Removal of SO4, uranium and other heavy metal ions from simulated solution by sulfate reducing bacteria

In the case of in-situ leaching of uranium, the primitive geochemical environment for groundwater is changed since leachant is injected into the water bearing uranium deposit. This increases the concentration of SO4^2-, uranium and other heavy metal ions and results in the groundwater contamination. The effects of pH values of the simulated solution on the reduction of SO4^2- and the removal of uranium and other heavy metal ions by sulfate reducing bacteria（SRB） were studied. The results show that, when the pH value of the simulated solution is about 8, the reduction rate of SO4^2- by SRB and the removal rate of uranium, Mn^2＋, Zn^2＋, Pb〉 and Fe^2＋ will reach their highest values. A bioremediation technique for remediation of groundwater in in-situ leaching uranium mine can be developed.     

Thermodynamics and kinetics of fluoride removal from simulated zinc sulfate solution by La(III)-modified zeolite

To understand the mechanism of fluoride removal from the simulated zinc sulfate solution by the La(III)-modified zeolite, the adsorbent was characterized by XRD, SEM and EDS. The effects of absorbent dose and contact time, the adsorption isotherms and the sorption kinetics were investigated. The experimental results were compatible with the Langmuir isotherm model. The theoretical maximum adsorption capacities are 20.83 and 23.04 mg/g at 303 and 313 K, respectively. And the physisorption is revealed using the Temkin isotherm model and the D–R isotherm model. The sorption process is more suitable by the pseudo-second-order kinetic models. Thermodynamic parameters such as standard free energy change (ΔG^Θ<0 kJ/mol), standard enthalpy change (ΔH^Θ=8.28 kJ/mol) and standard entropy change (ΔS^Θ=0.030 kJ/(mol·K)) indicate the spontaneity of adsorption and endothermic physical sorption. Furthermore, the fluoride concentration in the industrial zinc sulfate solution decreases from 98.05 to 44.09 mg/L with the adsorbent dosage of 15 g/L.     

SO_4~(2-)/ZrO_2-Nb_2O_5固体超强酸催化剂的制备与IR表征

引入元素Nb对SO42-/ZrO2进行改进,制备了SO42-促进的Zr-Nb新型二元氧化物固体超强酸催化剂SO42-/ZrO2-Nb2O5。以合成乙酸正丁酯为探针反应,考察了该催化剂的制备工艺,确定了最适宜的制备条件:催化剂中Nb2O5的质量分数为3%,浸渍液硫酸浓度为1.0mol·L-1,焙烧温度为600℃时,酯化率可达到95.3%。采用IR光谱法分析了不同制备条件下催化剂的性能。     

离子交换法吸金过程伴生元素在KCN介质中的扩散

用毛细管法测定了不同温度下Zn(CN)_4~(2-)、Co(CN)_6~(3-)、Ni(CN)_4~(2_)在1％KCN介质中的扩散系数及扩散活化能;探讨扩散系数D与扩散活化能ΔE的关系。由结果推测,温度升高,将显著提高离子交换法吸金过程的色谱柱效。     

氨基功能化CoFe2O4-SiO2 磁性复合材料的制备及其在去除水中重金属离子的吸附性能

钴-铁氧体纳米粒子(CoFe₂O₄ NPs)通过改良的共沉淀法制备,CoFe₂O₄-SiO₂磁性复合材料通过st?ber法合成,为了吸附重金属离子CoFe₂O₄-SiO₂进行了氨基功能化。这种吸附剂的晶体结构、形貌、颗粒尺寸、化学组成和分子结构采用X射线衍射图谱(XRD)、扫描电子显微镜(SEM)以及傅里叶变换红外光谱(FTIR)进行表征。此复合材料具有优良的磁性能,由于其高的饱和磁化强度,磁铁可以将其在30秒内快速分离。同时,CoFe₂O₄ NPs的磁性能可以通过烧结温度进行调节,随烧结温度提高,磁性能增强。溶液的pH及反应时间对重金属离子吸附的影响进行了研究,此外此吸附剂对Cu (II)、Cd (II)、Mn (II) 和Zn (II)具有较高的吸附容量和去除率,这一结果使此复合材料可以潜在应用于废水中重金属离子的吸附上。     

Na2S选择性浸出铜转炉烟灰中的砷及Fe2(SO4)3稳定化砷(英文)

研究砷(As₂O₃)的Na₂S碱性浸出,以及用Fe₂(SO₄)₃沉淀砷。采用基于中心组合设计的响应面法对相关因素的影响进行定量和定性分析,提出用于参数优化的统计模型。结果表明,在Na₂S浓度100 g/L,固液比0.163 g/mL和温度80℃的最优预测条件下,89%的砷可从烟灰中去除。研究发现,固液比和Na₂S浓度是影响浸出过程的显著因素。在沉淀过程中,当pH为4.8、Fe³⁺与砷的摩尔比和H₂O₂与砷的摩尔比分别为5:1和4:1时,浸出液中99.93%以上的砷以无定形砷酸铁的形式被除去。Fe³⁺与砷的摩尔比和pH值为最显著因素,而且他们之间的相互作用也是显著的。