Purification and Fractionation of Natural Petroleum Sulfonates by Liquid-Liquid & Soxhlet Extraction

Abstract

Natural petroleum sulfonates (PS) was separated, purified and divided into several fractions by a new method liquid-liquid & soxhlet extraction. The effects of heating time, volume ratio of extractants (isopropanol aqueous solution-50/50 (by volume) : n-pentane), gradient solvent types, extracting time & times on the separation efficiency are discussed, respectively. And the extracted mineral oil was anlalyzed by IR spectra, the average equivalent weight of each extracted PS fraction was measured by ESI-MS. The experimental results show that the volatiles in natural plant-manufactured PS can evaporate thoroughly in 3.5h at 130°C, and when the volume ratio of stated extractants is 3:1, after several times extraction & anti-extraction, the extracted mineral oil is PS-free, and the purified PS is successfully separated from inorganic salt, meanwhile the purified PS was divided into four fractions, whose average equivalent weight are (toluene extract) 595.03, (dichloromethane extract) 486.00, (isopropanol extract) 474.85 and (alcohol extract) 384.5g/mol, respectively. The proposed method is superior to the traditional liquid-liquid extraction for simplified steps and bifunction with PS purifying & fraction dividing, can separate efficiently industrial PS and other similar mixtures.