KOH为化学活化剂的活化过程探讨

以无烟煤为原料 ,KOH为化学活化剂进行活化过程中 ,通过热分析实验 。

化学活化剂对铬铁渣水泥复合材料力学性能及水化的影响

以工业废弃物铬铁渣替代不同比例的水泥,并添加不同含量的KCl作为化学活化剂,成功制备了铬铁渣水泥复合材料。分析了铬铁渣掺量及KCl添加量对铬铁渣水泥复合材料抗压强度的影响,并利用傅里叶红外光谱、扫描电子显微镜、热重-差热分析等方法对不同水泥复合材料的样品进行了测试。结果表明,10%(质量分数)铬铁渣掺杂具有较好的抗压强度,且符合Cr^6+排放标准;0.6%(质量分数)的KCl加入到10%(质量分数)铬铁渣含量的水泥复合材料中,抗压强度最高,养护7,28和90 d后抗压强度分别为46.13,67.45和78.98 MPa;化学活化剂KCl的加入加速了钙矾石和C-S-H凝胶的形成,有利于提高水泥复合材料的致密性,同时化学活化剂中的氯离子可与水泥复合材料中粉煤灰提供的活性Al2O3反应生成水铝钙石,促进了熟料的水合作用,提高了水泥复合材料的早期强度和耐久性。

高掺量粉煤灰混凝土活化的实验研究

通过?1.83m×6.4m的球磨机打磨及将硫酸盐+碱性矿粉配制而成的复合激发剂掺进高掺量的粉煤灰水泥内,实现粉煤灰早期活性的激发,经力学性能测试与微观分析,对化学法与机械法于粉煤灰水泥内对粉煤灰活性的激发机理进行分析,并将其应用于配制高掺量的粉煤灰混凝土。结果显示,化学活化法及机械活化法可有效促进粉煤灰早期水化速度,提高浆体强度。

PVP基碳纳米纤维的制备及其对亚甲基蓝的吸附性能

以聚乙烯吡咯烷酮(PVP)为原料,氯化锌、磷酸和乙酸锌为活化剂,通过静电纺丝技术,制备了PVP基碳纳米纤维,探究了不同活化剂对PVP基碳纳米纤维微观结构和形貌、比表面积、孔径分布以及对亚甲基蓝吸附性能的影响。结果表明:PVP基碳纳米纤维有较高的长径比,结构完整;此外,通过对比3种活化剂的活化效果表明乙酸锌对PVP基碳纳米纤维的活化效果最好,所对应碳纳米纤维的比表面积和总孔容分别达到965.46m^(2)/g、0.6075cm^(3)/g;最后用Langmuir方程分析了所制PVP基碳纳米纤维对亚甲基蓝的吸附性能,结果表明乙酸锌活化的PVP基碳纳米纤维的饱和吸附量达到255mg/g,相较于未活化PVP碳纳米纤维提升了77.1%。

Polyethoxylation and polypropoxylation reactions：Kinetics,mass transfer and industrial reactor design

Ethoxylation and propoxylation reactions are performed in the industry to produce mainly non-ionic surfactants and ethylene oxide(EO)–propylene oxide(PO) copolymers.Both the reactions occur in gas–liquid reactors by feeding gaseous EO,PO or both into the reactor containing a solution of an alkaline catalyst(KOH or Na OH).Non-ionic surfactants are produced by using liquid starters like fatty alcohols,fatty acids or alkyl-phenols,while when the scope is to prepare EO–PO copolymers the starter can be a mono-or multi-functional alcohol of low molecular weight.Both reactions are strongly exothermic,and EO and PO,in some conditions,can give place to runaway and also to explosive side reactions.Therefore,the choice of a suitable reactor is a key factor for operating in safe conditions.A correct reactor design requires:(i) the knowledge of the kinetic laws governing the rates of the occurring reactions;(ii) the role of mass and heat transfer in affecting the reaction rate;(iii) the solubility of EO and PO in the reacting mixture with the non-ideality of the reacting solutions considered;(iv) the density of the reacting mixture.All these aspects have been studied by our research group for different starters of industrial interest,and the data collected by using semibatch well stirred laboratory reactors have been employed for the simulation of industrial reactors,in particular Gas–Liquid Spray Tower Loop Reactors.

Electrochemical Oscillations Induced by Surfactants

A new type of electrochemical oscillation induced by surfactant was observed in experiments. The electrochemical system is a Daniell cell with a copper rod in CuSO 4 aqueous and an aluminum rod in Al(NO 3) 3 aqueous as electrodes. The surfactants are CTAB, TX-100, SLS. The addition of trace surfactant solution by a micro-syringe made the original monotonously changing electrochemical system produce obvious periodic phenomena. At the mean time, the copper ion selective electrode and Hg 2SO 4 reference electrode were used to monitor the copper electrode reaction and determine its rate constant k of first order reaction. According to the experimental results of electrode reaction kinetics, the possible mechanism was found to be the polarization induced from the directional adsorption of trace surfactant on the electrode surface. That is the electrochemical oscillations.

Steam reforming of methane over Ni catalysts prepared from hydrotalcite-type precursors: Catalytic activity and reaction kinetics

Ni/Mg–Al catalysts derived from hydrotalcite-type precursors were prepared by a co-precipitation technique and applied to steam reforming of methane. By comparison with Ni/γ-Al2O3 and Ni/α-Al2O3 catalysts prepared by incipient wetness impregnation, the Ni/Mg–Al catalyst presented much higher activity as a result of higher specific surface area and better Ni dispersion. The Ni/Mg–Al catalyst with a Ni/Mg/Al molar ratio of 0.5:2.5:1 exhibited the highest activity for steam methane reforming and was selected for kinetic investigation. With external and internal diffusion limitations eliminated, kinetic experiments were carried out at atmospheric pressure and over a temperature range of 823–973 K. The results demonstrated that the overall conversion of CH4 and the conversion of CH4 to CO2were strongly influenced by reaction temperature, residence time of reactants as well as molar ratio of steam to methane. A classical Langmuir–Hinshelwood kinetic model proposed by Xu and Froment(1989)fitted the experimental data with excellent agreement. The estimated adsorption parameters were consistent thermodynamically.

Kinetics of Treated Domestic Sewage Disinfection through Catalytic Oxidation with H2O2

The inactivation of bacterial cells through catalyzed oxidation using hydrogen peroxide as the primary oxidant agent is dependent on a series of factors, such as the concentration of the catalyst, the rate of hydroxyl radical formation in the controlled decomposition of the oxidant agent, and the concentration and toxicity of hydrogen peroxide. The objective of this study was to develop a mathematical model able to predict the kinetics of the inactivation Escherichia coli and total coliforms cells present in treated domestic sewage through catalytic peroxidation. The catalyst used was iron oxide supported on mineral coal （called CP）, and the effects of the operational conditions, including hydrogen peroxide concentration and dosage of catalyst, were evaluated. The results showed that the disinfection kinetics of the treated domestic sewage is dependent on the concentrations of hydrogen peroxide and catalyst dosage. The kinetic model was shown to be able to predict the behavior of the inactivation kinetics of the bacterium Escherichia coli ATCC-25922 when different concentrations of hydrogen peroxide （75 and 100 mg·L^-1） were used, regardless of the catalyst dosage.

Adsorption Studies of Chlorpropham and 3-Chloroaniline on Chemically Activated Halloysite

Chemically modified halloysite proved to be an effective adsorbent for the pesticide chlorpropham and 3-chloroaniline from an aqueous solution. Adsorption experiments were conducted using such procedures as the time-dependent （kinetic） procedure and the concentration dependent （isotherm） procedure. Results indicate that the adsorption process is related to the kind of the studied compound. The equilibrium data are well suited to a Freundlich isotherm in the case of both investigated compounds. Adsorption kinetics of chlorpropham and 3-chloroaniline on acid-treated halloysite was successfully described by pseudo-second order kinetic model and the model of Weber and Morris. From the present study, we suggest that the adsorption of chlorpropham and 3-chloroaniline on the modified halloysite is a rather complex process involving two steps： external mass transfer and intra-particle diffusion.

Carboxyl groups trigger the activity of carbon nanotube catalysts for the oxygen reduction reaction and agar conversion

Ozone treatment is a common way to functionalize commercial multi-walled carbon nanotubes （CNTs） with various oxygen functionalities like carboxyl, phenol and lactone groups, in order to enhance their textural properties and chemical activity. In order to detail the effect of each functional group, we correlated the activity with the surface density of each group, and found that the carboxyl groups play a pivotal role in two important catalytic reactions, namely the electrochemical oxygen reduction reaction （ORR） and agar conversion to 5-hydroxymethylfurfural （HMF）. During the processes, the hydrophilic surface provides a strong affinity for reaction substrates while the improved porosity allows the efficient diffusion of reactants and products. Furthermore, the activity of functionalized CNTs for agar conversion remained almost unchanged during nine cycles of reaction. This work highlights a strategy for improving the activity of CNTs for electrochemical ORR and agar conversion reactions, as well a promising application of carboxyl-rich CNTs as a solid acid catalyst to produce high-purity HMF--an important chemical intermediate.

Core/shell FePd/Pd catalyst with a superior activity to Pt in oxygen reduction reaction

Developing high-efficient non-platinum （Pt） catalysts for oxygen reduction reaction （ORR） is the key to reduce the usage of Pt and the palladium （Pd）-based cata- lyst is a promising alternative. Here, we presented a facile approach to core/shell FePd/Pd nanoparticle （NP） catalyst with the FePd core in chemically ordered face-centered tetragonal （fct-） structure and the shell in controlled thickness from 0.32 to 0.81 nm via the thermal annealing of FePd NP followed by an electro-anodization process. With a 0.71 nm-thick Pd shell, the fct-FePd/Pd shows a robust catalytic activity and durability for ORR with the mass activities at 0.85 and 0.90 V reaching 453 and 96.7 A/mgpd, respectively, which are about 3.0 and 2.1 times higher than those of commercial Pt in alkaline media. This work presents a new class of non-Pt catalyst with superior performance to Pt for ORR catalysis, and the strategy demonstrated here can be extended to design highefficient catalysts for other chemical reactions.

Surface-structure tailoring of ultrafine PtCu nanowires for enhanced electrooxidation of alcohols

Surface tailoring of Pt-based nanocatalysts is an effective pathway to promote their electrocatalytic performance and multifunctionality.Here,we report two kinds of one-dimensional(1D)ultrafine PtCu nanowires(smooth surface&rugged surface)synthesized via a wet chemical method and their distinct catalytic performances in electro-oxidation of alcohols.The alloyed PtCu nanowires having rough surfaces with atomic steps exhibit superior catalytic activity toward multiple electrochemical reactions compared with the smooth counterpart.Density functional theory simulations show the excellent reactivity of rugged PtCu na-nowires and attribute it to the surface synergetic Pt-Cu site which accounts for the promotion of water dissociation and the dehydrogenation of the carboxyl intermediate.The current study provides an insight into reasonable design of alloy nanocatalysts in energy-related electrocatalytic systems.

Integration of Chemical Methods and Biomarkers for Assessment of Chlorimuron-Ethyl Bioavailability in Soil

Bioavailability is a critical factor for assessing the environmental risk of organic pollutants in soil. In this study, extractions with 3 different solvents, including 2 aqueous solutions, calcium chloride(CaCl_2) and a phosphate buffer solution(PBS), and a mixture of aqueous solution and organic solvent, a PBS-methanol(8:2,volume/volume) mixture(PBS-M), were performed to assess the bioavailability of chlorimuron-ethyl in soil in comparison to a battery of toxicity tests in wheat seedlings. The results indicated that the peroxidase(POD) activity in wheat leaves after 7 d of exposure was one of the sensitive biomarkers of chlorimuron-ethyl in soil.The extractability of chlorimuron-ethyl by all the 3 solvents decreased with exposure time, and the rate of decrease of the PBS-M extraction between 1 and 7 d of exposure was substantially higher than those of the aqueous solution extractions. Chlorimuron-ethyl gradually changed from a water-soluble form into a soil organic matter(SOM)-bound form in the soil. The PBS extraction correlated best with the POD activity in the leaves after 7 d of exposure.