J. Appl. Environ. Biol. Sci., 4(11S)38-46, 2015 © 2015, TextRoad Publication ISSN: 2090-4274 Journal of Applied Environmental and Biological Sciences www.textroad.com * Corresponding Author: Zahra Hejri, Department of Chemical Engineering, Quchan Branch, Islamic Azad University, Quchan, Iran. The Experimental Study of the Effect of Hematite Iron Oxide (α–Fe 2 O 3 ) Nanostructure on Reducing Polluter's Chromium and Arsenic from Aqueous Solutions Zahra Hejri *1 , Esmaeil Koohestanian 2 , Mohammad Reza Abedi 3 and Iman FarahBakhsh 2 1 Department of Chemical Engineering, Quchan Branch, Islamic Azad University, Quchan, Iran 2 Young Researchers and Elite Club, Quchan Branch, Islamic Azad University, Quchan, Iran 3 Department of Applied Chemistry, Quchan branch, Islamic Azad University, Quchan, Iran Received: October 29, 2014 Accepted: December 31, 2014 ABSTRACT The inorganic solved compounds in wastewater include ions and cations, heavy metals and radioactive materials and in the meantime water pollution with heavy metals such as chromium and arsenic is one of the most challenging bio environmental issues. In this research, the effect of iron oxide nano structure on decreasing chromium and arsenic in aqueous solution was investigated. The results indicate that rate of reducing polluters chromium and arsenic will be increased by increasing nano structure and by increasing time of irradiation and also with respect to that iron oxide nanostructure causes to permeate hexavalent chromium into trivalent chromium, it can be concluded that after timing to solution, the rate of chromium reduction will be increased because of precipitation and in this order with 0.2 gr of iron oxide nano particles and after 120 m ultrasonic irradiation, arsenic and chromium polluters were eliminated from waste water 94%, 97% respectively. KEY WORDS: chromium, arsenic, superficial absorption, iron oxide nano structure. 1. INTRODUCTION Because of importance of environment pollution by waters contained heavy metals, concentration strongly has been increased in order to find filtering methods which are effective in light of efficiency and cost. The rate of chromium and arsenic into aquatic solutions can be decreased by different chemical, physical and biological methods. Since the cost of physical methods and chemical material for chemical filtering of waste water is high, the use of these methods has been limited. The density of the heavy metal in underground waters depends on the life of well and region geology. These waters included low amount of different heavy metals like cadmium, chromium, arsenic, copper, lead, mercury, nickel, silver and zinc. [1] The water pollution by arsenic and hexavalent chromium is one of the most challenging environmental problems [2]. Chromiumexists in different manners, but there are only states +3 and +6 constantly in most environments. Chromium (VI) is poisonous for plants and animals and also this kind of chromiumis very mobile in environment. On the other word, chromium (III) has lower toxicity and mobility and solvability and is permeating under weak acidic or alkaline medium to from CrOH 3 . It is reported that chromium (III) has lower toxicity than chromium (IV) about 10 – 100 times [2]. Various techniques for removal of chromium (VI) and arsenic have been used, including ion exchange, filtration, electrochemical deposition, adsorbing by activated carbon, etc. but these methods are often expensive and complex to their output [2]. Also several factors such as concentration of the pollutant and pH effect on removal of these pollutants [3]. So far different methods including process of reverse osmosis, electro dialysis, ion exchange and other methods have been considered to eliminate the heavy metals. These processes have special limitations because of uncompleted elimination of contaminants and also high cost. The process of superficial absorption with active carbon isn't one of the most effective substances to eliminate metals [4]. Generally, superficial absorption is process of materials aggregation in common section between two phases. The active carbon is one of the most effective which is used to absorb chromium. Since its restoration is costly and expensive, always it impels researches to search new absorbent in this field. A lot of studies have been performed to apply and use the absorbents which are easily useable and low cost [5]. Iron is one of the most abundant elements in the earth which is used as ideal for removal pollutions, because it is cheap and abundant, it is easily made and it is used in different systems and it will free water from any known toxic materials. Iron nano structure and iron oxide have greater area than larger powder or granular iron that leads to increase the reactivity of oxidation – reduction process (redox). It can be concluded that this nano structure is used strongly to decompose the halogenated hydrocarbons to harmless hydrocarbons and for removal contaminates such as anions and heavy metals. One of simple and cheap methods to synthesize iron oxide nano structure is mechanical milling process [6]. Also, iron nano particles are more reactive than iron micro particles which this property causes to be better than 38