Synthesis and performance of graphene and activated carbon composite for absorption of three-valance arsenic from wastewater

The presence of high levels of arsenic in the effluent is a major concern of human, and the removal of it from the wastewater is hard and costly. The most common techniques for removal of arsenic are membrane separation, ion exchange, oxidation, and coagulation. All of these technologies eventually lead to the separation of arsenic from wastewater and its accumulation among absorbent materials, which are precipitated as sludge or extracted from liquid intermediate phase. In this adsorption method, materials such as active alumina, active carbon, titanium oxide, silicon oxide, and many natural and artificial elements are used. Considering that active carbon is used as the most common arsenic adsorbent in wastewater treatment processes, this study has been considered as the main adsorbent and attempted to improve its surface properties by graphene nanosheets. Thus, by adding 4.5 w.% graphene to the carbon structure, its porosity increases, and the ion exchange behavior and surface load are corrected. In this research, the effects of time process, concentration of arsenic, and adsorbent are evaluated in different pH values. It has been observed that the maximum adsorption of arsenic is 91.8%; in addition, when graphene is used, the rate of absorption of Arsenic has increased about 5.2%, and the process time is shortened. In addition, using graphene is cost-effective. It is also observed that the efficiency of the adsorption process increases near neutral pH values; therefore, the adsorption method by graphene/activated carbon composite in neutral cells can be used as an additional method for industrial wastewater treatment.