Effect of carbonization temperature on the physicochemical and sorption properties of coals from plant biomass for dyes removal from solutions

The work is devoted to the synthesis and determination of the physicochemical properties of biochars obtained by the hydrothermal carbonization (HTC) of plant biomass, in particular, peach waste. The effect of material processing modes on the physicochemical properties of the materials was assessed, namely, the features of changes in the crystal structure and chemical composition depending on the carbonization temperature of the samples were determined. Various methods were used to analyze the physical, chemical and morphological characteristics of the obtained materials, including scanning electron microscopy, energy-dispersive elemental analysis, IR Fourier spectroscopy, Raman spectroscopy and X-ray phase analysis. It is shown that with an increase in the carbonization temperature, the concentration of elemental carbon in the samples increases and the content of functional groups decreases. Preliminary sorption studies were carried out for the obtained samples under static conditions on model solutions of organic dyes — methylene blue (MB) and Congo red (CR). It was found that carbonization increases the adsorption capacity of HTC coals by 2.5 – 3 times, but, in general, does not affect the speed of the sorption flow. The equilibrium time for both dyes was 15 minutes.