Sorptive ceramic membranes functionalized with HS-groups

Sol-gel method based on the reaction of hydrolytic copolycondensation of tetraethoxysilane (TEOS) or 1,2-bis(triethoxysilyl)ethane (BTESE) with 3-mercaptopropyltrimethoxysilane (MPTMS) was used to functionalize ceramic membranes with Si(CH2)(3)SH groups. The obtained samples were studied using FTIR spectroscopy, SEM, contact angle measurements, and tested for heavy metals ions retention in the Amicon stirred ultrafiltration cell using model Ag(I) nitrate solutions. It was determined that membrane functionalization is accompanied with the decreasing water flux through the membrane, confirming the deposition of polysiloxane and polysilsesquioxane layers. According to SEM, such layer is about 2.5 mu m thick and is composed of SH-containing nanoparticles of 60-70 nm in diameter. The gaps between nanoparticles determine porosity of the functionalized layer. According to filtration studies, the sample with low degree of modification (DM) possesses high flux (550 L/m(2)h), but its retention of silver(1) ions drops sharply with permeate collection, suggesting sorption mechanism of Ag(1) removal. Whereas, samples with higher DM values are characterized by low flux, but high retention, which increases (up to 70-90%) with permeate collection, suggesting that both sorption and size-exclusion mechanisms of heavy metal removal are involved. (C) 2014 Elsevier Inc. All rights reserved.