Fabrication of Polymeric Membrane for Water Treatment by using Reverse Osmosis Technology

Abstract

Water is one of the most abundant source in the world. Ground water fulfils much of our needs However, the presence of certain salts, excess minerals and other hazardous impurities may reduce the purity of the water. Salts have the most adverse effect in this regard. It is mainly present in the order of 3-4% in water, and increased amount reduces purity content of the water. Therefore it is imperative to separate salts from the water. For this purpose, it is proposed to use a polymeric membrane, which consists of TiO2 incorporated in a Polyamide (PA-6) matrix, or a polymer blend membrane. Amine modification of the TiO2 helps in the capture of salts like CaCl2, MgCl2 . The use of Polyamide loaded with TiO2 is helpful because of its flexible structure and fixed but tunable pores. Blend membranes work in much the same way, by including such groups in the matrix which have affinity for salts. In the present work, synthesis of a series of polymer blend membranes, consisting of a blend of polyamide (PA-6)/Formic Acid(FA) and DEMAC in an formic acid solvent system, and membranes of consist of Polyamide-6 in FA matrix, synthesized from a solution of the polymer and filler in formic Acid(FA) is carried out. These two membranes were then tested for water permeation using single and mixed water permeation testing (in water testing device which was designed), analyzed for their tensile strength using the Ultimate Tensile Testing Machine, their morphology and surface characteristics studied using SEM analysis and the presence of functional groups , salt rejection % and TiO2 was confirmed using FT-IR ,UV and XRD spectroscopy. It was found that the amino-modified TiO2 based PA membranes provided much better and superior single and mixed salts rejection % of 97.50% and 98.45% respectively for the membranes containing 20% polyamide (PA-6) in the formic acid, with permeability up to 38.5 (L/m-2hr). The membranes also exhibited uniformly pores structures, with pores observed under SEM magnifications up to 25000x. Moreover, they had a maximum tensile strength of about 20.673 MPa to 39.56MPa.