Process Optimization of High Surface Area Activated Carbon Prepared from Cucumis Melo by H3PO4 Activation for the Removal of Cationic and Anionic Dyes Using Full Factorial Design

Abstract

In this study, Chemical activation was used to prepare a low-cost activated carbon (AC) from agricultural waste material: Cucumis melo. It was used as a green biosorbent for the removal of cationic and anionic dyes from aqueous solutions (Methylene blue (MB) and Acid orange 7 (AO7)).A full factorial 24 experimental design was used to optimize the preparation conditions. The factors and levels included are activation temperature (300 and 500ºC), activation time (1 and 3 h), H3PO4 concentration (1.5 and 2.5 mol/L), and contact time (60 and 90 min). The surface area of the activated carbons and high removal efficiency of MB and AO7 was chosen as a measure of the optimization. The activated carbon prepared at 500 °C, for 3 hours with an H3PO4 concentration of 2.5 mol/L and a contact time of 90 min, have the largest specific surface area (475 m2/g) and the percentage of discoloration of methylene blue (99.4%). Furthermore, the greater value of AO7 removal (94.20%) was obtained at 3h - activation time, 500°C - activation temperature, 1.5 mol/L - H3PO4 concentration with a 90 min contact time.