The photo is sourced from pstu.ru
Granular activated charcoal is manufactured by mixing hard coal and adhesive substance under high temperature allowing for forming solid granules of that or another form from the received plastic paste. The activated charcoal quality depends on the viscosity of the adhesive substance and the content of coke residue in it, which is accumulated in the process of pyrolysis of solid fuel. The combination of relatively low viscosity and high coke residue content is optimal.
Wood-chemical tar is usually used as an adhesive component. This is a liquid product of timber processing featuring high viscosity. However, this wood-chemical tar has one serious disadvantage – low content of the already mentioned coke residue. Coke-chemical tar is an alternative, this is black oily liquid formed during high-temperature treatment of hard coal. However, it also has another serious disadvantage: high content of coke residue is combined with relatively high viscosity.
Scientists from Perm Polytechnical University attempted to resolve this dilemma by using various additives to coke-chemical tar. The researchers created samples of granular activated charcoal from pulverised hard coal and coke-chemical tar, which had the coke residue share of 22.51% and 30.77% of weight, respectively. The analysis of the used tar showed that heating the adhesive component to 60 degrees Celsius decreases the viscosity approximately 5 times.
“It is possible to improve the characteristics of the adhesive substance by introducing surfactant additives. In our research we used surfactants of various types (non-ionogenic, anion-genic, cation-genic). Also, we tried to use distilled water as an additive. In all cases we identified the dependency of viscosity of the adhesive substances on the amount of the introduced additives”, Perm Polytechnical University is citing Elena Farberova, one of the researchers, Candidate of chemical sciences.
The researchers performed a series of experiments adding surfactants to the coal-tar oil. It turned out that the best effect was achieved when non-ionogenic surfactants were used with adjustment for the temperature differential: under 40 degrees Celsius the viscosity of the samples decreased by 23-55%, and under 60 degrees Celsius – by 11-59%. On top of that, using surfactants allowed for increasing the surface of the granular activated charcoal by 23% thus improving its sorption capacity.
