Evaluation of phase transfer kinetics and thermodynamic equilibria of Reactive Orange 16 sorption onto chemically improved Arachis hypogaea pod powder

Biosorbent from pods of Arachis hypogaea (AhP) were inducted with sulphuric acid treatment and then the activated materials were employed to sequester a sulphonated textile dye; Reactive Orange 16 (RO16) from water system. The characteristic features of the surface functionalized AhP (Ct-AhP) were analysed using instrumentation techniques. The biosorption influencing variables like operating pH, agitating time, initial RO16 concentration and temperature effects were investigated. One-factor optimization revealed that 0.5 g Ct-AhP was sufficient to achieve maximum removal of RO16 (20-120 mg/L) within 180 min agitation at 150 rpm. The isotherm data were applied to non-linear isotherms viz., Freundlich, Langmuir and Temkin models as well as rate limiting steps were elucidated using kinetic models. Freundlich isotherm showed good fit and pseudo-second order kinetic data explained RO16 removal by Ct-AhP followed chemisorption. The outcome of thermodynamic parametric values infer that RO16 biosorption was spontaneous, feasible and involved exothermic type of heat. Elovich and intraparticle diffusion revealed the biosorption mechanisms. The maximum RO16 biosorption (56.48 mg/g) by 0.5 g Ct-AhP were witnessed in the system containing 120 mg/L RO16 agitated at 150 rpm operating at pH 7.0, 303 K for a span of 180 min. Thus, the Ct-AhP is considered to be a promising biosorbent which can be employed in treating the textile effluents. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

The study found that 0.5 g Ct-AhP was able to effectively remove 20-120 mg/L of RO16 within 180 minutes of agitation at 150 rpm. Freundlich isotherm showed good fit, and pseudo-second order kinetic data explained RO16 removal by Ct-AhP involving chemisorption. Thermodynamic parametric values indicated that RO16 biosorption was spontaneous, feasible, and involved an exothermic type of heat.