电动力联合可渗透反应墙修复铀污染土壤试验研究

以铀浓度为80 mg/kg的铀污染土壤作为研究对象,分别采用电动(EK)和电动-可渗透反应墙(EK-PRB)联合修复技术对铀污染土壤进行了修复对比试验,并重点考察了电流强度、pH、铀残余量和去除率等因素的变化,以及分别对两种方法修复效果的影响。结果表明,在初始pH为4.35,电压梯度1 V/cm的条件下,铀离子随着电渗流往阴极迁移效果明显。经过168 h的修复后,EK-PRB修复技术对铀的去除率最大,要比EK修复技术提高46.5%。研究表明,EK-PRB联合修复技术比单独EK修复技术有明显的优势,在修复铀污染土壤方面具有良好的发展应用前景。     

零价铁处理含铀废水的试验研究

就零价铁处理含铀废水进行了试验研究,考察了pH、震荡时间、静止时间、铁的投加量等因素对铀去除率的影响,得到了最佳实验条件.通过试验对比了铁粉和废铁屑对铀废水的处理效果,发现废铁屑比铁粉对铀的去除率更高.最后分析探讨了铁粉和废铁屑对废水中铀的去除机理,指出零价铁对废水中铀的去除符合Langmuir吸附规律.     

3种植物-人工湿地对铀尾矿库浸渍水修复效果比较

铀尾矿库浸渍水是核工业发展过程中产生铀浓度较高的工业废水,以芦苇-人工湿地(CW)、香蒲-CW、菖蒲-CW为试验组,以无植物-CW为对照组,比较研究了不同植物-CW修复铀尾矿库浸渍水的效果。结果表明,水力停留时间为36 h,经过5次循环后,3个试验组中的植物生长均未受到明显的抑制作用,各级植物-CW出水铀质量浓度均低于50μg/L,达到国家排放标准(GB 23727-2020),不同植物对铀的修复效果从高到低依次为香蒲>菖蒲>芦苇,3种植物对铀的富集系数(BCF)分别为47.16、44.60、36.68。其中铀尾矿库浸渍水经过香蒲-CW 3次循环处理后,各级CW出水铀质量浓度均低于50μg/L;经过5次循环处理后,最后一级CW出水的铀质量浓度降低至18.10μg/L,显著低于其他植物-CW的最后一级的出水铀浓度;其基质固定浸渍水中铀总量达到3.62 mg,显著高于其他处理模式。研究表明,香蒲-CW是一种具有潜在应用前景的修复铀尾矿库浸渍水的方法。     

核工业低浓度含铀废水处理技术进展

基于分析环境低浓度铀特点,总结了低浓度含铀废水传统处理方法,分析探讨乳化液膜法、膨润土法、零价铁法、生物吸附法等最新处理技术的原理、特点以及适用范围,指出多种方法综合利用是处理低浓度含铀废水的有效途径。     

脲酶驱动不同晶型碳酸钙微纳米颗粒的制备

巴氏芽孢八叠球菌（Sporosarcina pasteurii）产生的脲酶可水解尿素,生成的CO₂与氯化钙反应获得碳酸钙晶体,不同形式的脲酶溶液对碳酸钙晶型有显著影响。用发酵液上清液中的脲酶催化,可以获得由纳米级球霰石自组装成的介孔空心微米纯球霰石;用菌体中的脲酶催化可获得100%的方解石。红外光谱分析表明,细胞破碎后的粗脲酶溶液获得的椭圆形碳酸钙受到富含羟基物质的影响。进一步探究了脲酶活性和反应物浓度对球霰石的影响,并发现获得的纯球霰石在7 d内非常稳定,有望作为药物载体使用。     

纳米级零价铁处理含铀废水初步实验研究

研究了纳米级零价铁对废水中铀(Ⅵ)的去除效果,考察了纳米级零价铁投加量、pH及竞争离子等因素对处理效果的影响.结果表明,当模拟含铀(Ⅵ)废水的pH=5时,铀去除率达到99％.常见的阳离子对铀去除率没有明显影响,但二价阴离子SO42-、CO32-对铀去除率的影响显著.在相同条件下,纳米铁对铀(Ⅵ)的去除效果明显优于普通铁粉,还原速率比普通铁粉提高了15倍.     

低浓度含铀废水处理技术的研究进展

各种人为因素使得环境中的铀及其化合物越来越多,对水体造成了放射性污染。在分析环境中低浓度铀来源的基础上,介绍了对低浓度铀污染水体进行处理的最新技术,并着重探讨了应用植物修复技术处理铀污染的研究现状与发展趋势。     

啤酒酵母菌-活性污泥协同曝气处理含铀废水

采用啤酒酵母菌-活性污泥协同曝气处理含铀废水,研究了其吸附过程的吸附性能及吸附动力学。实验结果表明,啤酒酵母菌-活性污泥协同对UO22+具有良好的富集作用,在污泥质量浓度为8 g/L,啤酒酵母菌加入质量浓度为10 g/L(干质量),粒度为100—120目,吸附温度为25℃,曝气量为80—100 L/h的条件下,对初始质量浓度为100 mg/L,溶液pH值为5的铀溶液进行吸附1 h,其去除率达到96.3%。啤酒酵母菌-活性污泥协同曝气处理不同初始质量浓度铀的吸附等温线符合Langmuir和Freundlich等温吸附方程,相关系数达到0.98以上;吸附动力学过程是一个动态过程,可用准二级吸附速率方程来描述,相关系数达到0.99以上。     

土著菌群还原矿化修复铀污染地下水

本实验研究了β-甘油磷酸钠刺激下土著菌群对中性含铀模拟地下水的处理效果及机理。结果表明,β-甘油磷酸钠可同时激活生物还原和生物矿化菌群,其对铀的去除率达98%以上,微生物表面均匀沉积CaU(PO₄)₂和Mg(UO₂)₂(PO₄)₂·10H₂O等鳞片状矿物。土著菌群还原矿化铀的机理为：反应前期生物还原和生物矿化同时参与了铀的固定,且以生物矿化作用为主,Dysgonomonas,Propionispora,Macellibacteroides,unclassified＿Rhizobiaceae和unclassified＿Rhodocyclacea可能参与了溶液中U(Ⅵ)的还原,Acinetobacter促进生物矿化的发生;随后在Methyloversatilis和unclassified＿Enterobacteriaceae的作用下,部分矿化生成的U(Ⅵ)沉淀被微生物逐渐还原成U(Ⅳ)沉淀。本实验为今后微生物治理铀污染地下水的长效性能强化...     

酸法浸铀与生物浸铀浸泡试验的对比研究

近年来,生物技术在我国低品位砂岩型铀矿及老采区残留难浸铀矿的开发研究已开始起步。凭借生物浸铀具有的氧化性强、浸出液铀浓度及浸出率高等特点而成为开采该类铀矿的重要手段。文章以新疆某砂岩型难浸铀矿石浸泡浸出试验为例,系统开展了不同酸度条件下酸法浸出及不同Fe3+浓度条件下细菌浸铀试验。试验结果表明,生物浸铀在浸出液平均铀浓度、铀浸出率及浸出量等方面均高于酸法试验结果。     

Simultaneous desulfurization and denitrification of sintering flue gas via composite absorbent

Experiments on simultaneous absorption of SO_2 and NO_X from sintering flue gas via a composite absorbent NaClO_2/NaClO were carried out. The effects of various operating parameters such as NaClO_2 concentration(ms), NaClO concentration(mp), molar ratio of NaClO_2/NaClO(M), solution temperature(TR), initial solution pH, gas flow(Vg) and inlet concentration of SO_2(CS) and NO(CN) on the removal efficiencies of SO_2 and NO were discussed. The optimal experimental conditions were determined to be initial solution pH = 6, TR=55 °C and M = 1.3 under which the average efficiencies of desulfurization and denitrification could reach99.7% and 90.8%, respectively. Moreover, according to the analysis of reaction products, it was found that adding NaClO to NaClO_2 aqueous solution is favorable for the generation of ClO_2 and Cl_2 which have significant effect on desulfurization and denitrification. Finally, engineering experiments were performed and obtained good results demonstrating that this method is practicable and promising.     

无定形MnOx/SiO2催化剂的合成及低温催化氧化甲醛机理

甲醛因其污染范围广、持续时间长、危害性大等特性被视为室内有害物质的头号“杀手”。本文采用自组装法于SiO₂表面原位生长MnO_x（MnO_x/SiO₂催化剂）并用于低温催化氧化甲醛的研究,XRD、SEM-EDS、TEM和BET表征显示,MnO_x以无定形态均匀地分布在SiO₂载体表面,同时考察了MnO_x的负载量以及煅烧温度对甲醛催化活性的影响。实验结果表明,优选的质量分数13% MnO_x/SiO₂无定形催化剂具有较大的比表面积（高达164.85m²/g）和丰富的活性位点（Mn³⁺,75.6%）,而较大的比表面积有利于更多的甲醛分子吸附在催化剂表面并进行活化反应。对甲醛进行连续性动态检测,结果显示催化剂在连续催化6h后仍保持80%以上的去除效率,表明无定形催化剂具有良好的低温催化效果。随着温度的升高,催化甲醛过程中间产物（甲酸根）被进一步分解,有利于催化剂的再生使用,当温度达到90℃时,甲醛的去除效果可达90%。     

Comparative analysis of the transfer of alkaline and alkaline-earth cations across the water/1,2-dichloroethane interface

The transfer of alkaline and alkaline-earth cations across the water/1,2-dichloroethane interface in presence of 1,10-phenanthroline (phen) in the organic phase was studied using cyclic voltammetry in a concentration range wide enough to cover the following experimental conditions: C_M2+(w) C_phen(o) and C_phen(o) C_M2+(w).

The results obtained (when C_M2+(w) C_phen(o)) were compared with the theoretical voltammetric criteria reported by Homolka1l] for facilitated transfer. It appears that the transfer of all these cations occurs via a facilitated mechanism. The stoichiometry of all complexes formed in the organic phase is also reported. The stability constants for Ca²⁺-phen and Sr²⁺-phen complexes were estimated and compared with the tendency observed in the transfer potentials of these cations.     

A Co-precipitation Technique of Preparing LaNbO4 Powders

A simple co-precipitation technique was successfully used for the preparation of pure ultra fine, single-phase LaNbO₄ (LN). Aqueous sodium hydroxide was used to precipitate La³⁺ and Nb⁵⁺ cations as hydroxides simultaneously under basic conditions. For comparison, LN powders were also prepared by the traditional solid-state method. It is observed that the co-precipitation technique produces LaNbO₄ on heating at temperatures as low as ∼300°C, whereas complete phase formation occurs only at 900°C or higher in the solid-state method. The phase contents and lattice parameters were studied using powder X-ray diffraction (XRD). The XRD results show that phases obtained by both methods were different. The average particle size and morphology of these powders were analyzed by scanning electron microscope.     

亚微米LiFe0.05Mn1.95O4正极材料的制备及电化学性能

采用固相燃烧法合成了亚微米单晶多面体LiFe_0.05Mn_1.95O₄正极材料。借助XRD、FE-SEM、TEM、XPS和恒电流充放电等手段对样品的结构、形貌、物相组成和电化学性能进行测试。结果表明,Fe掺杂未改变尖晶石型LiMn₂O₄的立方晶系结构,其{400}和{440}衍射峰相对应的晶面出现显著的择优生长,形成了形貌为{111}、{110}和{100}晶面的单晶去顶角八面体晶粒。LiFe_0.05Mn_1.95O₄正极材料表现出比纯LiMn₂O₄材料更为优异的电化学性能,在1C和5C时有着114.7mA·h/g、104.7mA·h/g首次放电比容量,10C倍率下经1000次循环后,容量保持率为83.9%。循环伏安与阻抗分析得出掺杂后的样品有着较大的锂离子扩散系数与较小的活化能。对5C倍率循环1000次后Fe掺杂样品的极片分析发现,其晶体结构基本无变化,适量的Fe掺杂能够有效抑制尖晶石型LiMn₂O₄在充放电循环过程中的Jahn-Teller效应以及Mn的溶解,提升材料的结构稳定性与容量保持率。     

Radiation-induced release of hydrogen from C:H films: basic regularities and mechanism

Model calculations of the process of interaction between accelerated ions and C:H films have shown that the kinetics of the ion irradiation-induced hydrogen release (IIIHR) from C:H films and the final hydrogen concentration (ρ_f) depend only on the characteristics of the irradiating ions. The hydrogen release the cross-section K, the saturation dose Φ_sat and the ion energy loss dE/dx are connected by simple linear relationships. The final hydrogen concentration ρ_f is proportional to the number of vacancies per broken bond (C_v/P_i). The IIIHR processes are well described by the following parameter: C_v/P_i, dE/dx and C′₀. In the proposed model for the given a-C:H film and ion irradiation the primarily characteristics of the IIIHR, such as Φ_sat and ρ_f, can be estimated ‘a priori’.     

Phase Equilibria in System CaO-CO2-H2O and Related Systems, with Implications for Crystal Growth of Calcite and Apatite

Conditions for crystallization of calcite from melts in the presence of a vapor or gaseous phase are reviewed to provide possible guidelines for growth of calcite. Phase equilibrium data for the system CaO-CO₂ show that to precipitate calcite from molten CaCO₃ the temperature must be above 1230° C and excess CO₂ must be present at pressures greater than 39.5 bars. Phase equilibrium data for the system CaO-CO₂-H₂O show that calcite can be precipitated from melts at 650°C in the presence of an aqueous vapor phase at 10 bars or more. Crystallization can be induced either by introducing temperature variations, or by changing the composition of the coexisting aqueous vapor phase under isobaric, isothermal conditions. The system CaO-MgO-CO₂-H₂O is used to show that doped calcite crystals, Ca_xR₁-_xCO₃, could be precipitated, with precisely controlled compositions, from melts in the system CaO-RO-CO₂-H₂O. Apatite phase relations are also presented.     

Numerical study on hydrodynamic characteristics of spherical bubble contaminated by surfactants under higher Reynolds numbers

It is of significance to investigate deeply the hydrodynamic features of the bubble contaminated by impurities in view of the fact that the industrial liquid is difficult to keep absolutely pure. On the basis of the finite volume method, the bubble interface contaminated by the surfactant (1-pentanol) is achieved through solving the concentration transport equations in liquid and along the bubble interface, and solving the absorption and desorption equation at the bubble interface. And the three-dimensional momentum equation is solved at the same time. It is investigated in detail on the influence of interfacial contamination degrees (described with the cap angle θ) on hydrodynamic characteristics of the spherical bubble when the bubble Reynolds number (Re) is larger than 200. The θ is realized by changing the surfactant concentration (C₀) in liquid. The present results show that the hydrodynamic characteristics, such as interfacial concentration, interfacial shear stress, interfacial velocity and wake flow, are related to both Re and C₀ for the contaminated bubble. When C₀ is relatively low in liquid (i.e., the contamination degree of the bubble interface is relatively slight), the hydrodynamic characteristics of the bubble can still keep the 2D features even if Re > 200. The decrease of θ or the increase of Re can promote the appearance of the unsteady wake flow. For the present investigation, when Re > 200 and θ ≤ 60°, the hydrodynamic characteristics of the bubble show the 3D phenomena, which indicates that axisymmetric model is no longer valid.     

运用粒子图像测速仪研究双层桨搅拌槽内流体流动

The flow fields in a dual Rushton impeller stirred tank with diameter of 0.48 m （T） were measured by using Particle Image Velocimetry （PIV）. Three different size impellers were used in the experiments with diameters of D = 0.33T, 0.40T and 0.50T, respectively. The multi-block and 360° ensemble-averaged approaches were used to measure the radial and axial angle-resolved velocity distributions. Three typical flow patterns, named, merging flow, parallel flow and diverging flow, were obtained by changing the clearance of the bottom impeller above the tank base （C1） and the spacing between the two impellers （C2）. The results show that while C1 is equal to D, the parallel flow occurs as C2≥0.40T, C2≥0.38T and C2≥0.32T and the merging flow occurs as C2≤0.38T, C2≤0.36T and C2≤0.27T for the impellers with diameter of D=0.33T, 0.40T and 0.50T, respectively. When C2 is equal to D, the diverging flow occurs in the value of C1≤0.15T for all three impellers. The flow numbers of these impellers were calculated for the parallel flow. Trailing vortices generated by the lower impeller for the diverging flow were shown by the 10° angle-resolved velocity measurements. The peak value of turbulence kinetic energy （ k/V^2tip = 0.12-0.15 or above） appears along the center of the impeller discharging stream.     

Development of a new experimental method to determine critical pigment–volume–concentrations using impedance spectroscopy

The critical pigment–volume–concentration (CPVC) of a solvent-based epoxy coating with various pigment–volume–concentrations (PVC) was analyzed. It was shown that electrochemical impedance spectroscopy (EIS) is a suitable method to detect the CPVC of coatings. The CPVC can be derived from EIS Bode plots or by fitting the EIS-curves using simple equivalent circuit diagrams. The parameters pore resistance R_P, capacitance C of the constant phase element (CPE), the relative dielectric constant _R derived from C, and the exponent n of the CPE allow the determination of the CPVC.