Treatment of produced water by induced air flotation: effect of both TWEEN 80 and ethanol concentrations on the recovery of PAHs

Abstract

The present study investigates the application of induced air flotation (IAF) technique on PAHs (PAHs) removal performance from a real oilfield produced water of a separator cell. The quantification of total PAHs (PAHtot) was done using ultraviolet-visible spectrometry (UV-Vis) according to the naphthalene calibration curve. The UV-Vis spectra of naphthalene dissolved in a mixture of the binary solvent (water-ethanol) and the Tween 80 showed stability in the molecular orbital of C10H8. The use of small concentration of Tween 80 was revealed to be discrete in the quantification of PAH_tot. The flotation process was improved at the critical micelle concentration of Tween 80 (CMC) of 2 % and the critical coalescence concentration of ethanol (CCC) of 0.5 mL/L for the PAH_tot recovery of 49.76 % and the PAH_tot content in the pulp of 50.24 %. At these concentrations, half of PAH_tot was removed from produced water PW. Above the CMC and the CCC, the PAH_tot recovery decreased and the PAH_tot content in the pulp increased. It was found that there is a collector concentration at which the amount of water carrying from the pulp to the concentrate was increased and in parallel, the PAH_tot recovery increased and the PAH_tot content in the pulp decreased. Both of the CMC and the CCC have promoted the decrease on the conditioning time from 30 to 10 min and the flotation time from 20 to 6 min. Since the impeller speed and air flow rate were constant, the flotation of PAHs was limited. The flotation kinetics of PAH_tot was described by the Higuchi model.