燃烧与催化气化灰中铝溶出行为的研究

实验对比了燃烧灰与负载Na_2CO_3催化气化灰中Al的溶出行为,考察了Na_2CO_3负载量(0-15%,质量分数)和温度(600-1 000℃)对催化气化灰中主要矿物组成与Al溶出行为的影响。同时,采用XRD分析了燃烧灰、催化气化灰以及酸浸残渣的主要组成。结果表明,燃烧灰的主要组成为莫来石,而催化气化灰的主要组成为硅铝酸钠((Na_2O)_(0.33)NaAlSiO_4)。6 mol/L硫酸、60℃和30 min浸取条件下,燃烧灰的浸出率只有40%,而Na_2CO_3负载量为10%的催化气化灰的浸出率达到88%。催化气化灰更易于回收灰中的Al。     

还原焙烧红土矿的硫酸浸出动力学

研究了选择性还原焙烧红土矿的硫酸浸出动力学.实验考察了浸出温度(30 ℃～70 ℃)和硫酸浓度(0.01～0.5 mol·l-1)对Ni、Fe浸出率的影响.结果表明:红土矿的选择性还原焙烧可增快Ni的浸出而抑止Fe的溶解.Ni的浸出动力学可用Avrami方程描述,其浸出反应的表观活化能为(15.40±0.18) kJ·moL-1.Fe的浸出受内扩散过程控制,浸出的表观活化能为(55.16±1.37) kJ·moL-1.     

Influence of several experimental parameters on As and Se leaching from coal fly ash samples

Coal fly ash leaching process for As and Se is studied. Environmental parameters such as pH, temperature, solid-liquid ratio, particle size and leaching time are taken into account in order to simulate As and Se leaching process for disposal coal fly ash. Analysis of reference materials was carried out by using of hydride generation coupled to atomic fluorescence spectrometry. Plackett-Burman experimental design is used to know the significative parameters, and Box-Behnken experimental design is used to refine the results obtained for these significative parameters. pH and temperature shown a hardly influence in leaching process. Furthermore, leaching time was also significative. According our results, it may be assumed that percentage of As and Se leaching in experimental conditions tested is relatively low for acidic fly ashes.     

油页岩飞灰对重金属离子的吸附动力学及热力学

采用批式振荡吸附法研究了燃油页岩电厂循环流化床锅炉飞灰对重金属离子Pb²+、Cu²+、Zn²+、Cd²+的吸附动力学及吸附热力学特性,并提出了吸附机理。结果表明,油页岩飞灰对Pb²+、Cu²+、Zn²+、Cd²+的吸附平衡数据符合Langmuir和Freundlich吸附等温方程,但Freundlich方程能够更好地描述吸附等温线。在油页岩飞灰对重金属离子吸附的初始阶段,拉格朗日准一级动力学方程、准二级动力学方程、Elovich方程、粒子内扩散模型均能很好地反映吸附模式,而整个吸附过程则遵循二级反应动力学方程,其吸附过程是液膜扩散和粒子内扩散共同作用的结果。油页岩飞灰对Pb²+、Cu²+、Zn²+、Cd²+的吸附是吸热反应。     

Kinetics, selectivity, and mechanism of the reactions of arenes with adamantyl carbocations in sulfuric acid

Data on the kinetics, selectivity, kinetic isotope effect, and the effect of the acidity of the medium on the rate of the reactions of benzene and alkylbenzenes in sulfuric acid (59–78 wt.% H₂SO₄) solutions of 1-adamantanol at 30 °C indicate that the direct reagents are the adamantyl carbocations (Ad⁺) that alkylate the arenes. The ortho positions of the benzene ring are not accessible on account of steric hindrances. The rate of attack by the Ad⁺ cation on the accessible para and meta positions of the ring is controlled by the formation of a σ complex. __________ Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 42, No. 1, pp. 14–18, January–February, 2006.     

Kinetics of esterification of acetic acid with n-butanol over different homogeneous acid catalysts

The esterification reaction of n-butanol and acetic acid has been performed in batch reactor in the presence of different homogeneous acid catalyst, namely sulfuric acid, nitric acid, and para toluene sulfonic acid (p-TSA). The objective of present research work is to investigate kinetic behavior of esterification reaction over the temperature range of 60°C–80°C. The effect of reaction parameter such as catalyst loading varied from 1% to 5% v/v and acid to alcohol molar ratio of 1:1, 1:3, and 1:5 has been observed. A pseudo homogeneous kinetic model has been applied. Kinetic parameters such as equilibrium constant, reaction rate constant, enthalpy, activation energy, and entropy were calculated by the experimental data for different acid catalyst system. It was observed that sulfuric acid gives higher conversion 73% than p-TSA 68.5% and nitric acid 66.25% at temperature of 80°C, 1:1 molar ratio and 3% catalyst concentration. The activation energy was estimated 36448.49, 23324.31 and 19060.156 J/mol K for three different catalyst sulfuric acid, nitric acid and p-TSA respectively. The enthalpy and entropy of the esterification reaction of acetic acid with n-butanol over three different catalysts has been calculated (Enthalpy: 25.788 KJ/mol, 12.256 KJ/mol, 28.320 KJ/mol, Entropy: 88.1 J/mol K, 45.298 J/mol K, 91.44 J/mol K) and found enthalpy is having positive value that shows reaction is endothermic.     

碱熔酸浸试样–碘量法测定铜冶炼白烟尘中的铜

建立碱熔酸浸试样–碘量法测定铜冶炼白烟尘中铜的方法。采用氢氧化钾–硝酸钾混合溶剂熔融试样,用盐酸浸取,以溴消除砷、锑等元素的干扰,用碘量法测定铜的含量。对滴定条件及共存元素的干扰和消除进行了验证,从而确定了最佳测定条件。实验最佳条件:4 g氢氧化钾和0.5 g硝酸钾混合溶剂;马弗炉温度650 ℃;样品称样量0.300 0 g;硫代硫酸钠标准溶液浓度0.02 mol/L。采用该实验条件,铜冶炼白烟尘中的铜测定结果相对标准偏差在0.37%~0.83%之间(n=10),样品加标回收率为98.30%~101.40%。该方法分析时间短,测定结果准确可靠,具有良好的精密度,可用于铜冶炼白烟尘中铜的测定。     

Palladized aluminum as a novel substrate for electrosynthesis of polyaniline in sulfuric acid solutions

The electropolymerization of aniline on a palladized aluminum electrode (Pd/Al) by potentiodynamic as well as potentiostatic methods is described. The effect of the monomer concentration between 0.01 and 0.4 M on the polyaniline (PANI) formation and its growth on the Pd/Al electrode was investigated and a suitable concentration of 0.2 M is suggested. A similar study was carried out to investigate the effect of sulfuric acid concentration and 0.1 M sulfuric acid was chosen. A study on the influence of electropalladization time on the polymer formation and its growth suggested a convenient time of 40 s. The stability of the PANI film on the Pd/Al electrode was studied as function of the potential imposed on the electrode. For applied electrode potentials of 0.1–0.7 V, the first-order degradation rate constant, k, of PANI film varies between 1×10⁻⁶ and 2×10⁻⁵ s⁻¹, and a relatively low slope (i.e., 2.2) was obtained for the plot of log k versus E. The coatings were characterized by scanning electron microscopy (SEM), and cyclic voltammetric behavior of the PANI-deposited Pd/Al electrode is discussed. The electrocatalytic activity of the PANI-deposited Pd/Al electrode against para-benzoquinone/hydroquinone (Q/H₂Q) and redox systems were investigated and on the basis of of the corresponding cyclic voltammograms and the redox systems were identified as the reversible and quasi-reversible systems, respectively.     

煤矸石催化气化耦合气化灰提铝过程中K2CO3和Na2CO3作用的对比研究

以煤矸石为研究对象，对比研究了Na₂CO₃与K₂CO₃对煤矸石催化气化反应性及催化气化灰中Al的溶出行为的影响。同时，采用X射线衍射分析（XRD）和热重分析（TGA）研究了不同催化剂及温度作用下矸石中矿物质的热转变过程。结果表明，与K₂CO₃相比，煤矸石中的高岭石更容易与Na₂CO₃反应生成钠霞石，而酸浸可实现钠霞石中铝和硅元素的有效分离。此外，Na₂CO₃作为催化剂时，所得气化灰经盐酸浸取后铝的浸出率可达到94.2%。而K₂CO₃作催化剂时，其铝的浸出率只有83.7%。因此，对矸石催化气化耦合气化灰的铝提取来说，Na₂CO₃催化剂具有更好的选择性。     

Kinetics of the liquid phase esterification of acrylic acid withn-octanol and 2-ethylhexanol catalyzed by sulfuric acid

Kinetics of the liquid phase esterification of acrylic acid withn-octanol and 2-ethylhexanol catalyzed by sulfuric acid has been studied in an isothermal semibatch reactor. The reaction appears to be second order. The kinetic parameters have been determined.     

Kinetics of thermal decomposition of PVC/fly ash composites

In this study, the kinetics and mechanisms of thermal degradation of Poly Vinyl Chloride (PVC) composites reinforced with class-F fly ash are studied experimentally and numerically using Flynn–Wall model. The addition of fly ash to the polymer matrix results in a decrease in the primary degradation temperature and an increase in the secondary degradation temperature. The metal oxides in the fly ash act as acid absorbers, which results in the destabilization of PVC during its dehydrochlorination process. However, they also react with the chlorine free radicals, which prevents the formation of HCl during degradation. In addition, it is observed that calcium and iron oxides, present in fly ash, are more reactive to the chlorine radicals rather than the silicon and aluminum oxides. The effect of fly ash chemical composition on the degradation of PVC composites was studied by comparing the thermal properties of composites containing two different classes of fly ashes, class-F and class-C, at similar levels. Thermal stability of the composites is found to be dependent on the chemical composition of fly ash. Higher dehydrochlorination rate is observed in the case of composites filled with class-F fly ash than those reinforced with class-C fly ash.     

Kinetics and equilibrium of the complexation of Al3+ with poly(maleic, acrylic) acid

Kinetics and equilibrium of the complexation of Al³⁺ with a polycarboxylic acid (PCA, random copolymer of maleic and acrylic acid with a mean molecular weight of 92 kDa) are investigated by the stopped flow technique and potentiometric titration. The complexation proceeds according to the Eigen–Tamm mechanism, i.e. in first diffusion-controlled step an outer sphere complex is formed. The second rate determining step is the formation of the inner sphere complex, controlled by the exchange rate of hydration water. For this second step the rate constant is k ₁=3 s^-1. It is in the order of magnitude of the water exchange at the Al³⁺ ion as expected for the Eigen–Tamm mechanism. The activation parameters are also determined. Parallel to this direct reaction path a base catalyzed path is found, typical for complexation reactions of hydrolyzable metal ions. Stable complexes are formed for which the overall association constant K _ass=Q _o(1+K _i) is determined by two parts: a chemical (intrinsic) part, described by the inner sphere association constant K _i=3 and an electrostatically controlled part described by the outer-sphere association quotient Q _o. The evaluation of the kinetic experiments allows to determine the value of log(Q _o) as a function of pH: 3.3<log Q _o<4.6. From these data the potential is calculated in the range −67 to ∝93 mV at pH values between 2 and 4. For comparison, analogous experiments with the monomeric subunits of the polyacid, glutarate (GA), and tricarballylate (TCA), are performed. The complexation with the monomeric subunits glutaric- and tricarballylic acid can be explained within the classical view of a discrete outer sphere association constant Q _o. Received: 13 November 1997 Accepted: 24 March 1998     

Methylmercury determination in biological samples using electrothermal atomic absorption spectrometry after acid leaching extraction

An efficient and sensitive method for the determination of methylmercury in biological samples was developed based on acid leaching extraction of methylmercury into toluene. Methylmercury in the organic phase was determined by electrothermal atomic absorption spectrometry (ETAAS). The methylmercury signal was enhanced and the reproducibility increased by formation of certain complexes and addition of Pd-DDC modifier. The complex of methylmercury with DDC produced the optimum analytical signal in terms of sensitivity and reproducibility compared to complexes with dithizone, cysteine, 1,10-phenanthroline, and diethyldithiocarbamate. Method performance was optimized by modifying parameters such as temperature of mineralization, atomization, and gas flow rate. The limit of detection for methylmercury determination was 0.015 μg g⁻¹ and the RSD of the whole procedure was 12% for human teeth samples (n=5) and 15.8% for hair samples (n=5). The method’s accuracy was investigated by using NIES-13 and by spiking the samples with different amounts of methylmercury. The results were in good agreement with the certified values and the recoveries were 88–95%.     

粗硼砂的氯化铵溶液浸提动力学

研究了反应温度、溶液浓度、固液比、固体粒径大小和搅拌速度对氯化铵溶液浸提粗硼砂(十水四硼酸钠,Na₂B₄O₇·10H₂O)动力学的影响。结果表明反应速率随反应温度、溶液浓度的增加和固体粒径、固液比的减小而增加,但搅拌速度对溶解速率无显著影响。根据均相和多相动反应力学模型研究了粗硼砂的溶解过程。结果表明溶解速率遵从假一级均相反应模型。粗硼砂在氯化铵溶液中溶解的活化能为82.73 kJ·mol^-1。     

燃煤电厂异相凝并飞灰重金属淋滤特性

采集了燃煤电厂的异相凝并后飞灰，分析了其物理化学特性。并通过淋滤实验研究了飞灰中重金属As、Se、Pb的环境稳定性。结果表明，凝并飞灰的粒径峰值为138.04 μm，而粉煤灰为60.26 μm；凝并后细颗粒凝聚成了较大的颗粒；凝并飞灰中重金属As、Se、Pb含量均高于同工况下粉煤灰中的含量，且后序脱硫环节所产生石膏中重金属的含量有所下降；批淋滤实验研究结果表明，凝并飞灰中的重金属浸出能力受淋滤液的pH值影响较大，温和环境和碱性条件抑制了As的浸出，酸性和碱性条件抑制了Se的浸出，而碱性条件抑制了Pb的浸出。柱淋滤实验研究结果表明，在酸性溶液和水溶液中，凝并飞灰的重金属浸出能力均受到了抑制。     

氧化钙对流化床燃煤飞灰中砷的淋滤特性影响

在实验室小型流化床实验装置上,利用添加氧化钙研究了原煤中钙硫比变化对燃煤过程中砷在飞灰中的富集规律和飞灰中砷的浸出特性的影响。实验结果表明,增加钙硫比能有效促进砷在飞灰中富集,降低砷的排放。砷与氧化钙的反应受制于钙的硫化反应控制。飞灰中砷的浸出与滤液pH值关系显著,碱性飞灰导致滤液pH值增大,能有效抑制飞灰中砷的浸出。碱性飞灰中砷的浸出历程为飞灰中砷在短时间内快速溶出;随着滤液pH值增大,溶出的砷与钙发生二次反应形成钙砷化合物沉淀,降低滤液中砷浓度。     

电感耦合等离子体原子发射光谱（ICP-AES）法测定粉煤灰中的铝

采用碳酸钠-碳酸钾-硼酸分解试样,盐酸浸取,电感耦合等离子体原子发射光谱法测定粉煤灰中的铝含量。铝的测定范围5.00%~25.00%。经加标回收实验,铝元素的加标回收率为99.6%~106%(n=3),方法准确简单,适用于粉煤灰中铝的测定。     

垃圾焚烧飞灰基本特性研究

以三个正在运行的垃圾发电厂的除尘器飞灰为研究对象,实验测出它们的化学组成、热灼减率、灰熔点等物化特性和浸出毒性、腐蚀性等有害特性,对三种灰样的特性进行了对比、分析。结果表明,飞灰的物化特性主要受飞灰中MgO、CaO、SiO2和CaCl2等几种主要成分质量分数的影响。MgO和Al2O3质量分数较高而CaCl2质量分数较低的飞灰其灰熔点相对较高;CaO和CaCl2质量分数较高的飞灰其水分和热灼减率也相对较高;SiO2质量分数较高的飞灰其重金属的浸出率相对较低;CaO和Al2O3等碱性氧化物质量分数较高的飞灰其浸出液的pH值相对较高。     

Kinetics of oxidation of alkanes and their derivatives byn-decanepersulfonic acid

The kinetics of interaction ofn-decanepersulfonic acid with linear, branched, and substituted hydrocarbons was studied. The oxidation ofcyclo-C₆H₁₂/C₆D₁₂ occurs with a moderate kinetic isotope effect,k ^H/k ^D=2.2±0.3. A satisfactory correlation between the partial rate constants and the structure of hydrocarbons in terms of the Okamoto-Brown equation was found. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 5, pp. 822–825, May, 2000.