共查询到19条相似文献,搜索用时 265 毫秒
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充分利用疏浚土有机质含量高、吸附能力强和低透水性等特点,将其作为填埋场粘土衬垫的添加材料。等温吸附试验和扩散试验的结果表明:粉质粘土掺入疏浚土后,对金属离子的吸附能力得到增强,尤其对高价Cu2+的吸附能力显著提高,同时可以显著地降低Cu2+的扩散系数。研究表明,有机质对Cu2+的强吸附能力是Cu2+扩散系数降低的主要原因。粉质粘土掺入疏浚土后极大地提高了粘土衬垫的环境土工特性,非常适合作为填埋场粘土衬垫。 相似文献
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试验研究了pH值、吸附时间和吸附剂用量对膨润土吸附重金属离子Pb2 ,Zn2 ,Cr(VI)和Cd2 的影响.结果表明,在本试验的pH值、吸附时间及吸附剂用量条件下,膨润土对Pb2 ,Zn2 ,Cd2 的吸附效果均优于其对Cr(VI)的吸附效果;pH值是影响上述吸附的重要因素,离子交换和表面络合是上述吸附的主要形式. 相似文献
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重金属Pb(II)在膨润土上去除特性研究 总被引:1,自引:0,他引:1
深入研究成本低廉的膨润土对水溶液中Pb(II)的吸附特性,采用Batch试验方法,分析了土水比、pH、离子强度、反应时间、温度及Pb(II)的初始浓度对Pb(II)在膨润土上吸附性能的影响,并对吸附动力学和吸附平衡试验进行了探讨。Pb(II)在膨润土上去除率与pH、离子强度有很强的依赖性。当pH<7时,膨润土对Pb(II)的吸附主要是离子交换,而当7相似文献
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膨润土对重金属离子Pb2+,Zn2+, Cr(Ⅵ),Cd2+的吸附性能 总被引:3,自引:0,他引:3
试验研究了pH值、吸附时间和吸附剂用量对膨润土吸附重金属离子Pb^2+,Zn^2+,Cr(VI)和Cd^2+的影响.结果表明,在本试验的pH值、吸附时间及吸附剂用量条件下,膨润土对Pb^2+,Zn ^2+,Cd ^2+的吸附效果均优于其对Cr(Ⅵ)的吸附效果;pH值是影响上述吸附的重要因素,离子交换和表面络合是上述吸附的主要形式. 相似文献
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上海粉质粘土的三轴CT实时细观试验 总被引:2,自引:3,他引:2
采用CT实时试验对上海粘性土的三轴应力条件下的特性进行系统的试验研究.研究表明,上海灰色粉质粘土在三轴应力下细观变形基本上分为4个阶段,即微裂纹压密阶段,初期损伤阶段,损伤快速发展阶段和软化破坏阶段.粉质粘土初始状态为不均一的和初始损伤,受力过程中以局部变形为主,灰色粉质粘土的破坏是由于产生局部变形,形成剪切带造成的,裂纹在峰值强度及峰值强度后完全形成的. 相似文献
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疏浚土作为填埋场粘土垫层防渗材料的研究 总被引:1,自引:0,他引:1
基于填埋场粘土类防渗垫层的3个关键因素:渗透性、强度、吸附性,对混合土(疏浚土和粉质粘土)与原粉质粘土做了大量对比试验。结果表明,在最优含水量时,前者的渗透系数低于后者,且随疏浚土掺入量增加而降低;前者的不固结不排水抗剪强度高于后者,且随疏浚土掺入量增加而增加;前者对Cu2 ,Zn2 的吸附能力远高于后者,在高浓度时对K 的吸附能力也较后者强,且随疏浚土掺入量增加有所增强。 相似文献
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A novel adsorbent for arsenic (V) removal from wastewater was developed through simple chemical processes using a special iron-abundant fly ash. In the synthesis process, the inherent iron in the fly ash was rearranged and loaded on the surface of the fly ash by dissolution and precipitation processes. The adsorbent (HIOFAA) was characterized by XRD, FT-IR, SEM, LPS and BET surface area. The results showed that porous amorphous FeOOH was loaded on the surface of HIOFAA successfully. The BET surface area of HIOFAA was 22 times of those of the original fly ash, and furthermore, the mean particle size of HIOFAA increased 3 times compared to the raw fly ash, thus effectively accelerated the solid/liquid separation after the adsorptive treatment. The adsorption isotherm data could be well described by Langmuir isotherm model, and the adsorption capacity for arsenic removal was 19.46 mg g− 1. Accordingly, it is believed that the adsorbent developed in this study is effective for arsenic polluted wastewater treatment. 相似文献
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《Soils and Foundations》2009,49(1):85-98
This paper presents the role of fly ash on strength and microstructure development in blended cement stabilized silty clay. Its strength was examined by unconfined compression test and its microstructure (fabric and cementation bond) by a scanning electron microscope (SEM), mercury intrusion porosimetry (MIP), and thermal gravity (TG) analysis. The flocculation of clay particles due to the cation exchange process is controlled by cement content, regardless of fly ash content. It increases dry unit weight of the stabilized clay with insignificant change in liquid limit. This results in irrelevant difference in optimum water content (OWC) for the unstabilized and the stabilized clay since OWC of low swelling silty clay is mainly controlled by liquid limit. It is found from the microstructural and the strength test results that the reactivity of fly ash (pozzolanic reaction) is minimal, which is different from concrete technology. This is possibly due to less amount of Ca(OH)2 to be consumed. The role of fly ash in cement stabilization is to disperse the large clay-cement clusters into smaller clusters. Consequently, the reactive surfaces to be interacted with water increase, and hence the cementitious products (inter-cluster cementation bond). To conclude, the strength development in the blended cement stabilized clay is controlled by cementitious products due to combined effect: hydration and dispersion. Cementitious products due to hydration are governed by cement content, while cementitious products due to dispersion by fly ash content and fineness. Water content of 1.2OWC and 10% replacement ratio are regarded as the effective mixing condition for the stabilization, exhibiting the highest cementitious products. 相似文献
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《Construction and Building Materials》2005,19(3):243-247
In present paper fly ash in wet state with low quality was used as raw material to replace clay to make fired bricks. The effect of fly ash with high replacing ratio of clay on firing parameters and properties of bricks were studied. The results indicate that the plasticity index of mixture of fly ash and clay decrease dramatically with increasing of replacing ratio of fly ash. Additive A can be chosen to improve the plasticity index of mixture to meet plastic extrusion used in most brick making factories. The sintering temperature of bricks with high replacing ratio of fly ash was about 1050 °C, which is 50–100 °C higher than that of clay bricks. The properties of fired bricks were improved by using pulverized fly ash. The fired bricks with high volume ratio of fly ash were of high compressive strength, low water absorption, no cracking due to lime, no frost and high resistance to frost-melting. 相似文献
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粉煤灰加气混凝土吸水性能研究 总被引:1,自引:0,他引:1
试验表明,当粉煤灰加气混凝土在整体吸水时的吸水速度和吸水量明显大于粘土砖;粉煤灰加气混凝土一端吸水时的吸水性能与其成型时的膨胀方向密切相关,当吸水方向平行于加气混凝土膨胀方向时,粉煤灰加气混凝土的吸水速度和吸水量明显大于粘土砖;吸水方向垂直于加气混凝土膨胀方向时,粉煤灰加气混凝土的吸水速度和吸水量小于粘土砖。 相似文献
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The ability of bentonite clay to remove Pb(II) from aqueous solutions and from nitric acid, hydrochloric acid and perchloric acid solutions (1.0-1 x 10(-5)) has been studied at different optimized conditions of concentrations, amount of adsorbent, temperature, concentration of electrolyte and pH. Maximum adsorption of Pb(II), i.e. > 98% has been achieved in aqueous solutions, while 86% is achieved from 1.0 x 10(-5) M HCl using 0.5 g of bentonite. The adsorption decreases by increasing the concentration of electrolytes. Flame atomic absorption spectrometer was used for measuring lead concentration. Isotherm analysis of adsorption data obtained at 25 degrees C, 30 degrees C, 40 degrees C and 50 degrees C showed that the adsorption pattern of lead on bentonite followed the langmuir isotherm and freundlich isotherm, respectively. DeltaH(o) and deltaS(o) were calculated from the slope and intercept of ln K(D) vs. I/T plots. 相似文献
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试验表明,当粉煤灰加气混凝土在整体吸水时的吸水速度和吸水量明显大于粘土砖;粉煤灰加气混凝土一端吸水时的吸水性能与其成型时的膨胀方向密切相关,当吸水方向平行于加气混凝土膨胀方向时,粉煤灰加气混凝土的吸水速度和吸水量明显大于粘土砖;吸水方向垂直于加气混凝土膨胀方向时,粉煤灰加气混凝土的吸水速度和吸水量小于粘土砖。 相似文献
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南京粉质黏土与粉砂互层土为粉质黏土与粉细砂交互沉积,呈现"千层饼"状外貌;南京粉细砂是一种以片状颗粒成分为主的粉细砂,与通常的圆形颗粒石英砂有一定区别,片状颗粒成分使得南京粉细砂具有各向异性的性质。利用南京工业大学岩土工程研究所自行研制的DSZ-1型动三轴仪对南京粉质黏土与粉砂互层土及粉细砂进行对比试验,对其试验成果进行分析,从中发现:在均压固结条件下,由于粉质黏土与粉砂互层土独特的结构性,其振动孔压发展模式与粉细砂的不同,可以用双曲线进行拟合,而粉细砂的振动孔压发展模式与Seed提出的砂土的振动孔压发展模式相同,可以用反正弦三角函数拟合;在偏压固结条件下,两者的振动孔压发展模式相同,均可以用双曲线进行拟合。此外,无论是均压固结还是偏压固结条件,对于粉质黏土与粉砂互层土,当以轴向双幅应变5%作为液化标准时,其发生液化的振动孔压均达不到围压值。 相似文献
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通过静态平衡吸附试验对采用颗粒活性炭及酸活化膨润土改良的垃圾填埋场衬垫土壤材料吸附重金属的特性进行了观察。试验结果表明:研究中的所有土壤样本对Cr(Ⅵ)的吸附属于非线性的Langmuir模式。经颗粒活性炭及酸活化膨润土改良的衬垫土壤材料与天然黏土材料相比,对Cr(Ⅵ)的吸附强度有了很大的提高,说明颗粒活性炭和酸活化膨润土可以作为改良衬垫土壤的材料去吸附重金属。所有土壤样本对Cr(Ⅵ)的吸附量均随着温度的升高而增大,随着土壤固体颗粒浓度的增大而减小。Langmuir等温参数(qm,b)随着土壤固体颗粒浓度的增大而呈对数性减小,但随着土壤固体颗粒浓度进一步增大到某一临界值(例如200 g/L),其值基本稳定了,另外等温参数也随着温度的升高呈线性增大的趋势。由试验结果可以得出,采用较低的土壤固体颗粒浓度所确定的吸附参数值不适合模拟实际工程条件,其值将引起对垃圾填埋场衬垫的迟滞因子作出过高估计。因此,为了获得与实际工程条件比较接近的吸附参数值,静态平衡吸附试验必须在一个充分大的固体颗粒浓度条件下进行。 相似文献