Adsorption Isotherms, Thermodynamics, and Kinetic Modeling of Methylene Blue onto Novel Carbonaceous Adsorbent Derived from Bitter Orange Peels

This work reports the production of activated carbons (AC) from bitter orange peel by using ZnCl2 or H3PO4 as activating agent at two different carbonization temperatures (450 degrees C and 550 degrees C). Surface morphology analyses of produced bitter orange activated carbons (BOACs) were done by SEM. The surface areas of the produced BOACs, functional groups on the AC surfaces and compositions, were determined by using BET, FT-IR, and TGA analyses. Furthermore, their application for the removal of methylene blue (MB) was studied. The parameters affecting adsorption, such as pH and temperature, were evaluated. BOAC produced with ZnCl2 at 550 degrees C, exhibits the highest surface area (1450.6 m(2) g(-1)), whereas BOAC produced with ZnCl2 at 450 degrees C yielded with the highest adsorption capacity (108.9 m(2) g(-1)). Langmuir isotherm shows a good fit for the BOACs. Adsorption kinetics were studied and follows pseudo-second-kinetic model. The thermodynamic parameter studies indicate that the adsorption process is endothermic and spontaneous.