Microporous Activated Carbon from Pisum sativum Pods Using Various Activation Methods and Tested for Adsorption of Acid Orange 7 Dye from Water

HIGHLIGHTS: • Pisum sativum pods was used for producing porous activated carbon materials. • Two chemical methods and two gases were used in the activation processes. • Higher performances were achieved by applying ZnCl(2) and CO(2) for activation. • The products exhibited large surface areas and high AO7 dye adsorption performances. • RMS study of the AO7 dye removal by produced material was reported. ABSTRACT: This work demonstrates the preparation of high-surface-area activated carbon (AC) from Pisum sativum pods using ZnCl(2) and KOH as activating agents. The influence of CO(2) and N(2) gases during the carbonization process on the porosity of AC were studied. The highest specific surface area of AC was estimated at 1300 to 1500 m(2)/g, which presented characteristics of microporous materials. SEM micrographs revealed that chemical activation using an impregnation reagent ZnCl(2) increases the porosity of the AC, which in turn leads to an increase in the surface area, and the SEM image showed that particle size diameter ranged between 48.88 and 69.95 nm. The performance of prepared AC for adsorption of Acid Orange 7 (AO7) dye was tested. The results showed that the adsorption percentage by AC (2.5 g/L) was equal to 94.76% after just 15 min, and the percentage of removal increased to be ~100% after 60 min. The maximum adsorption capacity was 473.93 mg g(−1). A Langmuir model (LM) shows the best-fitted equilibrium isotherm, and the kinetic data fitted better to the pseudo-second-order and Film diffusion models. The removal of AO7 dye using AC from Pisum sativum pods was optimized using a response factor model (RSM), and the results were reported.