Synthesis and Application of Activated Carbon Magnetic Nanocomposite Modified by Calcium Oxide for Removal of Malachite Green dye from Aqueous Solution: Isotherm and Kinetic Study of Adsorption Process

Abstract

Dyes are one of the most important industrial environmental pollutants, and therefore their removal from industrial wastewater is very important. The malachite green is a very toxic dye for the environment and humans, therefore an economical and high-efficiency method to remove this dye from water solutions is necessary. In this study, the removal of malachite green was investigated using a economical and effective adsorbent, in which activated carbon from date kernel was used. Activated carbon from date kernel was modified by Fe3O4 magnetic nanoparticles and calcium oxide. The properties and characteristics of these adsorbents were investigated using FTIR, VSM, TGA, XRD and SEM analyzes. Parameters affecting the adsorption process such as pH, adsorbent dosage, contact time and initial concentration of malachite green were optimized. Equilibrium and kinetic study of adsorption process was performed using common models. The results showed optimal conditions for adsorption of malachite green using the adsorbent are: initial concentration equal to 10 mg/l, pH=7, contact time equal to 20 minutes, adsorbent dose for AC, AC/Fe3O4 and AC/Fe3O4/CaO equal to 3, 3 and 2 g/l, respectively. The Freundlich model also has a higher ability to describe process equilibrium behavior and the pseudo-second-order kinetics model has a good ability to express reaction kinetics. The Langmuir adsorption capacity of malachite green by the AC, AC/Fe3O4 and AC/Fe3O4/CaO was determined to be 50.9 mg/g, 85.7 mg/g and 107.4 mg/g respectively. The desorption and reuse ability of AC/Fe3O4/CaO was investigated up to 8 steps, which showed that the adsorbent has the ability to be reused several times in the adsorption process. The results showed that modification of activated carbon with magnetic Fe3O4 nanoparticles and calcium oxide increases its adsorption efficiency and makes it a suitable adsorbent for commercialization.