Concerning the size exclusion removal
mechanism, according to Nghiem et al. [41], the
membrane pore size affects the retention of
estrogenic compounds where retention by porous
membrane decreases with adsorption. Additionally
Additionally,
retention of micropollutants by NF membranes
can be enhanced by the existence of
organic matter as it interacts or absorbs and hence
increases molecular weight of the contaminant in
the water. It was found that larger organics have
a great influence and improves molecular weight
of the contaminants in the water [41].
Rejection quantification of EDCs mass transfer
through the NF sieving mechanism mostly
uses MWCO, desalting degree, porosity and surface
characteristics and morphology via atomic
force microscopy and scanning electron microscopy
[79]. The summary of the quantification
method via rejection due to sieving mechanism is
given in Table 4. Several researchers [73,75]
found that the MWCO of NF membrane cannot
be precisely used to predict and quantify for EDC
rejection due to the variation in MWCO determination.
This is because the MWCO variation
depends on filtration protocols, solute characteristics
and concentration and as well as operating
conditions. (i.e dead end, cross flow filtration)
[79]. Verliefde et al. [78] stated that MWCO of
membrane gives an underestimation of the
MWCO for hydrophobic compounds and an overestimation
MWCO for hydrophilic molecules.