Leaching behaviour of nano-titanium dioxide in municipal solid waste

Abstract

Over the past few decades, the use of nanomaterials (NMs) in consumer and industrial products has showed a rapid growth. Titanium dioxide (TiO2) is among the most commonly reported engineered nanomaterial (ENM) employed in numerous applications ranging from cosmetics, paints, food products to environmental remediation. Due to the widespread synthesis of TiO2 and its broad use in many commercial products, nano-TiO2 will eventually end up in landfills after the disposal of these products. The aim of this study is to assess the leaching potential of nano-TiO2 from real and synthetically prepared solid waste environments under different environmental conditions (e.g., pH, ionic strength, different concentrations of nano-TiO2). Batch experiments were conducted by using fresh real solid waste samples from a major landfill located in Kocaeli, Turkey and synthetic solid waste which was prepared according to the waste composition of the landfill site. The waste samples were treated by using nano-TiO2 stock solutions ranging in concentration between 0 and 100 mg/L. Acidic and basic pH conditions were considered as 5-6 and 8-9, respectively. High ionic strength on the leaching of nano-TiO2 was also adjusted. Leachate samples were regularly saved over a three-day period and analyzed for pH, electrical conductivity, and Ti content. Preliminary results represent that the leaching behavior of the nano-TiO2 indicates a complex transient. The majority of the nano-TiO2 in the batch reactors tends to adsorb on the waste media given the all environmental conditions, followed by a gradual release into the leachate.