Optimization of high surface area activated carbon production from miswak (Salvadora Persica) with ZnCl2 using Taguchi method and its application in methylene blue removal

Abstract In the first part of this two-stage study, the optimum conditions for one-step AC production from miswak with zinc chloride were examined using the Taguchi optimization method. Impregnation time (1–3 h), impregnation ratio (1:1–3:1), activation temperature (350–650 °C), and activation time (1–2 h) were selected as experimental parameters, and each parameter was examined at three levels. The AC produced under optimum conditions (impregnation time: 3 h, impregnation ratio: 3/1, activation temperature: 650 °C, and activation time 1 h) has a high surface area of 1702 m 2 /g. The characterization of AC produced under optimum conditions has been elucidated by advanced analytical methods such as SEM, FTIR, BET, and pH pzc . In the second part, the methylene blue removal performance of OAC was investigated with a series of batch adsorption experiments. The effects of pH (2–10), initial dye concentration (500–1500 mg/L), adsorbent dosage (0.5–3.5 g/L), and temperature (25–55 °C) on the methylene blue removal efficiency were examined. The adsorption data were applied to isotherm (Langmuir, Freundlich, and Temkin) and kinetics models (pseudo-first order, pseudo-second-order, Elovich, and intra-particle diffusion). The isotherm and kinetics models that best represented the adsorption of methylene blue by OAC were the Langmuir isotherm and the pseudo-second-order kinetic model, respectively.