Hydrophobation of Clay Particles by Asphaltenes Adsorption

In order to throw light on the mechanism of organic compounds–clay interactions and to control the preparation of hydrophobic fillers, the effect of asphaltene adsorption from water-saturated toluene onto various clay minerals (kaolinite, illite) was studied. The modification of the clay surface charge and wettability were characterized, respectively, by microelectrophoresis and Washburn contact angle measurements. Further, the alteration of the surface area and chemical composition of the clay particles due to asphaltene adsorption were assessed using various methods such as N₂-adsorption/desorption, X-ray diffraction (XRD) measurements, FT-IR and scanning electronic microscopy. The data indicate that upon asphaltene adsorption, the clay particles become hydrophobic, their contact angle with water increases, while their surface charge and surface energy are reduced. Furthermore, according to XRD data, no swelling of the clay by asphaltenes occurs in the water-saturated toluene, indicating that asphaltenes cover the clay's external surface and lead to their aggregation, either in water or in the vacuum dried state. Finally, we elucidate the mechanisms by which asphaltenes adsorb and modify the clay surface characteristics. Such mechanisms involve mainly interactions that occur between the asphaltenes' surface groups and silanol/aluminol groups of the mineral.     

Adsorption of Cr(VI) from Aqueous Solutions Onto Raw and Acid-Activated Reşadiye and Hançılı Clays

ABSTRACT

The adsorption of Cr(VI) from aqueous solutions onto raw and acid-activated clays—namely, Re?adiye region clay (R, raw Re?adiye region clay; R-H₂SO₄, acid-activated with H₂SO₄ Re?adiye region clay; R-HCl, acid-activated with HCl Re?adiye region clay) and Hanç?l? region clay (H, raw Hanç?l? region clay; H-H₂SO₄, acid-activated with H₂SO₄ Hanç?l? region clay; H-HCl, acid-activated with HCl Hanç?l? region clay)—was studied in a batch system. For optimization of the Cr(VI) adsorption on raw clays and acid-activated clays, the effect of pH, temperature, initial Cr(VI) concentration, time, and adsorbent dosage were investigated. X-ray diffraction analyses of raw and acid-activated clays were used to determine the effects of acid-activating on the layer structure of the clays. The surface characterizations of clays and modified clays were performed by using FT-IR spectroscopy. The Langmuir and Freundlich adsorption models were employed to describe the equilibrium isotherms, and thus the isotherm constants were determined. The data obtained from our investigations were well described by the Langmuir model. The adsorption capacity of the adsorbents Re?adiye and Hanç?l? clays were found to be 0.0269, 0.0144, and 0.0170 mmol/g for H, H-HCl, and H-H₂SO₄ and 0.0356, 0.0276, and 0.0422 mmol/g for R, R-HCl, and R-H₂SO₄, respectively. The results show that the adsorption was strongly dependent on pH of the medium, initial Cr(VI) concentration and temperature. The removal of Cr(VI) reached saturation in about 120 min, and the adsorption process of Cr(VI) was observed as exothermic. A maximum removal of 73% was noted at 1.0 × 10^?4 M concentration of Cr(VI) in solution for H-HCl. Furthermore the enhancement of removal of Cr(VI) was observed from pH 3 to 4. The results are discussed to highlight the influence of acid activation on Cr(VI) adsorption characteristics of the clays.     

THE ADSORPTION OF ANIONIC AND CATIONIC SURFACTANTS BY THE DIFFERENT CLAY MINERALS: FTIR SPECTROSCOPIC STUDY

The adsorption of an anionic surfactant LABS (Linear alkyl benzene-sulphonate) and a cationic surfactant DDAC (Distearly dimethyl ammonium chloride) by kaolinite, bentonite and sepiolite clays was investigated by vibrational spectroscopy. The samples prepared at different concentrations, and clay-surfactant spectra in the natural state, were recorded. The spectroscopic results indicate that the LABS and DDAC adsorbed on sepiolite and kaolinite. Bentonites are coordinated to either surface hydroxyls by H-bonding interacti on (sepiolite) or to exchangeable catoins (kaolinite, bentonite) through both sulphur and nitrogen atoms as ligands. Interactions of both surfactants showed similarities, in that LABS was coordinated on clay surfaces with broken ends, and the DDAC molecule was adsorbed on the clay surface.     

Crystal chemistry and Mössbauer spectroscopic analysis of clays around Riyadh for brick industry

A total of 30 clay samples were collected from the area around Riyadh city, Saudi Arabia. A complete chemical analysis was carried out using different techniques. X-ray diffraction studies showed that the clay samples were mainly of the smectite group with traces of the kaolinite one. The samples studied were classified as nontronite clay minerals. One of the clay fraction has been studied by Mössbauer spectroscopy as raw clay fraction and after being fired at 950–1,000 °C. The Mössbauer spectra showed accessory iron compounds in the form of hematite and goethite. The structural iron contents disintegrate on firing transforming into magnetic iron oxide and a paramagnetic small particles iron oxide.     

Adsorption and thermodynamic studies of Cu(II) and Zn(II) on organofunctionalized-kaolinite

Kaolinite-bearing clay samples from Perus, São Paulo state, Brazil, were used for chemical modification process with dimethyl sulfoxide and organofunctionalized with the silyating agent (RO)₃Si(CH₂)₃NH(CH₂)₂NH₂ in the present study. The resulting material and natural kaolinite were subjected adsorpion process with Cu(II) and Zn(II) from aqueous solution at pH 6.0 and controlated temperature of 298 K. The Langmuir adsorption isotherm model has been applied to fit the experimental data. The results showed that the chemical modification process increases the basal spacing of the natural kaolinite from 0.711 to 0.955 nm. The energetic effects caused by Cu(II) and Zn(II) interactions were determined through calorimetric titration at the solid–liquid interface and gave a net thermal effect that enabled the calculation of the exothermic values and the equilibrium constant.     

粘土矿物参与微生物利用木质素形成矿物-菌体残留物的结构特征研究

粘土矿物在催化木质素形成腐殖质方面具有重要贡献。为有效阐明微生物-木质素-粘土矿物三者间的关系，探明矿物-菌体残留物的结构特征，采用液体摇瓶培养法，以木质素为碳源，通过添加高岭石和蒙脱石，在接种复合菌剂后启动110 d液体培养，期间动态收集矿物-菌体残留物，利用傅里叶红外光谱及扫描电子显微镜技术对其结构特性进行了研究。结果表明：高岭石颗粒边缘多由管状体卷曲而成，在参与微生物利用木质素形成矿物-菌体残留物后，连片状细小颗粒结构进一步团聚，结合更加紧凑，短管状结构增多，但整体仍保持多水高岭石的结构特征；在初始富营养条件下，高岭石能够促进微生物繁衍，使大量菌体聚集于高岭石表面，掩蔽了Si-O和Si-O-Al键，且矿物-菌体残留物中脂族碳结构比例增加；菌体中多糖物质通过含氧官能团与高岭石表面的水化层在多个部位形成氢键，氢键的形成对于高岭石稳定木质素及其降解产物具有重要作用，芳香碳结构比例和多糖类物质含量随培养时间逐渐增加，而后复合菌株对掩蔽在矿物表面的菌体进行二次利用，使高岭石Si-O-Al键重现；蒙脱石多由浑圆的颗粒结构组成，接种微生物可使其表面产生溶蚀，团粒结构遭到破碎；与10 d相比，历经30 d培养所得矿物-菌体残留物中的多糖类物质增多，使原本归属蒙脱石Si-O-Si及Si-O结构的1 034~1 038 cm-1处吸收峰强度增加，而后因多糖类物质与蒙脱石表面羟基发生缔合，又使该处吸收峰强度减弱，同时发生了氢键键合，该作用是蒙脱石-微生物-木质素间相互作用、形成矿物-菌体残留物的主要机制；高岭石在稳定有机碳方面的能力要高于蒙脱石，更易促进HS前体物质的形成。     

显微-反射傅里叶变换红外光谱研究油酸钠与胶磷矿吸附机理

红外光谱已经成为浮选药剂作用机理研究的最重要手段之一。由于矿物本身具有较强的红外吸收,传统溴化钾压片透射光谱很难检测到矿物表面吸附药剂的微弱红外信号。采用显微-傅里叶变换红外光谱仪的反射模式,测定了不同浓度油酸钠在胶磷矿表面的吸附形式,并观察了吸附形貌。结果表明,与透射红外光谱相比,反射红外光谱对表面有更高的灵敏度,能更好地揭示实际浮选药剂浓度下的吸附机理。碱性条件下当油酸钠浓度较低时,油酸离子与表面晶格钙离子发生化学吸附,吸收峰在1 552 cm-1,同时也存在油酸钙沉淀的物理吸附,吸收峰在1 570和1 535 cm-1;当油酸钠浓度超过临界胶束浓度时,胶束使得胶磷矿表面亲水,导致油酸钠溶液残留在表面,吸收峰在1 560 cm-1,掩盖了其他吸收峰;表面经水洗涤后药剂吸收峰强度大幅减弱,是由于残留的油酸钠和物理吸附的油酸钙被洗掉。另外,随着油酸钠浓度增大,药剂二维形貌由点状吸附聚集为片状吸附,覆盖面积增大,但并不是完全覆盖,这与矿物表面异质性有关。以上研究结果有利于理解磷矿石提磷或铁矿石脱磷浮选体系中捕收剂与胶磷矿的作用机理。     

紫外光谱法研究黄药在黄铜矿表面的吸附热力学与动力学

在紫外吸收光谱范围内对黄药溶液进行扫描,发现在波长226.5和300 nm处有两个明显吸收峰,且300 nm处的吸收峰强于226.5 nm处的。采用标准曲线法对不同浓度的标准样品进行浓度测量,对所得数据进行线性拟合,结果表明：在波长226.5和300 nm处的线性相关性均较好,但在波长300 nm处的相关性更佳,在226.5 nm处进行高浓度黄药溶液测量,可在300 nm处进行低浓度黄药溶液测量。在300 nm下对不同浓度黄药溶液进行定量分析,结果表明,最大吸光度为1.672,最小吸光度为0.032时,黄药溶液标准曲线的线性相关性仍很好,吸光度继续增大时,相关系数降低,在进行定量分析时,黄药浓度最好不要超过20 mg·L-1。在不同pH条件下,在300 nm处对黄药溶液进行浓度测量,发现pH为3时,吸光度下降,黄药开始分解,当溶液pH为2时,所测吸光度为0,黄药已完全分解,pH值在5~10范围内,黄铜矿对黄药吸附较好,溶液最佳吸附pH值为9。在300 nm处测量黄药在黄铜矿表面吸附量,分别采用Freundlich和Langmuir等温吸附模型方程、准一级和准二级动力学方程模型对所得实验数据进行拟合,研究其在黄铜矿表面的吸附动力学和热力学。结果表明：在288～303 K范围内,温度变化对吸附量多少影响不大,黄药在黄铜矿表面的吸附等温线更符合Langmuir等温线模型,黄铜矿对黄药的实际平衡吸附量Q_e均小于或接近理论单层饱和吸附量,Q_m值均与实验值极为接近,说明黄药在黄铜矿表面的吸附以单层化学吸附为主。随着温度升高,吸附量增加,说明升高温度有利于吸附过程进行,黄铜矿对黄药的吸附为吸热过程,但吸附量增加幅度很小,说明黄药在黄铜矿表面吸附受温度影响较小。该吸附过程是一个熵增、吸热、自发进行的过程,热力学参数可通过范特霍夫方程计算得到,吸附焓变ΔH为48.703 41 kJ·mol-1,熵变ΔS为219.403 88 J·(mol·K)-1,吸附自由能变ΔG为-16.054 93 kJ·mol-1,推测该吸附过程属于化学吸附;黄铜矿对黄药的吸附更符合准二级动力学方程模型,Q_t值随着温度升高而增大,且变化幅度很小,表明黄药在黄铜矿表的吸附过程为吸热过程,但受温度变化较小,这与热力学分析的结论一致,对方程拟合所得Q_e值均与实验值极为接近。     

苯甲酰胺对高岭石插层的FTIR和XRD研究

苯甲酰胺在熔融状态下取代前驱体中的DMSO分子插层高岭石,产物经丙酮洗涤,得到纯净的高岭石/苯甲酰胺插层复合物。XRD结果显示高岭石层间距从0.717 nm膨胀到1.437 nm。插层作用使高岭石内表面羟基红外伸缩振动峰由3 696和3 657 cm-1移动至3 701和3 651 cm-1处;苯甲酰胺3 368和3 172 cm-1处NH₂基伸缩振动峰红移至3 474和3 184 cm-1处,1 659 cm-1处羰基峰移至1 640 cm-1处,这些表明原高岭石层间氢键的损失及与苯甲酰胺分子之间氢键的形成。插层反应于30 min迅速达到平衡,插层率随反应温度的增加先增加后减小,180 ℃时有最大插层率;以丙酮作为洗涤剂可以消除表面吸附和残余的苯甲酰胺晶体而不影响复合物的结构。     

Intercalation of acrylic acid and sodium acrylate into kaolinite and their in situ polymerization

Novel nano-composites of poly (acrylic acid)-kaolinite were prepared, and intercalation and in situ polymerization were used in this process. The nano-composites were obtained by in situ polymerization of acrylic acid (AA) and sodium acrylate (AA_Na) intercalated into organo-kaolinite, which was obtained by refining and chemically modifying with solution intercalation step in order to increase the basal plane distance of the original clay. The modification was completed by using dimethyl-sulfoxide (DMSO)/methanol and potassium acetate (KAc)/water systems step by step. The materials were characterized with the help of XRD, FT-IR and TEM; the results confirmed that poly(acrylic acid) (PAA) and poly(sodium acrylate) (PAA_Na) were intercalated into the interlamellar spaces of kaolinite, the resulting copolymer composites (CC₀ : copolymer-crude kaolinite composite, CC₁ : copolymer-DMSO kaolinite composite, CC₂ : copolymer-KAc kaolinite composite) of CC₂ exhibited a lamellar nano-composite with a mixed nano-morphology, and partial exfoliation of the intercalating clay platelets should be the main morphology. Finally, the effect of neutralization degree on the intercalation behavior was also investigated.     

Adsorption of hexavalent chromium onto montmorillonite modified with hydroxyaluminum and cetyltrimethylammonium bromide

Aluminum hydroxypolycation and cetyltrimethylammonium bromide (CTMAB) were chosen to synthesize inorganic-organic pillared montmorillonite. Three different methods were employed for the intercalation. The characteristics of natural and modified montmorillonite were determined with X-ray diffraction (XRD), Fourier transform infrared spectrum (FTIR), X-ray photoelectron spectrum (XPS), and zeta potential. It was found that aluminum hydroxypolycation and CTMAB had either entered the interlayer or sorbed on the external surface of the clay. Different intercalation orders can result in different structures. Batch adsorption of hexavalent chromium (Cr⁶⁺) onto modified montmorillonite was also investigated. The experimental data revealed that if aluminum hydroxypolycation was intercalated before CTMAB, the adsorption capacity was better than that of intercalated simultaneously or CTMAB pre-intercalated. The pH of the solution and environmental temperature had significant influences on the adsorption of Cr⁶⁺. The optimal pH for the removal was about 4, and the temperature of 298 K was best suitable. All adsorption processes were rapid during the first 5 min and reached equilibrium in 20 min. The adsorption kinetics can be described quite well by pseudo-second-order model. The adsorption rates of ACM, CAM and ACCOM were 3.814, 0.915, and 3.143 mg/g/min, respectively. The adsorption capacities of Cr⁶⁺ at 298 K on ACM, CAM, and ACCOM inferred from the Langmuir model were 11.970, 6.541, and 9.090 mg/g, respectively. The adsorption of Cr⁶⁺ on modified montmorillonite was mainly induced by the surface charge and the complexation reaction between CTMA⁺ and hexavalent chromium species at the edge of the clay particle.     

The adsorption of CO,O2, and H2 on Pt(100)-(5×20)

The adsorption/desorption characteristics of CO, O₂, and H₂ on the Pt(100)-(5 × 20) surface were examined using flash desorption spectroscopy. Subsequent to adsorption at 300 K, CO desorbed from the (5×20) surface in three peaks with binding energies of 28, 31.6 and 33 kcal gmol^?1. These states formed differently from those following adsorption on the Pt(100)-(1 × 1) surface, suggesting structural effects on adsorption. Oxygen could be readily adsorbed on the (5×20) surface at temperatures above 500 K and high O₂ fluxes up to coverages of $\text{2}\text{3}$ of a monolayer with a net sticking probability to ssaturation of ? 10^?3. Oxygen adsorption reconstructed the (5 × 20) surface, and several ordered LEED patterns were observed. Upon heating, oxygen desorbed from the surface in two peaks at 676 and 709 K; the lower temperature peak exhibited atrractive lateral interactions evidenced by autocatalytic desorption kinetics. Hydrogen was also found to reconstruct the (5 × 20) surface to the (1 × 1) structure, provided adsorption was performed at 200 K. For all three species, CO, O₂, and H₂, the surface returned to the (5 × 20) structure only after the adsorbates were completely desorbed from the surface.     

主晶相为莫来石复合纳米晶的制备、结构表征及性能测试

以高岭土为原料,采用水热晶化法,制得了主晶相为莫来石的复合纳米晶。利用XRD、TEM、BET及TG－TDA以在不同条件下制得的纳米晶物相、粒度及热稳定性进行了表征。对复合纳米晶进行了CO、SO2程序升温脱附性能测试。对负载Ni、Mo、Co进行程序升温还原测试。结果表明：在脱附物中检测出CO2与固体硫,证明吸附质在纳米晶表面发生了反应。微米晶与纳米晶负载Ni、Co、Mn后,随着粒度的不同,负载上的氧化物与载体的相互作用力不同,而表现出不同的峰温与峰面积,表面负载上Ni、Co、Mn的氧化物与载体有结构效应,且随晶体表面结构的不同,而表现出不同的H2消耗量。     

Density functional theory investigation of carbon monoxide adsorption on the kaolinite(001) surface

Carbon monoxide(CO) is a gaseous pollutant with adverse effects on human health and the environment. Kaolinite is a natural mineral resource that can be used for different applications, including that it can also be used for retention of pollutant gases. The adsorption behavior of carbon monoxide molecules on the(001) surface of kaolinite was studied systematically by using density-functional theory and supercell models for a range coverage from 0.11 to 1.0 monolayers(ML). The CO adsorbed on the three-fold hollow, two-fold bridge, and one-fold top sites of the kaolinite(001) was tilted with respect to the surface. The strongest adsorbed site of carbon monoxide on the kaolinite(001) surface is the hollow site followed by the bridge and top site. The adsorption energy of CO decreased when increasing the coverage, thus indicating the lower stability of surface adsorption due to the repulsion of neighboring CO molecules. In addition to the adsorption structures and energetics, the lattice relaxation, the electronic density of states, and the different charge distribution have been investigated for different surface coverages.     

传统陶瓷中结构羟基的光谱学研究

烧结粘土产品可以吸收水分子发生再羟基化,生成结构羟基的量与产品保存时间存在一定关系,基于该理论可以利用热重分析方法对陶器制品进行测年研究.红外与拉曼光谱技术也可以用来分析结构羟基信息,因此人们希望探索利用光谱分析方法代替热重法进行传统陶瓷无损测年分析.为了验证可行性,收集了多种典型矿物原料和可溯源的传统陶瓷样品,利用红...     

Electron loss spectroscopy of clean and oxygen covered GaAs(110) surfaces

Electron energy loss spectra of clean and oxygen covered GaAs(110) surfaces have been measured with a four grid retarding field analyser. Loss spectra of clean cleaved p- and n-type surfaces are slightly different and different states of adsorption for the oxygen on the two surfaces are found. The loss peaks which are common in the spectra obtained from clean surfaces of both types of material have been interpreted in terms of bulk and surface excitations. The data associated with the bulk excitations are in good agreement with previous optical and electron transmission data while loss peaks at 11.5 and 18.5 eV are interpreted as the surface plasma loss and a surface state transition respectively. For n-type material extra loss peaks were observed. In the case of oxygen adsorption on these surfaces new loss peaks were found at 13.5, 17.2 and 28.1 eV in both spectra and are assumed to be characteristic of the oxygen. Further, for n-type material an extra peak occurs at 8.2 eV.     

臭氧在SnO2表面吸附的红外光谱研究

以SnO2催化臭氧化降解高浓度糖蜜酒精废水为探针反应,研究SnO2催化臭氧化降解糖蜜酒精废水的活性,并采用红外光谱研究臭氧在SnO2及金属氧化物改性的SnO2催化剂表面的吸附行为。结果表明:由纯氧源制得的O3在SnO2表面吸附的红外光谱上的1 027和1 055 cm-1及2 099和2 122 cm-1处存在两处明显的吸收双峰,而空气制备的O3在SnO2表面与CO及CO2等存在竞争吸附,使得O3的吸附减少,催化臭氧化降解糖蜜废水的降解率下降。催化剂助剂对SnO2催化臭氧化降解糖蜜酒精废水有较大的影响。采用Fe2O3,NiO,CuO,ZnO,MgO,SrO及BaO等金属氧化物为助剂改性的SnO2在2 236和2 213 cm-1,1628和1 599 cm-1出现强度相似的吸收峰,但是几种催化剂对CO2和CO的吸附差别较大,过渡金属改性的SnO2在1 580~1 070 cm-1处出现较宽的吸收峰,碱土金属氧化物改性的SnO2催化剂在1 580~1 070 cm-1之间,出现了1 298和1 274 cm-1两个新的峰,从而引起了不同助剂催化臭氧化的活性差别,碱土金属改性的SnO2对糖蜜酒精废水的催化臭氧化脱色效果明显优于过渡金属改性的SnO2,其中BaO改性的SnO2催化剂的活性最好。     

赤铁矿和三羟铝石吸附Cu~(2+)的红外光谱研究

应用红外光谱法,研究了不同pH值和Cu2+浓度条件下,合成赤铁矿和三羟铝石吸附Cu2+后表面羟基结构及其特征吸收峰的变化。结果表明:(1)随Cu2+浓度增加,赤铁矿表面H—O—H和OH的变形振动参与了吸附反应,Cu2+强烈地缔结在Fe—O上,形成了Fe—O—(Cu)结构。(2)酸性条件下,H+破坏了赤铁矿表面的O—H结构,NO3-促使弱峰1 131 cm-1的产生。随pH值增大,赤铁矿表面OH-逐渐由伸缩振动转变为变形振动,Fe—OH和Fe3+—O2-结构不断发生改变。(3)三羟铝石对Cu2+的吸附发生在高波位,随Cu2+浓度增大,其表面游离羟基的O—H弯曲振动、水分子的OH-伸缩振动和H—O—H弯曲振动均参与了吸附反应,Al—O基中的Al3+渐被Cu2+取代从而加强了较低波位的振动强度。(4)随pH值增加,三羟铝石Al—OH的弯曲振动和Al—O的伸缩振动逐渐发生着改变,表明吸附Cu2+后,在其表面形成了AlOCu+与AlOCuOH结构。     

疏水表面上吸附态溶菌酶的DSC和FTIR研究

联合差示扫描量热 (DSC)和傅里叶变换红外吸收光谱(FTIR)分别研究了鸡蛋白溶菌酶(Lyz)在适度疏水吸附剂(PEG-600)表面上吸附和折叠时,不同盐(硫酸铵)浓度、表面覆盖度和变性剂(盐酸胍)浓度对无水环境的吸附态天然和变性溶菌酶构象变化及热稳定性的影响。研究发现：随着硫酸铵浓度和溶菌酶表面覆盖度的增加,吸附态天然和变性溶菌酶的吸热峰温度都逐渐降低,同时在较高温度下的微扰也增多。吸附发生后,α-螺旋结构减少,β-折叠和β-转角结构增多。在FTIR图谱中,吸附态变性溶菌酶在1 400～1 425 cm-1处的C—C拉伸振动峰和1 650～1 670 cm-1处的酰胺Ⅰ带特征峰都能明显观测到。但是,与之相比,相同条件下吸附态天然溶菌酶在1 650～1 670 cm-1处特征峰却几乎看不到。吸附态天然溶菌酶发生了结构丢失,表现得更加不稳定。     

The1HT 1 study of the influence of clay addition on Portland cement hydration

Effects of addition of three standard clay minerals, Na-montmorillonite, illite and kaolinite, on Portland cement hydration properties were studied. The¹H spin-lattice relaxation of exchangeable water was monitored during hydration time and the data were processed by spin-grouping analysis. The values and evolution dynamics of both resolvedT ₁ components and corresponding magnetization fractions show that each day mineral lowers the fluidity of Portland cement paste and accelerates its hydration in dormant. In advanced stages of hydration, the Na-montmorillonite provides the accelerating influence, while the kaolinite exhibits the retarding effect. The final values of gel pores to capillaries percentage fractions ratio indicate a slightly lower porosity of samples with Namontmorillonite and a higher porosity of pastes with the same percentage of illite or kaolinite, regarding to the pure hardened Portland cement.