Possibilities of Graphitization of Unburned Carbon from Coal Fly Ash

The paper presents the characteristics of products annealing at the temperatures of 2400 and 3000 °C of unburned carbon from coal fly ash in terms of its possible use as a starting material in the graphitization process. An amorphous substance (organic substance) with an admixture of some minerals has been found in samples subjected to graphitization. However, the graphite phase is dominant in products subjected to graphitization. Studies have also shown a diverse grain morphology in individual samples. The presence of plate-shaped and tube-shaped grains was found. As the graphitization temperature of the starting material increases (2400 and 3000 °C), the specific surface area in the graphitization products decreases. The total pore volume in the samples after the graphitization process was significantly lower than the pore volume of active carbons produced from other unburned carbon. Average pore diameter is similar to the pore diameter in active carbons. The reflectance value of the matrix for the sample graphitized at 3000 °C is characteristic for graphite. Unburned carbon from Polish fly ash can be used as the starting material for graphitization.

Methods of Obtaining and Physicochemical Properties of Modified Carbonaceous Sorbents

The variety of practical problems solved in recent years with the help of sorption methods requires expanding the range of used adsorbents. Active carbons are very promising porous adsorbents. Due to a whole complex of valuable properties of a highly developed porous structure, a variety of the chemical nature of the surface, special electrophysical properties, as well as chemical, thermal and radiation resistance, various active carbons are widely used for the absorption of gaseous and dissolved substances. The peculiar nature of carbon adsorbents contributes to the fact that solutes on coal can be adsorbed by completely different; mechanisms, their sorption may be due to the different nature of the forces involved in the adsorption process. The purpose of the work is to obtain multipurpose sorbents; to study methods of modification of carbonaceous sorbents from ash waste, as well as their physicochemical properties

Facile Preparation of Commercial Bi2O3 Nanoparticle Decorated Activated Carbon for Pseudocapacitive Supercapacitor Applications

In this work, a facile method to prepare commercial nano-Bi2O3/carbon composites with high pseudocapacitive properties was presented. The inorganic-organic composites synthesized by using commercial bismuth oxide and active carbon with different weight ratio. The composites were characterized using microscopic, spectroscopic, and diffractive methods. Our assessments confirmed that active carbons were successfully doped with commercial Bi2O3 nanoparticles with different dopant rates. The composites exhibited a maximum specific capacitance of 517 F/g at a current density of 1 A/g for 20% Bi2O3 nanoparticle doped activated carbon samples. Augmented discharging time was also achieved for increased Bi2O3 nanoparticle doping rate. Increased Bi2O3 dopant rate also increased the calculated specific capacitance.

Facile construction of highly redox active carbons with regular micropores and rod-like morphology towards high-energy supercapacitors

A facile route to high-performance carbon electrodes is proposed to simultaneously realize rich heteroatom electroactivity and precise structure optimization towards high energy supercapacitors.

Pyrolysis of ripe and thin aspen Wood

Изучен процесс пиролиза спелой и тонкомерной осиновой древесины в диапазоне конечной темпе- ратуры пиролиза 400–700 °С. Определены зависимости выхода древесного угля (ДУ) от температуры продолжительности пиролиза. Получены уравнения регрессии для основных показателей качества ДУ из осины, таких как содержание нелетучего углерода, суммарный объем пор, кажущаяся плотность и активность по йоду. Показано, что ДУ, полученный из спелой осиновой древесины при температуре не менее 600 °С, имеет сформированную углеродную матрицу и вполне пригоден для получения актив- ных углей. The process of ripe and thin aspen wood pyrolysis in the range of the final pyrolysis temperature of 400–700 °С is studied. The dependences of the charcoal yield on the temperature and duration of pyrolysis are determined. Regression equations for the main indicators of the aspen charcoal quality, such as content of non-volatile carbon, total pore volume, apparent density, and iodine activity are obtained. It is shown that the charcoal obtained from ripe aspen wood at a temperature of at least 600 °С has a formed carbon matrix and is quite suitable for the produc- tion of active carbons.

Kinetics and Thermodynamics of Methylene Blue Adsorption on Polyfurfuryl Alcohol-Derived Templated Carbon and Activated Carbon from H3PO4-Impregnated Moringa oleifera Seed Hull

This work probes the kinetics and thermodynamics of adsorption of methylene blue (MB) from aqueous phase on a templated carbon (TC) synthesized from polyfurfuryl alcohol using kaolinite template at 773 K; and activated carbon produced by the pyrolysis of H3PO4-impregnated Moringa oleifera seed hull (MOSH) at 723 K. Factors such as initial concentration of MB (1-3 mg/50 mL), reaction time (0-60 min.) and temperature (302-328 K) for the process were investigated using isotherms, sorption kinetics and thermodynamics. From the results obtained, adsorption of MB on TC fits both Langmuir and Freundlich isotherms well. The Langmuir isotherm describes adsorption of MB on the activated carbon from MOSH (MOSHC) better than the Freundlich isotherm. The adsorption capacities of the active carbons observed for MB were 29.3 mg/g for TC and 29.8 mg/g for MOSHC. The thermodynamic values evaluated: (14.15 kJ/mol. and 11.48 kJ/mol.), (87.93 kJ/mol. K and 49.55 kJ/mol. K) and (7.10 kJ/mol. and 14.26 kJ/mol.) for TC and MOSHC respectively, indicate endothermic and physical nature of adsorption, and enhanced randomness at the adsorbate-adsorbent interface. The sticking probability ( ) values (3.25 x 10–3 and 1.36 x 10–4 for TC and MOSHC respectively) show that the probability of MB molecules sticking on the surfaces of these active carbons is very high, with that for MOSHC being higher. Negative values (– 12.28 to – 14.68 kJ/mol.K and – 3.56 to – 4.92 kJ/mol.K) for TC and MOSHC respectively, at 302–328 K confirms a spontaneous adsorption process dominated by physisorption. Adsorption of MB on TC supports multilayer formation and was dominated by pseudo-second order kinetics while its adsorption on MOSHC was dominated by pseudo-first order kinetics with a single MB molecule occupying more than one active site. MOSHC, the low-cost adsorbent prepared, is thus very assuring for the removal of organic pollutants like MB from aqueous systems.