Malachite Green Adsorption by a Residue-based Microwave-activated Adsorbent

An adsorbent obtained by microwave activation of defective coffee press cake was evaluated for malachite green (MG) removal from aqueous solutions. Batch adsorption tests were performed and the effects of particle size, contact time, adsorbent dosage, initial solution pH, and initial dye concentration on MG removal from aqueous solutions were investigated. Adsorption kinetics was determined by fitting pseudo-first-and second-order kinetic models to the experimental data, with the second-order model providing the best description of MG adsorption onto the prepared adsorbent. The experimental adsorption equilibrium data were better described by the Langmuir model in comparison to Freundlich. The results presented in this study show that the produced adsorbent presents great potential as an inexpensive and easily available alternative for the removal of cationic dyes in wastewater treatments.