Effect of chlorination condition and permeability of chlorine species on the chlorination of a polyamide membrane

Transformation of end-of-life RO membranes into NF and UF membranes: Evaluation of membrane performance

“…Similar results of this study have also been found [22,23]. However it has been widely reported in literature that at acid pH conditions the membrane permeability declines severely [24,25]. Controversial results can be explained due to the differences in the membrane material studied such as the origin of the PA membrane layer (commercial or tailor made).…”

“…Salt rejection percentage was kept almost constant at neutral pH (rise 3.8%, from 94.82% to 95.45 %) and slight decreased at basic pH (drop 2%, from 92.57% to 90.75%). At low exposure level of ClO -at pH-10.5, only the highly reactive end amine groups are chlorinated and the carboxylic group (R-COOH) turn to (R-COO -) groups in the linear part of crosslinked aromatic PA [25,26]. This pH condition let increase the hidrophility of the membrane surfaces and in consequence, exist less resistance to water passage through the membrane [25].…”

“…At low exposure level of ClO -at pH-10.5, only the highly reactive end amine groups are chlorinated and the carboxylic group (R-COOH) turn to (R-COO -) groups in the linear part of crosslinked aromatic PA [25,26]. This pH condition let increase the hidrophility of the membrane surfaces and in consequence, exist less resistance to water passage through the membrane [25]. This fact has been observed also in other experimentation using NaOCl, where low chlorine exposure concentration [100-6,000] ppm·h was applied [23,27,28].…”

Long-Term Stability of Low-Pressure Reverse Osmosis (RO) Membrane Operation—A Pilot Scale Study

“…However, the RO process is still subject to numerous demands including the reduction of the operation and maintenance costs [1][2][3][4][5][6][7][8][9][10], prolonging the membrane lifetime [7][8][9][10][11][12][13][14][15][16][17], and advancing the membrane module and system configuration designs [7,8,18]. The development of a low-pressure (higher flow rate) RO membrane could accomplish some of these demands.…”

Protection of polymeric membranes with antifouling surfacing via surface modifications

“…Over the past three decades, polymeric membranes have become the most intense focus of many physicists, chemists, and biotechnical scientists [1][2][3][4] due to the unique membrane separation properties of selective and proficient separation without any chemicals and as these membranes can be utilized isothermally at low temperatures with less energy consumption compared with other energy intensive conventional methods [5][6][7]. Pressure-driven membrane process such as microfiltration (MF), ultrafiltration (UF), and nanofiltration (NF)) have been widely used because of strong demand in many industrial applications like water purification, seawater Desalination, wastewater treatment and reuse, food processing and bioseparation [8][9][10].The number of membrane separation applications continues to increase, but these processes suffer from concentration polarization and membrane fouling which limit the membrane flux during filtration and negatively impact production efficiency with corresponding increases in energy consumption [11][12][13].…”