粘土对纸面石膏板质量的影响

生产纸面石膏板的主要原料是石膏,因此,石膏原料质量的优劣直接影响着纸面石膏板的质量。本文就石膏原料中的粘土杂质含量对纸面石膏板质量的影响进行研究。１粘土对纸面石膏板影响的机理粘土呈细粒状存在于结晶矿物中,粘土中矿物的组成主要由氧化硅、氧化铝和水组成的含水硅酸盐,其中有些矿物还含有相当数量的铁、碱金属和碱土金属,大多数粘土矿物在湿润时具有塑性,代表性的粘土矿物是蒙脱石。文中所述的粘土主要是由蒙脱石矿物组成的膨润土。膨润土中蒙脱石的理论结构为（ＯＨ）４Ｓｉ８Ａｌ４Ｏ２０·ｎＨ２Ｏ,设有层间物质的理论…     

高岭土及其在化学建材中应用

高岭土因发现于中国景德镇附近的高岭村而得名,是多种矿物组成的含水铝硅酸盐混合体,主要是由高岭石族矿物组成的一种重要粘土,属1∶1型层状硅酸盐。我国是世界上最早发现并利用高岭土的国家,我国的高岭土因其成因类型齐全,储量丰富(12亿t 以上),质地优良而闻名于世。1.矿物学特征、理化性能及用途高岭土的基本组分为高岭石组、蒙脱石组和水云母组矿物。其中主要矿物是高岭石。高岭石的含量愈高,质量愈好;优质高岭土,其高岭石含量在90%以上。高岭石属单斜晶系,多为隐晶质,晶体呈细微的鳞片或板状体,外表经常是致密状、土状及疏松状结构。白色,因含杂质,也呈灰、黄、红、褐、蓝、绿等色。条痕为白色或淡绿色,珍珠光泽或无光泽,半透明至不透明。硬度1～2.5,比重2.2     

粒径对多孔介质中悬浮颗粒迁移—沉积特性的影响

粒径变化对悬浮颗粒在多孔介质中迁移—沉积过程影响的研究有重要意义。利用自主研发的砂层迁移—沉积模拟试验系统,研究不同粒径的悬浮颗粒在不同尺寸多孔介质中的迁移—沉积特性。结果表明,对于相同尺寸的多孔介质,随着悬浮颗粒粒径的增加,到达相对浓度峰值时间增加,而对应的相对浓度峰值降低;同时,对于相同粒径的悬浮颗粒,随着多孔介质尺寸增大,相对浓度峰值增加;另外,相对于多孔介质,悬浮颗粒粒径的变化对其迁移—沉积过程影响更为显著;随着多孔介质与悬浮颗粒粒径比增大,相对浓度的峰值和终值增大;根据粒径比不同将悬浮颗粒在多孔介质中的迁移—沉积类型划分为“滤饼过滤型”、“迁移—沉积型”、“自由迁移型”3种。研究结果为水源热泵回灌过程中悬浮颗粒在地层中的迁移—沉积特性进一步研究奠定了基础。     

Pu在板岩与粘土中的动态吸附模拟实验研究

以西南某地的板岩与粘土为吸附介质,采用动态吸附法来模拟放射性Pu废液在吸附介质的扩散与迁移,得出Pu浓度随时间与淋滤柱柱深的变化曲线。实验结果表明:Pu在粘土中分配系数约是板岩中4倍左右;粘土和板岩中同一柱深时,钚在土壤中数值要稍大于板岩中的含量,且流量变化是影响核素迁移的主要因素之一。     

多孔介质中悬浮颗粒迁移–沉积特性研究进展

研究多孔介质中悬浮颗粒的迁移–沉积特性对地下水回灌、石油开采、污染物迁移等问题具有重要意义。从数学模型和物理试验2个方面介绍和总结多孔介质中悬浮颗粒迁移–沉积特性研究现状。提出以现场监测及大量室内试验为手段,以不同条件下悬浮颗粒迁移–沉积特性研究为基础,以建立考虑颗粒速度修正系数、孔隙率修正系数、颗粒捕获率及孔隙率变化的颗粒迁移数学模型为前提的颗粒迁移–沉积特性研究方法。当前无论是物理试验还是数学模型研究,均存在很多不足:如未能准确描述多孔介质内部孔隙结构,没有考虑到颗粒在多因素耦合作用下的迁移–沉积特性,未能将宏观尺度下的过滤现象与细观尺度下的颗粒运动很好地结合等。因此认为以下4个方向是今后研究的重点和趋势:(1)开发动态三维试验装置;(2)建立完善的多孔介质空间模型;(3)建立多因素耦合影响下的颗粒迁移–沉积数学模型;(4)建立多孔介质多尺度颗粒分析方法与理论。     

矿物成分相关的黏土一维压缩特性分析

为了探索不同黏土矿物成分对黏土一维压缩特性的影响,采用高岭土、伊利土、蒙脱石及绿泥石,按不同质量比例混合来制备重塑土样,进行室内标准一维压缩试验。大量试验结果对比表明：①高岭土与伊利土混合土样的压缩指数（C_c）和回弹指数（C_s）都随伊利土含量的增加而增加;②高岭土、伊利土与蒙脱石混合土样的C_c和C_s随蒙脱石含量的增加而增大,且蒙脱石的作用占主导地位;③高岭土、伊利土、蒙脱石及绿泥石混合土样的C_c和C_s随蒙脱石与绿泥石二者含量之和的增加而增大,且蒙脱石的作用占主导地位。基于试验结果,总结出各黏土矿物成分影响的压缩指数与回弹指数的非线性表达式。此外,试验表明所有混合土样的压缩指数与回弹指数的比值（C_c/C_s）介于6.1和9.1之间变化。     

齐齐哈尔黑粘土、淘洗高岭土在电瓷配方中的应用

介绍了齐齐哈尔黑粘土和淘洗高岭土的矿物类型、原料特性。齐齐哈尔黑粘土属于高保水性、高结合性粘土矿物,少量引入可有效提高坯料的可塑性能和干燥弯曲强度;淘洗高岭土属于沉积岩类高岭土,经水化淘洗加工后,可塑性显著提高,但结合性较低,适当调整可取代同类型软质粘土。扫描电镜分析结果表明,齐齐哈尔黑粘土和淘洗高岭土都属于球粘土类型。采用两种粘土优选了两种配方,与原配方的对比实验结果表明,新配方的可塑性指标和干燥弯曲强度都显著提高。且提高了成形合格率,降低了碰损率,获得了较理想的应用效果。     

蒙脱石含量对压实膨润土孔隙结构的影响

粘土的微观结构对其的渗透性以及阻滞核素迁移的能力有重要的影响,为了探讨蒙脱石含量对高压实成型膨润土孔隙结构的影响,通过添加不同量石英砂改变蒙脱石含量,并使用压汞法对高压实成型膨润土的孔隙分布特征、孔隙大小和孔隙体积进行了研究,结果表明:(1)成型样品的孔隙比与蒙脱石含量间成线性关系;(2)样品的孔径分布由低蒙脱石含量下的"双峰"分布过渡为高蒙脱石含量下的"单峰"分布;(3)集合体间孔隙大小的峰值随着蒙脱石含量的增加而减小;(4)集合体间孔隙体积随着蒙脱石含量的增加而减小,集合体内的孔隙体积和极小孔隙体积随着蒙脱石含量的增加而增加。     

水源热泵运行中多组份溶质的反应迁移模拟

地下水源热泵系统以其优越的节能性和环保性在全国范围内得到了推广应用,为了准确地了解地下水源热泵回水对地下水质的影响,本文以安阳市第五人民医院地下水源热泵系统为例,采用TOUGHREACT建立反应物迁移转化模型,对水源热泵系统长期运行中地下水化学组分、含水介质中矿物组分和矿化度的变化情况进行模拟研究。研究结果表明:水源热泵抽回水过程中地下水组分浓度(K~+、Na~+、Ca~(2+)、Mg~(2+)、HCO_3~-)变化程度较小;含水介质中的方解石和云母均发生了不同程度的沉淀作用,钙长石矿物发生了溶解作用;回水井周边的含水介质孔隙度变小,预测期内孔隙度降低了0.0011。水源热泵系统的长期运行对地下水化学组分、含水介质中的矿物组分和孔隙度的影响较小。     

忻州盆地第四系含水系统三维水文地质结构建模

盆地水文地质结构三维可视模型可以从不同角度直观地、真实地展现盆地孔隙介质的地层、岩性变化特征,成为孔隙性含水系统结构分析的有效手段。本次研究建立了一套可行的、具有一定示范性的综合方法来实现忻州盆地孔隙介质结构的三维可视化。在充分收集整理忻州盆地基础资料的基础上,利用大量的地形、钻孔资料等数字信息建立系统数据库。通过第四系以来地质演变和沉积规律,即岩相、韵律与旋回等研究,辅助利用盆地地质剖面图及第四系地质沉积史来采集厚度控制点(或称虚拟钻孔),按照一定精度采集盆地已有的钻孔和厚度控制点。以GMS软件为平台构建盆地孔隙介质结构可视化模型,实现从不同角度直观地、真实地展示三维孔隙介质的分布规律。盆地含水系统的三维地层结构和岩性结构模型,宏观上反映了地下水含水介质与相对隔水介质的分布情况,有助于对水文地质问题的深入研究,为盆地地下水数值模拟计算奠定了结构基础。     

Colloid transport with wetting fronts: Interactive effects of solution surface tension and ionic strength

Transport of colloids with transient wetting fronts represents an important mechanism of contaminant migration in the vadose zone. The work presented here used steady-state saturated and transient unsaturated flow columns to evaluate the transport of a fluorescent latex microsphere (980 nm in diameter) with capillary wetting fronts of different solution surface tensions and ionic strengths. The saturated transport experiments demonstrated that decreasing solution surface tension and ionic strength decreased colloid deposition at the solid-liquid interface and increased colloid recovery in the column effluent. The effect of solution surface tension on colloid transport and deposition was greater at lower ionic strength, suggesting an interaction between these two factors. Under transient unsaturated flow conditions, the number of colloids retained in sand decreased exponentially with travel distance through the porous media. However, lowering the solution surface tension and ionic strength resulted in a more even distribution of colloids along the column. The measured zeta potentials of colloids in different solutions suggest that both lowering surface tension and ionic strength would enhance the electrostatic repulsion between colloid and sand. The experimental results revealed that the effects are nonlinear, implying the possible existence of critical threshold values, beyond which the effects were not significant. In addition, colloid migration slowed down as solution surface tension decreased due to reduction of capillary forces that drove liquid movement.     

Coupling of physical and chemical mechanisms of colloid straining in saturated porous media

Filtration theory does not include the potential influence of pore structure on colloid removal by straining. Conversely, previous research on straining has not considered the possible influence of chemical interactions. Experimental and theoretical studies were therefore undertaken to explore the coupling of physical and chemical mechanisms of colloid straining under unfavorable attachment conditions (pH=10). Negatively charged latex microspheres (1.1 and 3mum) and quartz sands (360, 240, and 150mum) were used in packed column studies that encompassed a range in suspension ionic strengths (6-106mM) and Darcy water velocities (0.1-0.45cmmin(-1)). Derjaguin-Landau-Verwey-Overbeek (DLVO) calculations and torque analysis suggests that attachment of colloids to the solid-water interface was not a significant mechanism of deposition for the selected experimental conditions. Effluent concentration curves and hyperexponential deposition profiles were strongly dependent on the solution chemistry, the system hydrodynamics, and the colloid and collector grain size, with greater deposition occurring for increasing ionic strength, lower flow rates, and larger ratios of the colloid to the median grain diameter. Increasing the solution ionic strength is believed to increase the force and number of colloids in the secondary minimum of the DLVO interaction energy profile. These weakly associated colloids can be funneled to small regions of the pore space formed adjacent to grain-grain junctions. For select systems, the ionic strength of the eluant solution was decreased to 6mM following the recovery of the effluent concentration curve. In this case, only a small portion of the deposited colloids was recovered in the effluent and the majority was still retained in the sand. These observations suggest that the extent of colloid removal by straining is strongly coupled to solution chemistry.     

Colloid transport in porous media: impact of hyper-saline solutions

The transport of colloids suspended in natural saline solutions with a wide range of ionic strengths, up to that of Dead Sea brines (10^0.9 M) was explored. Migration of microspheres through saturated sand columns of different sizes was studied in laboratory experiments and simulated with mathematical models.Colloid transport was found to be related to the solution salinity as expected. The relative concentration of colloids at the columns outlet decreased (after 2-3 pore volumes) as the solution ionic strength increased until a critical value was reached (ionic strength > 10^−1.8 M) and then remained constant above this level of salinity.The colloids were found to be mobile even in the extremely saline brines of the Dead Sea. At such high ionic strength no energetic barrier to colloid attachment was presumed to exist and colloid deposition was expected to be a favorable process. However, even at these salinity levels, colloid attachment was not complete and the transport of ∼30% of the colloids through the 30-cm long columns was detected.To further explore the deposition of colloids on sand surfaces in Dead Sea brines, transport was studied using 7-cm long columns through which hundreds of pore volumes were introduced. The resulting breakthrough curves exhibited a bimodal shape whereby the relative concentration (C/C₀) of colloids at the outlet rose to a value of 0.8, and it remained relatively constant (for the ∼18 pore volumes during which the colloid suspension was flushed through the column) and then the relative concentration increased to a value of one. The bimodal nature of the breakthrough suggests different rates of colloid attachment. Colloid transport processes were successfully modeled using the limited entrapment model, which assumes that the colloid attachment rate is dependent on the concentration of the attached colloids. Application of this model provided confirmation of the colloid aggregation and their accelerated attachment during transport through soil in high salinity solution.     

Colloid‐mediated transport of Pb through soil porous media

Intact soil column leaching experiments were used to assess the role of water dispersible soil colloids with diverse physicochemical and mineralogical composition in co‐transporting Pb in subsurface soil environments. There was essentially no elution of Pb (0 to < 1%) in 10mg/L control Pb solutions, suggesting a near complete attenuation by the soil column matrix. When the control Pb solutions were mixed with 300mg/L soil colloid suspensions, Pb transport increased by 10–3,000 times over that of control solutions. The presence of colloids increased the transport of both, the colloid bound and the soluble Pb fraction. Colloid‐induced transport was enhanced by increasing colloid surface charge, pH, organic carbon, and soil macroporosity and inhibited by increasing colloid size, Al, Fe, and quartz content. However, increased soil organic carbon content appeared to compensate for some of these limitations. Colloid binding and co‐transport appeared to be the dominant mechanism for increases in Pb transportability, but physical exclusion of soluble Pb species from matrix exchange sites blocked by colloids, competitive sorption, and organic complexation were also important. These findings suggest that the colloids play a dual role as Pb‐carriers and facilitators in the migration process and could have important ramifications on contaminant transport prediction and remediation applications.     

Impact of dissolved organic matter on colloid transport in the vadose zone: deterministic approximation of transport deposition coefficients from polymeric coating characteristics

Although numerous studies have been conducted to discern colloid transport and stability processes, the mechanistic understanding of how dissolved organic matter (DOM) affects colloid fate in unsaturated soils (i.e., the vadose zone) remains unclear. This study aims to bridge the gap between the physicochemical responses of colloid complexes and porous media interfaces to solution chemistry, and the effect these changes have on colloid transport and fate. Measurements of adsorbed layer thickness, density, and charge of DOM-colloid complexes and transport experiments with tandem internal process visualization were conducted for key constituents of DOM, humic (HA) and fulvic acids (FA), at acidic, neutral and basic pH and two CaCl₂ concentrations. Polymeric characteristics reveal that, of the two tested DOM constituents, only HA electrosterically stabilizes colloids. This stabilization is highly dependent on solution pH which controls DOM polymer adsorption affinity, and on the presence of Ca⁺² which promotes charge neutralization and inter-particle bridging. Transport experiments indicate that HA improved colloid transport significantly, while FA only marginally affected transport despite having a large effect on particle charge. A transport model with deposition and pore-exclusion parameters fit experimental breakthrough curves well. Trends in deposition coefficients are correlated to the changes in colloid surface potential for bare colloids, but must include adsorbed layer thickness and density for sterically stabilized colloids. Additionally, internal process observations with bright field microscopy reveal that, under optimal conditions for retention, experiments with FA or no DOM promoted colloid retention at solid-water interfaces, while experiments with HA enhanced colloid retention at air-water interfaces, presumably due to partitioning of HA at the air-water interface and/or increased hydrophobic characteristics of HA-colloid complexes.     

含水介质中渗透性突变的机理研究

通过盐度突变砂柱试验,对大沽河海咸水入侵区砂质含水层的渗透性突变进行了初步研究,并且探讨了咸淡水相互作用过程中渗透性降低的主要机制及对引起渗透性降低的主要影响因素进行分析。试验结果表明：盐浓度的突然降低会直接导致含水层渗透性发生急剧下降,同时在流出液中出现大量以粘土矿物为主的微粒物质;粘土矿物的含量和种类对含水介质渗透性降低幅度的影响非常大,盐度突变过程中,反应性粘土矿物对砂柱渗透性的影响要远远大于非反应性的微粒,且重量比为3％～4％时便可使砂柱的渗透系数降低到零。     

Direct observations of colloid retention in granular media in the presence of energy barriers, and implications for inferred mechanisms from indirect observations

In this paper we present direct observations of retention of colloids in granular porous media over a large size range (0.21-9.0 μm) and generalize the significance of attachment in grain to grain contacts and attachment on the open surface as a function of colloid:collector ratio. We examine reversibility of attachment via these mechanisms with respect to ionic strength reduction and fluid velocity increase. We relate these direct observations to existing literature, and in some cases offer alternative interpretations of mechanisms of retention drawn from indirect observations (e.g. via column effluent and retained concentrations).     

Effects of pH, ionic strength, dissolved organic matter, and flow rate on the co-transport of MS2 bacteriophages with kaolinite in gravel aquifer media

Viruses are often associated with colloids in wastewater and could be transported with colloids into groundwater from land disposal of human and animal effluent and sludge, causing contamination of groundwater. To investigate the role of colloids in the transport of viruses in groundwater, experiments were conducted using a 2 m long column packed with heterogeneous gravel aquifer media. Bacteriophage MS2 was used as the model virus and kaolinite as the model colloid. Experimental data were analyzed using Temporal Moment Analysis and Filtration Theory. In the absence of kaolinite colloid, MS2 phage traveled slightly faster than the conservative tracer bromide (Br), with little differences observed between unfiltered and filtered MS2 phage (0.22 μm as the operational cut-off for colloid-free virus). In the presence of kaolinite colloids, MS2 phage breakthrough occurred concurrently with that of the colloidal particles and the time taken to reach the peak virus concentration was reduced, suggesting a colloid-facilitated virus transport in terms of peak-concentration time and velocity. Meanwhile mass recovery and magnitude of concentrations of the phages were significantly reduced, indicating colloid-assisted virus attenuation in terms of concentrations and mass. Decreasing the pH or increasing the ionic strength increased the level of virus attachment to the aquifer media and colloids, and virus transport became more retarded, resulting in lower peak-concentration, lower mass recovery, longer peak-concentration time, and greater apparent collision efficiency. Increasing the concentration of dissolved organic matter (DOM) or flow rate resulted in faster virus transport velocity, higher peak-concentrations and mass recoveries, and lower apparent collision efficiencies. The dual-role of colloids in transport viruses has important implications for risk analysis and remediation of virus-contaminated sites.     

Mobilization and Leaching of Natural and Water Dispersible Colloids in Aggregated Volcanic Ash Soil Columns

Colloid-facilitated transport enhances migration of strongly sorbing compounds (e.g., radionuclides, phosphorus, heavy metals) in soil and groundwater. Mobilization, transport and deposition of soil colloids are the underlying processes governing colloid-facilitated contaminant transport. Although significant progress has been made in simulating mobilization and transport/deposition of model colloids in different collector systems, it may be inadequate for the prediction of natural colloidal behavior in the subsurface. This study quantifies the leaching of natural volcanic ash soil colloids (NC) as well as the simultaneous transport of applied water dispersible soil colloids (WDC) in aggregated volcanic ash soil columns. Two water-saturated soil columns were irrigated with artificial irrigation water (AIW) at an intensity of 80 mm/hr for 60 hours. Two additional columns were irrigated at the same intensity, but a colloidal suspension of 5 mg/L was applied after 20 hours for a period of 20 hours. Effluent colloid concentrations were measured in each experiment. HYDRUS-1D was used for the simulation and estimation of colloid transport parameters. The results clearly showed different kinetics for applied colloid transport and natural colloid leaching. Transport of applied WDC followed first-order attachment kinetics, while the two-site equilibrium/kinetic model with equal fractions of equilibrium and kinetic sites best described the leaching of NC. Coupling these best model approaches well predicted the simultaneous leaching of natural and applied colloids, hereby providing a useful tool for the design of colloid-based in-situ soil remediation systems.     

Colloid-Enhanced Desorption Of Zinc In Soil Monoliths

The desorption and co-transport of metals by ex situ water dispersible soil colloids moving through macropores was evaluated in a leaching experiment utilizing Zn-saturated soil monoliths. The monoliths were created by hydraulically driving steel pipe sections (50 cm diameter 2 50 cm length) into a Loradale silt loam soil (fine, silty, mixed, mesic Typic Argiudolls). Each monolith was saturated in excess of the soil cation exchange capacity (CEC) with ZnCl 2 , then leached at a constant flux with a suspension of water-dispersible colloids fractionated from either the Bt or O horizon of a Beasley (fine, montmorillonitic, mesic Typic Hapludalfs) or Rayne (fine-loamy, mixed, mesic, Typic Hapludults) soil, respectively. Eluents from the monoliths were collected and analysed periodically for colloid and Zn concentration in the soluble and sorbed phase. Colloid and Zn concentration in the eluents varied greatly with respect to colloid type. The Beasley colloid, which had a small particle diameter (< 800 nm) and high sorptive affinity for Zn, showed considerable migrating ability through the soil matrix and enhanced Zn desorption by up to 400 times over that exhibited by a distilled water flushing solution. Eluted Beasley colloids were saturated with Zn at concentrations greater than 50% of the soil's CEC. Enhanced Zn desorption by colloids generated from the organic horizon of the Rayne soil was insignificant because the large colloid size (> 1200 nm) limited transport through the soil matrix. Mineralogical analysis of the eluted colloids revealed that in situ colloid generation was negligible, thus confirming that nearly all of the desorbed Zn fraction was due to the ex situ applied colloid.