Thermodynamics of nitrogen adsorption on the zeolite H-FER

Adsorption (at a low temperature) of nitrogen on the protonic zeolite H-FER results in hydrogen bonding of the adsorbed N₂ molecules with the zeolite Si(OH)Al Brønsted acid groups. This hydrogen bonding interaction leads to activation, in the IR, of the fundamental NN stretching mode, which appears at 2331 cm⁻¹. From the infrared spectra taken over a temperature range, while simultaneously recording integrated IR absorbance, temperature and nitrogen equilibrium pressure, the thermodynamics of the adsorption process was studied. The standard adsorption enthalpy and entropy resulted to be ΔH° = −20(±1) kJ mol⁻¹ and ΔS° = −131(±10) J mol⁻¹ K⁻¹, respectively.     

Etching reaction of methylchloride molecule on the GaAs (0 0 1)-2 × 4 surface

Adsorption process of methylchloride (CH₃Cl) on the GaAs (0 0 1)-2 × 4 surface was studied by a scanning tunnelling microscopy (STM) measurement. The arsenic rich 2 × 4 surface, which was prepared by molecular beam epitaxy (MBE), was exposed to a supersonic molecular beam of CH₃Cl with a kinetic energy of 0.06 eV. New bright spots appeared on the CH₃Cl exposed surface. They were largely observed at the “B-type” step edge and divided into two types according to their locations. It was suggested that new spots were due to weakly adsorbed CH₃Cl molecules without any dissociation. The adsorption mechanism of CH₃Cl molecule was also studied by an ab initio Hartree-Fock calculation, which explained the experimental results well.     

喷动床内颗粒浓度的实验测量和理论模拟

颗粒浓度对于稠相流动体系中颗粒应力本构方程建立具有决定性的作用。本文采用双流体模型,并结合颗粒流动力学理论来描述固相应力的基础上实现了对喷动床的数值模拟,探讨了从喷射区到环隙区颗粒浓度的理沦变化趋势。同时采用自主开发的电容探针技术,不仅颗粒浓度测量值和理论值吻合较好,而且也准确地验证了颗粒非均匀夹带这一现象。电容探针还可灵敏地分辨出环隙区内不同床高处以及接近壁面处的颗粒浓度的细微变化。     

热烟气启动流化床的数学模型

1引言在流化床锅炉能够正常运行之前，必须进行点火操作，把惰性床料流化加热到足够高的温度，以使燃料能够开始燃烧。用高温热烟气经由布风板加热床层，传热效率较高，易于实现自动控制，能够明显缩短启动时间，减少辅助燃料消耗，目前国外普遍采用这种方法山。在我国第一台中试PFBC锅炉的启动中，就将采用热烟气启动的方式。为了对热烟气启动增压流化床进行模拟研究，提出了一种热烟气启动流化床的简化模型二本文提出的简化模型，考虑了扬析、磨损等因素，力求物理概念正确、简单实用、功能强；特别是借鉴对于间隙扬析过程的处理方法，…     

作物生长的土壤中氧气浓度场的稳态数值模拟

建立了一个描述土壤中热、湿、气耦合迁移的数学模型,对有冬小麦生长的圆柱形土壤床中的氧气浓度场进行 了数值模拟。结果表明,土壤床中的氧气浓度场与冬小麦的生长发育阶段、上壤的孔隙率以及土壤床的高度等因素密切相 关。     

玉米芯流化床快速热解制取生物油试验研究

本文在流化床上对玉米芯进行了快速热解制取生物油的试验研究.首先在非催化条件下考察了温度、气体流量、床高和物料粒径对热解产物产率的影响,得到了制取生物油的最优工况.在此工况下进行了催化热解试验,研究了FCC催化剂对热解产物产率和生物油品质的影响.结果表明,最优工况下生物油产率为56.8%.同未加催化剂相比,FCC催化剂的存在使得生物油中油组分和焦炭的产率降低,不凝结气体、水分和焦的产率增加.分级冷凝系统的应用较好的实现了重油、轻油和水的分离.对催化条件下第二级冷凝器收集的生物油分析表明,其油组分的氧含量和高位热值分别为13.64%和36.7 MJ/kg,具有很好的应用前景.     

Application of ZnO nanorods loaded on activated carbon for ultrasonic assisted dyes removal: Experimental design and derivative spectrophotometry method

A method based on application of ZnO nanorods loaded on activated carbon (ZnO-NRs-AC) for adsorption of Bromocresol Green (BCG) and Eosin Y (EY) accelerated by ultrasound was described. The present material was synthesized under ultrasound assisted wet-chemical method and subsequently was characterized by FE-SEM, TEM, BET and XRD analysis. The extent of contribution of conventional variables like pH (2.0–10.0), BCG concentration (4–20 mg L⁻¹), EY concentration (3–23 mg L⁻¹), adsorbent dosage (0.01–0.03 g), sonication time (1–5 min) and centrifuge time (2–6 min) as main and interaction part were investigated by central composite design under response surface methodology. Analysis of variance (ANOVA) was adapted to experimental data and guide the best operational conditions mass by set at 6.0, 9 mg L⁻¹, 10 mg L⁻¹, 0.02 g, 4 and 4 min for pH, BCG concentration, EY concentration, adsorbent dosage, sonication and centrifuge time, respectively. At these specified conditions dye adsorption efficiency was higher than 99.5%. The suitability and well prediction of optimum point was tested by conducting five experiments and respective results revel that RSD% was lower than 3% and high quality of fitting was confirmed by t-test. The experimental data were best fitted in Langmuir isotherm equation and the removal followed pseudo second order kinetics. The experimentally obtained maximum adsorption capacities were estimated as 57.80 and 61.73 mg g⁻¹ of ZnO-NRs-AC for BCG and EY respectively from binary dye solutions. The mechanism of removal was explained by boundary layer diffusion via intraparticle diffusion.     

火焰原子吸收法研究纳米钛酸锶钡粉体对铅的吸附性能

以氯化钡、氯化锶和四氯化钛为原料,以草酸作共沉淀剂,采用化学共沉淀法制备了纳米复盐吸附剂——钛酸锶钡粉体,并利用TEM,XRD和FTIR进行了表征。以火焰原子吸收为检测手段,详细考察了该纳米吸附剂对水中铅的吸附性能。结果表明：该法合成的钛酸锶钡粉体外形以棒状为主,平均粒径为36 nm,为纯净的钙钛矿纳米粉体。该纳米粉体对水中的铅具有较强的吸附能力,吸附量受介质的pH值影响较大,当pH值为6.0时,该吸附剂对水中铅的吸附容量可达13 mg·g-1。吸附于纳米钛酸锶钡上的铅可用0.5 mol·L-1的硝酸完全解脱。建立了纳米钛酸锶钡粉体吸附富集,火焰原子吸收法测定水中痕量铅的新方法,该法检出限为11 μg·L-1,相对标准偏差为2.6%。用于地表水中铅的测定,结果满意。     

显微-反射傅里叶变换红外光谱研究油酸钠与胶磷矿吸附机理

红外光谱已经成为浮选药剂作用机理研究的最重要手段之一。由于矿物本身具有较强的红外吸收,传统溴化钾压片透射光谱很难检测到矿物表面吸附药剂的微弱红外信号。采用显微-傅里叶变换红外光谱仪的反射模式,测定了不同浓度油酸钠在胶磷矿表面的吸附形式,并观察了吸附形貌。结果表明,与透射红外光谱相比,反射红外光谱对表面有更高的灵敏度,能更好地揭示实际浮选药剂浓度下的吸附机理。碱性条件下当油酸钠浓度较低时,油酸离子与表面晶格钙离子发生化学吸附,吸收峰在1 552 cm-1,同时也存在油酸钙沉淀的物理吸附,吸收峰在1 570和1 535 cm-1;当油酸钠浓度超过临界胶束浓度时,胶束使得胶磷矿表面亲水,导致油酸钠溶液残留在表面,吸收峰在1 560 cm-1,掩盖了其他吸收峰;表面经水洗涤后药剂吸收峰强度大幅减弱,是由于残留的油酸钠和物理吸附的油酸钙被洗掉。另外,随着油酸钠浓度增大,药剂二维形貌由点状吸附聚集为片状吸附,覆盖面积增大,但并不是完全覆盖,这与矿物表面异质性有关。以上研究结果有利于理解磷矿石提磷或铁矿石脱磷浮选体系中捕收剂与胶磷矿的作用机理。     

Ba和Sr原子在ZnO(0001)表面吸附的密度泛函理论研究

我们采用密度泛函理论下的平面波赝势方法研究Ba和Sr原子在ZnO(0001)表面的吸附结构和性质,仔细研究了三个吸附位（T4, H3 and Top）。发现Ba和Sr吸附在表面的H3和T4位时,他们之间的结合能相差很小,且这两种金属更易于吸附在表面的T4位,我们把计算的结果与贵金属在ZnO(0001)表面的吸附行为及前人的实验结果进行了比较,理论上发现Ag和Au易于吸附在ZnO(0001)表面的H3位,而实验上观察到即使在很小吸附比的条件下ZnO(0001)表面上也能形成Cu的团簇结构,这主要是由于Cu和ZnO(0001)表面衬底强的相互作用所致。