渗沥液污染下水泥固化高岭土透水及变形特性

针对填埋场衬垫在高荷载作用下开裂破坏的现状,采用水泥固化高岭土,评价其抗渗、抗开裂及固结压缩特性,探究其作为填埋场衬垫材料的可行性.采用纯高岭土与水泥掺量5%、10%、15%的固化高岭土进行试验,室内模拟填埋场衬垫受渗沥液污染的工况,通过渗透试验测定水力传导系数,分析其抵抗污染物渗透能力;通过固结试验测定压缩系数,分析其固结压缩特性;通过干湿循环开裂试验测定开裂因子,分析其抵抗开裂变形特性.结果表明:试样水力传导系数随时间增加而下降,其中纯高岭土下降40.4%,而水泥固化后高岭土仅下降16.0%~27.1%.由于试验高岭土属于中压缩性土,试样孔隙比随荷载压力上升而下降,水泥掺量越多,孔隙比下降越少,200kPa荷载下,0.25~64min的轴向位移变化量占总变化量的65.1%~70.7%;掺入水泥后试样的开裂面积明显减小,最大开裂因子降幅达52.6%,水泥掺量10%与15%的试样开裂因子差别较小.水泥固化后高岭土的强度及抗开裂能力提高,满足作为填埋场衬垫材料的要求.     

一种高岭土基多孔硅材料的制备及其对Ca2+和Mg2+的吸附

成功合成了一种高岭土基新型多孔硅材料（ASM）并以FTIR,XRD,FE-SEM和N₂吸附-脱附进行了系统的表征。ASM的制备过程涉及两步：SiO₃^2-提取和ASM的制备。SiO₃^2-提取的最优条件为煅烧温度为960℃,NaOH浓度为20%,反应温度为90℃,反应时间为90 min,在此条件下SiO₃^2-提取率为60.45%（w/w）。以此提取液为原材料,调整提取液中SiO₃^2-的浓度为12 g·L^-1,反应温度为90℃,反应时间为60 min,然后再搅拌2 h可制得ASM。以此ASM对Ca²⁺和Mg²⁺进行吸附研究,脱除率分别可达94.99%和62.32%。     

Impact of Various Parameters Over the Adsorption of Polyvinylpyrrolidone onto Kaolin

The adsorption of water-soluble polymer, polyvinylpyrrolidone having molecular mass 9.1 ± 1.43 × 10³Kg mole^?1 on kaolin has been investigated. The effect of different parameters like pH, molecular mass of polymer and pre-heat treatment on the adsorption of PVP has been deliberated. The 20.7% decrease in adsorption in pH ranging from 2–10 have been found, which was an indication of the fact that with the increase in pH the kaolin surfaces sites charge amount and ultimately sign changes. Maximum adsorption was observed at pH 5.6 that was also molecular mass dependent. By increasing the pretreatment temperature, the amount of polymer adsorbed was also increased. However, above the specific temperature adsorption of PVP was decreased and attributed to decrease in specific surface area of kaolin.     

镉污染高岭土微观特性的试验研究

通过Batch平衡法制备试验样本,对不同浓度镉污染高岭土的微观孔容、孔径以及TG-DTA特性进行了试验研究。结果表明:随着样品镉污染浓度的增大,镉污染高岭土宽度为1~2 nm的孔隙占总孔容的比例较少;宽度为2~20 nm的孔隙占总孔容的比例增加。这是由于随着镉污染物浓度的增加,高岭土试样中产生了氢氧化镉或者碳酸镉沉淀阻塞了孔径。通过TG—DTA曲线得出随着污染物浓度的增大,样品中氢氧化物及碳酸盐的含量逐渐增高,这与低温氮吸附试验结果相吻合。     

A Fluorescence Polarization Study of Polyaromatic Hydrocarbons Adsorbed on Colloidal Kaolin

Abstract

The adsorption of a number of polyaromatic hydrocarbons onto aqueous colloidal kaolin was studied. The fluorescence polarization and hence the fluorescence anistropy of the hydrocarbons was measured as a function of their concentrations in aqueous solutions containing the colloid. The fluorescence anisotropy was found to be highest for dilute solutions of polyaromatic hydrocarbons, with often sharp decreases at higher concentrations. More concentrated solutions gave an isotropies similar to those of plain aqueous solutions of the fluorophores. The concentration versus fluorescence anisotropy curves and BET surface area data were used to calculate surface coverage of the colloid by the adsorbed hydrocarbons. Coverage in the range of 1% to 14% of the colloid surface was found at surface saturation for the compounds studied. This suggested that colloidal clays have the potential of transporting polyaromatic hydrocarbons through environmental waters.     

牛蜱粗提物对家兔及人的抗凝血作用的实验研究

通过体外试验，观察牛蜱粗提物对家兔及人血浆的抗凝血效果．通过测定与比较加入牛蜱粗提物与未加牛蜱粗提物的兔血浆和人血浆的血浆复钙时间(RT)、凝血酶原时间(PT)、白陶土部分凝血酶激活时间(KPTT)，发现牛蜱粗提物能使兔血浆及人血浆RT、PT、KPTT均显延长，且其作用随着牛蜱粗提物用量的增大而增强．实验结果显示牛蜱粗提物具有明显的抗凝作用．     

Elucidation of Gram-Positive Bacterial Iron(III) Reduction for Kaolinite Clay Refinement

Recently, microbial-based iron reduction has been considered as a viable alternative to typical chemical-based treatments. The iron reduction is an important process in kaolin refining, where iron-bearing impurities in kaolin clay affects the whiteness, refractory properties, and its commercial value. In recent years, Gram-negative bacteria has been in the center stage of iron reduction research, whereas little is known about the potential use of Gram-positive bacteria to refine kaolin clay. In this study, we investigated the ferric reducing capabilities of five microbes by manipulating the microbial growth conditions. Out of the five, we discovered that Bacillus cereus and Staphylococcus aureus outperformed the other microbes under nitrogen-rich media. Through the biochemical changes and the microbial behavior, we mapped the hypothetical pathway leading to the iron reduction cellular properties, and found that the iron reduction properties of these Gram-positive bacteria rely heavily on the media composition. The media composition results in increased basification of the media that is a prerequisite for the cellular reduction of ferric ions. Further, these changes impact the formation of biofilm, suggesting that the cellular interaction for the iron(III)oxide reduction is not solely reliant on the formation of biofilms. This article reveals the potential development of Gram-positive microbes in facilitating the microbial-based removal of metal contaminants from clays or ores. Further studies to elucidate the corresponding pathways would be crucial for the further development of the field.     

悬浮物测定的质量控制方法

为完善现行国标法GB 11901–1989《水质悬浮物的测定重量法》中质量控制与质量保证相关内容,促进悬浮物标准品的研发,利用高岭土研制的标准溶液建立了悬浮物测定的质量控制方法。根据水样的属性,取样体积范围在50 m L~200 m L区间,采用水系0.45μm滤膜和三联抽滤装置对水样进行预处理操作,以重量法测定水样悬浮物的含量。确定方法的空白测定值稳定于上下警告线内波动,检出限为5 mg/L,样品6次测定结果的相对标准偏差小于10%,标准样品10次测定相对误差在±10%内,满足分析质量控制要求。     

高岭土煅烧过程白度和失重的变化及应用

本文通过测定高岭土煅烧过程中白度、失重变化,初步探讨煅烧过程中有机物质及铁、钛对白度的影响。     

Influence of Thermal Treatment on the Structure and Thermal Properties of Kaolin Modified Polyester Fibers

Modified polyester fibers were obtained using 2% and 6% of kaolin blends through melt spinning.The influences of two thermal treatments maintaining the original tension(180 ℃×2 min and 200 ℃×1 min)on the structure and properties of fiber were compared.The changes of grain size and crystallinity of fiber were investigated by X-ray diffraction(XRD).The changes of thermal properties of fibers were analyzed using dynamic mechanical analyzer(DMA).The results show that the crystalline structure of kaolin modified polyester fiber doesn't change with the thermal treatment.With the kaolin content increasing,the grain size of fiber changed.The higher the thermal treatment temperature is,the higher the crystallinity of fiber is.There are two glass-transition temperatures for kaolin modified:the lower one is the glass-transition temperature of polyester fiber matrix,and the higher one is derived from the heterogeneous blend of polyester matrix and nano kaolin.The higher the kaolin content is,the higher the glass-transition temperature is.Thermal treatment could increase the compatibility of polyester matrix and nano kaolin.There was only one glass-transition temperature for the thermal treatment fiber,and the heat resistance of fiber was improved.Thermogravimetric analysis-differential scanning calorimetry(TGA-DSC)results of kaolin modified polyethylene terephthalate(PET)matrix indicate that the decomposition temperature of PET fibers,kaolin modified PET fibers,and thermal treated fibers were little different within 40%-60% of weight loss rate range.