Malachite green adsorption from aqueous solutions onto biochar derived from sheep manure: adsorption kinetics, isotherm, thermodynamic, and mechanism

Abstract

The adsorption of Malachite Green (MG) from aqueous solution was achieved using biochar derived from sheep manure pyrolyzed at 450 °C. Sheep manure biochar was characterized before and after adsorption of MG by SEM and FTIR. In addition, surface area measurement was performed by BET surface area and pore analyzer. The influence of contact time, pH, dose, temperature, and initial MG concentrations on the adsorption of MG onto sheep manure biochar (SMB) was investigated in experiments. Langmuir, Freundlich, Temkin, and Dubinin-Raduskevich isotherm models were used to analyze the data. Results assumed best fitting model is Langmuir isotherm model (R 2 value 0.99). Mean free adsorption energy (E) was obtained 94.71 kJ mol−1, R L value was between 0.013 and 0.14. That indicates monolayer, favorable, and physisorption adsorption, as well as an endothermic adsorption process. Maximum uptake value from Langmuir model obtained 208.33 mg g−1. Surface area of SM biochar was 11.731 m2 g−1. NOVELTY STATEMENT This study is the first study on the adsorption of malachite green dye substance on sheep manure derived biochar. A natural and cheap adsorbent with high dye removal, such as 208,33 mg g−1. A guiding study for the conversion of agricultural waste into products with highly added value.