Fixed-bed Column Study For The Removal Of Arsenate From Aqueous Solutions Using Sand Coated By Magnetic Graphene Oxide Adsorbent

Arsenic is a well-known toxic substance. Due to the frequent human activities, such as the discharge of industrial wastewater with arsenic and ore mining, making increased content of arsenic in groundwater in some areas, speeding up the migration and transformation of arsenic in the environment, causing the accumulation of arsenic in the environment, resulting in arsenic contamination. In addition, drinking arsenic contamination of drinking water for a long time can cause various health problems may even cause cancer, increasing the risk to human health. Arsenic has been determined to be carcinogenic to humans by the international organization for cancer.Because of arsenic in water has great harm to human body, the levels of arsenic in water is more and more strict at home and abroad. How convenient and efficient removal of arsenic and its compounds in the water has caused people’s attention. And among them, adsorption, due to the easy operation, economy, and renewable characteristics, has been widespread application in arsenic removal. Among arsenic removal adsorption materials, iron oxide nano-material, due to their high surface area and high selectivity for arsenic, usually as adsorbent for As (V), and indicates its efficient effect adsorption for As (V). But it was difficult to directly be used as filter material in the fixed-bed column resulting from their small size. Graphene oxide, because of its larger specific surface area, high flexibility, and chemical stability, so, often used to be an important basal material to load other active nano-materials, therefore, can be used to synthesis of novel adsorbent. This experiment adopted the graphene oxide as a supporting body, to synthesis magnetic nano graphene oxide. And loaded it on the sand, synthesised of a new adsorbent:magnetic grapheme oxide load on sand (MGO-sand).In this work, magnetic graphene oxide coated sand (MGO-sand) was used as a bed filter for arsenate removal in column test. The MGO-sand was characterized by X-ray photoelectron spectroscopy (XPS) before and after As (V) adsorption. The influence of experimental parameters including column depth, pH, As (V) initial concentration and flow rate on As (V) breakthrough curves was conducted in detail. It was observed that column depth (10cm), acid condition (pH=5.5), As (V) initial concentration (1.0mg/L) and slower flow rate (20mL/min) had the better adsorption efficiencies on As (V). The interference of competing ions (i.e. HPO42-,HCO3-,SO42-,NO3-,Cl-,F-)was also measured.Results showed that the order of competing ions for inhibiting As(V)adsorption was HPO42->F-> HCO3->SO42->NO3->Cl-.The remarkable As(V)interference from HPO42-was contributed to their similar ad sorption densities and chemistry toward the MGO-sand filter adsorbent. The Yoon-Nelson model was used to fit the experimental data and well described the breakthrough curves.Furthermore,the average adsorption quantity of the MGO-sand was almost100-fold and200-fold than that of GO-sand and pure sand,respectively.