综合案例法在化学反应工程教学中的应用研究

化学反应工程学是一门研究涉及化学反应的工程问题的学科,是化工和应化等工科专业的专业基础课,在培养化工类专业人才中起着由理论到工程、由基础到专业的桥梁作用。本文提出"综合案例"教学法,以实际工程案例专题为例介绍了该方法在化学反应工程课程中的应用情况和实施效果。实践证明,综合案例式教学法优于传统教学法,实用性和趣味性较强,有助于加强和巩固学生的学习能力。     

糖蜜厌氧发酵制备生物燃气的快速启动

糖蜜是一种制糖的副产物,富含各类有机物,常被用作发酵底物制备各类化工品,但鲜有用于制备生物燃气的报道。本研究采用糖蜜为底物以液态连续进料的方式实现了厌氧发酵的快速启动,COD去除率达70%以上,沼气产率达0.65 m~3/kg以上,沼气甲烷含量达80%以上。该工艺可克服传统固体/半固体沼气发酵启动周期长,产气效率低等缺点,因此具有一定的产业化潜力。     

UV/Co-TiO_2/PMS体系催化氧化降解钻井废水的研究

采用浸渍法制备了Co-TiO_2复合催化剂,通过X射线衍射(XRD)、扫描电镜(SEM)和X射线能谱(EDS)对其进行表征,催化剂呈单一的锐钛矿结构,且Co均匀分布于TiO_2表面;研究了UV/Co-TiO_2/PMS体系对钻井废水的降解能力,考察了过硫酸氢钾(PMS)用量、催化剂用量、pH、温度等因素对钻井废水COD_(Cr)去除率的影响,并获得了最佳工艺参数:催化剂用量0.1 g,氧化剂PMS用量1.8 g,紫外功率250 W,温度35℃,初始pH为5,反应时间2.5 h。钻井废水COD_(Cr)去除率高达82.73%,BOD_5/COD_(Cr)值从0.0283提高至0.2646,明显改善了废水的可生化性。     

有机噻吩分子器件的研究进展

本文对分子电子学器件的发展历程作了简要回顾,着重阐述了基于有机噻吩的分子器件的研究进展,指出了噻吩分子器件研究过程中有待解决的一些问题,希望对噻吩分子器件的研究提供一个有意义的参考。     

Modeling the temperature-dependent mode I fracture behavior of adhesively bonded joints

An ethylene propylene diene monomer (EPDM) rubber film has been used as an inhibitor and insulation in solid rocket motors (SRMs) due to its excellent heat-insulating property. EPDM is wrapped on the surface of the grain layer-by-layer via an adhesive; thus, the adhesive property between EPDM films is one of the key factors that influence the structural integrity of an SRM. The adhesive properties are largely temperature dependent, therefore, it is essential to study the effect of temperature on the properties of the bonding interface between EPDM films. In this article, double cantilever sandwich beam (DCSB) and uniaxial tensile experiments were performed to study the temperature-dependent mode I fracture of the bonding interface, in the service temperature range of the SRMs. A comparison of experimental and numerical results obtained using experimental parameters indicates that the fracture parameters determined by the simple beam theory (SBT) and the compliance-based beam method (CBBM) are not accurate. Next, we obtained accurate parameters using an inverse analysis method. Moreover, we made an initial attempt to establish a temperature-dependent cohesive zone model to predict the temperature-dependent fracture behavior of adhesively bonded joints. Good agreement between experimental and numerical results demonstrates that this temperature-dependent model is applicable.     

有机亚砜类催化剂催化氧化脱硫脱硝研究

为了开发简易、有效和成本低的燃煤烟气污染物控制方法,搭建模化试验系统,对有机亚砜类催化剂催化氧化脱硫脱硝一体化技术进行了研究。结果表明,在烟气温度150℃左右,有机亚砜类催化剂可以高效脱除单质汞和硫氧化物,并且可以脱除合成烟气中的大量氮氧化物;通过添加氢氧化铵控制系统pH值,汞脱除效率可达95%;溶液pH6.3,SO_2脱除率99.5%以上,pH4时,SO_2脱除率低于60%;NO_x的脱除取决于烟气中的NO和NO_2的相对形态,实际操作中烟气入口处通入强氧化剂O_3,将NO氧化为N_2O_3和NO_2,再进行后续的脱除,可以保证烟气中氮氧化物的脱除效率不低于80%。结果表明采用有机亚砜类催化剂是在低温条件下处理燃煤烟气多种污染物的可行选择。     

Heterogeneous amino acid-based tungstophosphoric acids as efficient and recyclable catalysts for selective oxidation of benzyl alcohol

A series of organic-inorganic composite catalysts, prepared by modifying tungstophosphoric acid (TPA; H₃PW₁₂O₄₀) with different amino acids such as phenylalanine (Phe), alanine (Ala), and glycine (Gly) were synthesized. The physicochemical and acidic properties of these (MH) _x H_3?x PW₁₂O₄₀ (M=Phe, Ala, and Gly; x=1–3) composite materials were characterized by a variety of different analytical and spectroscopic techniques, namely TGA, XRD, FT-IR, XPS, and NMR, and exploited as heterogeneous catalysts for selective oxidation of benzyl alcohol (BzOH) with hydrogen peroxide (H₂O₂). Among them, the [PheH]H₂PW₁₂O₄₀ catalyst exhibited the best oxidative activity with an excellent BzOH conversion of 99.0% and a desirable benzaldehyde (BzH) selectivity of 99.6%. Further kinetic studies and model analysis by response surface methodology (RSM) revealed that the oxidation of BzOH with H₂O₂ follows a second-order reaction with an activation energy of 56.7 kJ·mol^?1 under optimized experimental variables: BzOH/H₂O₂ molar ratio=1 : 1.5 mol/mol, amount of catalyst=6.1 wt%, reaction time (x₃)=3.8 h, and amount of water (x₄)=30.2 mL.     

Microwave dielectric properties of (1‐x)Ba3.75Nd9.5Cr0.25Nb0.25Ti17.5O54–xNdAlO3 ceramics

This study presents the microwave dielectric properties calculation of (1‐x)Ba_3.75Nd_9.5Cr_0.25Nb_0.25Ti_17.5O₅₄–xNdAlO₃ ceramics where x denotes the volume molar fraction. From X‐ray diffraction results, the solid solution limit is calculated to be about 0.76, where it forms a single BaNd₂Ti₄O₁₂ phase in Region I (0≤x<0.76), and both BaNd₂Ti₄O₁₂ and NdAlO₃ coexist in Region II (0.76≤x<1). The solid solution limit is confirmed by independently calculating it from the dielectric constant data. There is less than 4% deviation between the measured dielectric constant (ε_r) and the one calculated from the Maxwell‐Wagner formula. The total quality factor (Q) remains almost constant in Region I and increases rapidly with the volume molar fraction of NdAlO₃ in Region II. The measured Q×f, where f is the resonant frequency, is also consistent with the calculated value in both regions. The temperature coefficient at the resonant frequency is ?1.4 ppm/°C, which agrees well with the calculated value of 0 ppm/°C. In addition, we observed a close correlation between the bulk density and the phase evolution.     

新型天然胶乳生物保存剂在标准胶制备中的应用研究

研究新型天然胶乳生物保存剂(简称生物保存剂)在标准胶制备中的应用,并与传统保存剂氨进行对比。结果表明:随着生物保存剂和氨质量分数的增大,天然胶乳的保存时间延长,当生物保存剂的质量分数大于0.010(按干胶计)时,天然胶乳的保存时间超过10 h;与采用氨保存的天然胶乳制备的标准胶相比,采用生物保存剂保存的天然胶乳制备的标准胶凝固用酸(甲酸)量大幅度减小,回收率较高,灰分含量、杂质含量、挥发分含量和塑性初值较大,塑性保持率和门尼粘度较低,胶料物理性能无明显差异,生产成本较低,生产环境改善。     

Microwave‐Assisted Hydrothermal Synthesis of Submicrometer Willemite Phase Zinc Silicate and Its Zinc Ion Release Behavior

As an important trace element in human bone, zinc (Zn) has a great influence on bone metabolism. The aim of this work was to prepare a Zn‐containing material that can release Zn ions. For this purpose, submicrometer willemite phase zinc silicate (Zn₂SiO₄, ZS) with poor crystallinity was synthesized at 110°C via the microwave‐assisted hydrothermal (MH) method. Under the MH condition, the growth of ZS was consistent with “multi‐core growth” mechanism. Moreover, the influences of the reaction temperature and the reactant concentration on the final products were investigated in detail. The inductively coupled plasma atomic emission spectroscopy (ICP) data indicated that the poor crystallinity ZS could successfully release Zn for at least 28 d as soaking in the simulated body fluid (SBF). Without the replenishment of SBF, ~333 μM Zn was released from ZS synthesized at 110°C (ZS‐110). If SBF was periodically replenished once a day, more Zn was released from ZS‐110, and the parascholzite phase calcium zinc phosphate hydrate (CaZn₂(PO₄)₂·2H₂O) formed during the soaking process of ZS‐110. Under the concentration of 6.25 mg/mL, the extract of ZS‐110 was proved to be nontoxic by assessing with mouse osteoblast cells (MC3T3). Therefore, the poor crystallinity ZS has potential to be incorporated into the orthopedic reconstructive materials as a source of Zn ions, which can improve the bioactivity of the materials.