NOVELTY - Imidazoline mixtures are produced from oil extracted from waste coffee grounds by extracting ground coffee waste through biphasic water-methanol-heptane or water-heptane extraction procedure, separating heptanic layer, concentrating to dryness, retrieving heptane to be reused, recovering most of methanol, transesterifying coffee oil catalyzed with potassium hydroxide (KOH) to obtain coffee biodiesel and glycerol, separating glycerol from mixture, aminolyzing coffee biodiesel with aminoethylethanolamine (AEEA), heating to 140-160 degrees C, and performing heat cyclation process.    USE - Production of imidazoline mixtures from oil extracted from waste coffee grounds used as corrosion inhibitor in hydrocarbon transport, processing, and storage industry (claimed).    ADVANTAGE - The method provides a solution to decontaminate coffee waste, which is recognized as a soil and water bank pollutant due to toxic nature of caffeine, through a process where residual caffeine is eliminated from coffee waste. The imidazoline mixtures have high performance as corrosion inhibitors, with low toxicity and good biodegradability. Using the method, the degreased residue improves the qualities of coffee as a fertilizer and as a raw material for compost, given that the biphasic process used to extract oil, completely eliminates any residual caffeine. The glycerol present in imidazoline mixtures of corrosion inhibitor composition does not affect the performance of the product.    DETAILED DESCRIPTION - Imidazoline mixtures of formula (I) are produced from oil extracted from waste coffee grounds by extracting ground coffee waste through biphasic water-methanol-heptane or water-heptane extraction procedure, separating heptanic layer, concentrating to dryness under moderately reduced pressure of 100-200 mmHg, retrieving heptane to be reused, leaving oil completely free of volatile components, recovering most of methanol by distilling aqueous layer, transesterifying coffee oil catalyzed with KOH to obtain coffee biodiesel and glycerol, separating glycerol from mixture through decantation in a tank, aminolyzing coffee biodiesel with AEEA, heating to 140-160 degrees C, and performing heat cyclation process at the same temperature and 200-300 mmHg until stoichiometric amount of water is removed.    R=hydrocarbonated chain of fatty acids contained in coffee oil consisting of linoleic acid in higher proportion, palmitic acid, oleic acid, and stearic acid.    INDEPENDENT CLAIMS are included for:    (1) imidazoline mixture which is obtained using the method in which incorporating linoleic acid contained in coffee oil in its structure, which is polyunsaturated, confers properties of superior adherence to metallic structures to such imidazolines;    (2) glycerol-free imidazoline mixture which is obtained using the method; and    (3) mixture of imidazolines comprising natural glycerol as a by-product of oil triglycerides obtained through the method.    DESCRIPTION OF DRAWING(S) - The drawing shows a flowchart of the process to extract and transform waste coffee oil into imidazolines.