Naslov
Mass transfer of differently sized organic solutes at spacer covered and permeable nanofiltration wall

Autori
Dražević, Emil ; Košutić, Krešimir ; Dananić, Vladimir

Izvornik
Chemical engineering journal (1385-8947) 244 (2014); 152-159

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

Ključne riječi
nanofiltration; porosity; concentration polarization; pore size distribution; mass transfer coefficient

Sažetak
Concentration polarization (CP) phenomena may significantly affect water permeability and removal of organics solutes in cross- flow nanofiltration (NF) making it an important optimization parameter. Most of the models predict CP using mass transfer coefficients that may be estimated using model Sherwood (Sh) relations of a general form, Sh = a*Reb Scc. In many cases Sh relations are able to predict mass transfer coefficients remarkably well ; however, such relations are in general valid only for non – permeable walls. Sh relations are usually experimentally validated using a binary solution of single solute and water where Schmidt numbers (Sc) are varied by changing the temperature or density of the solution, at a constant or varied Reynolds number (Re). A different approach is used herein and each of ten organic solutes, of different diffusivity at constant concentration and viscosity of solutions, represented one Sc covering a range from 850 – 2022. This study evaluated the Sh relation in predicting the mass transfer of differently sized organic solutes in rectangular channel at spacer covered and permeable NF wall of defined porosity. Comparison of experimental Sh, obtained using the velocity variation method, and model Sh showed that model Sh relation correctly predicts mass transfer of organics when particular solute flux through the NF permeable wall is sufficiently low. A correction correlation is proposed for coefficient c on Sc in model Sh relation, where c approaches the model Sh value, 0.42, with the increase in size of the solutes. In addition, data presented show that the removal of organic solutes from the water may be significantly improved, up to 280%, by changing the hydrodynamics in the channel.

Izvorni jezik
Engleski

Znanstvena područja
Kemijsko inženjerstvo, Interdisciplinarne tehničke znanosti

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