Linear and nonlinear regression methods for isotherm and kinetic modelling of iron ions bioadsorption using Ocimum sanctum Linn. leaves from aqueous solution

Abstract

Iron concentration in drinking water higher than the recommended value imposes different health problems. There are advanced chemical-based iron extraction techniques, in spite of having certain limitations in developing countries. Due to this, iron removal by using locally available plants is a paramount sustainable option. Therefore, the current study was intended to explore the iron removal efficiency of the powder of Ocimum sanctum Linn. (OSL) leaves from water and investigate its capability by assessing various conditions of operation. The bioadsorption equilibrium isotherm and kinetics of iron extraction onto OSL leaf powder were studied and modelled. The experimental adsorption equilibrium observations served as the basis for a comparison of linear and nonlinear regression techniques for predicting the optimal isotherms and kinetics. The optimum conditions for the extraction of iron were observed to be pH of 5, biomass concentration of 0.2 g, contact time of 2 h, speed of agitation of 150 rpm at 25 °C temperature, while maximum bioadsorption capacity was 123.26 mg/g. The batch bioadsorption of iron obeys the Fritz–Schlunde isotherm and the pseudo-first-order-kinetic model. The isotherm and kinetics parameters obtained using the nonlinear regression method outperformed the linear approach. Moreover, the potential applicability of OSL leaves-based bioadsorbent could be further examined on a large-scale for industrial application. HIGHLIGHTS The potential of Ocimum sanctum Linn. (OSL) leaf powder for iron removal under various experimental conditions was presented.; Maximum adsorption capacity of OSL leaf powder was 123.26 mg/g at pH 5.; Thermodynamic parameters indicate that the bioadsorption process was possible, spontaneous, and exothermic.; The comparison of linear and nonlinear regression approaches for isotherm and kinetics modelling was discussed.;

Keywords

• adsorption kinetics
• iron removal
• isotherm models
• linear and non-linear regression
• plant based bioadsorbents