While removal efficiency of most components in water by RO membranes is very satisfactory,
the removal of some trace elements such as boron by RO membranes, especially those with
long service life, is relatively low. The interplay between pH and ionic strength is believed to
be the key to understand the boron removal by RO membranes. Boron, with pKa of 9.25, in
water at low concentration is normally in the form of boric acid (B (OH) 3) at neutral pH and it
is dissociated into negatively charged borate (B (OH) 4−) form at high pH. Correspondingly …

While removal efficiency of most components in water by RO membranes is very satisfactory,
the removal of some trace elements such as boron by RO membranes, especially those with
long service life, is relatively low. The interplay between pH and ionic strength is believed to
be the key to understand the boron removal by RO membranes. Boron, with pKa of 9.25, in
water at low concentration is normally in the form of boric acid (B (OH) 3) at neutral pH and it
is dissociated into negatively charged borate (B (OH) 4-) form at high pH. Correspondingly …