Abstract
Have been determined the technical characteristics and elemental composition of milk casein. Pyrolysis experiments of casein carried out at different heating temperatures and determined the yields of obtained solid (biochar), liquid (tar and pyrolysis water) and gas products. A temperature around 550ºC determined as an optimal heating temperature of pyrolysis and approximately 28.33% biochar, 37.38% tar, 13.23% pyrolysis water and 20.84% gas obtained after pyrolysis. First time a biochar with higher content of nitrogen was obtained by pyrolysis of casein and determined it is elemental composition and technical specifications. The porous structure of casein biochar was characterized by mercury porosimeter and SEM analysis confirmed that casein biochar has mostly meso and macro pores. The casein tar had the elemental composition: C-66.7%, H-8.3%, N-12.1%, O-12.9% and was completely soluble in 1-methyl-2-pyrroldinone. The tar consisted mostly of moderate molecular mass components with SEC elution times between 18-26 min and an estimated mass range up to 3000-5000 mass units as well as some larger size components, possibly 3-dimentional. The property and determined chemical composition of casein tar by GC/MS analysis were an evidence for using it as a curing agent for crosslinking reactions of epoxy resins. The necessary amount of tar for curing reaction of epoxy resin was determined experimentally as a 15-20% for the stoichiometric amount of reactive epoxy groups (15-20% epoxy group content) in epoxy resin and obtained cured epoxy resin with 95% degree of crosslinking reaction. Have been suggested several curing reaction schemes of epoxy resin with amines, nitriles and phenols of the casein tar
Highlights
Casein, the main product of dairy industry is a food protein [1]
Pyrolysis of casein was performed in a standard laboratory quartzium retort at different heating temperatures with constant heating rate 20oC/min and the yields of products including biochar, tar, pyrolysis water determined by weighing and the yield of uncondensed gas by differences (Figure 1). These results show that the yield of tar, pyrolysis water and gas increased with rising the temperature of pyrolysis
After crosslinking reactions of epoxy resin with tar formed a glass like solid material with 95% degree of curing reaction, which is a confirmation of the tar to be a curing agent for epoxy resin
Summary
The main product of dairy industry is a food protein [1]. Besides it is relevance as a nutritional product, casein has been used for a long time in nonfood applications, as a binding material for plastics, man-made fibres, coatings, glues and dyes [24]. Have been obtained insoluble gel from sodium hydroxide solution of casein and ion exchange material from vetted casein by crosslinking with formaldehyde [7] After all these had an idea to do thermal decomposition or pyrolysis of casein to obtain a hard, liquid and gas products. Casein has a lower thermal stability (T5%=125oC and T50%=355oC) and it means that it is thermal decomposition is very easy [8] After these investigations have been decided to work on pyrolysis of casein and characterize obtained hard and liquid products. This paper contains the results on pyrolysis of casein aimed to obtain a hard residue (biochar) with high developed porosity structure and a condensed liquid product (tar) with content of unknown composition and. The yields of pyrolysis products including solid residue (biochar), tar (condensed liquid product) and pyrolysis water determined by weighing, and the yield of gases by differences. After finishing of extraction the sample in filter paper have to dry at 105oC in oven until constant weight and will be determined the insoluble in acetone fraction (gel fraction or degree of curing reaction of epoxy resin, %)
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