Adsorption studies of KOH-modified hydrochar derived from sugarcane bagasse for dye removal: Kinetic, isotherm, and thermodynamic study

Abstract

Toxicity of methylene blue (MB) in water bodies has a negative effect on environment and living organisms. The presence of MB in water could last longer in view of the non-biodegradable characteristic. In this study, hydrochar was used as adsorbent to remove MB from aqueous solution. Hydrochar derived from bagasse was successfully prepared by hydrothermal carbonization treatment at temperature of 270oC, and pressure of 10 Bar for 30 minutes. For enhancing the adsorption ability, hydrochar was activated by adding KOH that was able to increase the percent removal by ~11%. The hydrochar was characterized using FTIR before and after adsorption. The results showed that the dominant functional groups of hydrochar included O-H, C=O, -O- and aromatic compounds. Whereas, the functional group of azo groups such as N-H and N=N appeared after adsorption. The maximum adsorption capacity (Qmax) was 5.1204 mg/g, while the adsorption isotherm of MB onto hydrochar followed the Langmuir and Freundlich model. The adsorption mechanism belongs to chemical adsorption, and the rate of diffusion can be neglected because the adsorption kinetics fitted well with pseudo-second order and the value of k2 > kdif > k1. Thermodynamic studies indicated that the adsorption process is classified as endothermic and reversible at room temperature. The results showed that hydrochar could be the alternative adsorbent for removing MB in wastewater. In addition, sugarcane bagasse has a great potential as feedstock of hydrochar.

One-stage microwave-assisted activated carbon preparation from Langsat peel raw material for adsorption of iron, manganese and copper from acid mining waste

“…This chemisorption process aligned with previous studies on agricultural waste [ [70][71][72]. The proximity of the coefficient of regression (R²) to unity (1) [73][74][75] was employed to assess how well the determined model suited the data, so as a result, the predicted R 2 values from the PSO model matched well with the experimental values. This is also in line with the research findings that the data follows Langmuir isotherm adsorption (monolayer).…”

Enhanced Adsorption of Rose Bengal Dye from Aqueous Solution Using NaOH Activated Hydrochar Derived from Corncob Waste

“…As C increases, the boundary layer thickness also increases, highlighting the significance of the diffusion rate that cannot be disregarded. When the sorption process is governed by diffusion, the sorbate will be transported gradually across the layers and into the active sites of the sorbent [56]. Meanwhile, this study demonstrated that the sorption did not match the Weber-Morris model well, and the diffusion rate might be disregarded because of the presumption of the tiny particle size and thinner boundary layer.…”

Methylene Blue Dye Adsorption on Iron Oxide-Hydrochar Composite Synthesized via a Facile Microwave-Assisted Hydrothermal Carbonization of Pomegranate Peels’ Waste

“…Hydrothermal carbonization R% = 60-80 [36] Hydrochar-MgAl double hydroxide Hydrothermal route q L = 157 mg/g [56] Activated hydrochar Hydrothermal carbonization q L = 357 mg/g [50] Hydrochar Hydrothermal carbonization q L = 5.12 mg/g [58] Magnetic biochar Microwave pyrolysis q L = 144.9 mg/g [59] Activated Hydrochar Hydrothermal carbonization q L = 200.01 mg/g [60] q L is maximum Langmuir removal capacities, R% is the removal efficiency.…”