Use of Sarkanda grass lignin as a possible adsorbent for as (III) from aqueous solutions – kinetic and equilibrium studies

Abstract

Considering the negative effects of polluting species on the environment and human health, in particular heavy metals, and the need for efficient use of resources, the present study investigated the adsorption of As (III) from aqueous solutions under static conditions onto chemically unmodified Sarkanda grass lignin. In order to optimize the adsorption process, the retention of As (III) was tested under various experimental parameters (pH of the initial solution and adsorbent, concentration of aqueous solutions, adsorbent dose and contact time of the two phases). The experimental data obtained were interpreted based on the classical models of Freundlich and Langmuir isotherms, which was useful in establishing the equilibrium conditions and in evaluating the adsorption capacity for a solute. The adsorption dynamics was studied using the Lagergren pseudo-first order and the Ho and McKay pseudo-second order models. The analysis of the obtained experimental data recommends chemically unmodified Sarkanda grass lignin as a future alternative adsorbent for water remediation, taking into account its practical applicability in the retention of As (III) from aqueous solutions, in terms of both adsorbent and adsorbed doses, as well as the time required for adsorption.