Bio-lubricant with high viscosity and method

A bio-lubricant composition comprising:

• a first component that includes a first triglyceride, which is part of waste cooking oil;
• a second component that includes a first epoxidized triglyceride, which originates from a second triglyceride, which is part of the waste cooking oil, wherein the second triglyceride has been epoxidated to obtain the first epoxidized triglyceride;
• a third component that includes a hydroxylated triglyceride, which originates from a third triglyceride of the waste cooking oil, wherein the third triglyceride was epoxidized to form a second epoxidized triglyceride and the second epoxidized triglyceride was hydroxylated to form the hydroxylated triglyceride;
• a fourth component that includes a first fatty acid ester moiety, which originates from a first free fatty acid of the waste cooking oil;
• a fifth component that includes a first epoxidized fatty acid ester, which originates from a second free fatty acid of the waste cooking oil, and the second free fatty acid was esterified to form a second fatty acid ester moiety and the second fatty acid ester moiety was epoxidated to form the first epoxidized fatty acid ester;
• and
• a sixth component that includes a hydroxylated fatty acid ester, which originates from a third free fatty acid of the waste cooking oil, and the third free fatty acid was esterified to form a third fatty acid ester moiety, the third fatty acid ester moiety was epoxidated to form a second epoxidized fatty acid ester, and the second epoxidized fatty acid was hydroxylated to form the hydroxylated fatty acid ester,
• wherein a mixture of the first to sixth components at room temperature has a viscosity between 40 and 200 centipoise, and
• wherein the composition is substantially free of free fatty acids.

A method for making a bio-lubricant composition from waste cooking oil, the method comprising:

• purifying the waste cooking oil with an activated biochar to obtain purified cooking oil, wherein the purified cooking oil includes triglycerides and free fatty acids;
• esterifying the purified cooking oil to transform substantially all the free fatty acids into fatty acid methyl ester moieties, wherein this step maintains a viscosity of the purified cooking oil when transformed into a first mixture of the triglycerides and the fatty acid methyl ester moieties;
• stabilizing a structure of the triglycerides and the fatty acid methyl ester moieties by epoxidation, which results in a second mixture of epoxidated triglycerides, epoxidated fatty acid esters, the triglycerides, and the fatty acid methyl ester moieties;
• and
• increasing the viscosity of the second mixture by opening epoxy rings with a hydroxylation process, which results in a third mixture of the triglycerides, the fatty acid methyl ester moieties, the epoxidated triglycerides, the epoxidated fatty acid esters, hydroxylated triglycerides, and hydroxylated fatty acid esters,
• wherein the third mixture at room temperature has a viscosity between 40 and 200 centipoise.