Process to obtain mixtures of imidazolines and corrosion inhibitors from coffee waste

Abstract

The biphasic extraction from coffee waste without a prior drying process, to obtain coffee oil, which is transesterified with KOH catalyzed methanol to produce mixtures of glycerol free methylic esters, also known as coffee oil biodiesel, which is subjected to an aminolysis reaction with aminoethylethanolamine (AEEA) by heating to 140-160 C. at atmospheric pressure with a subsequent dehydration reaction at the same temperature but at a reduced pressure of 200 to 300 mmHg, in order to achieve cyclization of the intermediary amides into the corresponding imidazolines. Alternatively process, coffee oil can be submitted to the same aminolysis procedure with aminoethylethanolamine (AEEA) at 140 to 160 C. and atmospheric pressure with a subsequent dehydration reaction at the same temperature but at a reduced pressure of 200 to 300 mmHg, to produce imidazolines that contain the residual glycerol of the original triglycerides.

Claims

1. A process for producing imidazoline mixtures, by processing oil extracted from waste coffee grounds, characterized by the following general formula in the mixture of Imidazolines (I), ##STR00002## where the R represents the hydrocarbonated chain of one of the following fatty acids contained in coffee oil:linoleic acid in higher proportion, palmitic acid, oleic acid and stearic acid, wherein the process comprises the following stages: a) extraction of ground coffee waste through a biphasic water-methanol-heptane or water-heptane extraction procedure, with the corresponding separation of the heptanic layer and the concentration to dryness under moderately reduced pressure between 100 and 200 mmHg, retrieving heptane to be reused and leaving the oil completely free of volatile components, a majority of the methanol used is recovered through the distillation of the aqueous layer, b) coffee oil is submitted to a transesterification process catalyzed with KOH, obtaining coffee biodiesel and glycerol, with the glycerol then being separated from the mixture through a decantation process in a tank; and c) the coffee biodiesel obtained is submitted to aminolysis procedure with aminoethylethanolamine (AEEA), heating to between 140 and 160 C. and a later heat cyclation process at the same temperature and 200 to 300 mmHg until removal of the stoichiometric amount of water, to produce a mixture of imidazolines of general formula (I).

2. A process for producing imidazoline mixtures processing the oil extracted from ground coffee waste, wherein that the imidazoline mixture obtained presents the following general formula (I), ##STR00003## where R represents the hydrocarbonated chain of one of the following fatty acids contained in coffee oil:linoleic acid in greater proportion, palmitic acid, oleic acid and stearic acid, wherein the process comprises the following stages: a) extraction of ground coffee waste, through a biphasic water-methanol-heptane or water-heptane extraction procedure, with the corresponding separation of the heptanic layer and the concentration until dryness and moderately reduced pressure between 100 and 200 mmHg retrieving heptane to be reused and leaving the oil completely free of volatile components; the larger amount of methanol is retrieved through the distillation of the aqueous layer; and b) the coffee oil obtained is submitted to an aminolysis procedure with aminoethylethanolamine (AEEA), heating to between 140 and 160 C. and a later heat cycling process at the same temperature and 200 to 300 mmHg until eliminating the stoichiometric amount of water, to produce a mixture of imidazolines of general formula (I).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1. Representation of the chemical structure of polyunsaturated imidazoline and its interactions with the metallic surface. The nitrogen and OH locations are marked. The foreseeable interactions with the metallic surface are marked in dotted lines, including the electronic clouds of such interactions.

(2) FIG. 2. Flowchart of the process to extract and transform waste coffee oil into imidazolines. Includes process A with three stages and process B with two stages.

(3) FIG. 3. Diagram of the process to obtain mixtures of imidazolines from coffee oil.

(4) FIG. 4A. Test of the 1-hydroxyethyl-2-alkyl imidazolines as a corrosion inhibitor at a concentration of 5 ppm.

(5) FIG. 4B. Test of the 1-hydroxyethyl-2-alkyl imidazolines as a corrosion inhibitor at a concentration of 10 ppm.

(6) FIG. 4C. Test of the 1-hydroxyethyl-2-alkyl imidazolines as a corrosion inhibitor at a concentration of 25 ppm.

(7) FIG. 4D. Test of the 1-hydroxyethyl-2-alkyl imidazolines as a corrosion inhibitor at a concentration of 50 ppm.

(8) FIG. 4E. Test of the 1-hydroxyethyl-2-alkyl imidazolines as a corrosion inhibitor at a concentration of 100 ppm.

DETAILED DESCRIPTION

(9) This invention describes two processes related to the preparation of imidazoline mixtures processing the oil obtained from ground coffee waste.

(10) The structure of the main imidazolines of general formula (I) obtained from coffee oil is presented below:

(11) ##STR00001##

(12) Where position 1 of the imidazoline ring presents a 2-hydroxyethyl chain; and in position 2 (R), a hydrocarbonated chain of the following fatty acids present in oil obtained from coffee waste, mainly linoleic acid (Between 44 and 46%, preferably 44%) CH2(CH2)6CHCHCH2CHCH(CH2)4CH3; palmitic acid (between 32 to 35%, preferably 34%) CH2(CH2)13CH3; and other minority fatty acids, among which oleic acid (Between 9 and 10%, preferably 9%, CH2(CH2)6CHCH(CH2)7CH3; and stearic acid (between 6 and 7%, preferably 7%), CH2(CH2)15CH3 can be found.

(13) The main advantage of the imidazolines derived from linoleic acid is the presence of two double bonds on the hydrocarbonated chain, which confer the property of better adherence to metallic surfaces and consequently better performance as a corrosion inhibitor. This is due to the better stabilization capacity of the oxide layer and the longer duration of the hydrophobic effect, which minimizes contact of humidity with the metallic surface.

(14) This invention includes two alternative processes to obtain the imidazoline mixtures derived from oil extracted from coffee waste. The first of these procedures, which we named process A, has three stages:

(15) Stage 1. The extraction of the oil present in coffee waste, without previous drying, on a biphasic water-methanol-heptane system for batch processes or a water-heptane system for continuous processes, with the corresponding separation of the heptane layer and concentration until reaching dry state at moderately reduced pressure between 100 and 200 mmHg, retrieving heptane for reuse through a simple distillation method leaving oil totally free of volatile components, such as water or solvents.

(16) Stage 2. The transesterification with methanol of the extracted coffee oil, catalyzed by KOH, to obtain biodiesel, with the subsequent separation of glycerol through a decantation process in a low ball tank with a see-through glass.

(17) Stage 3. The final stage consists of two consecutive reactions: the aminolysis of biodiesel with aminoethylethanolamine (AEEA), at temperatures ranging between 140-160 C. and then the cyclization, by heating the sample at the same temperature, at pressures of 200-300 mmHg.

(18) The second process for production of imidazolines from coffee waste contemplated by this invention, which we have named Process B, has two stages:

(19) Stage 1. The extraction of the oil present in coffee waste, without previous drying, on a biphasic water-methanol-heptane system for batch processes or a water-heptane system for continuous processes, with the corresponding separation of the heptane layer and distillation at moderately reduced pressure between 100 and 200 mmHg, retrieving heptane for reuse through a simple distillation method, leaving oil totally free of volatile components, such as water or solvents.

(20) Stage 2. Direct aminolysis of the oil extracted from waste coffee grounds with AEEA at temperatures ranging between 140-160 C. and then cyclization by heating the mixture at the same temperature, at pressures between 200-300 mmHg.

(21) The imidazoline mixture mixture obtained according to process A is characterized by being glycerol free and the imidazoline mixture obtained according to process B is characterized by containing natural glycerol as a byproduct of the triglycerides of the oil. The imidazoline mixture obtained using any of the two alternative processes, presents high-performance properties as a corrosion inhibitor, including low toxicity and good biodegradability.

EXAMPLES

(22) The examples presented below show the stages to produce the imidazoline mixtures for processes A and B respectively, as described in this invention's specifications.

(23) Process A.

(24) Stage 1

(25) Coffee Waste Extraction

(26) There was loaded 1 Kg of waste coffee with 60% humidity in a 5 L three-neck flask, 1 L of methanol and 1.4 L of heptane was added, and the mixture was heated until reflux with mechanic stirring at 489 RPM for 2 hours. It was cooled down to 35-40 C. and then filtered, the layers were separated and the methanol layer returned to the flask along with the solids. The heptane layer was concentrated under vacuum until dry. There was obtained 50.53 g of oil and 900 mL of heptane. The filter cake was loaded into the original flask, 1 L of heptane was added, and the mixture was heated at reflux for one additional hour, then cooled down to 25 C., filtered and the layers separated. The heptane layer was concentrated to dryness, obtaining 8.63 additional grams of oil. The oil obtained was submitted to obtain coffee biodiesel.

(27) Stage 2

(28) Coffee Biodiesel.

(29) 12.3 g of coffee oil was heated at 50 C. for 10 minutes, then a solution of 0.65 M of KOH/MeOH (184 mg in 5 mL) and was heated in an oil bath up to 80 C. for one hour. The complete transformation was verified by TLC (heptane-MTBE 9:1; iodine reagent). It was then cooled down to 25 C. and 130 L, of AcOH was added, verifying pH=7. There was added 4 mL of MTBE and 6 mL of brine, stirred, and the layers were separated. The organic layer was dried over sodium sulfate and concentrated to retrieve 10.2 g of coffee biodiesel which was later processed to produce glycerol free imidazoline mixtures.

(30) Stage 3

(31) Preparation of Glycerol Free Imidazolines.

(32) 10 g of coffee biodiesel was loaded into a 25 mL flask and 3.42 g of aminoethylethanolamine were added. The mixture was then heated in oil up to 140 C. with a vacuum of 43 Kpa (322.5 mmHg) for four hours and then one hour at 16-20 mmHg. Transformation was verified by TLC (heptane-MTBE 9:1), (dichloromethane-MeOHNH4OH 7:3+100 L/mL). 12.12 g of raw imidazoline mixture was obtained.

(33) Process B.

(34) Stage 1

(35) Coffee Waste Extraction.

(36) There was loaded 1 Kg of waste coffee with 60% humidity in a 5 L three-neck flask, 1 L of methanol and 1.4 L of heptane was added, and the mixture was heated until reflux with mechanic stirring at 489 RPM for 2 hours. It was cooled down to 35-40 C. and then filtered, the layers were separated and the methanol layer returned to the flask along with the solids. The heptane layer was concentrated under vacuum until dry. There was obtained 50.53 g of oil and 900 mL of heptane. The filter cake was loaded into the original flask, 1 L of heptane was added, and the mixture was heated at reflux for one additional hour, then cooled down to 25 C., filtered and the layers separated. The heptane layer was concentrated to dryness, obtaining 8.63 additional grams of oil. The oil obtained was submitted to obtain coffee biodiesel.

(37) Stage 2.

(38) Direct Preparation of Imidazolines with Glycerol.

(39) A 25 mL flask was loaded with 5 g of coffee oil and 1.636 g of AEEA and heated between 140-145 C. for one hour at atmospheric pressure and four hours at a reduced pressure of 322 mmHg. The complete disappearance of the triglycerides present in the oil was verified using TLC (heptane-MTBE 85:15) and (DCM-MeOH 7:3+100 L/mL of NH4OH). There was obtained 5.3 g of a semisolid brownish mass. The imidazoline mixtures obtained using this process are characterized by containing natural glycerol.

(40) Pilot Plant Scale Up

(41) In a 100 gallon glass reactor (R-1), 52.5 kg of wet waste coffee grounds (63.14% humidity) was loaded, along with 66.33 Kg of methanol and 107.45 Kg of heptane. The mixture was heated to reflux with 120 RPM stirring for two hours and it was then cooled down to 35-40 C. It was then filtered in a Nutsche filter and the biphasic filtrate was transferred into a separating tank (T-1) to decant the lower methanol-water layer into the R-1 reactor, along with the filtered ground cake. The upper layer of T-1, which contained the heptanic oil extract, was transferred into a 100 gallon stainless steel reactor (R-2). The contents of R-1 were stirred and refluxed with 107.45 kg of heptane for two hours, then cooled down to 35-40 C. It was again filtered through a Nutsche filter, transferring the filtrate into a separating Tank (T-1). The aqueous-methanolic layer was transferred into a 50 gallon reactor to recover methanol; the residue was then sent to the treatment plant to be disposed. The upper layer was mixed in R-2 with the first extract. It was then concentrated at a reduced pressure of 200 mmHg down to a volume of 50-55 L and the residue was then concentrated to dryness in a 50 L rotavapor, yielding 3.93 kg of coffee oil (20.3% dry base).

(42) Corrosion Inhibition Tests

(43) The effectiveness of the coffee residue imidazoline mixture produced using the procedures mentioned above was demonstrated conducting harmonic analysis and polarization resistance electrochemical corrosion tests. The corrosion tests were made on AISI 1018 type steel immersed in corrosive electrolytes at 3% NaCl, CO2 and H2S at saturation. FIGS. 4A, 4B, 4C, 4D and 4E, show the charts for the concentrations of the Imidazoline mixture at five, 10, 25, 50 and 100 ppm dissolved in the electrolytes mentioned above, and where the Y axis shows corrosion rate and the X axis shows time in minutes. The imidazoline mixture obtained showed effectiveness to mitigate corrosion below 0.05 mils of an inch per year at the concentrations mentioned.