Removal of Acid blue 93 dye from aqueous media using an agro-industrial waste as bioadsorbent: An OPAT and DoE Approach

The current article reports an effective and low-cost removal of Acid blue 93 dye using synthesised peanut (Arachis hypogaea) shells. In first step, the adsorbents were examined using pH(pzc), TG-DTG, FTIR and SEM characterisation techniques. In the second phase, the parameters such as contact time (CT), pH, adsorbent dosage (AD) and initial concentration of dye (ICD) were assessed using one parameter at a time adsorption study (OPAT). Selecting the same parameters an effort was also made using design of experiment (DoE). It was found that, for maximum removal both the studies, OPAT and DoE delivered similar optimum conditions as CT 60 min, pH 7, AD 7 g l(-1) and ICD 50 mg l(-1). In addition, DoE added an edifying output in terms of percentage of contribution: ICD (36.35%) > AD (31.39%) > CT (27.03%)> pH (5.24%). In accordance with the above studies, kinetics, isotherm and thermodynamic analysis were also performed followed by error analysis. In kinetics, pseudo-second-order model was superior; in isotherm study, Langmuir model was dominant with a q(m) value of 23.36 mg g(-1). Thermodynamic parameters such as Delta G(circle), Delta H-circle and Delta S-circle stated the adsorption endothermic and spontaneous. The novelty of this work is in the development of the pre-treated peanut (A. hypogaea) shells for efficient and low-cost removal of Acid blue 93 dye from aqueous media.