Application of several plant roots as biosorbent and nanobiosorbent for the removal of Pb2+ and Zn2+ from aqueous solutions

The aim of this paper is full study about the abilities of the roots of castor, pear, peach, apple, almond, walnut, sour cherry, berry, ginger, sunflower, red flower, mallow, grapevine, hot pepper, hollyhock, tomato, astragalus, and black eggplant as biosorbents for the removal of heavy metal ions from water. The obtained results indicate that the grapevine root particles can adsorb heavy metal ions better that other roots and also, lead and zinc ions can be better adsorbed than other ions. In the next step, the grapevine root is milled into nanoparticles by an innovative ball mill. The prepared nanoparticles are characterized by DLS, transmission electron microscopy, scanning electron microscopy, and Fourier-transform infrared spectroscopy. The results show that the average diameter of grapevine root nanoparticles (GRN) is 63 nm. The prepared GRN is used as nanobiosorbent to remove lead and zinc ions from water. Based on the experimental results, MD' and Zn ions can quantitatively remove from water by a spontaneous exothermic process in the conditions including pH 4, initial solution volume 50 mL, initial concentration of each metal ion 50 mg L-1, sorbent dosage 4 g L-1, and contact time 30 min at room temperature. The isothermal and kinetic studies show that the adsorption of Pb2+ and Zn2+ ions on GRN can be well described by Langmuir isotherm and pseudo-second-order kinetic models. Based on the Langmuir isotherm model, the maximum capacities are found 24.6 and 26.3 mg g(-1) for the adsorption of Pb2+ and Zn2+ ions on GRN, respectively.