NaOH-Activated Betel Nut Husk Hydrochar for Efficient Adsorption of Methylene Blue Dye

In this study, betel nut husk (BNH) was used to produce activated hydrochar using sodium hydroxide (NaOH). Activated BNH hydrochar (BNH-HAC) served as an adsorbent for methylene blue (MB) adsorption. The produced BNH-HAC was characterized by identifying its textural, morphological, and chemical properties. Batch equilibrium method was conducted to examine the factors that influenced MB adsorption by the BNH-HAC including initial concentration, contact time, solution pH, and temperature. The attained BNH-HAC revealed the BET surface area of 517.60 m(2)g(-1) and mean pore diameter of 25.13 nm. The experimental data can be better characterized with the Freundlich isotherm model than the Langmuir isotherm model where, the maximum adsorption capacities attained were 324.4, 387.4, and 429.6 mg/g at 30 degrees C, 40 degrees C, and 50 degrees C, respectively, of BNH-HAC. Adsorption process regarding the BNH-HAC was regulated by film diffusion model, and its thermodynamic data revealed that the adsorption process is endothermic in character, and kinetic data better suited the pseudo-second order than the pseudo-first order model. The study findings confirmed that BNH-HAC can be an efficiently advanced adsorbent for the adsorption of MB.