# Removal of Cationic and Anionic Dyes from Aqueous Solution with Activated Biocarbons Obtained from Black Chokeberry Seeds

## TL;DR

Researchers made activated biocarbons from black chokeberry seeds to effectively remove both cationic and anionic dyes from water.

## Contribution

Microwave-assisted chemical activation of black chokeberry seeds produced biocarbons with high adsorption capacity for synthetic dyes.

## Key findings

- Microwave-assisted activation created biocarbons with a high specific surface area of 884 m²/g.
- Maximum adsorption capacities of 194.5 mg/g for methylene blue and 68.6 mg/g for Congo red were achieved.
- Heating method during activation significantly influenced the physicochemical properties and adsorption performance of the biocarbons.

## Abstract

The main objective of the work was to prepare a series of new activated biocarbons by chemical activation of black chokeberry seed and to assess their suitability for removing cationic and anionic dyes from an aqueous medium. Activation of the precursor was performed at 550 °C with orthophosphoric acid, using conventional or microwave-assisted heating. The activated biocarbons were characterized in terms of elemental composition, textural parameters, surface morphology, acid-base character of the surface, as well as electrokinetic properties. Adsorption tests were carried out against two organic compounds: methylene blue (thiazine dye of cationic character) and Congo red (azo dye of anionic character). The influence of the initial dye concentration (5–120 mg/L), temperature (20–40 °C), and solution pH (2–10) on dye removal efficiency from the liquid phase was investigated. Additionally, kinetic adsorption tests were carried out to determine the rate and mechanism of the dyes removal process. Microwave-assisted chemical activation with H3PO4 proved to be a very effective approach for generating a high specific surface area (884 m2/g) and a micro/mesoporous structure, which directly increases the adsorption capacity of activated biocarbons towards cationic and anionic synthetic dyes. The maximum adsorption capacities for methylene blue and Congo red were 194.5 and 68.6 mg/g, respectively. It was also confirmed that the choice of heating method at the activation stage plays a key role in determining the physicochemical properties and adsorption performance of the activated biocarbons prepared from waste biomass. In general, carbonaceous adsorbents derived from black chokeberry seeds exhibit high potential for the treatment of dye-contaminated wastewater.