Study On The Selective Capture Of Hyperoxic Anions In Water By Micro - Nanostructures Of δ - Bi <2 O ₃ Micro - Nanostructures

The economy is growing with prosperous development of the energy /manufacturing industry, while environment is being badly hurt by the increasing harmful pollutants, e. g., the radioactive iodide and selenium-oxygen anions are the most common carcinogens in the industrial wastewater. The waste of the energy / manufacturing industry contain high concentration of ionized and toxic radioactive iodide（I131 and I129）and SeO_x^2-（x=3, 4） anions. How to effectively and selectively capture of these anions is a sticky problem that needs prompt solution. In this thesis, d-Bi₂O₃ adsorbent was prepared and used for capturing of radioactive I- / SeO_x^2- anions in the wastewater. The structural /crystal change of d-Bi₂O₃ after immobilization of anions was characterized.Sectionâ… :Selective Capture of Iodide from Solutions by Microrosette-like δ?Bi₂O₃.Radioactive iodine isotopes which are produced in nuclear power plants and used in medical research institutes could be a serious threat to the health of many people if accidentally released to the environment since the thyroid gland can absorb and concentrate them from a liquid. For this reason, uptake of iodide anions was investigated on microrosette-like d-Bi₂O₃. The d-Bi₂O₃ adsorbent showed a very high uptake capacity of 1.44 mmol g- 1by forming insoluble Bi4I2O5 phase. The d-Bi₂O₃ also displayed fast uptake kinetics and could be easily separated from a liquid after use due to its novel morphology. In addition, the adsorbent showed excellent selectivity for I- anions in the presence of large concentrations of competitive anions such as Cl- and CO32-, and could work in a wide pH range of 4-11. The superior sorption property of δ? Bi₂O₃ is mainly attributed to its unique crystal structure.Section â…¡:Selective Removal of SeO_x^2- from Water Using Microsphere-like δ-Bi₂O₃.Removal of the toxic selenium compounds from wastewater before discharge（20ppb） is becoming increasingly imperative in industrialized countries. To meet this challenge, microsphere-like δ-Bi₂O₃ was designed to adsorb SeO_x^2- from aqueous solutions. δ-Bi₂O₃ was shown to have the superior adsorption capacity with a high uptake capacity of 160 mg g-1 for SeO32-（58 mg g-1 for SeO42-）, and fastest uptake rates for both selenate and selenite with achieving equilibrium time within 3 min under low concentrations, which shows the highest adsorptive performance. In addition, δ-Bi₂O₃ was tested for its ability to selectively capture of selenate and selenite anions from aqueous solutions in the presence of high concentration of competitive anions（Cl-, NO3-, SO42-,CO32- and PO43-）. Herein, the mechanism of selenate and selenite adsorption is explored to determine the important features that make δ-Bi₂O₃ a superior adsorbent for this application.