Cloud point extraction of phenolic compounds from pretreated olive mill wastewater

Olive mill wastewater (OMW) causes many environmental problems, mainly in the Mediterranean area. The phenolic content of OMW is principally responsible for the phytotoxicity and microbial growth inhibitory effects. However, these effluents can be considered as a source of powerful natural antioxidants. Cloud point extraction method was used to recover and separate phenolic compounds from pretreated olive mill wastewater. The OMW samples were ultrafiltered on 50 kDa polyethersulfone (PES) membrane. The Triton X-100 was used as surfactant at concentrations ranging from 1 to 10% (w/w). Three temperatures (70 °C, 80 °C and 90 °C) above the cloud point temperature of the surfactant were tested. After 30 min at the desired temperature the mixture form two phases: a diluted phase and a concentrated phase called coacervate. The efficiency of the extraction was evaluated by determining the phenolic compounds concentration and the volume of the both phases. The obtained results show the possibility to extract up to 66.5 ± 3.2% of the phenolic content from OMW using one step CPE. The highest yield was obtained when using 10% of Triton X-100 at 90 °C. The results obtained for volume fraction (ϕc) and rate of recovery (R%), by response surface methodology were in agreement with the experimental data. The results show that the CPE can be an efficient alternative to the classic methods of extraction since it can offer a mixture of natural antioxidants suitable for pharmaceutical, cosmetic or food applications.