Responsive polymer particles for fouling removal during membrane filtrations

Aksoy, Canan
In this study, temperature and ionic-strength responsive polymeric microgels are used for fouling removal in membrane filtrations by adding them into feed solutions such that they deposit on the membrane surface together with the foulants during filtration. For removal of the fouling layer, the microgels in collapsed form are brought into swollen phase or vice versa by applying temperature change. Recently, in literature, there are several studies that stimuli-responsive surfaces have been shown to be effective in removing the fouling by “shaking off” the foulants from the membrane surface in response to appropriate stimuli. In the filtrations, PES (polyethersulfone) and PES/PVP (polyvinylpyrrolidone) blend membranes were used. It was observed that flux declined less with PVP addition than PES membrane owing to its hydrophilicity. Poly(N-isopropylacrylamide), p(NIPAm), and poly(N-isopropylacrylamide-co-sulfobetainemethacrylate), p(NIPAm-co-SBMA), microgels were synthesized by precipitation polymerization and used in the filtrations as responsive microgels. Pure water permeances (PWP) of clean membranes, filtration permeances and PWP of the used membranes after cleaning were compared in terms of flux recovery and fouling resistances. Bovine serum albumin (BSA) and humic acid (HA) were used as foulants in the presence and absence of microgels. For fouling removal, cleaning was done by stirring and simultaneously heating or cooling the filtration cell above or below lower critical solution temperature (LCST) depending on filtration condition, e.g. cleaning was done above LCST for the filtration performed below LCST in order to change size of the responsive microparticles. Thermo-responsive p(NIPAm) and p(NIPAm-co-SBMA) microgels used had swelling ratios of 2.9 and 2.1, and LCST of 32 and 29C, respectively. Addition of p(NIPAm-co-SBMA) microgel enabled less fouling resistance and more efficient cleaning compared to microgel-free cases for HA filtrations where the microgels were hydrophilic during filtration. In consequent filtrations, flux was almost completely recovered after HA filtrations for both PES and PES/PVP membranes either in pure water and in 0.5 M NaCl while flux recovery was around 60, 92 and 80% for PES membrane in pure water, PES/PVP blend one in pure water and 0.5 M NaCl, respectively. However, P(NIPAm) microgels did not provide better cleaning efficiency in neither BSA nor HA fouling for the filtrations above LCST where the microgels were hydrophobic.


Use of ionic strength responsive polymeric microgels for fouling removal in membrane filtration
Çalılı, Fatma; Çulfaz Emecen, Pınar Zeynep; Asatekin, Ayşe; Department of Chemical Engineering (2019)
Stimuli-responsive polymeric surfaces can improve non-fouling properties of membranes and control their pore size and permeation characteristics upon alteration of stimulus intensity. In this study, zwitterionic poly(sulfobetaine methacrylate) (P(SBMA)) microgels have been added into the feed or deposited on the membrane surfaces to clean foulant deposits formed on the surface of the membranes after the filtration. Salt-responsive P(SBMA) microgels have altered their phase from swollen to shrunk, swollen to...
Polycarbonate based zeolite 4a filled mixed matrix membranes: preparation, characterization and gas separation performances
Şen, Değer; Yılmaz, Levent; Department of Chemical Engineering (2008)
Developing new membrane morphologies and modifying the existing membrane materials are required to obtain membranes with improved gas separation performances. The incorporation of zeolites and low molecular-weight additives (LMWA) into polymers are investigated as alternatives to modify the permselective properties of polymer membranes. In this study, these two alternatives were applied together to improve the separation performance of a polymeric membrane. The polycarbonate (PC) chain characteristics was a...
Development and characterization of composite proton exchange membranes for fuel cell applications
Akay, Ramiz Gültekin; Baç, Nurcan; Department of Chemical Engineering (2008)
Intensive research on development of alternative low cost, high temperature membranes for proton exchange membrane (PEM) fuel cells is going on because of the well-known limitations of industry standard perfluoro-sulfonic acid (PFSA) membranes. To overcome these limitations such as the decrease in performance at high temperatures (>80 0C) and high cost, non-fluorinated aromatic hydrocarbon based polymers are attractive. The objective of this study is to develop alternative membranes that possess comparable ...
Fabrication of helical polymeric hollow fiber membranes and characterization of their fouling behaviours
Yücel, Hazal; Çulfaz Emecen, Pınar Zeynep; Department of Chemical Engineering (2018)
Membranes are used in many separation processes such as gas separation, microfiltration, ultrafiltration and hemodialysis. Hollow fiber membranes are advantageous since they have a high surface area per volume and are easily backwashed which is an advantage for fouling removal. The most important factors that affect the performance of filtration membranes are concentration polarization and fouling. They increase operational cost and reduce membrane lifetime and permeate flux. One approach that can reduce co...
Scale dependence of reaction rates in porous media
Meile, C; Tuncay, Kağan (Elsevier BV, 2006-01-01)
Elemental turnover in porous media depends on substrate concentrations at the pore-scale. In this study, the effect of small scale variability in concentration fields on reaction rate estimates and the validity of the continuum approximation in reactive transport models are investigated via a pore-scale numerical model. Artificial porous media are generated using an identical overlapping sphere algorithm. By comparison between explicit pore-scale simulations and macroscopic continuum approximations, it is s...
Citation Formats
C. Aksoy, “Responsive polymer particles for fouling removal during membrane filtrations,” M.S. - Master of Science, Middle East Technical University, 2018.