Shi You Li

Efficiency of Adsorption of Wastewater Containing Uranium by Fly Ash

The effects of pH, different initial concentrations of uranium and adsorption time were investigated to study the properties of the sorption of uranium by fly ash. The results show that pH value is the major factor of dominating adsorption rate. The highest adsorption capacity was obtained at pH 5 and the adsorption time was 60 minutes. The increasing of initial uranium concentration resulted in the decreasing of U removal rate and the increasing of adsorption quantity, and the maximum adsorption capacity was 8.38mg/g. The adsorption behavior accorded with both the Freundlich and Langmuir isotherms.

Adsorption characteristic of U(VI) on Fe-immobilized bentonite

Fe-immobilized bentonite, prepared with bentonite and FeCl3 was used for the adsorption of uranium(VI) in this study, solution pH, ion strength, contact time and temperature were investigated, structural characterization of Fe-immobilized bentonite was assayed by X-ray Diffraction and Fourier Transform Infrared Spectroscopy. Results indicated that the adsorption capacity were strongly affected by the solution pH and ion strength, the adsorption efficiency was 91.8% when pH value was 6 and ion strength was 0.01 mol•L-1, higher or lower pH did not favor the U(VI) adsorption. The adsorption mechanism was discussed by the views of reactive kinetics and thermodynamics along with Scanning Electron Microscope. The adsorption kinetics process was fitted well with the second-order kinetic equation, when the initial U(VI) concentration was less than 38.08mg/L, Langmuir equations could describe the adsorption isotherm of U(VI) well with the maximum adsorption capacity of 169.5mg/g at 303K

Discussion on the Water Supply Engineering Planning of Small Towns in Southern China

With the example of the water supply engineering planning of small towns in southern china, the effects of town water consumption forecast, water resource selection, water site choice, pipe network planning on the present engineering planning of water supply were investigated. The analyses show that the water consumption forecast should adopt many kinds of methods to check each other, and finally determine a proper value. To ensure water yield of source water reliable and water quality to meet the requirements are the first principle of the water resource selection. The location of water plant should be determined according to the characteristics of the water source and the hydrological and hydrogeological conditions, in accordance with the relevant requirements specification. The basic requirements of the pipe network layout are as follows: the security of water quality; the reliability of the water volume and water pressure; the operation reliability and the least investment. As a part of the overall planning, the water supply engineering planning should proceed from reality to deal with the relationship of the recent construction and long-term development in order to push small towns economy to a rapid growth.

Study on Adsorption of Uranium in Wastewater by Clay

The effectives of pH value, contact time，sorbent dose and different initial concentration were analyzed to study the properties of the adsorption of uranium in wastewater by clay. The results show the highest adsorption capacity was obtained around neutral pH.The amount adsorbed of uranium on clay increase rapidly with increasing initial uranium concentration, but the removal rates of uranium are declined.Clay has a good adsorption capability to uranium with 18.25mg/g of adsorption capacity. The adsorption data on clay are followed by both Langmuir and Freundlich models and the results are well described by Langmuir isotherm. The pseudo-second-order kinetic model is more appropriate for the sorption process.

Effect of Culture Parameters on the Biosorption of Uranium onto Chlorella pyrenoidosa

The usefulness of chlorella pyrenoidosa were investigated for the removel of U(Ⅵ) from aqueous solution. Employing monofactorial and orthogonal experiment method for evaluating the biosorption of U(Ⅵ) onto chlorella pyrenoidosa, respectively, the influence of U(Ⅵ) concentration、pH、N/P and temperature on the biosorption of U(Ⅵ) by chlorella pyrenoidosa were studied.The results showed that the pH and U(Ⅵ) concentration were significant to remove U(Ⅵ) and that the increases of pH as well as U(Ⅵ) concentration was beneficial to the U(Ⅵ) absorption. However, the U(Ⅵ) absorption was affected less by the N/P and the temperature. Confirmed through orthogonal experiment, the optimum condition composition to attenuate U(Ⅵ) was 3.4mg/L U(Ⅵ) concentration at pH 6.0 with temperature 293K,and 3/1 of N/P. It was also proved that fresh cell of 1g/L(in dry weight) was able to attenuate U(Ⅵ) in wastewater from 3.4mg/L to 0.72 mg/L after batch experiments under the optimum conditions, which indicated good prospect in its future application.

Influence and Mechanism of Cu2+ on Removal of U(VI) by Sulfate Reducing Bacteria

In order to research on the inhibition of Cu2+ to removal of U(Ⅵ) by sulfate reducing bacteria(SRB), the experiment investigated the removal of U(Ⅵ) by SRB through H2S reduction process, elecrton transfer process and adsorption process respectively. The results showed that the electron transfer was the main process in removing of U(Ⅵ) by SRB, It accounted for 80% of the total removal. Extracellular polymeric substances (EPS) adsorption of U(Ⅵ) had little effect. When the concentration of Cu2+ was 5mg/L, Cu2+ had little effect on the removal U(Ⅵ) by SRB; It inhibited the removal of U(Ⅵ) significantly when the concentration was 15mg/L because of the competition of H2S and the electronics of lactic acid between Cu2+ and U(Ⅵ); When the concentration of Cu2+ exceeded 25mg/L, it would damage the integrity of SRB’s membrane and the removal of U(Ⅵ) was completely inhibited.