Synthesis of TiO2/graphene oxide/PEDOT nanocomposite and its application in Photocatalytic degradation of illicit drugs in wastewater

Environmental problems have called the alarm for the human community. Removal of chemical wastes is one of the most important goals to protect human health and environment. Since the introduction of some chemical wastes into the water resources can cause irreversible damage to humans and other organisms, removing these pollutants from water is one of the most important activities of countries [1]. Nowadays, emerging new technologies, made it possible to use more efficient methods to destruct chemical wastes so that secondary environmental problems would not reproduce after the destruction [2]. One of the new methods for the destruction of chemical wastes is photodegradation using photocatalysts in the presence of sunlight as a clean, inexpensive, and powerful light source [3].The purpose of this study is to synthesis a robust nanophotocatalyst for photocatalytic degradation of amphetamine group as model of illicit drugs. For this purpose, various photocatalysts were applied: graphitic carbon nitride, and titanium dioxide and its composite with reduced graphene oxide, as well as its silver chloride doped. These nanophotocatalysts were fabricated and characterized by several methods. In the experimental part, the destruction of illicit drugs of amphetamines were studied in three series of experiments including the photocatalytic degradation of amphetamine with graphitic carbon nitride (g-C3N4); titanium dioxide and nanocomposite of TiO2 with poly ethylenedioxy thiophene (PEDOT) and reduced graphene oxide (TiO2/PEDOT/RGO) coated on a stainless-steel mesh. Photodegradation processes were evaluated in the presence of direct sunlight and UV irradiation. In order to achieve the best photodegradation efficiency, pH, type of photocatalyst, the weight of photocatalysts, and illicit drug concentration were studied. The developed nanocomposite was characterized through FT-IR spectroscopy, SEM-EDX, thermogravimetric (TG) and XRD analyses. The efficiency of photocatalytic process was evaluated with GC-FID and GC-MS analyses. The photodegradation of amphetamine 6.5 μg/l was performed by treatment of wastewater solution (adjusted at pH 7.5) with CS/TiO2/RGO immobilized on stainless steel mesh in the 60min where the reaction temperature was set to 45°C. However, by increase in illicit drug concentration, the required time for photodegradation, may increase. The prepared nanocomposite is a cheap photocatalyst, non-toxic, with a simple preparation method, could destroy illicit drugs with high degradation efficiency. Titanium dioxide is a powerful photocatalyst that has been enhanced with compositing and doping, successfully eliminated amphetamine which is a tough chemically degradable drug. The life time experiment for one coated steel mesh showed no significant loss in performance of composite coating over 20 times of photodegradation owing to the high chemical stability of TiO2/PEDOT/RGO nanocomposite. The thermal and mechanical stability of the prepared nanomaterial and the high relative recovery make this nanophotocatalyst superior to conventional photocatalyst for degradation of illicit drugs in wastewater.

کلیدواژه ها:

Nanophotocatalyst ، Illicit drugs ، TiO2/PEDOT/RGO ، Photocatalytic degradation