The physicochemical characterization, equilibrium, and kinetics of heavy metal ions adsorption from aqueous solution by arrowhead plant (Sagittaria trifolia L.) stalk

The arrowhead plant stalk (APS) has been investigated as a novel biosorbent for removal of Cd(II), Pb(II), and Cr(III) ions from aqueous solution. The surface physicochemical properties favorable for metals adsorption were systematically characterized. The Langmuir isotherm fitted well with Cd(II) and Pb(II) adsorption process onto APS while Dubinin-Radushkevich model best described Cr(III) sorption. The maximal adsorption capacities of APS for Cd(II), Pb(II), and Cr(III) were up to 38.2, 97.1, and 23.5 mgg(-1), respectively. The adsorption kinetic data of individual metal fitted the pseudo-second order model best. The adsorption of Cd(II) was exothermic, whereas the Pb(II) and Cr(III) underwent endothermic reaction. Overall, this investigation indicated, for the first time, APS is a potentially efficient biosorbent applied in Cd(II), Pb(II), and Cr(III) adsorption. It is also helpful for further utilizing the abundant quantity of APS which were abandoned in dietary arrowhead processing. Practical applicationsThe growing food industry around world generates large quantity of by-products. The high value-added utilization of food processing by-products is one of the most important area in food industry. An attempt was made in present study to use the food by-product, arrowhead plant stalk (APS), as a novel biosorbent for removing Cd(II), Pb(II), and Cr(III) ions. In present study, it was evidenced that the adsorption capacities of APS for Cd(II), Pb(II), and Cr(III) were obviously higher than those of most reported agricultural by-products. This finding is significant for sustainable utilization of food crop arrowhead plant and elimination of environmental issues arising from the abandoned arrowhead plant stalk.