FABRICATION OF PAPER BASED THERMO-RESPONSIVE MEMBRANES AND INVESTIGATION FOR THEIR USE IN ADSORPTION OF EMERGING WATER CONTAMINANTS

Abstract

<p>Endocrine disrupting substances have been frequently reported to exist in potent concentrations in wastewater treatment plant effluent and other surface waters. Common techniques of wastewater treatment have varied effectiveness to remove estrogens from wastewater. A thermo-responsive smart membrane technology is investigated for its use in adsorptive removal of 17β-estradiol from a background electrolyte solution. A simplified fabrication method is adapted for hydrogel-substrate composite thermo-responsive membranes. Deposition of hydrogel occurs through aqueous polymerization in a coating process dissimilar to common grafting techniques. Acrylamide and acrylic acid monomers are polymerized in two different structures, a random copolymer as well as an interpenetrating network, to form a positive volume-phase transition hydrogel coating. Subsequent membranes experience high permeability at low temperatures with a gating mechanism reducing permeability upon heating. The effects of crosslinker content, monomer ratio, mass loading and butylmethacrylate content are investigate. Only mass loading was found to have significant influence on the behaviour of the membranes in all cases. The variations of the other factors were too little to have great influence. The membranes with the most stable permeability response function were then used in 17β-estradiol adsorption tests, investigating the binding capacity at both colder water temperatures (10oC) and warmer water temperatures (40oC). In the collapse and swelling of the volume-phase transitions, the membranes changed their solution properties which were hypothesized to also alter surface functionality. After introducing the estradiol sample, the membranes were subjected to temperature change with the expectation that any bound material would elute once the surface functionality of the membranes became adequately altered. Only some membranes produced an elution fraction while others appeared to undergo irreversible binding with a possible delayed elution. Removal of dosed 17β-estradiol is reported as adsorbed mass per area of membrane.</p>