Water contained in crude oil, forms so-called water-in-oil emulsions, the presence of which negatively affects the transportation and processing of oil. Demulsifiers are the special mixtures that are used to remove water from emulsions. The present paper is devoted to obtaining the demulsifiers by catalytic acid esterification of fatty acids mixture extracted from gossypol resin with isopropanol. Fourteen mixtures, containing mainly fatty acids and their ethers, were obtained and tested for demulsifying performance by using the bottle test. The relationship of the following values with the demulsibility of final mixtures was determined: the conditions of fatty acids esterification, the content of fatty acids in the demulsifier, the relative solubility number of the demulsifier, the toluene/water dynamic interfacial tension. The following conditions of fatty acids mixture esterification provided 64.8% of water removal at the dosage of 20 ppm of demulsifier: 385 K; 4 h; H2SO4/fatty acids mixture ratio 2.5 wt.%.

Saline water necessarily contained in crude oil forms complex and stable water-in-oil (w/o) emulsions with oil. Due to the negative impact of this emulsion on the oil’s transportation and refining, special materials are added to help break the emulsion and separate water. Herein, a comparative study of the demulsifying ability concerning w/o emulsion of the original and freshly milled quartz (FMQ) particles isolated from river sand was carried out. The effect of quartz with a mesh size of 75 μm on reducing emulsion stability was investigated using rheological measurements, interfacial tension measurements, demulsification tests, as well as routine methods for characterizing solid and liquid materials. With the addition of 3 wt% FMQ, 97% demulsification efficiency was achieved after 100 min of settling, against 140 min for the original quartz. The role of milling quartz is to increase the ability of water to adhere and thus locally increase the pH value; this results in a reduction in the stability of the emulsion and its destruction. The prolonging effect of quartz milling lasted about 2.5–3.0 h, after which the demulsifying ability of milled quartz became comparable to that of the starting material.