Modelling the rejection of nanofiltration membranes using zeta potential measurements

Removal of fluoride and uranium by nanofiltration and reverse osmosis: A review

“…Membrane charge is determined by the ionisable functional groups on the surface (Childress and Elimelech, 1996;Vankelecom et al, 2005). The isoelectric points of most NF membranes usually fall in the range of pH 3-6 so they are negatively charged at neutral and alkaline pH (Hagmeyer and Gimbel, 1999). Due to the dissociation of functional groups, charge repulsion between the polymer chains increases and forces the membrane pores to 'open up' (Braghetta et al, 1997).…”

Transport coefficients and cadmium salt rejection in nanofiltration membrane

“…It depends espeei- Table 2 Transport coefficients and mixture salt flux distribution at T = 30°C ally on the nature of the surface ionic groups of membrane [14][15][16] and changes on the speciation on solution [8,17]. The charge of a membrane varies with the pH around its isoelectric point.…”

Arsenic Removal by Membrane Filtration

“…After agitation the sample is given 6 to 8 hr for settling; after settling the extract is filtered through a filter paper of 0.45 μm pore size. The California Wet Extraction Test (CWET) [27] is also performed for assessing the stability of arsenic in the arsenic-bearing solid precipitate. The principle of this test is similar to that of TCLP, where the distinguishing features lie in using 0.2 M sodium citrate and an agitation time of 48 hr in the CWET.…”

“…The flux for the charged particle through the nanofiltration (NF) membrane can be measured using the extended Nernst-Planck equation [27,28]. A modified Nernst-Planck equation determines ionic flux (Na + ) from the NaCl solution, which is passed through a nanofiltration membrane [29].…”

“…27 shows variation of pure water flux as well as arsenic rejection by the NF-1 nanofiltration membrane during cross-flow filtration run under varying transmembrane pressure.The volumetric flux in LMH increases from 48 to 145 LMH as transmembrane pressure increases from 5 to 18 kgf/cm 2 . Beyond a pressure of 16 kgf/cm 2 , improvement in flux is very marginal.…”