Investigation on the reaction of phenolic pollutions to mono-rhamnolipid micelles using MEUF.

Micellar-enhanced ultrafiltration (MEUF) processes of resorcinol, phenol, and 1-Naphthol with rhamnolipid as an anionic biosurfactant were investigated using polysulfone membrane. The effects of retentate/permeate concentration of phenolic pollutants (C R/C P), distribution coefficient of phenolic pollutions (D), concentration ratios of phenolic pollutions (α P) and rhamnolipids (α R) and adsorption capacity of the membrane (N m) were studied by operating pressure, pH condition, feed surfactant, and phenolic pollution concentrations. Results showed that C R (with pH) increased and ranked in the following order: resorcinol > phenol > 1-Naphthol, which is same with C R (with pressure), C R (with surfactant), C R/C P (with pollution), α,P and D, while C P (with pH), C P (with pressure), and C P (with surfactant) ranked in the reverse order. The operating pressure increased the solubility of phenolic from 0 to 0.1 MPa and then decreased slowly above 0.1 MPa. The concentration ratio of rhamnolipid was nearly at 2.0 and that of phenolic pollution was slightly above 1.0. D of phenolic pollutants reached the maximum at phenolic pollution concentration of 0.1 mM and the feed rhamnolipid concentration at 1 CMC. Moreover, zeta potential in feed stream and retentate stream and membrane adsorption of phenolic pollutions were firstly investigated in this article; the magnitudes of zeta potential with the feed stream of three phenolic pollutions were nearly the same and slightly lower than those with the retentate stream. The adsorption capacity of the membrane (N m) was calculated and compared to the former research, which showed that rhamnolipid significantly decreases the membrane adsorption of phenolic pollutions at a relatively lower concentration. It was implied that rhamnolipid can be substituted for chemical surfactants.