表面活性剂对Ni-P-Al2O3复合镀层性能的影响

目的 改善Ni-P-纳米Al2O3复合镀层的均匀性,提高其耐蚀性能.方法 采用化学镀法在Q235钢表面制备Ni-P纳米Al2O3复合镀层,分析纳米Al2O3添加量(0～10g/L)对镀层形貌的影响.施镀过程中选用不同种类的表面活性剂来分散纳米Al2O3,通过XRD分析镀层的相组成,采用SEM、EDS研究镀层形貌和成分,通过测量施镀前后纳米Al2O3的Zeta电位来研究非均一镀液的稳定性和纳米粒子的分散性能,利用电化学阻抗手段研究镀膜样品在3.5％NaCl水溶液中的耐蚀性能,从而分析镀液中表面活性剂的种类和用量对复合镀层的影响.结果 随着镀液中纳米粒子添加量的增加,镀层中Al2O3含量先增加后趋于稳定,同时镀层表面纳米Al2O3团聚现象也随之加剧.添加一定量表面活性剂之后,镀层变得均匀,纳米粒子团聚减少,其中阳离子表面活性剂(十六烷基三甲基溴化铵)在低浓度下就能对纳米Al2O3分散产生显著作用,而阴离子表面活性剂(十二烷基苯磺酸钠)需在较高浓度下才能达到相似效果.结论 当镀液中阴离子表面活性剂用量为1.25cmc,Al2O3添加量为6g/L时,镀层最为均匀,且样品在3.5％NaCl水溶液中耐蚀性能最好.     

Hydrotalcite as sorbent for trinitrophenol: Sorption capacity and mechanism

The aim of this work was to evaluate the sorbent power of hydrotalcite compound [Mg₃Al(OH)₈]₂CO₃·xH₂O (HT) and its calcined product Mg₃AlO₄(OH) (HT500) for 2,4,6-trinitrophenol (TNP) from water solution. The adsorption behaviour of TNP was investigated at diverse solid/solution ratios, pH and TNP concentration by batch equilibration technique. The L and H type adsorption isotherms obtained in those sorbents respectively indicated a chemisorption process which was irreversible and fitted the Langmuir equation model well. Sorption capacity and energy were found to be very high for HT500. The X-ray diffraction and IR spectroscopy techniques applied to TNP-HT and TNP-HT500 products indicate that anionic TNP is adsorbed by anion exchange in the interlayer of HT to 20% of the anion exchange capacity (AEC) and, by reconstruction of the layered structure on HT500, to 40% of the AEC. The results suggested the potential use of HT500 as a filter for TNP, being also easily recyclable.     

Nickel powder blended activated carbon cathodes for hydrogen production in microbial electrolysis cells

Although pure Ni catalysts can achieve a hydrogen production rate similar to Pt in microbial electrolysis cells (MECs), a reduction in the amount of Ni used is needed to reduce the cost. In this study, nickel powder (pNi) was blended with activated carbon (AC) to reduce the mass of Ni used, while improving catalytic activity for the hydrogen evolution reaction (HER) by increasing the active surface area. Ni powder blended AC cathodes (AC-pNi) were fabricated at different nickel powder loadings (4.8, 19, 46 mg/cm² with AC and 77 mg/cm² without AC as control). AC-pNi4.8 (Ni loading: 4.8 mg/cm²) produced higher hydrogen production rates (0.38 ± 0.04 L-H₂/L-d) than pNi77 (0.28 ± 0.02 L-H₂/L-d) with a 16 times less Ni loading. Cathodic hydrogen recovery of using the AC-pNi4.8 (98 ± 5%) was also higher than pNi77 (82 ± 4%), indicating catalytic activities were improved by AC blending. Nickel dissolution into the catholyte after completion of each cycle was negligible for AC-pNi4.8 (<0.2 mg/L), while Ni dissolution was detected for pNi77 (5–10 mg/L). These results indicate that AC blending with Ni powder can improve hydrogen production in MECs while minimizing the amount of Ni in the cathode.     

机械蒸汽再压缩系统的设计及其在食品工业中的应用

从热力学的角度对MVR系统进行了分析,并主要对蒸发器、蒸汽压缩机、预热器进行数学模型的构建。综述MVR技术在国内外食品工业上的应用。     

Hydrogen production from formaldehyde steam reforming using recyclable NiO/NaF catalyst

Harmless disposal of formaldehyde for hydrogen production is attractive in energy and environmental science. Herein, hydrogen production from formaldehyde steam reforming (FSR) using recyclable NiO/NaF was investigated, and the optimized 4 wt% catalyst exhibited 100% formaldehyde conversion, 104.9% H₂ selectivity and excellent stability at 400 °C. The used catalysts can be easily recycled by water washing and pickling, and the activity of the regenerated catalyst is comparable to that of fresh one. We confirmed that FSR was a rapid surface reaction process, and the special contribution of NaF ensured the high activity of NiO/NaF with low specific surface areas. F ions in the carrier could activate the surface OH, which promoted adsorption and oxidation to reactants. Furthermore, the in situ DRIFTs study revealed that formate species (HCOO) was the key intermediate in formaldehyde steam reforming. Formaldehyde was first oxidized to HCOO and then decomposed into CO₂ and H.     

Ni-SDC cermet anode fabricated from NiO–SDC composite powder for intermediate temperature SOFC

We report a cost-effective processing method for fabricating intermediate temperature solid oxide fuel cells (SOFCs) with Ni-samaria doped ceria (SDC) anode. First, SDC and NiO powders were mechanically treated to make their composite powder. Then, the composite powder was applied into a ceramic tape casting method to form a thick layer for the anode supporting. Finally, an anode supported single cell with a configuration of Ni-SDC/SDC/La_0.6Sr_0.4Co_0.2Fe_0.8O_3 − δ (LSCF) was prepared. Because of the usage of the composite powder, homogenous distribution and connection of each Ni and SDC were achieved. Peak power densities of 460, 750 and 910 mW cm⁻² were obtained on the single cell at 550, 600 and 650 °C, respectively.     

Improved corrosion performance of electrophoretic coatings by silane addition

Organosilanes are incorporated into a commercial cathodic electrophoretic paint, resulting in significant improvement in the long-term corrosion protective properties of the paint. The addition of organosilanes have strengthened mechanical properties, improved hydrophobicity, lowered water uptake and less decrease in glass transition temperature of the coatings, suggesting the enhancement in bulk structure of the polymeric coatings. In addition, silane-enriched layer preferentially forms at the metal/coating interface during the electrophoresis process, leading to better adhesion between the substrate and the coating. The structural enhancement in both the coating and the metal/coating interface explains the improved corrosion performance of silane-incorporated electrophoretic coatings.     

Hollow core–shell ZnMn2O4 microspheres as a high-performance anode material for lithium-ion batteries

The hollow core–shell ZnMn₂O₄ microspheres are successfully prepared by a solvothermal carbon templating method and then a annealing process. The crystal phase and particle morphology of resultant ZnMn₂O₄ microspheres are characterized by XRD and TEM. The electrochemical properties of the ZnMn₂O₄ microspheres as an anode material are investigated for lithium ion batteries. The results show that the ZnMn₂O₄ microspheres exhibit a reversible capacity of 855.8 mA h g⁻¹ at a current density of 200 mA g⁻¹ after 50 cycles. Even at 1000 mA g⁻¹, the reversible capacity of the ZnMn₂O₄ microspheres is still kept at 724.4 mA h g⁻¹ after 60 cycles. The enhanced electrochemical performance suggests the promising potential of the hollow core–shell ZnMn₂O₄ microspheres in lithium-ion batteries.     

Synthesis,characterization and spectroscopic properties of some new azo disperse dyes derived from 4-hydroxybenzo[h]quinolin-2-(1H)-one as a new synthesized enol type coupling component

4-Hydroxybenzo[h]quinolin-2-(1H)-one (IV) was synthesized from the cyclocondensation of 3-(naphthalen-1-ylamino)-3-oxopropanoic acid (I) or N,N′-di(naphthalen-1-yl)malonamide (II) and subsequently coupled with diazotized p-substituted aniline derivatives. The structures of the synthesized dyes were determined by spectroscopic and analytical methods. Solvent effects on the ultraviolet–visible absorption spectra of these novel azo dyes were studied in six pure organic solvents with different polarities. The color of the dyes is discussed with respect to the nature of substituents on the benzene ring. The tautomeric structures of the azo compounds were studied by ¹H NMR spectroscopy in DMSO-d₆ and CDCl₃. The effects of acid and base on the visible absorption spectra of the dyes were also reported. Ionization constants, pK_a, for these dyes were determined in 80 vol. % ethanol–water medium at room temperature and correlated with the substituent constant, σ_p.