Naslov
Permeability and Selectivity of Reverse Osmosis Membranes: Correlation to Swelling Revisited

Autori
Dražević, Emil ; Košutić, Krešimir ; Freger, Viatcheslav

Izvornik
Water research (0043-1354) 49 (2014); 444-452

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
reverse osmosis; nanofiltration; permeability; swelling; salt rejection; dielectric exclusion

Sažetak
Membrane swelling governs both rejection of solutes and permeability of polymeric membranes, however very few data have been available on swelling in water of salt-rejecting reverse osmosis (RO) membranes. This study assesses swelling, thickness and their relation to water permeability for four commercial polyamide (PA) RO membranes (SWC4+, ESPA1, XLE and BW30) using atomic force microscopy (AFM) and attenuated total reflection Fourier transform IR spectroscopy (ATR- FTIR). ATR-FTIR offered a significantly improved estimate of the actual barrier thickness of PA, given AFM is biased by porosity ("fluffy parts") or wiggling of the active layer or presence of a coating layer. Thus obtained intrinsic permeability (permeability times thickness) and selectivity of aromatic polyamides plotted versus swelling falls well on a general trend, along with previously reported data on several common materials showing RO and NF selectivity. The observed general trend may be rationalized by viewing the polymers as a random composite medium containing molecularly small pores. The results suggest that the combination of a rigid low dielectric matrix, limiting the pore size, with multiple hydrophilic H-bonding sites may be a common feature of RO/NF membranes, allowing both high permeability and selectivity.

Izvorni jezik
Engleski

Znanstvena područja
Kemijsko inženjerstvo, Interdisciplinarne tehničke znanosti

POVEZANOST RADA