粉煤灰及改性粉煤灰对邻甲酚吸附性能的研究

研究了水溶液中粉煤灰(FA)和浸渍粉煤灰(IFA)吸附有害的邻甲酚,试验了颗粒大小、浸渍条件、pH值和温度等因素对吸附量的影响.结果表明,在稀溶液中进行吸附时,提高温度、减小粒径和pH值,可增加粉煤灰对邻甲酚的吸附量;用Al3+离子浸渍的粉煤灰具有较大的吸附量;吸附过程机理主要是多孔物质和静电作用的共同结果所致.     

粉煤灰及改性粉煤灰对邻甲酚吸附性能的研究

研究了水溶液中粉煤灰（ＦＡ）和浸渍粉煤灰（ＩＦＡ）吸附有害的邻甲酚,试验了颗粒大小、浸渍条件、ｐＨ值和温度等因素对吸附量的影响。结果表明,在稀溶液中进行吸附时,提高温度、减小粒径和ｐＨ值,可增加粉煤灰对邻甲酚的吸附量;用Ａｌ＾３＋离子浸渍的粉煤灰具有较大的吸附量;吸附过程机理主要是多孔物质和静电作用的共同结果所致。     

改性粉煤灰净化含磷废水的研究

采用改性粉煤灰对含磷废水进行净化,考察了pH、吸附剂用量、吸附时间和吸附温度对净化效果的影响。结果表明:(1)当pH为9时,磷净化率达到最大值。(2)当改性粉煤灰用量为30g/L时,磷净化率可达99.53%,磷净化后质量浓度为0.91mg/L,达到《污水综合排放标准》(GB8978—1996)中二级标准限值(1.0mg/L);当改性粉煤灰用量为40g/L时,磷净化率可达99.75%,磷净化后质量浓度为0.48mg/L,达到GB8978—1996中一级标准限值(0.5mg/L)。(3)改性粉煤灰对废水中磷的净化速度较快,吸附5min即可使吸附过程达到平衡;进一步提高吸附时间,磷净化率及净化后浓度几乎不再变化。(4)吸附温度对磷净化率的影响较小,当吸附温度为20～40℃时,磷净化率为97.00%～98.62%。(5)改性粉煤灰对磷的吸附等温线较符合Freundlich方程,且1/n=0.374,吸附过程易进行,改性粉煤灰可作为磷的吸附剂用于废水中磷的净化。     

改性粉煤灰处理低浓度含磷废水的研究

以酸改性粉煤灰为吸附剂,处理低质量浓度(1 mg/L左右)磷酸盐溶液,探讨了改性剂的种类、改性剂用量、吸附剂用量、反应时间、pH以及温度对除磷效果的影响.结果表明:(1)经过酸改性后粉煤灰的磷去除率显著提高,而且硫酸改性粉煤灰的除磷效果更好,磷去除率最高可达97.68％.(2)最佳条件:选择硫酸用量为5 mL/g进行改性,硫酸改性粉煤灰投加量为2.0g,反应时间为60 min,pH为7.2～10.8,温度为25℃(即室温).(3)改性粉煤灰对磷的吸附更符合Freundlich吸附等温模型,既有物理吸附,也有化学吸附,并以Ca、Mg氧化物与磷形成磷的沉淀物为主.     

铁屑粉煤灰组合处理含磷废水

实验研究了铁屑粉煤灰组合处理含磷废水的除磷效果.通过单因素实验,考查了铁屑粉煤灰质量比、反应时间、pH值和投加量对除磷效果的影响.实验结果表明,该法除磷的最优条件为铁屑和粉煤灰的质量比为2∶1,反应时间为20 min,pH值为6,投加量为20 g/L.在最优实验条件下磷的去除率达到了97.5％.对比了该法和粉煤灰吸附法与传统铁屑法的除磷效果.与单一粉煤灰吸附法和传统铁屑法除磷的结果相比较,铁屑粉煤灰组合除磷的方法具有明显优势.     

粉煤灰对水溶液中磷的吸附性能及机理

以粉煤灰为吸附剂去除溶液中的磷,考察了其吸附除P动力学特征、热力学特征以及溶液初始pH和粉煤灰投加量对吸附除P效果的影响,并对其吸附除P机理做了初步探讨。结果表明,在给定实验条件下,粉煤灰对P具有较好的去除效果,随着初始P浓度从10 mg/L升高到80 mg/L,平衡吸附量为0.46～2.44 mg P/g粉煤灰,吸附效率从92.2%降低至61.1%;对不同浓度的含P溶液,粉煤灰最适用量为0.6～1.5 g粉煤灰/mg P;相同反应条件下,当温度由25℃升高到45℃时,P初始吸附速率提高了3倍;粉煤灰对P的吸附过程能够较好地拟合Langmuir、Freundlich及D-R吸附等温模型,相关系数均在0.98以上。通过对吸附饱和的粉煤灰进行解析实验发现,初始P浓度较低(<50 mg/L)时,以化学吸附为主,而在初始P浓度较高(>80 mg/L)时,则以物理吸附为主。     

粉煤灰对Cr(Ⅵ)的吸附特性

通过间歇实验研究了粉煤灰对重金属Cr(Ⅵ)的吸附特性。探讨了固液比、pH、反应时间、温度、离子强度和初始浓度等因素的影响。实验结果表明,固液比、pH、温度与离子强度都对去除率有较大影响。当温度为20℃、pH=1、Cr(Ⅵ)的初始浓度为10 mg/L,固液比为100 g/L时,去除率达到50.13%。动力学实验结果表明,粉煤灰对Cr(Ⅵ)的吸附为快速反应,在180 min内可达到平衡,伪二级动力学模型可较好地拟合实验结果。等温吸附实验结果表明,Freundlich模型与Langmuir模型均可较好地拟合等温吸附实验结果。低温有助于粉煤灰对Cr(Ⅵ)的吸附。     

HDTMA改性粉煤灰吸附酸性嫩黄染料废水

使用HDTMA（十六烷基三甲基溴化铵）对粉煤灰(FA)进行改性，并使用改性后粉煤灰（MFA）吸附处理酸性嫩黄染料废水。研究发现，由于改性剂HDTMA被涂敷在粉煤灰表面，使粉煤灰表面电性改变，大大增强了对酸性嫩黄的处理效果，酸性嫩黄去除率可由13.2％提高到95％以上。实验结果还表明，当染料浓度为50 mg/L时，100 mL染料中MFA的最佳投加量为700 mg；pH值对吸附效果没有显著影响；低温有利于吸附。HDTMA改性粉煤灰对酸性嫩黄染料的吸附规律可用Langmuir吸附等温式描述。     

CeO_2-CuO/粉煤灰吸附SO_2/NO性能分析

利用室温液相浸渍法将粉煤灰制备成CeO_2-CuO/粉煤灰,提高了粉煤灰对SO_2/NO的吸附效率。采用XRF、XRD、SEM等手段对其进行表征测试,结果表明,粉煤灰的晶相结构主要为石英和莫来石,且改性后表面变得更为粗糙,孔隙增多。利用吸附反应装置优化SO_2/NO的反应条件,结果表明:在样品量为0.3 g、温度为50℃、SO_2流速为8 mL·min~(-1)、O_2流速为4 mL·min~(-1)时,CeO_2-CuO/粉煤灰对SO_2吸附效果最佳;在样品量为0.4 g、温度为70℃、NO流速为6 mL·min~(-1)、O_2流速为4 mL·min~(-1)时,对NO吸附效果最佳。共吸附会降低各自的吸附效率。利用原位FTIR分析表明:SO_2在CeO_2-CuO/粉煤灰表面主要生成硫酸盐和亚硫酸盐物种;NO则主要生成硝酸盐和亚硝酸盐物种。     

粉煤灰对直接耐晒翠兰染料吸附性能的研究

在实验室条件下对粉煤灰吸附处理直接耐晒翠兰染料溶液的影响参数进行了研究。探讨了染料溶浓度ＰＨ值和粉煤灰活化温度,吸附温度,粒径等对粉煤灰吸附性能的影响。试验结果表明,粉煤灰吸附符合Ｆｒｅｕｎｄｌｉｃｈ方程。随着吸附温度的升高,粉煤灰吸附能力下降,而随着粉煤灰粒径的减小,其吸附能力有所增加。粉煤灰吸附的最佳ＰＨ值范围和活化温度分别为６．３－６．６和６００℃。     

粉煤灰利用研究进展

本文对粉煤灰综合利用的研究现状进行综述。内容包括粉煤灰用于烧结砖、蒸养砖、墙体材料和水泥生产、隔热防水材料、絮凝剂和肥料制备、土壤改良和废水处理等。此外,还对从粉煤灰中回收金属矿物和炭粒等进行了讨论。     

Removal of cationic dyes from aqueous solutions using microspherical particles of fly ash

Batch sorption experiments were carried out for the removal of cationic dyes (methylene blue and malachite green) from their aqueous solutions using sorbent made from fly ash-a waste material. Effects of various experimental parameters: initial dye concentration, contact time, pH, adsorbent dosage, solution temperature, surfactant addition and ionic strength on the fly ash sorption of dyes were evaluated. The isothermal data for sorption followed the Langmuir model. The maximum sorption capacity obtained for methylene blue and malachite green was 36.05 mg/g and 40.65 mg/g, respectively. Kinetic studies indicate that sorption on fly ash follows the pseudo-second order kinetics. Present research suggests that fly ash could be an appropriate adsorbent for the removal of basic dyes from aqueous solutions.     

Effect of fly ash on sorption behavior of metribuzin in agricultural soils

This investigation was undertaken to determine the effect of two different fly ashes [Kota and Inderprastha (IP)] amendment on the sorption behavior of metribuzin in three Indian soil types. The IP fly ash was very effective in increasing the metribuzin sorption in the soils. The sorption with IP amendment was increased by 15-92%, whereas with the Kota fly ash an increase in sorption by 13-38% was noted. The adsorption isotherms fitted very well to the Freundlich adsorption equation and, in general, slope (1/n) values less then unity were observed. Although both the fly ashes significantly decreased metribuzin desorption, the IP fly ash was comparatively more effective in retaining metribuzin in the soils. Metribuzin sorption in the IP fly ash-amended soils showed strong correlation with the fly ash content and compared to K(f)/K(d) values, K(FA) values (sorption normalized to fly ash content) showed less variation. Metribuzin sorption-desorption did not correlate to the organic carbon content of the soil-fly ash mixture. The study demonstrates that all coal fly ashes may not be effective in enhancing the sorption of metribuzin in soils to the same extent. However, among the fly ashes used in this study, the IP fly ash was observed to be significantly effective in enhancing the sorption of metribuzin in soils. This may play an important role in reducing the run off and leaching losses of the herbicide by retaining it in the soil.     

Edaphological characteristics of unweathered and weathered fly ashes from Gondwana and lignite coal

Naturally weathered and unweathered samples of fly ashes produced from Gondwana and lignite coals were characterized for their edaphological properties. The particle size distribution in these fly ashes varied widely, and the percentage of [Formula: see text] size particles governed their water holding capacity. All fly ashes were noncoherent in the dry state and had lower particle density than quartz and mulite. The fly ashes were low in available N, but were sufficient in available P, K, Ca, Mg, S, Cu, Fe, Mn, Zn and B. Among the fly ashes, unweathered lignite fly ash was the richest source of K, Ca, Mg, S and Fe, while weathered lignite fly ash had the highest amounts of Mn, Zn and B. The pH of the fly ashes was closely related to the ratio of exchangeable Ca to exchangeable Al. The fly ashes were high in soluble salt, but were poor in cation exchange capacity. As an amendment to correct soil pH, the fly ashes had a poor buffering capacity. Weathering decreased the total Fe, available S and exchangeable Na percentages, but increased the organic C content of the fly ashes. Invariably, an excess of soluble salts and exchangeable Na could limit plant growth on fly ash dumps. Toxic levels of B and Al existed in only some fly ashes.     

工业废渣基除磷材料的静态吸附研究

研究了高效除磷材料（EPRC）对磷素的吸附特性，考察了投加量、初始浓度、初始pH值、粒径等对EPRC吸附性能的影响，分析了不同条件下EPRC的吸附过程。结果表明，最佳投加量为3.5 g/250 mL时，去除率达91.07%，出水TP浓度为0.45 mg/L。随着粒径减小，EPRC对磷素的吸附量增大，吸附平衡时间缩短。溶液初始pH值在碱性条件下，吸附容量变大。     

Improving phosphate removal of sand infiltration system using alkaline fly ash

Septic tank effluent is customarily disposed of by soil infiltration. Coarse, sandy soil such as those found in Perth, Western Australia, exhibit low attenuation capabilities for phosphate (PO4(3-)) during effluent infiltration. Amendment of such soil with different amounts of alkaline precipitator and lagoon fly ashes was investigated as a means of reducing phosphorus (P) leakage to ground water. Alkaline precipitator fly ash possessed the highest P sorption capacity in terms of its Langmuir and Freundlich isotherm parameters during initial batch tests. The test materials were repeatedly contacted with fresh PO4(3-) solutions over 90 contacting cycles to gain a better indication of long-term P sorption capability. Again, precipitator fly ash exhibited higher P sorption capacity than lagoon fly ash and Spearwood sand. Column studies assessed the influence of various application rates of alkaline precipitator and lagoon fly ashes on the P removal of septic tank effluent. Septic tank effluent was applied at the rate of 4 cm/day to the column for 12 weeks. Concentrations of P were monitored in the column effluent. All the fly ash columns were more efficient in reducing P migration compared to the sand column. Increased levels of fly ash in the soil columns resulted in increased P attenuation. Lagoon fly ash was inferior to precipitator fly ash for P removal; high application rates of fly ash caused clogging of the infiltration bed apparently due to their lower permeability. It is reasoned that 5-15% precipitator fly ash, and less than 30% lagoon fly ash could be added to coarse sands to produce an infiltration bed, which would result in a better quality effluent than can be obtained with untreated sand alone.     

粉煤灰技术在污水处理中的应用研究及存在问题讨论

对国内外污水处理中应用粉煤灰技术的现状进行了文献综述 ,并从环境保护与市场机制这个视角对粉煤灰在污水处理中的应用及存在问题进行了分析讨论。粉煤灰具有一定的吸附性能以及细微粒径特征 ,在污水处理中可以获得较好效果。但是同时会产生数倍的污泥增量 ,有些污泥甚至是有毒的 ,会产生二次污染。通过对历史事件的回顾认为以粉煤灰为原料制备混凝剂等 ,尽管在技术上可行 ,但是从市场经济角度看是不可取的     

A pilot study of mercury liberation and capture from coal-fired power plant fly ash

The coal-fired electric utility generation industry has been identified as the largest anthropogenic source of mercury (Hg) emissions in the United States. One of the promising techniques for Hg removal from flue gas is activated carbon injection (ACI). The aim of this project was to liberate Hg bound to fly ash and activated carbon after ACI and provide high-quality coal combustion products for use in construction materials. Both bench- and pilot-scale tests were conducted to liberate Hg using a thermal desorption process. The results indicated that up to 90% of the Hg could be liberated from the fly ash or fly-ash-and-activated-carbon mixture using a pilot-scale apparatus (air slide) at 538 degrees C with a very short retention time (less than 1 min). Scanning electron microscope (SEM) evaluation indicated no significant change in fly ash carbon particle morphology following the thermal treatment. Fly ash particles collected in the baghouse of the pilot-scale apparatus were smaller in size than those collected at the exit of the air slide. A similar trend was observed in carbon particles separated from the fly ash using froth flotation. The results of this study suggest a means for power plants to reduce the level of Hg in coal-combustion products and potentially recycle activated carbon while maintaining the resale value of fly ash. This technology is in the process of being patented.     

Dechlorination and destruction of PCDD,PCDF and PCB on selected fly ash from municipal waste incineration

The potential of fly ash to dechlorinate and destroy PCDD, PCDF and PCB was tested under oxygen deficient conditions in the laboratory. Specifically, two types of fly ash were compared, originating either from a fluidized bed incinerator using Ca(OH)₂ spray (FA1), or a stoker incinerator without Ca(OH)₂ impact (FA2).

Results from the present study indicate that on FA2 type fly ash, the degradation processes of OCDD, OCDF and D₁₀CB occurred primarily via dechlorination/hydrogenation up to temperature settings of 340 °C. In contrast, FA1 type fly ash was found to effect both dechlorination and destruction of these compounds already at temperature settings of 260 °C.

The dechlorination velocity of PCDD and PCDF did not differ significantly. However, the first dechlorination step of OCDF in the 1,9-position occurred faster compared to the first dechlorination step of OCDD.

The isomer pattern resulting from the dechlorination processes was quite similar on both FA1 and FA2, indicating that differences in alkalinity or elemental composition of the two types of fly ashes do not have a significant influence on the position of dechlorination. PCDD and PCDF dechlorination of the 2,3,7,8-positions was not favoured over dechlorination of the 1,4,6,9-positions on either type of fly ash. In contrast, dechlorination of PCB occurred predominantly on the toxicological relevant 3- and 4-positions.

The dechlorination/destruction processes were completed on both types of fly ash at 380 °C within one hour, which correlates well with results obtained from actual plant operation practices.