Lignin processing products have an extensive using range. Because products properties depend on lignin precursor quality it was interesting to study lignin isolated from rice husk being a large tonnage waste of rice production and its structural transformations during carbonization. Lignin isolated by the thermal hydrolysis method with H₂SO₄ 1 wt % solution and its carbonized products prepared under different carbonization conditions were characterized using elemental analysis, IR, TPD-MS, XRD, TEM, and EPR. It was shown lignin degradation takes place over the wide (220–520 °C) temperature range. Silica presenting in lignin affects the thermal destruction of this polymer. Due to the strong chemical bond with phenolic hydroxylic group it decreases an evaporation of volatile compounds and as a result increases the temperature range of the lignin degradation. Rice husk hydrolytic lignin transformations during carbonization occur with generation of free radicals. Their concentration is decreased after condensation of aromatic rings with carbon polycycles formation, i.e., the graphite-like structure. Quantity and X-ray diffraction characteristics of the graphite-like phase depend on carbonization conditions. Morphology of the lignin-based carbonized products is represented by carbon fibers, carbon and silica nanoparticles, and together with another structure characteristics provides prospective performance properties of lignin-based end products.

Coke-based carbon sorbent (CBCS) was produced using special coke fines with the following characteristics: ash, 4.5%; iodine adsorption capacity, 52%; specific surface area, 600 m² g⁻¹; and total pore volume, 0.4 cm³ g⁻¹. Gold adsorption from real production cyanide solutions in batch and column laboratory experiments was studied. The optimum adsorbent/solution ratio was 0.2 g/20 cm³. Sorption equilibrium occurred after 60 min of phase-time contact. The CBCS maximum adsorption capacity for gold was found to be 1.2 mg g⁻¹. Both the Langmiur and Freundlich isotherm models confirmed that gold adsorption by CBCS proceeds favorably, but the Freundlich isotherm best describes the adsorption equilibrium. The CBCS dynamic exchange capacity (100 g t⁻¹) and full dynamic exchange capacity (4600 g t⁻¹) for gold were determined in column tests. It was revealed using SEM that adsorbate was retained in sorbent pores. The possibility of completely eluting gold from CBCS was demonstrated. A CBCS pilot test to recover gold from 200 dm³ of the cyanide solution containing (mg dm⁻³) 2.6 Au, 0.42 Ag, and 490 Cu was carried out. The total amount of noble metals (Au + Ag) adsorbed was 99.99% and gold ions was 94%. The CBCS maximum adsorption capacity for gold reached 2900 g t⁻¹.

The process of silicon-carbon produced out of the rice husk treatment with HCl solution has been investigated and elaborated to purify from aluminum and phosphorous to their contents were less than 0.1 % each. Silicon-carbon with such contents of these impurities meets the requirements to as the multifunctional material for its application in various branches of industry and agriculture. It was demonstrated that the required content of aluminum and phosphorus in silicon-carbon can be achieved by two ways. Namely, by silicon-carbon production out of the pre-treated rice husk or by purification of silica-carbon obtained out of untreated rice husk. Considering the output of silicon-carbon out of rice husk equals to 33 %, it is more reasonable to submit the minor material mass to the acid treatment that is the silicon-carbon. The silicon-carbon treatment produced out of untreated rice husk (52.3 % С, 35.9 % SiO2, 0.2 % Al and 0.12 % P) was carried out with 0.5 – 3 % hydrochloric acid solutions at the temperature of 70-80 °С. As a result of laboratory studies and pilot testing, the processing method hydrochemical treatment of silicon-carbon was elaborated. The following optimal processing parameters were recommended: hydrochloric acid concentration in aqueous solution – 1 %, 75-80 °С, and treatment time is 60 minutes. The aluminum content was at the level of 0.085 %, and phosphorus was 0.04 % in the processed silicon-carbon. The obtained silicon-carbon with low level of inorganic elements can be applied as the charging material for smelting low-aluminum ferrosilicon and pure silicon, as the filler of carbon construction materials and elastomers.