Simultaneous removal of nonionic surfactant and heavy metal(II)

Abstract

Simultaneous sorption of nonionic surfactant (alkylmonoethers ALM-10) and heavy metal cations (lead, nickel) by Purolite C 106 carboxylic acrylcationic exchanger has been investigated. Sorption isotherms and kinetic curves were measured using spectrophotometric determination for nonionic surfactant and complexometric titration for heavy metals. The sorption of metal cations, surfactant molecules and products of their interaction takes place simultaneously. In the absence of surfactant the sorption of metal cations determined experimentally corresponds to that calculated from the change in the equilibrium solution pH, assuming that two hydrogen cations are replaced by one metal cation. In the presence of surfactant the change in pH is lower than that without surfactant; the total sorption of metal determined experimentally is higher than that calculated from the change in pH. It is because the sorption of metal takes place in the form of not only free cations but also cations bonded to the surfactant. The sorption of metal bonded to the surfactant can be evaluated from both the total metal adsorbed which was determined experimentally and the sorption of the free cations. The total sorption of lead(II) is higher than that of nickel(II) (transition metal). Subsequently the action of lead(II) results in the decrease of the equilibrium sorption of surfactant while the action of nickel(II) on the equilibrium sorption of surfactant is insignificant. The sorption of metal cations decreases in the presence of surfactant.