Hrvatske vode
 
Utjecaj hidrodinamičkih uvjeta u membranskom uređaju na separacijsku učinkovitost reverzno osmotskih i nanofiltracijskih membrana
Impact of hydrodynamic conditions in the membrane plant on the separation efficiency of reverse osmosis and nanofiltration membranes

Emil Dražević1*, Krešimir Košutić1

Sažetak/Abstract: 

Predviđanje koncentracijske polarizacije (KP) na membranama je nužno radi optimiranja procesa s ciljem postizanja veće separacije i konverzije. KP neizbježan je i nepovoljan fenomen u bilo kojem membranskom sustavu, a opisuje se preko koeficijenta prijenosa tvari, k, koji se može izračunati iz Sherwoodove značajke. U ovom radu predstavljen je novi pristup određivanja Sherwoodove relacije u svrhu matematičkog opisa KP, a ispitivanje je izvršeno u laboratorijskom membranskom uređaju SEPA II. Testirane su dvije reverzno osmotske (RO), SWC4+ i XLE, i jedna nanofiltracijska (NF) NF270 membrana s različitim organskim tvarima pripadajućih Schmidtovih značajki, pri različitim brzinama strujanja pojne otopine, odnosno Reynoldsovih značajki, na dva promotora gibanja. Sherwoodove relacije dobivene u ovom radu uspoređene su s relacijama u literaturi. Izračunate vrijednosti koeficijenta prijenosa tvari, k, pokazale su dobro slaganje s eksperimentalno dobivenim vrijednostima s prosječnom pogreškom od 11%.

 

Anticipation of the concentration polarisation (CP) on the membranes is necessary for process optimization in order to achieve greater separation and conversion. The concentration polarisation is an unfavourable phenomenon which cannot be avoided in any membrane system. It is described with the mass transfer coefficient (k), which can be calculated from the Sherwood number. This paper presents a new approach to determination of the Sherwood relation for mathematical description of the CP. The testing was conducted in the laboratory membrane plant SEPA II. Two reverse osmosis (RO) membranes, SWC4+ and XLE, and one nanofiltration membrane (NF) NF270 were tested by using different organic matter with accompanying Schmidt characteristics, at different flow velocities of the feed solution, i.e. Reynolds characteristics, on two motion stimuli. The Sherwood relations obtained in this paper are compared with the relations found in literature. The calculated values of the mass transfer coefficient k have a good correspondence to experimentally obtained values, with an average error of 11%.

Kategorija: 
Izvorni (originalni) znanstveni članak / Original Scientific Paper
Ključne riječi/Key words: 

reverzna osmoza, nanofiltracija, koncentracijska polarizacija, koeficijent prijenosa tvari

reverse osmosis, nanofiltration, concentration polarisation, mass transfer coefficient

Podaci o autorima/Authors affiliations: 

1Fakultet kemijskog inženjerstva i tehnologije Sveučiliišta u Zagrebu, Marulićev trg 19, 10000 Zagreb,  edraz@fkit.hr

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