Leaching behavior of ZnO nanoparticles in municipal solid waste

Abstract

The use of engineered nanomaterials (ENMs) in commercial products has been increasing in our daily lives and in the industry day by day. Among the ENMs, zinc oxide nanoparticles (ZnO NPs) have being used in many consumer products such as cosmetics, textile, electronics, medicine, paints, agriculture and environmental remediation. As a result of extensive use, ENMs containing wastes end up their life cycle in treatment facilities such as wastewater treatment plants, incineration units and sanitary landfills ultimately. However, there is still a lack of knowledge about the fate and behavior of ENMs in the landfill and landfill leachate. Therefore, in this research it is aimed to investigate the leaching behavior of three different kinds of ZnO NPs such as powder (uncoated), powder Z-Cote HP1 (coated) and dispersion (slurry) in fresh municipal solid waste (MSW). Batch reactors (1 L) were used to observe the leaching potential of ZnO NPs under acidic, basic and high ionic strength (IS) conditions. The reactors were filled with 250 g fresh MSW. Each reactor was loaded 10, 25 and 100 mg/L ZnO NPs. The reactors loaded with ZnO NPs and control reactors were shaken for 72 hours. 10 mL of leachate samples were regularly taken from batch reactors at pre-determined time intervals and they were analyzed for Zn concentration, pH, conductivity and particle size distribution. The results showed that nano-ZnO mass retained in the solid waste matrix with ratio between 84-93%. There was no significant influence of pH and IS on the leaching potential of nano-ZnO.