Many agro-industrial companies grow amaranth for the subsequent production of amaranth oil, flour, cereals, flakes, and bran. After the grain is extracted, waste in the form of inflorescences remains, which can be used to obtain useful new products. This work investigated the use of pyrolysis to recycle amaranth inflorescence wastes (AIW). Thermochemical conversion experiments in an inert medium were carried out in a laboratory setup at 550 °C and a heating rate of 10 °C/min. It was found that the AIW pyrolysis produced 37.1 wt.% bio-oil, 35.8 wt.% pyrogas and 27.1 wt.% biochar. The oil fraction of the obtained bio-oil contains 41.8% of hydrocarbons. Thermogravimetric analysis of AIW was performed in the temperature range from 40 to 1000 °C at heating rates of 10, 15, and 20 °C/min in argon medium (75 mL/min). The kinetic parameters were determined by the model-free Friedman, Ozawa-Flynn-Wall, and Kissinger-Akahira-Sunose methods. The average activation energy values are in the range of 208.44–216.17 kJ/mol, and they were used to calculate the thermodynamic parameters. The results indicate that the pyrolysis application will allow efficient conversion of AIW into value-added products.

The thermal decomposition of two types of peat from the Vladimir oblast of Russia in an inert atmosphere of argon was studied for the first time with the c

Amaranthus retroflexus or redroot pigweed is a second generation lignocellulosic fuel. Each biomass sample (leaves, inflorescences and stems) was pyrolyzed in a lab-scale furnace, in a nitrogen atmosphere under non-isothermal conditions at heating rates of 10 °C/min until the furnace temperature reached 550 °C. The pyrolysis characteristics of the three major components were also studied through thermogravimetric analysis. The thermal decomposition of the biomass samples is similar to the process of pyrolysis of lignocellulosic materials and proceeds in three main stages: dehydration, devolatilization, and carbonation. The highest bio-oil yield was obtained for inflorescences (55%) and leaves (45%). Gas chromatography—mass spectrometry analysis was carried out for oil fractions of the pyrolysis liquid from Amaranthus retroflexus. The composition of the pyrolysis oil fraction from the leaves had an overbearing aliphatic hydrocarbon nature whereas the oil fraction from inflorescences and stems was composed mainly of oxygen-containing components. The use of Amaranthus retroflexus biochars can lead to slag formation in power equipment, so it is advisable to use them to produce composite fuel, for example, mixed with coal. The results would help to better understand the thermal behavior of Amaranthus retroflexus biomass and its utilization for fuels or chemicals.

The article presents the results of experimental studies of the process of thermochemical conversion of sunflower husk by pyrolysis at a temperature of 550 °C and heating rate of 10 °C/min. The main physico-chemical characteristics of this plant raw material correspond to commercial fuels. Ashes are dominated by potassium (38.7%), calcium (26.9%) and iron (13.6%) oxides. Thermochemical conversion of sunflower husks produces 56.49% of pyrolysis liquid, 29.26% of carbonaceous residue and 14.25% of gas. Experimental data of pyrolysis fluid viscosity dependence on temperature in the range from –6 to +23.5 °С were obtained. As a result of GC-MS analysis mass spectra of 90 substances of organic nature were obtained, of which 20 were identified, which corresponds to 77.3% of the entire fraction. Pyrolysis fluid contains acids, alcohols, esters, ketones, amides, aldehydes, alkenes, phenols. Taking into account boiling points of the components included in the liquid fraction, it was found that it is reasonable to extract acetic acid and methyl alcohol. The acetic acid content in the pyrolysis liquid under study reaches 31.98% and the methanol content 12.05%. It should be noted that the content of propanoic acid, 2-oxo-, ethyl ester (6.20%) is high enough, but its boiling point coincides with a number of other components, so distillation of this component is inexpedient. Thus, the obtained pyrolysis liquid is a source of raw materials for obtaining at least two high added value products.

As the result of the biogas plant work , a lot of sludge (effluent) is formed, which can be used for various purposes. This article shows the possibility of appliance solids of effluent as an organic fertilizer, as well as fuel for generating thermal energy. The studied effluent was obtained after anaerobic fermentation of cow dung and biomass of the plant Amaranthus retroflexus L. In addition, mixtures of effluent with residues of plant biomass were examined . They are a mixture of seeds, stems and leaves in a ratio of 1:1,1:1,6. Five samples were examined: 100% effluent; 75% effluent and 25% biomass; 50% effluent and 50% biomass; 25% effluent and 75% biomass; 100% plant biomass. The content of nutrients (total nitrogen, phosphorus, potassium) in the samples significantly exceeds the indicators recommended by GOST 33380-2015. It was established that studied samples have high concentrations of copper and zinc. The studied effluent can not be used in its pure form as a fertilizer, but it is advisable to mix it with other components characterized by a “poor” mineral composition, such as peat. For the production of soil additives, the weight ratio of dry raw materials of effluent to lowland peat is 1:5. The lowest heat value of effluent in a mixture with plant biomass was from 12.4 MJ/kg to 14.1 MJ/kg. For heat value, it is most effective to use pure effluent and composite fuel consisting of 75% effluent and 25% biomass of the plant Amaranthus retroflexus L. The high ash content of the studied samples is due to the increased content of Cao and SiO2 oxides.