Biosorption behaviors of Cu, Zn, Cd and mixture by waste activated sludge

Biosorption of heavy metal ions, such as Cu²⁺, Cd²⁺ and Zn²⁺, was carried out using waste activated sludge from municipal sewage treatment plant as adsorption material, and the effects of parameters, such as pH value, temperature, reaction time and sorption duration, were studied in detail. The results indicate that the removal rates of Cu²⁺, Zn²⁺ and Cd²⁺ with low concentration are 96.47%, 80% and 90%, respectively, adsorbed by waste activated sludge. Little effect of dosage of activated sludge on the adsorption of Cu²⁺ and more effects on the adsorption of Zn²⁺ and Cd²⁺ are observed. Little effect of temperature is observed, while pH value and adsorption time exert important influence on the sorption process. The adsorption behaviors of heavy metal ions all have parabolic relationships with pH value. The optimum pH value is between 6 and 10, and the optimum adsorption time is 1 h. In single heavy metal ion system, the sorption processes of Cu²⁺, Zn²⁺ and Cd²⁺ are in accordance with Freundlich model, which indicates that it is suitable for the treatment of these three heavy metal ions using intermittent operation. In addition, the sorption capacity of the sludge for Cu²⁺ is preferential to the other two ions.     

几种缓蚀剂对膨润土中16MnR钢的缓蚀作用

在放射性废物地质处置中,膨润土是首选的回填材料。膨润土膨胀、收缩过程中产生的应力会破坏废物容器的防腐蚀涂层;考虑到回填材料和地下水中含有的氯离子,可侵入到钢与膨润土界面,使钢去钝化而发生局部腐蚀。在结合工程实际的基础上,取现场地下水和柯尔碱膨润土对16MnR钢试片进行挂片腐蚀试验,分别添加六种常用的缓蚀剂,通过扫描电镜分析挂片表面腐蚀形貌,并用静态失重法计算腐蚀速率和缓蚀效率。试验结果显示,在0.5%的质量比添加条件下,缓蚀性能由高到低依次为亚硝酸钠、重铬酸钾、硅酸钠、钨酸钠、磷酸钠和钼酸钠,说明采用添加缓蚀剂改善16MnR钢废物容器腐蚀环境的方法是可行的。     

Electrochemical behavior of carbon steel with bentonite/sand in saline environment

Current designs for the geological disposal of high-level radioactive waste in Japan use carbon steel overpack containers surrounded by a mixed bentonite/sand buffer material, which will be located in a purpose-built repository deep underground. Though there are many suitable sites for a repository in Japan, the coastal areas are preferable from a logistical point of view. It is, therefore, important to evaluate the long-term performance of the carbon steel overpack and the mixed bentonite/sand buffer material in the saline groundwaters of coastal areas. In the current study, the passivation behavior and initial corrosion rates of carbon steel with and without mixed bentonite/sand were tested as a function of the pH and salt concentration in representative saline groundwaters. The main findings indicate that the passivation of carbon steel encapsulated in a buffer material will be unlikely in a saline environment, even at high pH (12), and that the corrosion rate of carbon steel is more strongly affected by the presence of the buffer material than by the salt concentration.     

Issues Relevant to Recycling of Stainless-Steel Pickling Sludge

Stainless-steel pickling sludge is a hazardous solid waste. Harmless treatment and recycling of this sludge are major research topics. Based on the sludge formation process, two typical types of stainless-steel pickling sludge were chosen and their physiochemical properties determined by chemical analysis, differential thermal analysis/thermogravimetry, and x-ray diffraction analysis. Possible approaches to recycle the sludge were suggested, and relevant problems are discussed. Based on its high water and sulfur contents, as well as the valuable metals that could be recovered from sludge, drying, roasting, and reduction tests were carried out. It was found that Fe and Cr were mainly present in oxides, Ca in Ca(OH)₂ and CaF₂, and sulfur in CaSO₄. Natural drying was a very slow process, but forced drying at temperatures above 423 K was effective. Sulfur could be partly removed from sludge through roasting and reduction at high temperatures, with most of the sulfur being transferred to gas and slag in the reduction process; however, this treatment did not allow sludge with high sulfur content to be used as a suitable raw material in terms of sulfur level requirements. It is suggested that prepickling and pickling waste liquors should be treated to reduce output of high-sulfur sludge to promote sludge recycling. Optimized reduction conditions were identified in terms of additional carbon content (1.3 times as suggested by theoretical data) and temperature (above 1673 K) for high metal recovery.     

Reaction of native copper in contact with pyrite and bentonite in anaerobic water at elevated temperature

Copper pellets were reacted with different solutions, reference minerals, and well-characterised bentonites to investigate the effect of different bentonites on the stability of native copper in repository concepts for high-level radioactive waste. The reaction of Cu in contact with bentonite used as barrier material to store high-level radioactive waste was significantly affected by the presence of sulphides (e.g. pyrite) leading to a specific corrosion. Bentonites free of pyrite are not actively involved in a reaction with Cu. Nevertheless, slightly different Cu mass losses were found for different bentonites. For different bentonites, different coatings were found on the Cu surface. The characteristics of these coatings are probably responsible for different Cu mass losses of Cu in contact with different bentonites. As an example, particularly dense coatings led to a decrease in Cu mass loss. No relation of the Fe-corrosivity of different bentonites with Cu mass loss was found, which proves that the Fe-corrosion mechanism differs from the Cu-corrosion at the metal/bentonite interface. The experiments also demonstrated the importance of the presence even of traces of oxygen.     

异丙酚对大鼠脊髓背角神经元TTX敏感型钠通道失活和去失活效应的影响

目的: 观察异丙酚对急性分离的大鼠脊髓背角神经元TTX敏感型钠通道电流的影响及相关机制。方法: 取出生后7d的雄性SD大鼠,击昏后断头取脊髓腰膨大部位,分离背角神经元,应用全细胞膜片钳记录模式记录钠电流。距离神经细胞100μm施加0.3～30 μmol/L不同浓度的异丙酚,应用-10mV(持续30ms)刺激电压诱发钠电流,求出异丙酚对钠电流的半效抑制浓度(IC₅₀)。观察异丙酚对钠通道失活效应的影响时,应用从-80mV至-20mV的预刺激电压(阶差为10mV,持续30ms),再应用0mV刺激电压(持续30ms)诱发钠电流产生,向神经细胞施加IC₅₀水平的异丙酚。观察异丙酚对钠通道去失活效应的影响时,应用-10mV的预刺激电压(持续30ms),再给予-10mV、持续30ms的刺激电压诱发钠电流产生,两刺激电压的间隔时间为2～24ms。结果: 异丙酚可浓度依赖性地抑制TTX敏感型钠电流,其IC₅₀为(5.35±0.25) μmol/L。钠通道失活实验中,预刺激电压在-60mV到-40mV范围内,IC₅₀水平的异丙酚可显著抑制由刺激电压(0mV)诱发的钠电流(P<0.05)。钠通道去失活实验中,两刺激的间隔时间在2～6ms之间时,IC₅₀水平的异丙酚可显著性抑制由刺激电压(-10mV)诱发的钠电流(P<0.01,P<0.05)。结论: 异丙酚可抑制大鼠脊髓背角电压依赖性钠通道电流,这一作用与促进钠通道的失活和抑制钠通道的去失活有关。     

HCO3-和SO42-对Cu点蚀行为的影响

在不同浓度配比的HCO₃^-和SO₄^2-混合溶液中,利用循环极化电化学测试方法和SEM,对Cu工作电极的循环极化行为和点蚀表面形貌进行了系统的研究.结果表明,在高电位范围的循环极化实验中,Cu的点蚀行为可分为活性溶解型点蚀和钝化膜破裂型点蚀;随SO₄^2-浓度的升高Cu点蚀的敏感性增大.由于HCO₃^-与SO₄^2-的协同作用,随HCO₂^-浓度升高点蚀敏感性呈先增大后减小的规律.在钝化膜破裂型点蚀中,SO₄^2-提高Cu点蚀的诱发能力;HCO₃^-降低Cu点蚀的诱发能力.2种离子对点蚀自修复能力的影响无明显规律.     

基于微透析技术及HPLC-ESI-MS测定大鼠关节腔透析液中双氯芬酸钠浓度及其应用

目的: 利用微透析技术为采样平台,以双氯芬酸钠为工具药,建立大鼠膝关节腔透析液中双氯芬酸钠的HPLC-ESI-MS测定方法,满足非甾体类抗炎药物靶部位药物采集及测定的需求。方法: 采用HPLC-MS单极四极杆联用技术,通过优化色谱、质谱条件,建立快速灵敏的双氯芬酸钠的液-质测定方法,并将该法应用于大鼠关节腔透析液中双氯芬酸钠浓度的测定。本法所用色谱柱为Waters Symmetry-C₁₈(dp 5 μm,150 mm×2.1 mm ID),流动相为甲醇-0.1%甲酸 (80∶20,V/V)。结果: 本实验建立的大鼠膝关节腔透析液中双氯芬酸钠的HPLC-ESI-MS测定方法的最低定量限为 1.95 ng/mL,在 1.95~125 ng/mL 范围内线性关系良好,批内批间精密度均小于10%。介质效应在 99.9%~113.4%之间。结论: 本实验成功地将微透析技术引入到大鼠关节腔部位的取样过程中, 建立的大鼠关节腔透析液中双氯芬酸钠的HPLC-ESI-MS测定方法快速,灵敏。两者的结合有助于实现对以双氯芬酸钠为代表的非甾体类抗炎药物作用靶部位的取样及其药动学研究。     

第一性原理研究掺杂过渡元素对碳化钨性能的影响

碳化钨(WC)在高温动力装备上应用越来越多,WC的脆性和高密度限制了其更广泛的使用,金属原子掺杂是提高WC性能的一种方法。采用基于第一原理的广义梯度作为近似交换相关函数,研究了A_0.25W_0.75C(A为Ti、V、Cr、Mn、Co和Ni)的弹性、电子和X射线吸收特性。数值分析结果显示,Ti_0.25W_0.75C的B/G值(B为体模量,G为剪切模量)为1.869,改性为延性材料,其它均为脆性材料。掺杂25%的V、Co、Ni原子可使WC的脆性降低,掺杂25%的Cr、Mn原子可使WC脆性增大。掺杂后化合物的态密度分布范围减小,费米能级处数值增大,金属性增强,其中Mn_0.25W_0.75C金属性最强。参杂后X射线吸收谱蓝移,在软X射线波段存在吸收波段,其中Cr、V、Ti在15.74~22.25nm波段出现强吸收峰。研究结果有助于塑性低密度WC类化合物的实验和应用研究。     

Nanocrystalline LaNi4−xMn0.75Al0.25Cox electrode materials prepared by mechanical alloying (0≤x≤1.0)

Polycrystalline hydrogen storage alloys based on lanthanum (La) are commercially used as negative electrode materials for the nickel–metal hydride (Ni–MH_x) batteries. In this paper, mechanical alloying (MA) was used to synthesize nanocrystalline LaNi_4−xMn_0.75Al_0.25Co_x (x=0, 0.25, 0.5, 0.75 and 1.0) hydrogen storage materials. XRD analysis showed that, after 30 h milling, the starting mixture of the elements decomposed into an amorphous phase. Following the annealing in high purity argon at 700 °C for 0.5 h, XRD confirmed the formation of the CaCu₅-type structures with a crystallite sizes of about 25 nm. The nanocrystalline materials were used as negative electrodes for a Ni–MH_x battery. Cobalt substituting nickel in LaNi₄Mn_0.75Al_0.25 greatly improved the discharge capacity and cycle life of the LaNi₅ material. For example, in the nanocrystalline LaNi_3.75Mn_0.75Al_0.25Co_0.25 powder, discharge capacities up to 258 mA h g⁻¹ (at 40 mA g⁻¹ discharge current) were measured. Mechanical alloying is a suitable procedure to obtain LaNi₅-type alloy powders for electrochemical energy storage.     

Influence of Deteriorated Bentonite Sediments on the Corrosion Behavior of NiCu Low Alloy Steel

The corrosion evolution of steel disposal container largely depends on the evolution of surrounding bentonite environment in the long-term geological disposal of high-level radioactive wastes. This study focused on the influence of the deteriorated bentonite sediments on the corrosion behavior of NiCu low alloy steel in the top supernatant and bottom slurry formed by Gaomiaozi bentonite and 0.05 M NaHCO₃ + 0.1 M NaCl + 0.1 M Na₂SO₄ solution. In the top supernatant, the cathodic process of the steel corrosion was transformed from the reduction in oxygen to the reduction in ferric corrosion products with time as same as that in the blank solution. While in the bottom bentonite slurry, the cathodic process always maintained as the hydrogen evolution reaction due to the coverage of more bentonite sediments. Meanwhile, the corrosion rate of NiCu steel was obviously decreased. In addition, the localized corrosion tendency of the steel could also be reduced by the large amount of deteriorated bentonite sediments.     

An anode for solid oxide fuel cells: NiO+(Ce0.9Ca0.1O1.9)0.25(YSZ)0.75 solid solution

A (CCO)_0.25(YSZ)_0.75 solid solution (YSZ is Y₂O₃-stabilized ZrO₂; CCO is an abbreviation of Ce_0.9Ca_0.1O_1.9) was successfully synthesized by a solid-state method. A composite anode material, NYC_x (60 wt% NiO+40 wt% (CCO)_x(YSZ)_1−x), for SOFCs (solid oxide fuel cells) was prepared. XRD results suggest that a solid solution reaction occurs between YSZ and CCO after sintering at 1400 °C for 10 h. From the impedance results, the conclusion can be drawn that the (CCO)_0.25(YSZ)_0.75 solid solution is a mixed conductor (ionic and electronic). Its total conductivity is greater than that of YSZ. The NYC_x (x>0) anodes exhibited better performance than the commonly used Ni+YSZ anode with regards to overpotential and anode interfacial impedance, with the NYC_0.25 anode exhibiting the best performance     

Characterization of Corrosion Behavior of Irradiated X65 Low Carbon Steel in Aerobic and Unsaturated Gaomiaozi Bentonite

2.98 kGy/h(1007 h) gamma irradiation and 90 ℃(2000 h) thermal aging were exerted to X65 grade low carbon steel buried in Gaomiaozi bentonite containing 17 wt% Beishan groundwater. The average corrosion rate of X65 low carbon steel was measured. The elemental and phase distribution on cross section was characterized by using electron probe micro-analysis, high-resolution X-ray diffraction, and micro-X-ray diffraction. The following conclusions can be made: the average aerobic corrosion rate of the carbon steel is(45.16 ± 1.53) μm/year. Taking the original surface as boundary, the corrosion scale is divided into an internal dense product layer(DPL) mainly composed of Fe_3O_4 with segregated FeCO_3 at the corrosion front and an external DPL mainly composed of Fe_3O_4 with segregated α-Fe_2O_3 and bentonite at some relics.Si, S, and Cl are concentrated at the corrosion front of the internal DPL, while Si and Al are concentrated at the external DPL.     

Microstructure and Mechanical Behavior of CrFeNi2V0.sWx (x=0, 0.25)High-Entropy Alloys

CrFeNi₂V_0.5W_x (x = 0, 0.25) alloys based on these parameters of mixing enthalpy (ΔH_mix), mixing entropy (ΔS_mix), atomic radius difference (δ), valance electron concentration, and electronegativity difference(Δχ) were designed and prepared. The microstructure and room-temperature mechanical behavior of both alloys were investigated. Compressive test results showed that the CrFeNi₂V_0.5W_0.25 alloy had higher yield strength than that of the W-free CrFeNi₂V_0.5 alloy, although they all exhibited quite larger compressive plasticity (ε > 70%). Compression fracture surface of CrFeNi₂V_0.5W_0.25 alloy revealed a ductile fracture in the face-centered cubic (FCC) phase and a brittle-like fracture in the σ phase. Moreover, tensile test results indicated that the CrFeNi₂V_0.5W_0.25 alloy exhibited excellent mechanical property with an ultimate tensile strength of 640 MPa and a high tensile elongation of 15.7%. The tensile deformation mode of the FCC phase in the CrFeNi₂V_0.5W_0.25 alloy is dominated by planar glide, relating to dislocation configurations, high-density dislocations, and dislocation wall. Therefore, dislocation slip plays a significant role in tensile deformation of CrFeNi₂V_0.5W_0.25 high-entropy alloy. The higher strength of CrFeNi₂V_0.5W_0.25 alloy is predominantly due to the solid solution strengthening of W element and σ phase precipitation strengthening. Combination of the higher tensile strength and plasticity suggests that the CrFeNi₂V_0.5W_0.25 alloy can be a promising aerospace material.     

The thermal treatment of galvanic sludges for environmental compatibility

Eleven galvanic sludges were investigated on a laboratory scale at the Institute of Metallurgy, Technical University of Berlin. Rotary, flash, and arc-furnace techniques were used to pyrometallurgically treat and melt the sludges. The waste material was leached before and after thermal treatment. Concentrations of metals in the eluates were compared with drinking water as well as land filling (dumping) standards. The results show that the slag, obtained after melting the galvanic sludge, is the only environmentally agreeable product. Drying, glowing, or roasting the sludge deteriorated the environmental compatibility. Alloys were produced by flash smelting (Cu-Ni) and arcfurnace processing (Fe-Si-Cr), but they do not satisfy quality standards.     

磷酸肌酸钠停搏液对心功能不全瓣膜病患者的心肌保护作用

目的: 探讨磷酸肌酸钠(CP)对心功能不全瓣膜病患者术后心肌保护作用。方法: 将82例择期行瓣膜置换术或成形术的慢性心功能不全患者随机分为两组:(1)对照组,常规使用4∶1含血心脏停搏液;(2)外源性磷酸肌酸钠组(CP组),在心脏停搏液中加入注射用磷酸肌酸钠。于转机前及术后 24 h 分别采血测定心肌酶谱,记录术后血管活性药物使用及机械通气等情况。结果: CP组的心肌酶谱各指标均显著低于对照组(P<0.05);心脏自动复跳率明显高于对照组(P<0.05);机械通气时间也较对照组缩短(P<0.05);血管活性药物应用量均较对照组小(P<0.05)。结论: 心脏停搏液中加入磷酸肌酸钠有明显的心肌保护作用,有利于心功能不全瓣膜病患者术后心功能恢复。     

连铸铁泥制备纳米α-Fe2O3及光催化去除Cr(Ⅵ)

连铸铁泥富含铁元素,资源化利用是必然选择。以连铸铁泥为原料,采用水热法成功制备纳米α-Fe₂O₃,实现高附加值利用。研究结果显示,所制备的纳米α-Fe₂O₃为均匀的球状介孔结构,比表面积为48.78 m²/g,平均晶粒尺寸约40～50 nm,较大的比表面积与较小的晶粒尺寸可提供大量的光催化活性位点,有利于提升材料的光催化性能。将纳米α-Fe₂O₃应用于Cr(Ⅵ)脱除的光催化剂,显示较好的Cr(Ⅵ)废水脱除效果,180 min内去除率可达100%。经过5次循环后,Cr(Ⅵ)的去除效率仍可达到89.2%,说明纳米α-Fe₂O₃具有良好的可重复使用性。对光催化去除Cr(Ⅵ)的反应机理进行研究,表明光生电子(e^-)、羟基自由基(·OH)和超氧阴离子(·O₂^-)是参与Cr(Ⅵ)去除的主要活性物质。本研究可将工业副产品连铸铁泥转化为高附加...     

Mortars for encapsulating sacrificial zinc anodes in reinforced concrete

Expansion measurements, chemical analysis and petrography have been undertaken to assess a possible side‐effect of using strongly alkaline additives (lithium hydroxide or sodium hydroxide) in encapsulating mortars used to promote the activity of sacrificial zinc anodes employed for galvanic cathodic protection of steel in concrete. Very high concentrations of lithium hydroxide in the encapsulating mortars were found to cause no deleterious expansion associated with alkali‐silica reaction (ASR) in surrounding “model” concrete specimens even when the latter contained aggregate of known susceptibility to ASR and a near‐threshold level of intrinsic alkalinity. Encapsulating mortars formulated with an equivalent molarity of sodium hydroxide, however, were found to induce significant expansion due to ASR in similar specimens.     

Effect of rapid solidification on the microstructure and corrosion behaviour of Al-Zn-Mg based material

The corrosion behaviour of Al-5Zn-3Mg-0.6Cu-0.8Zr-0.25Cr-0.15Ni-0.15Ti alloys, produced by traditional and powder technologies, with similar thermo-mechanical treatments, in 3% sodium chloride solution, has been examined by electrochemical methods, scanning electron microscopy, transmission electron microscopy and X-ray microanalysis. The alloys reveal similar precipitation but of different shape, size and distribution; further, both alloys experience localized corrosion. Copper-rich precipitates initiate the dissolution of surrounding particles, enriched in Zn and Mg. As a result, the surface is enriched with other alloying elements after a full polarisation run. Cast material has lower corrosion properties because of the higher heterogeneity of the structure. The structure heterogeneity of the cast material involves a more non-uniform distribution of the precipitates, larger Zn- and Mg-rich particles, and depletion of the matrix and areas around the precipitates by alloying elements compared with the powder material.     

Rapid preparation of ceramic moulds for medium-sized superalloy castings with magnesia-phosphate-bonded bauxite-mullite investments

Phosphate-bonded investments have already been widely utilized in dental restoration and micro-casting of artistic products for its outstanding rapid setting and high strength.However,the rapid setting rate of investment slurry has up to now been a barrier to extend the use of such slurry in preparation of medium-sized ceramic moulds.This paper proposes a new process of rapid fabrication of magnesia-phosphate-bonded investment ceramic moulds for medium-sized superalloy castings utilizing bauxite and mullite as refractory aggregates.In order to determine the properties of magnesia-phosphate-bonded bauxite-mullite investments (MPBBMI),a series of experiments were conducted,including modification of the workable time of slurry by liquid(mL)/powder(g)(L/P) ratio and addition of boric acid as retard agent and sodium tri-polyphosphate (STP) as strengthening agent,and adjustment of bauxite (g)/mullite(g)(B/M) ratio for mechanical strength.Mechanical vibration was applied to improve initial setting time and fluidity when pouring investment slurry;then an intermediate size ceramic mould for superalloy castings was manufactured by means of this rapid preparing process with MPBBMI material.The results showed that the MPBBMI slurry exhibits proper initial setting time and excellent fluidity when the UP ratio is 0.64 and the boric acid content is 0.88wt.%.The fired specimens made from the MPBBMI material demonstrated adequate compression strength to withstand impact force of molten metal when the B/M ratio is 0.89 and the STP content is 0.92wt.%.The experimental results confirmed the feasibility of the proposed rapid fabricating process for medium-sized ceramic moulds with MPBBMI material by appropriate measures.