Preparation of polyacrylonitrile grafted onto nano-clay for removal of aluminum from aqueous solutions

Abstract

Heavy metals are extremely carcinogenic and show mutagenic properties when taken into the body. Aluminum (Al) is a toxic metal that is frequently encountered in daily life and can be taken into the body through drinking water, food, drugs and the air we breathe. Aluminum-based pollutants are found in the wastewater of many industrial sectors such as textile, plastic and food. Removal of toxic pollutants from wastewater has a significant role in terms of health and environment. As a result of many studies on the removal of heavy metals from wastewater, new treatment methods have been discovered. Adsorption is used as the most reliable method preferred for Aluminum among these methods. Polymeric clays are preferred more often than natural clays as adsorbent in the removal of heavy metal-derived pollutants such as Al from wastewater by adsorption method. Polymeric adsorbents with high adsorption capacity and large surface area are obtained by polymerizing functional groups in the structure of the clay and polymer types with desired properties. It has been determined by the studies on this subject that the adsorption ability of the clay is increased by forming a new sorbent with a suitable polymer. In this thesis, a new PAN grafted onto nano-clay was synthesized. 1.095 g (0.006 mole) hydrophilic bentonite nanoclay was wetted with 5 mL of distilled water. In a separate beaker, 0.8 g (0.001 mole) ammonium cerium (IV) nitrate used as initiator in redox polymerization was dissolved with 15 mL of distilled water in the presence of 1 mL (0.024 mole) nitric acid. This mixture was added to the wetted clay and the 10 mL (0.152 mole) of acrylonitrile and 15 mL (0.287 mole) of acetonitrile was put the polymerization medium. The graft polymerization was performed at room temperature for 18 h. Pure nano-clay and polymeric nano-clay were characterized by FTIR analysis. In addition, the Aluminum holding capacity of the polymeric nano-clay was characterized spectrophotometrically by sorption studies. In this study, Eriochrome Cyanine R (ECR) was used as a reagent in Al sorption experiments and all analytical measurements were carried out at pH 6 and using a UV-vis spectrophotometer at 535 nm. Al removal experiments were carried out depending on pH. Furthermore, Al removal studies from aqueous solutions using PAN grafted onto nano-clay as adsorbent were carried out at four different temperatures between 25 °C and 50 °C. In addition, according to the results obtained after the sorption study, kinetic models were applied and adsorption isotherm models were also investigated. When we look at the results of the kinetic models applied in this study, high correlation coefficient values here revealed that the data obtained as a result of the experiment showed a better fit with the pseudo second-order kinetic model.