Fixed-bed removal of crystal violet dye using activated carbon fibers: Experimental and numerical investigation,

Adsorption-based water treatment is widely employed for the removal of organic pollutants such as dyes. In this study, the use of oxidized activated carbon fibers (Felt-Ox) for efficient crystal violet (CV) dye removal in a fixed-bed adsorption was investigated. The performance of Felt-Ox was compared with three other activated carbon-based adsorbents. The physicochemical properties of the adsorbents were systematically characterized by conducting gas sorption analysis, scanning electron microscopy, X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy. The maximum CV adsorption capacity of the adsorbents was quantitatively evaluated by fitting the experimental breakthrough curves to the Yan model. The results revealed that the Felt-Ox material exhibited the highest maximum adsorption capacity (19.6 mg/g) among all tested adsorbents when using 12 mm bed height. In addition, the effects of adsorbent mass (bed height) on adsorption and the presence of glass wool layers in the column were also examined. Increasing column height improved adsorption performance, while glass wool showed only a minor contribution to CV removal, particularly at higher Felt-Ox loading. To further elucidate the system behaviour, a computational fluid dynamics (CFD) model was developed to assess the influence of key operational parameters, including flow rate and inlet concentration, on adsorption performance. The CFD analysis showed good agreement with the experimental results, particularly in the initial and transition regions of the breakthrough curve. This agreement demonstrates that CFD can be used to predict both the column adsorption behaviour and the evolution of the CV concentration within the adsorbent bed.