Removal of Heavy Metal Ions from Wastewater Using Bio- and Nanosorbents

Abstract

The rapid industrial development and urbanization have intensified environmental pollution and caused deterioration of ecosystems by accumulation of many pollutants, especially heavy metals. Most of the heavy metals are toxic, and their ions are not biodegradable with the tendency to accumulate in the soil, water resources and the living organisms; hence, they are significant environmental pollutants. Therefore, the treatment of the heavy metal ions and their elimination from water and wastewater is very important for environmental protection and thus the public health. In the frame of this work, the adsorption abilities of natural and nanosorbents, particularly natural peanut husks, expanded perlite and graphene, to remove Ni(II), Pb(II), and Fe(II) ions from water systems, were investigated. The influence of the pH (4–8) of the solution, the amount of adsorbent (0.5–5.5 g/l), the initial metal ion concentration (0.3–2.0 mg/l), and the contact time (5–180 min.) on the efficiency of removal of metal ions was investigated. Thus, the optimal conditions for achieving maximal effectiveness for heavy metals removal were determined. The characterization of the sorbents was performed utilizing the following techniques: SEM and TGA. Adsorption equilibrium of the systems was analyzed using the following isotherms: Langmuir, Freundlich, Langmuir–Freundlich, and Redlich–Peterson. The maximal adsorption capacity of the peanut husks, perlite and graphene for Ni(II), Fe(II), Pb(II) was obtained, and the percentage of removal was determined. A comparative analysis for the efficiency of all used sorbents for Ni(II), Pb(II), and Fe(II) ions removal from the three component systems was conducted at the end. The expanded perlite gave the best results for the removal of Ni (II) and Pb (II) ions, while graphene proved to be excellent adsorbent for Fe(II) ions with an efficiency of 100%.