Synthesis of adsorbents for the removal of toxic heavy metal ions is a continuing objective in the research undertaken to control environmental pollution. In this study, the adsorption of Pb+2, Cu+2 and Ag+ cations was improved by modifying ZnO nanoparticles. For this purpose, the compound 3-hydroxy-3-(4-methoxyphenyl)-7-propyl-2H-thiazolo [3,2-α] pyrimidine-5 (3H)-one was used to modify the surface of the ZnO nanoparticle. Flame atomic absorption spectrometry was used to determine the concentration of cations in a solution. Pb+2, Cu+2 and Ag+ cations were completely removed at pH ≥4 after stirring 25 mL of 4 mg L-1 solution of these three ions with 35 mg of the modified adsorbent for 30 min. Up to an acceptable level of other cations, there is no interference with the driver cations. The experimental data were analyzed using the Langmuir, Freundlich and Temkin adsorption models. The adsorption isotherms were well described by the Langmuir isotherm model and the maximum capacity of the adsorbent was found to be 115, 210 and 240 µg of Pb+2, Cu+2 and Ag+ cations per each mg of the adsorbent, respectively. The adsorption of metal ions was studied at three different temperatures and the ΔH° and ΔS° were obtained from the Van’t Hoff plot. The negative value of the Gibs free energy and the desired value of other thermodynamic parameters show that the removal process is spontaneous and endothermic. Finally, the modified ZnO nanoparticles exhibited an excellent adsorption capacity towards the analyzed cations in water and wastewater samples.   

4.23.2018