Removal Of Phosphate From Aqueous Solution By Magnetic Fe-Zr Binary Oxide

Phosphorus, as an essential resource and material, is widely used in the areas of agriculture and industry. However, a large amount of phosphate promotes the growth of the alga due to its extensive use. Some algae are toxic, which lead to the disturbance of organisms balance in water. The rapid depletion of dissolved oxygen level makes the fish and other aquatic life dead when the algae decay. Therefore, phosphorus has a great impact on the lakes, rivers and seas which people depend on. It is of significant importance to control the amounts of phosphorous in water to maintain a green environment for the forthcoming generation.There are mainly three kinds of methods to remove phosphate including chemical precipitation, biological treatment, and adsorption. Chemical precipitation method was first used to resolve the problem of rich nutritional pollution. It was also applied in treating industrial wastewater containing high concentration of phosphate. Moreover, this method could produce high-quality of phosphate precipitates such as struvite. However, the cost was expensive and the recovery of phosphorus from chemical sludge was very difficult. Biological treatment was widely used in the removal of organophosphorous chemicals in food and domestic wastewater. People utilized polyphosphate accumulative organisms (PAOs) or plants assimilating phosphate to reduce the phosphorous concentration. Nevertheless, this method had disadvantages of slow treatment speed, complex operation process and requiring considerable infrastructure investment. Furthermore, it was unsuitable for treating wastewater containing high concentration of phosphate. Adsorption methodology could overcome the problems existed in chemical precipitation and biological treatment. Adsorption method was found to be superior to above techniques for removal of pollutants from aqueous solution in terms of flexibility and simplicity of design, ease of operation and insensitivity to toxic pollutants. It also did not result in the formation of harmful substances.In this thesis, magnetic Fe-Zr binary oxide was synthesized and used as adsorbent for removing phosphate from aqueous solution. The adsorbent was characterized by energy dispersive analysis system of X-ray, scanning electron microscopy (SEM), infrared spectrum (IR), X-ray powder diffraction (XRD) analysis and BET surface area measurements. Zeta potential was used to detect the surface charge of this material. The results showed that Lots of mesopores were present on the surface of Fe-Zr binary oxide adsorbent. The BET surface area of Fe-Zr binary oxide adsorbent was106.2m2/g and the isoelectric point of the adsorbent was at pH3.24. Different sorption conditions were also studied in batch experiments, including contact time, pH value, ionic strength, initial concentration of phosphate, and various other anions. Kinetic data followed a pseudo-second-order model and equilibrium data were well fitted by the Langmuir model. The maximum adsorption capacity was13.65mg P/g at pH4. The adsorption mechanism was mainly derived from ion-exchange of zirconium species and partly originated from magnetite species of Fe-Zr binary oxide. The main advantages of magnetic Fe-Zr binary oxide adsorbent consisted in its separation convenience and highly efficient reusability compared to the other adsorbents.