金色链霉菌连续培养特性及其动力学研究

研究了以碳源为限制性底物时金色链霉菌连续培养特性和动力学。实验结果表明,Streptomycesaureofaciens的比生长速率与限制性底物浓度的关系符合Monod方程,并得到动力学参数max=0.0649h-1和Ks=8.47gL-1。菌体和产物金霉素chlortetracycline的得率系数分别为1.866gg-1和2.580gg-1,维持系数为0.0051g(gh)-1。菌体和产物的最大产率为0.859g(Lh)-1和0.0299g(Lh)-1。菌体和产物对氧的得率系数分别为60.81gmol-1和64.33gmol-1,对氧的维持系数为0.3390mmol(gh)-1。磷氧比P/O等于2.77。呼吸商RQ与m呈线性正比关系,随着m的减小,碳源代谢流从酵解途径逐渐向戊糖途径增强。代谢流的这种迁移有利于产物金霉素chlortetracycline的合成。     

FeII(EDTA)络合吸收NO体系中吸收液的生物再生

利用驯化的微生物对FeII(EDTA)NO的再生进行了研究.结果表明,驯化过程中,分子量相对较低的乙醇比葡萄糖更适合于作为该体系的碳源200mg·L-1的乙醇添加量可以使9.92 mmo1·L-1FeII(EDTA)NO完全再生,添加过量碳源对反应速率没有促进作用.当FeII(EDTA)NO浓度为7.3 mmol·L-1,菌体接种量大于80mg(菌体干重)·L"时就能满足再生需要.生物再生的适宜pH值和温度范围分别为6 5～7.5和30～42.5℃;实验考察条件下,该反应符合一级降解动力学,最大反应速率ymax为5.4mmo1·L-1·h-1,半饱和速率常数km为63.8mmo1·L-1.     

复盐结晶法生产磷酸二氢钾结晶动力学研究

研究了用三聚氰胺结晶法由湿法磷酸生产磷酸二氢钾的结晶动力学过程。考察了搅拌、振动、杂质对结晶过程的影响及不同降温速率对结晶习性的影响,拟合并给出结晶动力学方程,采用差热分析和热重分析仪测试了结晶产品的脱水特性。     

IPN中聚氨酯固化反应动力学的FTIR研究

用傅立叶变换红外光谱(FTIR)研究纯聚氨酯弹性体和聚氨酯/聚二甲基硅氧烷IPN中聚氨酯的固化反应动力学。结果表明,在PU/PDMS IPN体系中聚氩酯的交联反应仍为二级反应,聚二甲基硅氧烷的存在大大降低了PU/PDMS IPN的交联速率,并提高了反应活化能。     

Oxidative decomposition of naphthalene by supported metal catalysts

A fixed-bed reactor was utilized to investigate the activities of six metal catalysts (1% Pt, 1% Pd, 1% Ru, 5% Co, 5% Mo and 5% W on γ-Al₂O₃ support) in decomposing naphthalene, based on the production of carbon dioxide and the disappearance of naphthalene. The Pt and Pd catalysts were found to exhibit higher naphthalene oxidizing activity than other catalysts tested. The Co catalysts, whose activity is similar to that of the Ru catalysts, are promising for naphthalene oxidation. The kinetic results of naphthalene oxidation over 1% Pt/γ-Al₂O₃ catalysts are reported for the first time. A first-order reaction with respect to P_naphthalene was found, while the reaction order with respect to P_O2 decreased with increasing reaction temperatures. A Langmuir–Hinshelwood model was used to describe the observed kinetic behavior. Oxygen adsorption dominates at higher reaction temperatures (>140 °C), and consequently the oxidation of naphthalene over the Pt catalysts appeared to be insensitive to P_O2.     

Oxidation kinetics for <Emphasis Type="Italic">cis</Emphasis>-9,<Emphasis Type="Italic">trans</Emphasis>-11 and <Emphasis Type="Italic">trans</Emphasis>-10,<Emphasis Type="Italic">cis</Emphasis>-12 isomers of CLA

The autoxidation processes of the cis-9,trans-11 (c9,t11) and trans-10,cis-12 (t10,c12) isomers of CLA were separately observed at ca. 0% RH and different temperatures. The t10,c12 CLA oxidized faster than the c9,t11 isomer at all tested temperatures. The first half of the oxidation process of t10,c12 CLA obeyed an autocatalytic-type rate expression, but the latter half followed first-order kinetics. On the other hand, the entire oxidation process of c9,t11 CLA could be expressed by the autocatalytic-type rate expression. The apparent activation energies and frequency factors for the autoxidation of the isomers were estimated from the rate constants obtained at various temperatures based on the Arrhenius equation. The apparent activation energies for the CLA isomers were greater than those for the nonconjugated n−6 and n−3 PUFA or their esters. However, the enthalpyentropy compensation held during the autoxidation of both the CLA and PUFA. This suggested that the autoxidation mechanisms for the CLA and PUFA were essentially the same.     

US/H2O2系统协同降解苯酚的动力学研究

超声波 过氧化氢 (US H2 O2 )复合氧化过程在废水处理领域有很广泛的应用前景 ,但在动力学方面的研究很少 ,为此研究了US H2 O2 工艺降解苯酚的动力学 .结果表明 ,苯酚在单独超声波辐射 (US)、过氧化氢 (H2 O2 )氧化和超声波 过氧化氢 (US H2 O2 )协同下的降解均符合表观一级动力学 .在单独的超声波辐射或者过氧化氢氧化下苯酚去除率很小 ,而在复合氧化过程US H2 O2 工艺中有显著的提高 ,表明协同效应存在 .苯酚去除的速率常数增强因子可达到 6 90 4 .进一步从US H2 O2 系统中存在US、H2 O2 和羟基自由基 (·OH) 3部分协同作用的降解机理 ,推导出了简化的机理动力学模型 ,很好地反应过氧化氢浓度过量条件下苯酚的降解 .     

One‐pot synthesis of binderless zeolite A spheres via in situ hydrothermal conversion of silica gel precursors

One‐pot synthesis route was explored for preparing binderless zeolite A via an in situ hydrothermal transformation process involving the preformation of silica gel precursors. Synthesis process was optimized and resulting samples were characterized using XRD, Raman spectroscopy, EDS, ²⁹Si and ²⁷Al NMR spectroscopy, SEM, HRTEM, and pore structure analyses. Furthermore, the kinetics for the in situ synthesis was investigated and the underlying crystallization mechanism was interpreted. The transformation of silica precursors was accomplished via controlling the synthesis parameters which govern the crystallization through determining the dissolution rate of silica nanoparticles, diffusion of Al species into silica precursors and crystal nuclei growth. Subsequently, Al species could contact and react with released Si species from silica nanoparticles to build the structural units that finally construct the LTA framework through self‐organized arrangement. On pure zeolite A phase basis, the synthesized binderless sample exhibits higher specific surface area and n‐paraffins adsorption capacity than binder‐containing zeolite. © 2018 American Institute of Chemical Engineers AIChE J, 64: 4027–4038, 2018     

The effect of curing temperature on thermal,physical and mechanical characteristics of two types of adhesives for aerospace structures

The effects of cure temperatures on the thermal, physical and mechanical characteristics of two types of thermosetting structural epoxy film adhesives were determined in detail. The aim of this paper is to assess the effect of cure temperatures (82–121 °C) on the degree of cure of the two adhesives and the relevant void formations that need to be addressed in bonded part production and repair. Two thermal parameters were used to characterize the advancement of the reaction, such as degree of cure and glass transition temperature. The joint properties with respect to the cure temperatures were characterized by void content and bond-line thickness measurements and lap shear strength tests. Experimental results presented that all lap shear strengths were well within minimum shear strength (29 MPa) required by the specification of the film-type adhesive. However, the lap shear strength testing after aging at 82 °C and 95%R.H for 1000 h showed that the improved durability when the adhesive is cured at 121 °C did not occur for the 82 °C cure. Low curing conversion (75–77% degree of cure) combined with high voids (over 2 areal%) has a catastrophic effect on the bonding qualities at the metal-adhesive interface and due to lack of cohesion in the adhesive. The changes in the interface caused by the low temperature curing may contribute to an increased susceptibility of the bonded joint to moisture and consequent bond-line degradation.