (or ion-exchange resins) such as activated carbons are used in the granular forms because the pressure drop in fixed-bed operation is low enough; however, both specific surface area provided and adsorption rate are limited. These problems are expected to be overcomed if the micro- or nano-scale adsorbents or resins were used. In this case, the recovery and reuse of the adsorbents should be considered using other unit operations instead of fixed bed.This three-year project attempts to prepare functionalized chitosan mixed-matrix fibrous membranes by electrospinning method, in which the chitosan polymer will be chemically pre-modified with various functional ligands and mixed with various micro- or nano-scale adsorbent particles (activated carbon, zeolite ZSM-5, graphene oxide, etc.). It is therefore expected that such fibrous membranes reveal excellent ability for adsorptive separation of inorganic and organic species from aqueous solutions owing to the functional characteristics of chitosan and the ligands as well as the high specific surface area of the adsorbent particles. In the first year, chitosan polymer will be chemically modified with polyethylenimine (PEI) and pyridine for the separation of phosphate and indoxyl sulfate anions, whereas the chitosan polymer will be modified with ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA) or PEI for the removal of Cu2+, Ni2+, or Pb2+ cations in the second year. In the third year, chitosan polymer is modified with triethylenetetramine and ethanediamine for the removal of organic species p-cresol, phenol or 4-chlorophenol. In each year, the preparation and characterization of the electrospum fibrous chitosan membranes, adsorption equilibrium and kinetic tests in batch mode, and continuous adsorption experiments in cross-flow mode will be performed. Due to inherent properties of chitosan including biocompatibility, biodegradability, biological adhesion, non-toxicity, and no side effects, the application of such chemically modified fibrous chitosan membranes to biomedical fields such as blood purification or hemoadsorption is hopeful in the near future.

Project ID:PB10907-2481
External Project ID:MOST109-2221-E182-024-MY3