Примена на природни сорбенти и наноматеријали за отстранување на тешките метали дистрибуирани во системот подземни води на микролокалитетот Дрисла

Abstract

The generation of the leachate and its free release into the environment is one of the main problems of the municipal solid waste landfills. This applies to the single modern landfill for municipal solid waste in our country, the landfill Drisla. In order to prevent the passage of the heavy metals present in the leachate into the groundwater system, a system of protective layers which would include such materials that have the ability to retain heavy metal ions, need to be set up at the bottom of the landfill site. For this purpose, in the frame of the doctoral work, the adsorption abilities of natural and nanosorbents, particularly of natural peanut husks, expanded perlite and graphene, to remove Ni(II), Pb(II) and Fe(II) ions from water systems, were investigated. In order to enhance the adsorption properties, acid-base activation of natural peanut husks, and acid activation of graphene, were performed. 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. Adsorption equilibrium of the systems was analyzed using the following isotherms: Langmuir, Freundlich, Langmuir - Freundlich and Redlich - Peterson. The parameters of these isotherms and the coefficients of correlation were obtained applying MATLAB/Curve Fitting Toolbox. The linear forms of the I and II order, pseudo I and pseudo II order and model of Elovic are the kinetic models used to interpret the kinetic experimental data of the adsorption processes. 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 %. The characterization of the sorbents was performed utilizing the following techniques: SEM, TGA, TEM, Raman spectroscopy.