Preparation of a Highly Porous Carbon Material Based on Quinoa Husk and Its Application for Removal of Dyes by Adsorption.

A porous carbon material was prepared from quinoa husk (QH) by carbonization and chemical activation with KOH. A series of experiments, including SEM (Scanning electron microscopy), FT-IR (Fourier transform infrared), XRD (X-ray diffraction), Raman, X-ray photoelectron spectroscopy (XPS), and N₂ adsorption/desorption, were carried out on the porous carbon produced from quinoa husk (PC⁻QH). The results showed that PC⁻QH was mainly composed of activated carbon and graphite. Moreover, PC⁻QH exhibited a high level of porosity with a BET (the Brunauer⁻Emmett⁻Teller theory) surface area of 1713 m² g. As a representative dye, malachite green (MG) was selected to evaluate the performance of PC⁻QH to absorb the contaminants in dyeing wastewater. In batch adsorption experiments, PC⁻QH exhibited a high adsorption rate toward malachite green (MG). An uptake capacity of 599.90 mg g was achieved in the initial 5 min, and the MG adsorption capacity of PC⁻QH reached 1365.10 mg g, which was higher than many other adsorbents. The adsorption data were well fitted with the Freundlich isotherm model and the pseudo-second-order kinetic model. PC⁻QH also displayed a high absorption rate to rhodamine B (RhB), methyl violet (MV), methylene blue (MB), and methyl orange (MO). The results in this study suggest that PC⁻QH can be a promising adsorbent for quick treatment of dyeing wastewater.