粘土矿物成分对聚羧酸减水剂吸附性能的研究

劣质砂石料中的含泥对聚羧酸减水剂的性能具有强烈的抑制作用,表现为混凝土坍落度损失快,工作性能变差等.通过对粘土中蒙脱石、伊利石、高岭石等粘土矿物成分的砂浆流动度和吸附量随时间变化规律的研究,表明蒙脱石对聚羧酸减水剂的吸附能力最强.从分析矿物的晶体结构上探讨了粘土矿物成分对聚羧酸减水剂吸附的作用机理.     

聚羧酸减水剂在粘土中的插层行为及影响研究进展

聚羧酸减水剂在粘土中的吸附、插层行为会对水泥混凝土的性能产生影响.综述了聚羧酸减水剂在粘土中的吸附行为及在粘土矿物蒙脱石中的插层行为的机理、性能表征及对水泥净浆凝结时间、流动度、抗压强度;水泥胶砂流动度、抗压强度、抗折强度;混凝土和易性、坍落度、抗压强度的影响,总结了粘土与聚羧酸减水剂对水泥混凝土性能影响的评价方法,阐述了调控插层行为的措施,展望了调控聚羧酸减水剂插层行为的研究前景.     

水泥和黏土矿物对不同减水剂的吸附特性

采用有机碳测定仪和紫外分光光度计,分别研究了聚羧酸减水剂、萘系减水剂和木质素磺酸钠在水泥、高岭土和蒙脱石颗粒表面的吸附特性,并对掺高岭土和蒙脱石的水泥净浆的流动度和黏度进行了测试,用三维视频显微镜观察了三种颗粒的形貌特征。结果表明:水泥、高岭土和蒙脱石对不同减水剂的吸附量不同;水泥比高岭土和蒙脱石对萘系减水剂的吸附量大,高岭土和蒙脱石比水泥对聚羧酸和木质素磺酸钠减水剂的吸附量大;水泥和高岭土颗粒表面较平滑,蒙脱石表面较粗糙;在掺入不同减水剂的水泥浆体中,蒙脱石和高岭土的掺入都会降低浆体流动度,提高浆体黏度,并且蒙脱石的影响更大。     

细骨料中的泥对聚羧酸减水剂性能的影响

本文研究了细骨料中泥对聚羧酸减水剂性能的影响;利用XRD分析了泥的矿物组成,用重铬酸钾法对泥进行有机质含量的测定,分别测试了不同的含泥量、矿物组成、有机质含量等条件下水泥净浆流动度,利用紫外可见分光光度计测试了水泥与不同种类泥对聚羧酸减水剂的吸附量.研究表明泥的存在不利于水泥净浆的流动度且含泥量越高影响越大;泥的种类和有机质含量的变化均会对水泥净浆流动度有不同程度的影响,含蒙脱石及伊利石等矿物的泥对水泥净浆流动度的影响大且对聚羧酸减水剂的吸附量也较大;泥的有机质含量越高越不利于水泥净浆流动度.     

蒙脱石对聚羧酸减水剂的层间吸附特性

为了研究集料中泥土的矿物组成对聚羧酸减水剂的吸附性能,采用总有机碳测定仪测定了水泥以及蒙脱石、伊利石、高岭石对浓度为4g/L的聚羧酸减水剂溶液中聚羧酸减水剂的吸附量。结果表明：蒙脱石对聚羧酸减水剂的吸附量最大,约为水泥颗粒的3倍,伊利石和高岭石的吸附量也比水泥颗粒略大。并对吸附了聚羧酸减水剂的蒙脱石进行热重、Fourier 红外光谱、X 射线衍射分析,测定了其所含的有机官能团以及层间距变化,结果表明聚羧酸减水剂吸附进入了蒙脱石的层间,这是造成其吸附量大于其他矿物的主要原因。     

β-环糊精侧链对聚羧酸减水剂抑制蒙脱土的影响

采用水泥净浆和混凝土试验,详细研究了β-环糊精侧链对聚羧酸减水剂抑制蒙脱土负效应的影响。试验表明,与仅含有聚氧乙烯侧链的传统聚羧酸减水剂相比,蒙脱土对掺加含有β-环糊精侧链的聚羧酸减水剂水泥净浆流动度的负作用影响明显减弱;蒙脱土(1.0%,以砂质量计)存在时,为获得与无蒙脱土时相同的混凝土坍落度,β-环糊精类聚羧酸减水剂的掺量增幅减小,掺加β-环糊精类聚羧酸减水剂的混凝土抗压强度下降幅度减小。结合吸附试验分析,β-环糊精类聚羧酸减水剂抑制蒙脱土负效应能力的增强应归功于其侧链中的β-环糊精基团,β-环糊精基团具有中空筒状的刚性结构,其显著的空间位阻效应将阻止蒙脱土颗粒继续吸附其他β-环糊精类聚羧酸分子,进而提高聚羧酸减水剂抑制蒙脱土负效应的能力。     

聚羧酸减水剂在水泥颗粒表面的吸附性能研究

通过水泥净浆流动度试验和TOC吸附试验研究了聚羧酸减水剂在水泥颗粒表面的吸附量与吸附时间和减水剂浓度之间的关系.研究表明,水泥对聚羧酸减水剂的吸附量随时间的延长而增加,最终达到平衡.通过Gibbs吸附等温式得出吸附量随浓度的增加存在饱和吸附量,并根据Langmuir等温吸附模型计算出其饱和吸附量.     

β-环糊精侧链对聚羧酸减水剂抑制蒙脱土的影响

采用水泥净浆和混凝土试验，详细研究了β-环糊精侧链对聚羧酸减水剂抑制蒙脱土负效应的影响。试验表明，与仅含有聚氧乙烯侧链的传统聚羧酸减水剂相比，蒙脱土对掺加含有β-环糊精侧链的聚羧酸减水剂水泥净浆流动度的负作用影响明显减弱；蒙脱土（1.0%，以砂质量计）存在时，为获得与无蒙脱土时相同的混凝土坍落度，β-环糊精类聚羧酸减水剂的掺量增幅减小，掺加β-环糊精类聚羧酸减水剂的混凝土抗压强度下降幅度减小。结合吸附试验分析，β-环糊精类聚羧酸减水剂抑制蒙脱土负效应能力的增强应归功于其侧链中的β-环糊精基团，β-环糊精基团具有中空筒状的刚性结构，其显著的空间位阻效应将阻止蒙脱土颗粒继续吸附其他β-环糊精类聚羧酸分子，进而提高聚羧酸减水剂抑制蒙脱土负效应的能力。     

水泥和泥对聚羧酸减水剂的吸附性能研究

本文选用水泥、砂中泥和种植泥作为试验研究对象,利用紫外可见分光光度计法(UV),测定反应设定时间后的聚羧酸减水剂浓度,研究水泥和泥对聚羧酸减水剂的吸附性能.试验结果表明:聚羧酸减水剂在水泥和泥表面的吸附量随时间延长而增加,最后达到平衡;聚羧酸减水剂在泥颗粒表面的吸附存在优先选择性和亲和性,使得其在泥颗粒表面的吸附速率和吸附量大于水泥;泥种类不同,吸附量大小不同,对净浆流动度的影响程度不同;泥的掺入会大大降低水泥净浆的流动度,增大流动度经时损失量,且掺量越大影响越大,因此在工程应用中,对原材料泥含量进行控制,降低泥对聚羧酸减水剂的吸附量,对提高减水剂的减水率,保证混凝土坍落度保留值具有重要意义.     

磺化木质素对蒙脱土吸附聚羧酸减水剂的抑制作用及机理EI北大核心CSCD

通过木质素与亚硫酸钠的化合反应得到磺化木质素。将其与聚羧酸减水剂（PC）双掺入含蒙脱土的水泥净浆中,观察净浆流动度的变化。采用X射线衍射仪,总有机碳测定仪和zeta电位仪等研究磺化木质素抑制蒙脱土吸附聚羧酸减水剂的作用机理。结果表明：磺化木质素可有效降低蒙脱土对水泥浆体流动性能的危害。磺化木质素分子链包裹水泥体系中的蒙脱土颗粒,将其铝硅层间距由1.42 nm压缩至1.23 nm,导致聚氧化乙烯侧链没有足够的空间嵌入,从而抑制了蒙脱土对PC的吸附,提高了聚羧酸减水剂对黏土的耐抗性。     

抗泥型聚羧酸减水剂的制备及性能

以甲基丙烯酸（MAA）、甲基丙烯酸羟乙酯（HEMA）为单体,过氧化氢（H₂O₂）/抗坏血酸（Vc）为引发剂,甲基烯丙基磺酸钠（SMAS）为链转移剂,合成了一种抗泥型聚羧酸减水剂,通过红外光谱（FTIR）、凝胶渗透色谱（GPC）对聚合物进行结构表征,通过水泥净浆流动度、蒙脱土层间官能团、X射线衍射和吸附量测试,对其分散性能及抑制蒙脱土机理进行了探究。结果显示：合成的抗泥型聚羧酸减水剂在摩尔比为2.5：1时分散性能最佳,当减水剂折固掺量为0.25%时,水泥初始净浆流动度为268mm;与普通聚羧酸减水剂相比,合成的抗泥型减水剂对蒙脱土敏感性较低,与蒙脱土作用后的层间未出现抗泥型减水剂的特征官能团,层间距为1.40nm,抗泥型减水剂在蒙脱土上的吸附量远小于普通减水剂的吸附量。     

Adsorption of proteins and nucleic acids on clay minerals and their interactions: A review

The understanding of adsorption of proteins and nucleic acids on clay minerals and their interactions is important in biological applications for soil ecosystem, the earth's biochemical evolution and origin of life, delivery of drug, etc. This review summarizes adsorption of proteins and nucleic acids (DNA, RNA) on natural clay minerals of layer phyllosilicates such as montmorillonite, kaolinite and illite and their interactions. Recent advances in adsorption mechanisms, adsorption sites and effect of various factors on adsorption are discussed. The interaction mechanisms are suggested to be cation exchange, electrostatic interactions, hydrophobic/hydrophilic interactions, ligand exchange, cation bridge, water bridge, hydrogen bond and van der Waals forces. The physical and chemical characteristics of clay minerals and proteins and nucleic acids are mainly responsible for the absorption of these biomolecules by clay minerals besides external conditions, for instance pH and ion strength of absorption solution. Finally, comments on the perspectives and potential benefits of the studies on adsorption of proteins and nucleic acids on clay minerals and their interactions are also made.     

页岩中黏土矿物吸附特性分子模拟

页岩的吸附解吸特性对页岩气资源开发具有重要意义。为深入了解页岩中黏土矿物微观吸附机理, 利用Material Studio 分子模拟软件构建了伊利石、蒙脱石和高岭石3种黏土矿物分子模型, 采用巨正则Monte Carlo(GCMC)方法对3种模型的等温吸附量和吸附热进行了模拟计算。研究表明, 在相同温度和压力条件下3种黏土矿物对CH₄分子的吸附量大小顺序是伊利石>蒙脱石>高岭石;随压力增大3种黏土矿物对CH₄分子的吸附量均有所增加, 而且伊利石和蒙脱石对CH₄分子的吸附量对压力变化更为敏感;3种黏土矿物的等量吸附热均小于42 kJ·mol^-1, 对CH₄的吸附为物理吸附;随着温度的升高, CH₄分子的吸附热和吸附量均减小。     

端羟基双子季铵盐对聚羧酸盐减水剂抗泥性能的影响

以1,4-对二氯苄为连接基团，分别以三乙胺和N,N-二甲基乙醇胺为头基，合成了具有不同端基的双子季铵盐（分别标记为KNJ-1和KNJ-2）。将其作为抗泥剂与聚羧酸盐减水剂复配以改善粘土对减水剂的负面效应，探究端羟基的引入对抗泥效果的影响。通过FT-IR和1H NMR对其进行结构表征。净浆流动实验考察抗泥剂的对流动度的影响，并结合XRD、XPS和 Zeta电位分析其与蒙脱土的作用机理。实验结果表明：与KNJ-1相比，加入0.3‰KNJ-2使水泥净浆初始流动度提高了35mm, 2h后流动度提高了165mm,表现出更好的抗泥效果。XRD和 XPS结果表明KNJ-2在蒙脱土的表面和层间吸附均优于KNJ-1，Zeta电位结果显示KNJ-2的加入使表面电位从初始的-15.67mV上升到-0.15mV。表明羟基可通过氢键作用优先吸附在蒙脱土的表面和层间，占据大量活性位点，减少了对聚羧酸盐减水剂的吸附，保障减水剂的高效分散能力，从而达到对粘土抑制的效果。     

Arsenic adsorption mechanism on clay minerals and its dependence on temperature

In the present study, the As(V) removal efficiency of different clay minerals was investigated as a function of solution pH, time, As(V) concentration, and temperature. Arsenic mobility was also investigated by determining the As(V) released from the loaded samples by leaching with various aqueous solutions. The kinetics of adsorption was observed to be fast and reached equilibrium within 3 h. As(V) adsorption on studied clays was pH dependent and maximum adsorption was achieved at pH 5.0. The maximum adsorption capacity was calculated by fitting the Langmuir equation to the adsorption isotherms and found to be 0.86, 0.64, and 0.52 mg As(V)/g of kaolinite, montmorillonite, and illite, respectively. The negative effect of temperature on As(V) adsorption showed the interactions to be exothermic. Based on the results, it was found that among the studied clay minerals, kaolinite was the best As(V) adsorbent and montmorillonite had strong retention capacity. The electrokinetic behavior of kaolinite and montmorillonite was modified in the presence of As(V), indicating that adsorption involves inner sphere surface complexation and strong specific ion adsorption.     

Sodium hexametaphosphate interaction with 2:1 clay minerals illite and montmorillonite

The interaction of an efficient deflocculant, sodium hexametaphosphate (NaHMP), with illite and montmorillonite (Mt) samples of different origins was investigated analyzing the HMP uptake (adsorption on mineral surface and/or intercalation inside the interlayer space) and the ion release mechanisms. HMP adsorption isotherms on a standard Na-saturated illite were determined at different temperatures which yielded the thermodynamic parameters of the process and the maximum adsorbed amount of the ion on this mineral. The data indicate that the adsorption process is hindered with respect to that on kaolinite and is consistent with adsorption of HMP on the aluminol edge sites, forming Al–O–P linkages. The effect of HMP on the natural illite and Mt samples was analyzed using different techniques. Inductively coupled plasma optical emission spectroscopy (ICP-OES) was used to detect the concentration of P, Si, Al, Ca, Mg and K in deflocculant solutions wetting the clay minerals in order to identify the immobilization, dissolution and exchange reactions associated to the deflocculant activity. Thermal analysis and XRD measurements were used to gain information on the properties of the HMP-treated clay minerals. The peculiar ability of Mt samples to immobilize HMP is proposed to be due to intercalation processes involving the formation of Ca^2 +/HMP complexes inside the interlayer space. These processes could be responsible of the well known decrease in the deflocculant efficiency of HMP in ceramic slurries rich in Mt.     

Investigation of the clay sensitivity and cement hydration process of modified HPEG‐type polycarboxylate superplasticizers

In this work, three kinds of HPEG‐type polycarboxylate superplasticizers (PCs) were synthesized with three kinds of typical functional monomers: [diallyl dimethyl ammonium chloride (DMDAAC), 2‐hydroxyethyl methacrylate (HEMA), and 2‐(dimethylamino) ethyl methacrylate (DMAM), respectively. The effects of montmorillonite clay on the fluidity of cement/PC pastes were investigated. It was found that the fluidity was negatively affected by the clays in the order: DMAM‐PC < HEMA‐PC < conventional PC (CPC) < DMDAAC‐PC. The DMAM‐PC was found to disperse cement well even in presence of montmorillonite clay. The dispersion performance of DMDAAC‐PC was much more effectively affected by clay due to the reaction between ammonium and montmorillonite. More study including mortar fluidity, adsorption behavior and morphology of the cement samples were investigated in details. Thermogravimetric analysis and X‐ray diffraction experiments allowed us to observe the influence of PCs on the hydrated products. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46572.     

不同磷酸酯单体的EPEG型聚羧酸减水剂的制备及抗泥性能

以乙二醇单乙烯基醚（EPEG）为大单体，丙烯酸（AA）为小单体，2-羟乙基甲基丙烯磷酸酯（HEMAP）或封端酰胺磷酸酯（CAP）为功能单体，采用水溶液自由基共聚法合成了两种EPEG型抗泥型聚羧酸减水剂PCE-EP1和PCE-EP2。采用FTIR、1HNMR对减水剂结构进行表征，通过水泥净浆流动度测试了合成的减水剂对水泥的分散性能以及抗泥性能，并结合XRD，XPS探究了减水剂与水泥、蒙脱土之间的作用机理。结果表明：当减水剂折固掺量为0.2%，蒙脱土掺量为2%时，掺PCE-EP1和PCE-EP2有一定的抗泥性。XRD表明说明减水剂PCE-EP1、PCE-EP1对蒙脱土没有进行插层吸附，从而提高了该减水剂对泥土的分散能力。     

HEAT-OF-WETTING VALUES OF UNFIRED AND FIRED CLAYS*

The heats of welting of unfired and fired clay minerals were measured on samples of montmorillonite, illite, and kaolinite types of clays. Autoclaved and unautoclaved samples of fired clays were studied. These data were obtained as a contribution to the knowledge of changes taking place in fired clayware through exposure to water vapor.