铁、钴、镍、铜和锌催化剂催化氨硼烷水解产氢性能研究

采用浸渍-还原法制备了铁、钴、镍、铜和锌催化剂,考察了其催化氨硼烷水解产氢性能,并优化了钴催化剂的制备条件和反应条件。结果发现,铁催化剂中铁以Fe₂B合金相存在,钴催化剂中钴以金属钴存在,镍催化剂中镍以金属镍和Ni（OH）₂·2H₂O存在,铜催化剂中铜以金属铜和氧化亚铜存在,锌催化剂中锌以Zn₄SO₄（OH）₆·4H₂O存在。铁、钴、镍、铜和锌催化剂催化氨硼烷水解产氢活性由大到小顺序为钴催化剂、镍催化剂、铜催化剂、铁催化剂、锌催化剂。显然,具有金属钴相的钴催化剂、金属镍相的镍催化剂和金属铜相的铜催化剂催化氨硼烷产氢活性高于具有Fe₂B合金相的铁催化剂。锌催化剂在制备条件下不能被还原为金属相,它几乎没有催化氨硼烷产氢活性。氯化钴与还原剂硼氢化钠的物质的量比为1∶1.3、还原温度为303 K时制备的钴催化剂催化BH₃NH₃水解产氢性能最佳。反应动力学计算表明钴催化剂催化BH₃NH₃水解产氢反应对氨硼烷浓度的反应级数为零级,对钴催化剂浓度的反应级数为一级,活化能为58 kJ/mol。     

无机盐对生物硝化功能的影响

为确定不同的无机盐对硝化菌群的抑制作用,采用批量实验研究了氯化钠、硫酸钠和氯化钙3种无机盐在不同浓度下的生物硝化过程。研究结果表明:3种无机盐质量浓度均为10 g/L时,硫酸钠对硝化菌群的抑制作用最小,氯化钠对硝化菌群的抑制作用最大。3种无机盐质量浓度均为20 g/L时,硫酸钠对硝化菌群的抑制作用最小,氯化钙对硝化菌群的抑制作用最大。无机盐对硝化菌群的抑制作用除了与渗透压有关以外,还与处理系统p H有关。     

Papain Adsorption on Chitosan-Coated Nylon-Based Immobilized Metal Ion (Cu2+, Ni2+, Zn2+, Co2+) Affinity Membranes

A novel immobilized metal affinity membrane was prepared for papain adsorption in this article. Higher papain adsorption capacity between 43-67 mg/g was observed and the adsorption isotherm fitted the Freundlich equation. Experimental data were analyzed using two adsorption kinetic models. The pseudo-second-order kinetic model provided better correlation to the experimental results. A significant amount of the adsorbed papain was eluted by 1.0 M NaSCN at pH 5.0 for all affinity membranes. It was concluded that the novel chitosan-coated nylon-based immobilized metal ion affinity membrane could be applied for the large-scale isolation of papain without resulting in enzyme denaturation.     

Microstructural evolution and mechanical properties of (Mg,Co,Ni,Cu,Zn)O high-entropy ceramics

The reaction sequence and mechanical properties were studied for (Mg,Co,Ni,Cu,Zn)O high-entropy ceramics that were synthesized using field-assisted sintering technology. The evolution from binary oxide starting powders to a single-phase rock salt structure exhibited a distinct incorporation sequence. For the rock salt oxides, MgO and CoO had the lowest vacancy formation energies and were the first to be incorporated into the high-entropy ceramic followed by NiO, which had a higher vacancy formation energy. Both CuO and ZnO had different crystal structures, and were incorporated into the single phase structure after the rock salt oxides due to the additional energy barrier associated with the transformations from their original structures to the rock salt structure. Distinctive morphological features including Cu-rich regions and lattice distortion were observed in the high entropy ceramic. In addition, a trade-off between densification and grain growth resulted in a maximum in strength (323 MPa) and elastic modulus (108 GPa) after densification at 900°C. This study has revealed new information that can be used to design other high-entropy ceramics including selection criteria for constituent compounds based on crystal structure and defect formation energy as well as the effects of grain size and porosity on control strength and elastic modulus.     

Particle Size Comparison of Soft-Chemically Prepared Transition Metal (Co, Ni, Cu, Zn) Aluminate Spinels

Nanocrystalline MAl₂O₄ (M=Co, Ni, Cu, Zn) spinel powders are synthesized by pyrolysis of complex compounds of aluminum and transition metal (cobalt, nickel, copper, and zinc) with triethanolamine (TEA). The precursor materials are formed on complete dehydration of the soluble complexes of aluminum–TEA and transition metal–TEA (Co, Ni, Cu, Zn), maintaining the resulting pH of each of the solutions at 4–5. The precursors are heat treated at different temperatures to provide phase formations. Single-phase MAl₂O₄ spinel powders were obtained after heat treatment of the precursor material at 600°C, but for CuAl₂O₄, the precursor passed through an intermediate-phase CuO at a lower treatment temperature. The precursor and the heat-treated powders were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectrometry, thermal gravimetric and differential thermal analysis, and transmission electron microscopy (TEM); the surface area was measured by a Brunauer–Emmet–Teller (BET) adsorption isotherm. The average particle sizes that were obtained from XRD, TEM, and BET adsorption isotherm were compared.     

The interaction between Cu,Pb, Zn and Ni in their biosorption onto polyurethane‐immobilised Sphagnum moss

The uptake of Cu(II), Pb(II), Zn(II) and Ni(II) was investigated both individually and from mixed metal ion solutions using Sphagnum moss biomass immobilised in a polyurethane support. The data were evaluated using the Langmuir isotherm equation, and sorption capacities were calculated for different concentration ranges. It was concluded that care must be taken in presentation and interpretation of results when this modelling approach is applied at low concentrations. Repeated metal loading cycles also gave lower values for sorption capacity compared with the maximum potential value, due to equilibrium effects. The uptake capacity for the different metals on a weight basis was in the order lead > copper > zinc > nickel, but on a molar basis this changed to copper > lead > nickel > zinc. Sorption from a multi‐component metal system showed that lead and copper competed equally for binding sites and much more effectively than zinc and nickel. Equations were derived to predict the percentage effect on a given metal ion of other metals in a multi‐metal system based their behaviour in the relevant single and binary systems. Copyright © 2005 Society of Chemical Industry     

Aqueous sulphur dioxide leaching of Cu,Ni, Co,Zn and Fe from smelter slag in absence of oxygen

Smelter slag and sulphur dioxide are waste products of non‐ferrous pyrometallurgical processes. Dissolution behaviour of Co, Cu, Fe, Ni and Zn from smelter slag in aqueous sulphur dioxide was studied. Experiments were carried out in batch mode, under near ambient conditions. Under the conditions studied, 81% Co, 60% Fe, 35% Ni and 68% Zn extraction were achieved within 3 h, while Cu behaved very differently. The initial dissolution of Cu was rapid, but subsequent precipitation lowered its overall extraction. The precipitation of Cu was more temperature sensitive than its dissolution. At 65°C all the dissolved Cu was precipitated in 2.5 h. The successive precipitation was explained based on the solution chemistry of the Cu‐Fe‐S(IV) system. Dissolution kinetics of the other metals were evaluated using the shrinking core model. Diffusion through the product/ash layer appeared to be the rate controlling step. SEM‐EDS analysis was used to characterize the slag and to confirm the existence of a product/ash layer after leaching.     

Fenton处理对污泥脱水性、重金属形态及生物淋滤效率影响

为考察污泥预处理过程中重金属迁移转化规律,通过投加不同量的Fenton试剂对污泥进行处理,分析了Zn、Cd、Mn、Ni四种重金属的化学形态变化与后继生物淋滤过程的溶出行为。研究结果表明,污泥经Fenton处理后,毛细吸水时间在短时间内降低,但对生物淋滤后最终的污泥脱水性没有显著提升作用;重金属Zn、Cd、Mn的不稳定态（弱酸提取态、可还原态）比例不同程度提高,当投加Fe²⁺=1.00g/L、H₂O₂=9.00g/L时,其比例分别由37%、84%、79%上升至90%、93%、84%,但Ni无明显变化。此外,Fenton处理污泥中Zn、Cd、Mn、Ni四种重金属生物淋滤后含量分别由3451.52mg/kg、6.45mg/kg、443.40mg/kg、94.96mg/kg降至376.74mg/kg、1.10mg/kg、141.66mg/kg、21.77mg/kg,比单独生物淋滤处理污泥重金属残余量分别降低了36.20%、26.17%、30.92%和27.89%。利用动力学方程较好地描述了生物淋滤过程中Zn、Cd、Mn、Ni四种重金属的溶出速率的相对大小,排序为Mn＜Cd＜Zn＜Ni。     

Defect structure and transport properties in (Co,Cu,Mg,Ni,Zn)O high entropy oxide

The defect structure and chemical diffusion in the (Co,Cu,Mg,Ni,Zn)O high entropy oxide were investigated. The material was synthesized in a form of pellets by means of a solid-state reaction, through sintering the mixture of composing oxides at 1273 K for 20 h, followed by the air quenching. The presence of the single-phase, high entropy solid solution structure was confirmed with the use of SEM + EDS and XRD methods and later confirmed after each of the experimental steps. The modification of the standard marker experiment was applied, to determine the predominantly disordered sublattice, which turned out to be the anionic one. The nonstoichiometry and its dependence on the oxygen partial pressure were investigated by means of the thermogravimetric method. The results allowed establishing the (Co,Cu,Mg,Ni,Zn)O_1-y general formula, with values of y reaching values as high as 0.07 under low oxygen partial pressures. The non-logarithmic character of the obtained pressure dependence suggests the presence of a complex structure of interacting point defects. The chemical diffusion coefficient was also determined, based on the measured re-equilibration kinetics. The obtained values of diffusivity are within the range typical for the transition metal oxides, do not confirm the presence of the sluggish diffusion effect in high entropy oxides. The established strong dependence of the chemical diffusion coefficient on the p(O₂), further confirms the presence of the complex defect structure.     

Influence of chemical speciation on the separation of metal ions from chelating agents by nanofiltration membranes

The simultaneous separation of various metal ions (nickel, copper, calcium, and iron) from chelating agents (EDTA and citric acid) in water streams using Nanofiltration membranes is analyzed. Assuming that multiply-charged species are highly rejected, chemical speciation computations reproduce the observed patterns of metal and ligand rejection at different pH values and concentrations. The separation of metal ions from citric acid is achieved in acidic conditions, where multiply-charged free metal ions and neutral or singly charged free chelating species are abundant. Overall, speciation studies help to evaluate the applicability of Nanofiltration for recycling chelating agents used for metal extraction.     

FA与FNA对两级UASB-A/O处理垃圾渗滤液短程硝化的影响

采用两级UASB-A/O组合工艺处理实际高氨氮城市生活垃圾渗滤液,在获得稳定的有机物与氮同步去除的前提下,重点考察游离氨(FA)与游离亚硝酸(FNA)对短程硝化稳定性的影响。在UASB1中进行反硝化同时产甲烷以去除部分TN和部分COD,在UASB2通过产甲烷进一步去除COD,在A/O反应器中主要实现高氨氮的短程去除和剩余COD的降解。试验共进行104 d,历经短程硝化稳定、破坏和恢复3个阶段。结果表明,当最小FA浓度控制在3.1 mg.L-1以上时,系统可维持稳定的短程硝化,NH+4-N去除率、NO-2-N积累率、TN去除率分别可达到99%、95%和86%。当FA浓度小于0.6 mg.L-1时,在原水碱度充足且过曝气的条件下,仅依靠FA对NOB的抑制作用,难于维持短程硝化,NO-2-N积累率下降到29%。前两阶段的FNA浓度均低于0.011 mg.L-1,没有对NOB起到抑制作用,而在第3阶段,FA浓度仍维持在较低浓度,但系统FNA浓度通过降低pH值而大幅度提高(最大值为0.414 mg.L-1),从而利用FA和FNA的协同抑制作用迅速恢复并维持短程硝化,NO-2-N积累率升高到92%。可见FA与FNA是实现并维持城市生活垃圾渗滤液短程硝化的重要影响因素。     

Electroflotation Studies on Cu,Ni, Zn,and Cd with Ammonium Dodecyl Dithiocarbamate

Abstract

The concentration of Cu, Ni, Zn, and Cd ions by electroflotation using the ammonium salt of dodecyl dithiocarbamic acid as an anionic collector is examined. Quantitative studies reveal better separation efficiency by this method as compared to column flotation using dodecyl dithiocarbamic acid ligand as a chelating surfactant.     

pH值和碱度对生物硝化的影响

研究了低pH值和低碱度条件下好氧硝化菌对氨氮的硝化作用.试验表明,硝化细菌的硝化效果良好.在实际应用中可以少投加或不投加碱源,依靠来水维持好氧池中硝化细菌所需碱度,节省污水处理成本.     

苯酚对氨氧化菌硝化和污泥性能冲击影响

以苯酚为毒性抑制剂,短程硝化污泥为对象,分析研究了不同苯酚浓度对氨氧化菌硝化过程的抑制特性和抑制动力学,以及对污泥胞外聚合物组分及呼吸速率的短期冲击影响。结果表明,55 mg·L-1苯酚的存在使硝化速率降低37%;低浓度苯酚条件下（< 80 mg·L-1）符合Monod单分子一级动力学方程,且为可逆性抑制,恢复后呼吸速率可达20～25 mg O2·L-1·h-1;且因接种污泥含大量异养菌使得抑制常数（52.871 mg·L-1）远大于纯硝化菌群系统。另外,苯酚的存在促使菌群启动自我保护机制产生更多的胞外聚合物(EPS)抵抗环境变化。苯酚浓度升至135 mg·L-1时,蛋白质和多糖分别增加87.4%和311.7%;而且EPS组分发生相应变化,蛋白质/多糖（P/C）与初始COD/氨氮（C/N）比呈负相关性,P/C从22.1降至3.80。     

干灰化-火焰原子吸收分光光度法测定头发中钙铁锌铜

采用干灰化法处理发样,用火焰原子吸收分光光度法连续测定其Fe、Zn、Ca、Cu的含量。结果表明,本方法相对标准偏差≤2%,加标回收率83.65%~113.2%。本法简便有效,能同时大批量测定样品,检测结果准确。