Glycerol, the molecular formula C3H5(OH)3, is a sweet viscous liquid, so-called glycerol. It can be miscible with water at any ratio and has strong hygroscopicity. It’s an important basic organic material. Glycerin was first known in 1779 when the Swedish chemist Scheele accidentally obtained it from the reaction of olive oil with lead monoxide.
At first, people only used glycerin as a skin moisturizer, until 1846, when Sobrero reacted glycerin with nitric acid to get nitroglycerin. Twenty years later, Nobel made nitroglycerin and diatomite into safe explosives, so that nitroglycerin can be successfully used in the production of Dana explosives. Nowadays, glycerin is widely used in medicine, cosmetics, alkyd resin, tobacco, food, beverage, polyurethane, celluloid, dynamite, textile printing, and dyeing. It has about 1,700 USES.
Due to the increasing consumption of non-renewable energy such as petroleum, it has become the obligatory duty of chemical workers to find clean renewable energy. Glycerin, which comes from nature, is non-toxic and harmless and is an ideal chemical raw material. Therefore, how to develop glycerin well and find its new use has become a research hotspot.
Glycerol is widely found in nature in the form of glycerides. Thus, for a long time, most glycerol was obtained as a by-product of soap production by the saponification of oils and from hydrolysis of fats to fatty acids. It was not until 1858 that glycerin could be made by fermentation. In Germany during the first world war, due to the shortage of glycerin, it was the first to ferment glycerin from sugar beets. Since 1948, the method of synthesizing glycerol with propylene has been applied in industry, and the output has been rising year by year with a rapid development trend. Currently, the industrial production methods of glycerol can be divided into three categories according to the source of glycerol, namely, the production of natural glycerol, the production of fermented glycerol, and the production of synthetic glycerol. The first two types of raw materials are renewable.
The production of natural glycerin
Mainly from the soap production and oil cracking process by-products. Before 1948, glycerin was completely recovered from the by-products of vegetable and animal oils used to make soap. Up to now, natural oils and fats are still the main raw materials for producing glycerol, among which about 42% of natural glycerol comes from the by-production of homemade soap, and 58% comes from the production of fatty acids
The method is based on natural oil and glycerin is a by-product, so our Chinese chemical workers think that it can be used in the wastewater treatment and utilization of oil foot, which can play an environmental protection role and obtain the certain economic effect. For example, Ge Wenguang recycled glycerol from wastewater after producing fatty acids from cotton oil feet. Feng Liwen et al., Anhui Institute of Applied Technology, published technical papers on the production of oleic acid, glycerin, stearic acid and polyamide resin from animal and vegetable oils and oily feet. Wang Xisheng et al., from the national fatty acid technology research and promotion center, introduced the new process of “production of oleic acid, glycerin and stearic acid”, a high-efficiency environmental protection project “national key promotion plan of scientific and technological achievements”.