Initial reverse osmosis composite membrane (IniM) is a thin-film-composite (TFC) membrane prepared through the interfacial polymerization technique without post-treatment

such as water washing

heating

etc.Trimesoyl chloride (TMC) and m-phenylenediamine (MPD) were used to prepare some IniMs through the interfacial polymerization technique on the polysulphone supporting membrane without heat-treatment and washing.Then the in situ modification was performed with tetraethylenepentamine (TEPA) on the surface of IniMs.Modified membranes were characterized by using X-ray photoelectronic spectroscopy (XPS)

contacting angle and permeation experiments with salt water of different pH values.The results showed that tetraethylenepentamine reacted with acyl chloride (—COCl) on the surface of IniM

because the ratio of O/N of the modified membrane surface was lower than that of unmodified membrane.Furthermore

the contacting angle of modified membrane was larger than that of unmodified membrane.It is interesting that the water flux and rejection of modified membrane decreased with increasing pH value for sodium chloride solution

while the unmodified membrane was just on the contrary.The reason was that functional groups on the modified and unmodified membrane were different

the former were amino (—NH2) and imino (=NH)

and the latter was carboxyl (—COOH).