Investigation of influence of the additives of expired paracetamol (PR) and naproxen (NP) on the changes in volume of heated charge of a higher rank coal

Abstract The paper focuses on the changes taking place during carbonization in the charge of a commercial sample of a higher rank coal under the influence of two additives of expired pharmaceuticals that change the volume of such charge in a different way. The changes in volume of the charge were determined by X-raying. The influence of the additives on the mass loss of coal during pyrolysis and the composition of formed products was determined by the TG/FT-IR technique. The plasticized coal from the charge with and without additives was extracted by a mixture of methanol and chloroform. The obtained extracts were investigated using the FT-IR and UV spectroscopies. The research of the influence of 2 wt% additive of naproxen (NP) as well as 2 wt% additive of paracetamol (PR) on the thermal behavior of coal having a volatile matter content of 22% proved the following: a) additives promote a tendency to increase the temperature interval of viscous-liquid state in the plastic layer of coal blends with additives; b) the additives change the contribution ratio of saturated and unsaturated hydrocarbons in the composition of volatile products of pyrolysis in a different way; c) the contribution ratio of CO in the composition of volatile products of pyrolysis of a blend of coal with PR decreases substantially in the FT-IR spectra; d) a decrease in the contribution ratio of CO in the composition of volatile matter suggests that the reactions of coal gasification between the solid products of pyrolysis and CO 2 formed in the charge with PR proceed to a small extent; e) at the stage of coal grain swelling in the carbonized charge under the influence of PR additive, a 1.4-fold reduction in growth in volume is observed; f) NP additive enhances an increase in volume of the heated charge at the stage of coal grain swelling that results in generation of a dangerous coking pressure. It is suggested that the PR and NP additives modify the composition of volatile pyrolysis products being formed and the course of secondary reactions between these products inside swollen grains. This causes the differences in degree of swelling of coal grains and in changes in volume of carbonized charge.