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. "

Comparison Adsorption of Cd (II) onto Lignin and Polysaccharide-Based Polymers

“…Adsorption isotherms offer information about the distribution of solute particles between the two phases of the adsorption system [ 17 , 18 , 26 , 27 ]. The adsorption efficiency of Cd (II) was evaluated by Equation (1): q = (c i − c e )V/m, (mg/g) where c i —initial concentration (mg/mL), c e —equilibrium concentration (mg/L), V—volume of metal ion solution (L), m—mass of adsorbent (g).…”

“…The Freundlich isotherm uses the empirical Equation (3), where, q e —amount of metal ions adsorbed per unit of mass of adsorbent (mg/g) at equilibrium, k F —Freundich constant, indicating adsorption capacity, n—constant characterizing the affinity of metal ions to sorbent, c e —concentration at equilibrium of metal ions in solution (mg/L) [ 26 , 27 ]: q e = k F ·c e 1/n …”

“…[ 1 ]. “Low-cost” materials seem to be a lever for the future in terms of the retention of heavy metal ions, and lignin, this main aromatic component of biomass, can be considered an alternative raw material for fossil resources which can represent a plausible solution in some previous studies demonstrating the efficiency of this lignocellulosic waste in the adsorption of lead, zinc, and arsenic ions [ 26 , 27 ].…”

“…The initial pH, sorbent dose, the concentration, the contact time, and the temperature are very important factors in optimizing the adsorption process of polluting species [ 26 , 27 ]. To obtain information about the adsorption capacity of a given material under well-defined experimental conditions that can then be used for the design of a large-scale industrial wastewater treatment system, it is necessary to model the equilibrium data obtained experimentally [ 30 ].…”

“…Considering these aspects, the present study proposed to test the adsorption capacity in static conditions of unmodified Sarkanda grass lignin, used as a chemical substrate for an aqueous solution of Cd (II), considering the results obtained in other previous studies through which Sarkanda grass lignin is recommended as an effective adsorbent for Pb (II), Zn (II), and As (III) retention [ 26 , 27 ].…”