铂钯精矿中氯化银的浸出预处理研究

铜阳极泥分铜液所得铂钯精矿中的银主要以氯化银(AgCl)形态存在，可用氨水或亚硫酸钠作为浸出剂去除银。绘制了Ag⁺与NH3、SO2- 3配体组分图，结合电位-pH图分析表明，氨浸的pH值范围为7.7~13.5，亚硫酸钠浸出宜在中性或碱性条件下进行。优化条件实验结果表明，银的氨浸浸出率为95.3%，碲浸出率为14.9%，有微量铂、钯浸出；以亚硫酸钠为浸出剂，银的浸出率为97.3%，碲浸出率为11.5%，金、铂和钯均不被浸出。亚硫酸钠更适于作为铂钯精矿预处理除银的浸出剂。     

纯镁表面硅烷/透明质酸钠复合涂层的结构及腐蚀性能研究

纯镁因较快的腐蚀速率使其用于手术移植材料成为了一个障碍。为了控制其降解速率,本研究采用BTSE(1,2-(三乙氧基硅基)乙烷)硅烷化处理和共键嫁接1-(3-二甲氨基丙基)-3-乙基碳二亚胺盐酸盐(EDC)/N-羟基丁二酰亚胺(NHS)交联改性的透明质酸钠涂层的两步制备工艺在纯镁上制备复合涂层。同时使用红外光谱(FTIR)、X射线光电子能谱(XPS)、原子力显微镜(AFM)和静态接触角方法(CA)分析涂层的物化性能,通过电化学行为分析涂层在模拟体液中的耐腐蚀性能。FTIR和XPS结果表明在纯镁表面上成功的制备出复合涂层;其他结果显示,交联透明质酸钠涂层表面较裸镁、硅烷表面更平整、光滑,且呈现出亲水性,提高了其生物活性;与未改性的纯镁相比,复合涂层的腐蚀电流密度减小了2个数量级,阻抗值提高3个数量级,表现出很好的耐腐蚀性能。表明这种复合涂层作为手术移植材料在医学上具有很大的应用前景。     

球磨工艺和分散剂对陶瓷结合剂粉体解团聚的影响

通过球磨工艺和添加分散剂相结合的方法对陶瓷结合剂团聚体进行解团聚，研究球磨参数和分散剂添加量对解团聚效果及结合剂机械性能的影响，并用激光粒度分析仪、SEM、万能材料试验机测试结合剂粉体解团聚前后的粒度、显微形貌、抗折强度。结果表明:采用小粒径(5 mm)的磨球，添加质量分数为2.5%的分散剂球磨2 h后，结合剂粉体分散性良好，基本没有团聚现象，其D₅₀可降至0.186 μm，且球磨后的粉体在700 ℃烧结后，其抗折强度达到26.2 MPa，比原始团聚体烧结后样品的强度提升了近45%。      

水煤浆管道输送摩阻损失研究

以十二醇醚为分散剂,进行了水煤浆管道输送实验研究,分析了分散剂浓度和煤浆浓度变化对煤浆摩阻损失的影响。煤浆管道输送数据分析及理论计算结果表明: 分散剂浓度越大,煤浆摩阻损失值越小; 水煤浆浓度越大,摩阻损失值越大。实验数据拟合结果表明有效黏度与平均切变率成线性关系,从理论上给出了煤浆摩阻损失的计算公式,计算值与实测值偏差不大于18%。     

Inferring kinetic dissolution of NaCl in aqueous glycol solution using a low-cost apparatus and population balance model

An experimental methodology for inferring brine dissolution rate in monoethylene glycol (MEG) solutions at different temperatures using a webcam combined with a mathematical model is presented. The measurement system is designed to track the RGB (red, green, and blue) colour variations during the dissolution process. A dynamic model augmented with the population balance equation is applied to describe the dissolution process. Moreover, the dissolution rate is consistently related to the temperature and MEG concentration through the driving force based on the Gibbs energy and chemical affinity. The applied low-cost measurement apparatus proved to be a useful resource for tracking the dissolution dynamics in a wide range of undersaturation.     

Li-doping stabilized P2-Li0.2Na1.0Mn0.8O2 sodium ion cathode with oxygen redox activity

The discovery of the oxygen chemistry phenomenon reveals bright future toward new sustainable layered Na-based transitional oxides. However, the poor capacity retention problem of the cathode has hindered the development of sodium ion batteries (SIBs). In this work, a new Li-doped compound Li_0.2Na_1.0Mn_0.8O₂ is proposed, which demonstrates refined cycling durability with 51.6% after 100 cycles at 50 mA g⁻¹, superior than Na_1.2Mn_0.8O₂ with only one cycle. Then in situ X-ray diffraction (XRD) and density function theory (DFT) are employed to explore the lattice distortion and confirm stable lattice framework introduced by Li atoms with eliminated P2-O2 phase transition upon cycling, guaranteeing outstanding electrochemically stable performance. In addition, Li_0.2Na_1.0Mn_0.8O₂ demonstrates activation of Mn as well as O chemistry redox in the lattice, detected by ex situ electronic paramagnetic resonance spectroscopy (EPR) as well as in situ Raman, which indicate not only Na-deficient Mn-based layered oxide but also Na-rich Mn-based compound can represent oxygen redox.     

Phase diagram of the Li2SO4–Na2SO4 system

The thermal analysis and X-ray powder diffraction studies of the Li₂SO₄–Na₂SO₄ system, including the high-temperature X-ray diffraction technique, have elucidated four phases of variable composition: three solid solutions based on the α-Li₂SO₄, α-Na₂SO₄, and α-LiNaSO₄ high-temperature polymorphs, and a low-temperature β-LiNaSO₄ phase. α-Na₂SO₄-Base solid solution disintegrates into two phases via a monotectoid phase transformation. It is quite probable that the monotectoid process is related to the conversion of the second-order phase transition to the first-order phase transition.     

Nickel cobalt oxide nanowires-modified hollow carbon tubular bundles for high-performance sodium-ion hybrid capacitors

Sodium-ion hybrid capacitors are a prospective energy storage device candidate that couples the superiorities of battery-type and capacitive storage mechanisms. In this study, we fabricate a composite of NiCo₂O₄ nanowires with carbon tubular bundles (CTBs) via a facile hydrothermal and annealing procedure. The density functional theory (DFT) calculations are performed to evaluate the bonding strength between the two components of the composite, the binding energy of the NiCo₂O₄ is calculated to be −0.952 J m⁻², indicating that the NiCo₂O₄ nanowires can be stabilized on both sides of the carbon tubular bundles, which leads to a good cycling performance. Moreover, the composite in this work exhibits a metallic property because of the introduction of carbon material. As expected, when used for sodium storage, the NiCo₂O₄/CTBs shows a high capacity of 298 mA h g⁻¹ at 1 A g⁻¹ and high capacity retention of 92% after 500 cycles, which are superior than the bare NiCo₂O₄ electrode. Consequently, the sodium-ion hybrid capacitor is also assembled with NiCo₂O₄/carbon tubular bundles and commercial activated carbon, which achieves high energy density of 99 Wh kg⁻¹ in a wide potential range from 0.5 V to 4.0 V.     

Peracetic acid as a single endodontic irrigant: effects on microhardness,roughness and erosion of root canal dentin

The aim was to assess the effects of 1% peracetic acid (PAA) as a single endodontic irrigant on microhardness, roughness, and erosion of root canal dentin, compared with 2.5% sodium hypochlorite (NaOCl) and with 2.5% NaOCl combined with 17% EDTA. Forty human, single‐rooted tooth hemisections were submitted to Knoop microhardness test, before and after the following irrigation protocols: PAA = 1% PAA; NaOCl = 2.5% NaOCl; NaOCl‐EDTA‐NaOCl = 2.5% NaOCl +17% EDTA +2.5% NaOCl; and SS = saline. Another 40 roots were instrumented, irrigated with the same protocols, and sectioned longitudinally. The roughness analysis was performed on the mesial section using a confocal laser scanning microscope, whereas erosion was analyzed on each third of the distal section, using a scanning electron microscope. The data were analyzed using ANOVA and Tukey post‐tests, and Kruskal‐Wallis and Dunn post‐tests (α = .05). The PAA and NaOCl‐EDTA‐NaOCl groups showed no significant differences (p > .05); both promoted reduction in microhardness and increase in roughness, compared with the NaOCl and SS groups (p < .05). NaOCl‐EDTA‐NaOCl promoted higher erosion in the cervical and middle thirds than the other groups (p < .05); there was no difference among PAA, NaOCl, and SS (p > .05). There was also no difference among the groups regarding the apical third (p > .05). PAA used as a single endodontic irrigant caused reduction in root canal dentin microhardness and increase in roughness in a similar way to NaOCl‐EDTA‐NaOCl; however, PAA caused less erosion than NaOCl‐EDTA‐NaOCl.