Sustainable management of agro industrial waste as potential adsorbent for wastewater treatment: Kinetic, thermodynamic and equilibrium study

Abstract

In the current work, the malachite green (MG) dye was removed from synthetic wastewater by employing a sustainable adsorbent, Cajanuscajan (Tur dal husk) as an adsorbent. The activated carbon based on Tur dal husk has been prepared and characterized using Brunauer-Emmett-Teller analysis, scanning electron microscopy, and Fourier transform infrared spectroscopy techniques. The impacts of multiple causes, specifically pH, adsorbent quantity, contact duration, and the concentration of dye, have been investigated on the elimination of MG dye. The equilibrium isotherms underwent analysis through the Freundlich and Langmuir models. The highest ability to absorb is obtained as 24.81 mg/g, 30.95 mg/g, and 36.49 mg/g at 303K, 313K, and 323K, respectively. The separation factor value confirmed that the adsorption is beneficial at the adsorption conditions. The kinetics exhibited behavior consistent with pseudo-second-order kinetics. The thermal variables, involving entropy, Gibbs free energy, and enthalpy, revealed that adsorption is a process that occurs naturally and absorbs heat during the process.