# Assessment of Hydrochar and Porous Carbon from Tectona Grandis Seeds for Removal of Acridine Dyes

## TL;DR

This paper investigates using materials derived from Tectona grandis seeds to effectively remove acridine dyes from water.

## Contribution

The study introduces a new sustainable material from Tectona grandis seeds with high dye removal efficiency compared to commercial activated carbon.

## Key findings

- AC-850-5 achieved 198 mg/g adsorption capacity for AYG and 171 mg/g for ABO, outperforming commercial activated carbon.
- The adsorption process was found to be spontaneous, endothermic, and best described by the Langmuir isotherm model.
- Adsorption kinetics followed the pseudo-second-order model, indicating surface site availability as a key factor.

## Abstract

This study explores the use of lignocellulosic Tectona grandis seeds (TGs), hydrochar (HC-230-4), and activated carbon (AC-850-5) produced via hydrothermal carbonization and followed by CO2 activation for removing acridine yellow G (AYG) and acridine orange 14 (ABO) from water. HC-230-4 showed a rich presence of surface functional groups and irregular morphology with some sphere-like structures. In contrast, AC-850-5 exhibited a much higher surface area (729.7 m2/g), though with fewer surface functional groups than HC-230-4. The batch method was used to study the effects of contact time, pH, dye concentration, and temperature. Among the materials, AC-850-5 showed the highest adsorption capacity of 198 mg/g for AYG and 171 mg/g for ABO at 25 °C, around 12% higher than commercial activated carbon. The adsorption process was spontaneous and endothermic, fitting well to the Langmuir isotherm model, suggesting monolayer coverage. The adsorption kinetics followed the pseudo-second-order model, indicating that the rate depends on the surface site availability. Intraparticle diffusion analysis further confirmed a multi-step adsorption process. These findings show the strong potential of TG-derived activated carbon as an effective and sustainable material for removing acridine dyes from polluted water.