超声波辅助粉煤灰去除水中亚甲基蓝染料的动力学分析

为了开发更多的粉煤灰用途,采用粉煤灰去除水中的染料污染物,达到以废治废的目的。采用超声波辅助粉煤灰的方法,以亚甲基蓝染料作为模拟污染物,考察此工艺的可行性,讨论亚甲基蓝的去除效果,分析其动力学。研究结果证明,超声波-粉煤灰联合体系（US-FA体系）具有良好的去除染料污染物的能力,超声波的引入能提高粉煤灰对染料污染物的去除率,协同效应非常明显,粉煤灰投加量0.3、0.5、1.0和2.0 g的情况下,协同因子分别达到1.05、1.32、1.55和2.27。在本实验体系内,经过恒温控制后,超声波的热效应可以忽略,主要通过粉煤灰吸附和羟基自由基降解两大主要途径去除污染物,超声波对去除性能的促进作用主要体现在以下几个方面：一是超声波空化作用产生羟基自由基,超声波和粉煤灰表面相互作用产生更多的羟基自由基;二是超声波能促进粉煤灰表面产生更多的活性位,促进了吸附过程的化学反应步骤,由于粉煤灰对亚甲基蓝的吸附过程以化学反应为控制步骤,所以超声波能大为促进粉煤灰的吸附性能;三是超声波的引入加剧了固液混合,促进污染物向固相表面移动,促进更多的污染物进入到吸附剂颗粒内部,改善了传质。     

Removal of methylene blue from aqueous solution by adsorption onto zeolite synthesized from coal fly ash and its thermal regeneration

BACKGROUND: The removal of cationic dyes from wastewater is of great importance. Three zeolites synthesized from coal fly ashes (ZFAs) were investigated as adsorbents to remove methylene blue (MB), a cationic dye, from aqueous solutions. Experiments were conducted using the batch adsorption technique under different conditions of initial dye concentration, adsorbent dose, solution pH, and salt concentration. RESULTS: The adsorption isotherm data of MB on ZFAs were fitted well to the Langmuir model. The maximum adsorption capacities of MB by the three ZFAs, calculated using the Langmuir equation, ranged from 23.70 to 50.51 mg g^?1. The adsorption of MB by ZFA was essentially due to electrostatic forces. The measurement of zeta potential indicated that ZFA had a lower surface charge at alkaline pH, resulting in enhanced removal of MB with increasing pH. MB was highly competitive compared with Na⁺, leading to only a < 6% reduction in adsorption in the presence of NaCl up to 1.0 mol L^?1. Regeneration of used ZFA was achieved by thermal treatment. In this study, 90–105% adsorption capacity of fresh ZFA was recovered by heating at 450 °C for 2 h. CONCLUSION: The experimental results suggest that ZFA could be employed as an adsorbent in the removal of cationic dyes from wastewater, and the adsorptive ability of used ZFA can be recovered by thermal treatment. Copyright © 2010 Society of Chemical Industry     

Removal of mercury in aqueous solution by fluidized bed plant fly ash

Coal combustion in power plant produces fly ash. Fly ash may be used in water treatment to remove mercury (Hg²⁺) from water or to immobilize mercury mobile forms in silts and soils. Experiments were carried out on two kinds of fly ashes produced by two circulating fluidized bed plants with different chemical composition: silico-aluminous fly ashes and sulfo-calcic fly ashes. For the two kinds of fly ashes, adsorption equilibrium were reached in 3 days. Furthermore, removal of mercury was increased with increasing pH. Sulfo-calcic fly ashes allow us to remove mercury more efficiently and more steady. The chemical analysis of fly ash surface was carried out by electron spectroscopy. The results show that mercury is bound to ash surface thanks to several chemical reactions between mercury and various oxides (silicon, aluminium and calcium silicate) of the surface of the ashes.     

Study on the phosphate removal from aqueous solution using modified fly ash

In this work the fly ash was modified by sulfuric acid for the removal of phosphate. It was found that modification of fly ash could significantly enhance the phosphate immobilization ability of the fly ash. The specific surface area of the fly ash increased from 8.8 to 32.5 m²/g after treated with sulfuric acid. The modification of the fly ash also resulted in the mobilization of acid-soluble metal ions due to partial or complete dissolution of the metals under the acidic conditions. Both adsorption and precipitation contributed to the removal of phosphate by the modified fly ash but precipitation was a major mechanism of phosphate removal. The experimental results showed that adsorption of phosphate by the modified fly ash was rapid, the removal percentage of phosphate could reach maximum in 5 min. In the range of 5–9, pH did not significantly affect the removal of phosphate and the removal percentage of phosphate increased with the increase of adsorbent dosage. The adsorption of phosphate by the modified fly ash could be described well by Langmuir isotherm equation, the Langmuir constant Q₀ was 9.15 mg g⁻¹. The XRD patterns and the SEM images of modified fly ash after sorption revealed that CaHPO₄·2H₂O was formed in the removal of phosphate. In addition, phosphate also formed precipitate with aluminum and iron.     

Removal of Cr(V1) from aqueous solutions by adsorption on fly ash-wollastonite

The ability of a homogeneous mixture of fly ash and wollastonite (1:1) to remove Cr(V1) from aqueous solutions by adsorption has been investigated. The extent of removal is dependent on concentration, pH and temperature of the solution. The applicability of the Langmuir isotherm for the present system has been tested and the surface mass transfer coefficient at 30°C and pH 2.0 determined. Maximum removal was observed at pH 2.0 and 30°C. The adsorption is first governed by diffusion followed by surface compound formation. The thermodynamic parameters, desorption results and infrared studies indicated that the surface compounds, formed by interaction of adsorbate ions and different constituents of mixed adsorbent, were stable in nature.     

粉煤灰的活化及其对活性深蓝K-R的吸附

以粉煤灰(FA)经碱熔融和酸处理制得活性粉煤灰(AFA),并将其用于模拟废水中活性深蓝K-R的吸附,探讨了AFA的制备条件和影响吸附的因素。结果表明:在m(Na2CO3)∶m(FA)为1∶5,焙烧温度为850℃,HCl浓度为4mol/L,搅拌溶解温度为80℃的制备条件下,所制得的AFA对3500mg/L活性深蓝K-R的吸附量为335.98mg/g,活性深蓝K-R去除率达94.5%;染料起始浓度、pH、吸附时间和温度均对吸附效果产生影响;吸附动力学可用准二级吸附动力学方程进行描述(R2=1.000);等温吸附符合Langmuir方程。AFA可有效去除水溶液中高浓度的活性深蓝K-R。     

维多利亚蓝B共振光散射法测阿莫西林

建立了测定阿莫西林的共振瑞利散射法.在pH 9.98的Tris-HCI缓冲溶液中,阿莫西林和维多利亚蓝B相互作用后,共振瑞利散射显著增强,在337 nm处呈现最高散射强度.阿莫西林的质量浓度在0～0.4μg/mL范围内与△IRRS成正比,检出限(3Sb/S)为0.027μg/mL.该法简便、快速、灵敏,用于人体尿液、市...     

Ge extraction from gasification fly ash

Water-soluble germanium species (GeS₂, GeS and hexagonal-GeO₂) are generated during coal gasification and retained in fly ash. This fact together with the high market value of this element and the relatively high contents in the fly ashes of the Puertollano Integrated Gasification in Combined Cycle (IGCC) plant directed our research towards the development of an extraction process for this element. Major objectives of this research was to find a low cost and environmentally suitable process. Several water based extraction tests were carried out using different Puertollano IGCC fly ash samples, under different temperatures, water/fly ash ratios, and extraction times. High Ge extraction yields (up to 84%) were obtained at room temperature (25 °C) but also high proportions of other trace elements (impurities) were simultaneously extracted. Increasing the extraction temperature to 50, 90 and 150 °C, Ge extraction yields were kept at similar levels, while reducing the content of impurities, the water/fly ash ratio and extraction time. The experimental data point out the influence of chloride, calcium and sulphide dissolutions on the Ge extraction.     

The removal of phosphate ions from aqueous solution by fly ash, slag, ordinary Portland cement and related blends

Phosphate ions have been removed from aqueous solution by fly ash, slag, ordinary Portland cement (OPC) and related cement blends. The rate and efficiency of PO₄³⁻ removal were found to increase in the order: fly ash, slag, OPC, apparently mimicking the order of increasing percent CaO in the adsorbents. Blending OPC with fly ash or slag evidently results in diminished PO₄³⁻ removal efficiency. Better removal was obtained at higher solute concentration, acidic pH and higher temperature. The effect of particle size and the speed of mixing were found not to be significant. A first-order kinetic model was used to obtain values for overall sorption rate constants and intraparticle diffusion constants. The Frumkin isotherm was found to be the appropriate equation for modelling isotherms from the experimental adsorption data, and values have been obtained for the isotherm constants. A 400-mg/l PO₄³⁻ (as P) solution was fed at a steady velocity of 2.0 cm/min through a 2.0-cm fixed-bed column (at pH 9.0 and 25 °C), and breakthrough curves were constructed to obtain estimated adsorption capacity values of 32, 60, 75, 78 and 83 mg PO₄³⁻/g adsorbent for fly ash, slag, OPC+fly ash, OPC+slag and OPC, respectively.     

Removal of congo red from aqueous solutions by biogas waste slurry

Removal of Congo Red was carried out using biogas waste slurry as adsorbent at different concentrations of dye, adsorbent dosage, agitation time and pH. The process follows the first-order rate expression. The equilibrium data fit well in the Freundlich model of adsorption. Maximum removal of dye, 95%, was observed in the pH range 2.3–9.4. Desorption of Congo Red showed that it is solubilised in 50% acetic acid to the extent of 6% and the remainder appears to be chemically complexed irreversibly to the adsorbent. Low desorption of dye from the adsorbent surface in water indicates that the process may not be, essentially, a reversible one.     

Removal of boron from coal fly ash by washing with HCl solution

Boron as an environmentally regulated substance is well known to condense in the coal fly ash generated from coal combustion plants. Since boron in the coal fly ash tends to elute into the soil easily, a technology for its stabilization or removal from fly ash is required. An acid washing process is proposed and studied as one of the candidate technologies for the removal of boron from coal fly ash. A laboratory-scale investigation is conducted on the dissolution behavior of boron in the coal fly ash in a diluted HCl solution. The dissolution of boron and alkaline species is considerably fast and exhibits a behavior different from that of aluminum and silicon, which are major components of the ash. From the kinetic model, it is expected that boron in the ash may mainly be in the form of alkaline or alkaline earth borates that are deposited on the surface of relatively large ash particles of alumino-silicate or may be precipitated as fine particles during coal combustion. This acid washing process is extended to a bench-scale plant and boron is successfully removed from the coal fly ash until its content is less than the regulation limit.     

菌体/粉煤灰复合吸附剂吸附酸性蓝

采用菌体/粉煤灰复合吸附剂吸附酸性蓝,通过单因素实验探究其吸附条件和吸附机理。结果表明：处理模拟酸性蓝废水最佳条件为：pH值6.6（自然）,投加量3 g/L,搅拌时间25 min,静置时间1 h,此时去除率在85%以上。热力学和动力学的研究结果表明,Langmuir模型和Freundlich模型均可以用来描述吸附剂对酸 性蓝的吸附,且吸附较好地符合Freundlich 等温吸附模型;吸附剂对酸性蓝的吸附属于单分子层吸附,且 其吸附过程容易进行,由 Langmuir 吸附计算得到吸附剂的最大吸附量为303.0303 mg/g。吸附剂对酸性蓝 的吸附属于Lagergren准二级吸附动力学模型,菌体/粉煤灰对酸性蓝的吸附速率控制化学吸附过程,饱和吸附 量为137.32 mg/g。     

粉煤灰微波改性及其对含铬废水的吸附性能

将取自于西安市西郊热电厂的原粉煤灰(FA)球磨5h得到超细粉煤灰(UFA),再经过微波辐照处理得到微波辐照改性超细粉煤灰(MFA),并研究其对含铬废水的吸附性能.动力学研究结果表明,改性粉煤灰对Cr(VI)的吸附符合二级吸附动力学模型,通过模型计算出的FA,UFA和MFA的二级吸附速率常数(k2)分别为2.45×10-2 ,3.88×10-2 和5.14×10-2g·mg-1·min-1; 热力学研究结果表明,吸附过程可以用Langmuir方程描述.     

电渗析法处理飞灰及其浸出液的研究进展

综述了电渗析技术处理飞灰,并探讨了电渗析技术处理飞灰的研究动态。     

Fly ash effects: I. The morphological effect of fly ash

The morphological effect is an important part of fly ash effects. The paper analyzes emphatically this effect and points out that it is composed of the filling role, surface role and lubricating role. For different fly ash, these roles are different. They must be considered synthetically when the morphological effect is analyzed. Analyzing result shows that the filling role is relative to the particle size, the surface role is relative to the specific surface area and the water affinity and the lubricating role is relative to the shape of particle. The morphological effect of fly ash is the synthetical embodiment of these roles.     

粉煤灰吸附水中磷的研究

本文研究了粉煤灰对磷酸盐的等温吸附特征，并以保定市护城河生活污水中的磷为吸附处理对象，研究了ｐＨ值、浓度及粉煤灰颗粒大小对平衡吸附量的影响。     

硝酸脱除褐煤粉煤灰中的砷

基于砷在褐煤粉煤灰中的赋存状态,建立了酸法脱除粉煤灰中部分砷的新方法,考察了反应温度、时间、pH值等对脱砷率的影响. 结果表明,褐煤灰中的砷大多富集在煤灰表面并以砷酸钙等砷酸盐形式存在,脱砷率与pH值和反应温度成反比. 综合考虑脱砷率、溶损率等因素,确定酸法最优脱砷条件为pH=1、反应温度20℃、反应时间1 h,此时脱砷率为66.34%.     

Nano-crystal glass-ceramics obtained from high alumina coal fly ash

Glass has been obtained by melting high alumina coal fly ash with fluxing additives. A thermal treatment was employed to convert the obtained glass into nano-crystal glass-ceramics. X-ray diffraction (XRD) patterns show that the main crystalline phases in both the glass-ceramics are anorthite (CaAl₂Si₂O₈) and wollastonite (CaSiO₃). The crystals are homogeneously dispersed within the parent glass. The average crystal size is below 200 nm. Physical and mechanical properties, such as density, thermal expansion coefficient, hardness, and bending strength, of the glass have been examined and the corresponding microstructures are discussed. The results demonstrate that the glass-ceramics have potential for a wide range of construction application.     

NaOH改性花生壳对亚甲基蓝染料吸附性能的研究

花生壳用5%的NaOH溶液改性作吸附剂处理亚甲基蓝染料废水,考察pH值、吸附剂投加量、染料浓度和温度及吸附时间对染料吸附性能的影响。结果表明,吸附最佳的工艺条件为:温度25℃,吸附剂投加量0.3 g,亚甲基蓝的初始浓度3.5 g/mL,反应时间135 min,pH值7。此时改性花生壳对亚甲基蓝的吸附率达99.57%。