Concentration polarization on surface patterned membranes

Abstract

Surface pattern is a promising approach to enhance membrane performance while contradictory results have been reported on its impact on concentration polarization.Here, we provide an experimental and modeling study of the concentration polarization on patterned membranes by varying pattern size, solute size, surface hydrophilicity, and membrane orientation. Interesting trends were observed when comparing different membrane orientations, where relative concentration polarization degree (CPD) was found depend on molecular weight. Salts and small organic molecules encountered more severe CPD in the transverse mode, while molecules larger than a threshold value showed a different trend. Such threshold molecular weight increased at larger pattern size. Simulation results were consistent with experimental observations, and revealed the critical role of diffusivity on such phenomena. Results also showed more severe concentration polarization on patterned membranes in both parallel and transverse modes in most cases, compared to smooth membrane.

Smart Organic–Inorganic Polyoxomolybdates in Forward Osmosis for Antiviral-Drug Wastewater Treatment and Drug Reclamation

“…This is mainly attributed to the asymmetric structure of the PA-PES TFC membrane. When the draw solution flows along the porous PES side (FO mode), the solutes are inclined to penetrate the membrane interior, causing the occurrence of internal concentration polarization (ICP), as observed elsewhere. − The presence of ICP induces a detrimental effect on the transmembrane osmotic pressure difference and reduces the net driving force, resulting in a declined water flux. By contrast, no ICP exists with the PRO mode, and thus, the water transfer rate is immune from ICP.…”

Interfacial polymerization at unconventional interfaces: an emerging strategy to tailor thin-film composite membranes

“…While the antifouling performance of patterned TFC membranes has largely been confirmed through experiments [96][97][98][99][100][101][102][103][104][105] and numerical modeling, 101,105,106 certain studies have found that under specific conditions, the presence of patterns on the membrane surface can actually intensify concentration polarization. 107,108 Further research is needed to more comprehensively understand the impact of experimental parameters, including the cross-flow rate, the morphology and dimensions of the patterns, and the molecular properties of the solutes, on concentration polarization.…”

Construction and Chlorine Resistance of Thiophene-Poly(ethyleneimine)-Based Dual-Functional Nanofiltration Membranes

“…Although dechlorination is carried out after disinfection, free chlorine is unable to be completely removed from water in this process. In addition, live COVID-19 viruses have been detected in both the excreta of virus-infected people and aquatic systems in the current global COVID-19 epidemic. , More chlorine-containing disinfectants are then used during the epidemic to cut off the virus transmission route, resulting in a significant increase in the content of free chlorine in the water. − However, PA membranes are vulnerable to the attack of free chlorine when exposed to a chlorine-containing environment. As a result, the residual N–H groups of PIP on the PA membrane surface are either converted to N–Cl or oxidized to hydroxylamines .…”