抄録
Froth flotation is one of the surfactant-based separation processes which is suitable for treating dilute oily wastewaters. The objective of this study was to investigate the relationship between ultralow interfacial tension (IFT) and the efficiency of diesel removal from wastewater by continuous froth flotation technique. Branched alcohol propoxylate sulfate, sodium salt (Alfoterra 145-5PO) and sodium dodecyl sulfate (SDS) were used for both microemulsion formation and froth flotation studies. Surfactant concentration, salinity, and oil to water ratio were varied in the microemulsion formation experiment in order to determine the compositions required to obtain ultralow IFT. The effects of surfactant concentration, salinity, and HRT on the oil removal were investigated. From the results, the oil removal efficiency of the froth flotation process did not correspond to the minimum IFT of the system indicating that the ultralow IFT alone cannot be used as a sole criterion for froth flotation operation. Foam stability was revealed to be another crucial factor in the froth flotation operation. The system with 0.1 wt% Alfoterra, 0.5 wt% SDS, 4 wt% NaCl, an oil:water ratio of 1:19, an air flow rate of 0.15 L/min, a foam height of 26 cm, and a HRT of 49 min gave the maximum oil removal (90.37 %).
