Adsorption study of methylene blue dye using activated carbon prepared from waste palm fiber.

The study investigated the utilization of waste palm fiber as an adsorbent for methylene blue (MB) removal. The waste palm fiber was treated by a series of steps to prepare an activated charcoal adsorbent. The adsorption process of MB on the activated charcoal was modeled using the Box-Behnken design (BBD) in the response surface methodology (RSM). Adsorbent mass, solution pH, temperature, and time were selected as factors, while removal efficiency and adsorption capacity were chosen as responses. Both models were significant with correlation factors of 0.85 and 0.99 for removal efficiency and adsorption capacity, respectively. Optimal conditions for MB removal were achieved at an initial pH of 7, an adsorbent dose of 0.05 g/L, and a contact time of 30 min, resulting in a 99% removal efficiency. The adsorption of MB using the activated charcoal indicates the physical nature of the reaction.

Modeling and Optimizing the Crystal Violet Dye Adsorption on Kaolinite Mixed with Cellulose Waste Red Bean Peels: Insights into the Kinetic, Isothermal, Thermodynamic, and Mechanistic Study.

In this study, a new eco-friendly kaolinite-cellulose (Kaol/Cel) composite was prepared from waste red bean peels (Phaseolus vulgaris) as a source of cellulose to serve as a promising and effective adsorbent for the removal of crystal violet (CV) dye from aqueous solutions. Its characteristics were investigated through the use of X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and zero-point of charge (pHpzc). The Box-Behnken design was used to improve CV adsorption on the composite by testing its primary affecting factors: loading Cel into the composite matrix of Kaol (A: 0-50%), adsorbent dosage (B: 0.02-0.05 g), pH (C: 4-10), temperature (D: 30-60 °C), and duration (E: 5-60 min). The significant interactions with the greatest CV elimination efficiency (99.86%) are as follows: BC (adsorbent dose vs. pH) and BD (adsorbent dose vs. temperature) at optimum parameters (A: 25%, B: 0.05 g, C: 10, D: 45 °C, and E: 17.5 min) for which the CV's best adsorption capacity (294.12 mg/g) was recorded. The Freundlich and pseudo-second-order kinetic models were the best isotherm and kinetic models fitting our results. Furthermore, the study investigated the mechanisms responsible for eliminating CV by utilizing Kaol/Cel-25. It detected multiple types of associations, including electrostatic, n-π, dipole-dipole, hydrogen bonding interactions, and Yoshida hydrogen bonding. These findings suggest that Kaol/Cel could be a promising starting material for developing a highly efficient adsorbent that can remove cationic dyes from aqueous environments.