Sorption dynamics of organic dyes from aqueous solutions using activated carbon derived from peach modified with carbon nanotubes

This study synthesized nanocomposite activated carbon (AC) from plant raw materials (peach production waste), modified with carbon nanotubes (CNTs). The first stage in obtaining all samples involved hydrothermal carbonization (HTC) of peach pomace in an aqueous environment with the addition of a specific amount of CNTs, after which the biomass was gradually carbonized and activated using an alkali (KOH) in an inert atmosphere. The aim of the study was to evaluate the effect of CNTs on the structure and physicochemical and functional properties of the nanocomposite AC. It was established that the carbon obtained from the initial mixture containing 0.05 wt. % CNTs showed a specific surface area according to the BET model of 2876 m2⋅g–1 and a total pore volume of 1.643 cm3⋅g–1. It is presumed that the interaction of the biomass with the nanotubes occurs at sites on the surfaces of the samples after HTC, where functional groups are located. The sample with 0.05 wt. % CNTs exhibited minimal ID/IG and d100 values, indicating a higher order of the carbon structure. For all carbons, the sorption capacity relative to synthetic dyes – malachite green (MG) and Congo red (CR) – was determined. A general correlation was found between the changes in the ID/IG and d100 values and the activity of the AC samples. The AC with 0.05 wt. % CNTs demonstrated the highest capacity for both dyes in static mode: 2987 mg⋅g–1 for MG and 1201 mg⋅g–1 for CR, respectively. For this particular sample, an assessment of the sorption kinetics was conducted.