# Surface and Structural Characterization of Buckwheat Husk-Derived Activated Carbons: Correlation of SEM, Elemental, FTIR, Raman, and Porous Properties with Electrokinetic Behavior

## TL;DR

This paper studies how to make activated carbon from buckwheat husks and how different modifications affect its properties for water purification.

## Contribution

The study introduces a novel method of modifying buckwheat husk-derived activated carbon with KOH, urea, and Prussian Blue to enhance its electrokinetic and adsorption properties.

## Key findings

- Modification with KOH and urea increases basic surface properties, while Prussian Blue introduces acidic characteristics.
- BH-KOH-Fe showed the best performance for water purification applications.
- The materials are effective for removing heavy metals and radionuclides from water.

## Abstract

This study focuses on the synthesis and characterization of buckwheat husk-derived activated carbon, chemically activated with potassium hydroxide (KOH) and subsequently modified with urea and Prussian Blue (PB). The obtained carbons were evaluated in terms of particle-size distribution, surface morphology, structural features, and electrokinetic properties using scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM–EDS), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, and electrophoresis, as well as N2 adsorption–desorption (BET surface area and porosity analysis). The results confirmed that both pyrolysis conditions and the type of modifier significantly affect the physicochemical properties of the activated carbon and its behavior in electrolyte solutions. Colloidal stability and particle size were strongly dependent on pH and the type of anions present in solution, with sodium nitrate (NaNO3) systems showing higher stability than sodium chloride (NaCl). Modification with KOH and urea imparted a more basic surface character, whereas PB introduced more acidic properties. All samples exhibited predominantly negative surface charges and mesoporous structures, which are favorable for adsorption processes and enhance affinity for heavy-metal cations. Among the tested materials, BH-KOH-Fe (Fe-modified KOH-activated carbon) showed the most favorable performance for the targeted application, while BH-KOH (KOH-activated buckwheat husk-derived carbon) exhibited high surface area and good colloidal stability. The prepared materials show promising applicability for water purification, including the removal of organic pollutants and radionuclides (e.g., 137Cs and 90Sr), as well as metal cations (K+, Na+, and Li+).