Process For Extracting Cholesterol From Lanolin

As a widespread natural steroid resource, cholesterol can be used for synthesis of steroid drugs, cosmetics and liquid crystal materials. Lanolin is a by-product extracted from wool lotion. As one hydrolysis product of lanolin, lanolin alcohol is rich in cholesterol and lanostreol.This thesis supposed a process route to extract cholesterol from lanolin alcohol, which included molecular distillation and selective crystallization. The process is more environmentally friendly while lanosterol could also be recycled. A RP-HPLC method was established to analyze cholesterol in lanolin alcohol. Retention time and peak area using external standard method was used for the qualitative and quantitative analysis respectively. The average recoveries are 97.56~101.60%, the relative standard deviations are 0.86~1.31%. This method is simple, accurate and reproducible.The sopanification product of lanolin alcohol was trated by molecular distillation. The distillate was composed of cholesterol, lanosterol and fatty alcohols, which was called refined lanolin alcohol. The color of refined lanolin alcohol was improved. Using response surface methodology, the experimental conditions of molecular distillation were optimized, and the optimal model was established. The optimum balance between the content and recovery of cholesterol is obtained. The reliability of the model was validated by three parallel experiments. The average content and recovery of cholesterol reached 17.47% and 90% respectively. Using selective crystallization method, lanosterol, high-level fatty alcohols, and cholesterol were isolated step by step. The main influential factors in selective crystallization process were investigated, including solvent volume, cooling rate, cooling temperature, and crystallization time. Under the optimum operating conditions, the purity of crude cholesterol was 76.24%, and the recovery of cholesterol was 79.81%.Solubility of cholesterol in six solvents was determined by steady method. The variation of solubility with temperature was correlated byλh model and Apelblat equation, and correlation coefficient R2 0.95, which indicated two models were appropriate and effective.The purity of cholesterol achieved more than 92% after recrystallization with acetic acid or methanol-isopropanol as solvent.