High-porosity geopolymer membrane supports by peroxide route with the addition of egg white as surfactant

Metakaolin-based geopolymer membrane supports were synthesized by gelcasting using hydrogen peroxide with the addition of albumen powder as surfactant. A geopolymer slurry was prepared using metakaolin and an alkaline medium at room temperature, the obtained viscous paste was expanded by means of the decomposition of peroxide in combination with protein-assisted foaming, and the geopolymerization was conducted in a closed environment at 75 °C. The combination of peroxide and albumen protein enabled the production of geopolymer membrane supports with a total porosity of ~74.29%, open porosity as high as ~65.25%, and possessing a compressive strength of ~4.47 MPa. Moreover, factors that influence the compressive strength, the porosity, and the pore size distribution were investigated. The results showed that the sizes of cell could be controlled by adding different content of peroxide and protein, and by heat-treating at different temperatures.     

Highly Porous Geopolymers Through Templating and Surface Interactions

The natural porosity of geopolymers and the simplicity of geopolymer synthesis make them a potential candidate for the formation of highly porous ceramics. Here, the synthesis of highly porous (≈70 vol% or more) metakaolin geopolymer is demonstrated using a novel emulsion preparation with one‐pot curing and hydrophobization of the interior pores with alkylalkoxysilanes. Using mercury intrusion porosimetry, tailoring of the characteristic percolation pore size is demonstrated over a range of ≈200 nm to 10 μm. Using powder X‐ray diffraction, reactivity was shown to be decreased versus typical geopolymers, but substantial geopolymerization still occurred and the samples formed cohesive monoliths. Optional calcination under inert conditions allowed for formation of a glassy ceramic with a notable SiC phase, as well as further increasing the porosity by removing the hydrophobic pore coatings.     

Influence of clay addition on the properties of olive oil in water emulsions

The behaviour of olive oil-in-water emulsions (O/W) was studied in the presence of smectite particles. The distribution of these particles in the emulsions and the effect of their interaction with the surfactant on the stability of the emulsions were investigated. Whereas the variation of surfactant and/or clay content did not seem to affect the nature of the emulsion, it had a significant influence on emulsion stability. This observation led to two main assumptions on the distribution of clay particles within the emulsion, either exclusively in the continuous phase, or also at the oil-water interface.In the absence of clay, the variation of surfactant concentration (from 0 to 17% (w/w)) allowed to distinguish 3 domains. In the first concentration domain (0–4.2%) emulsions stability increased with the content of surfactant. Within the second domain (4.2–8.5% (w/w)), a slight decrease in stability was observed due to flocculation by depletion. For surfactant concentrations equal or higher than 8.5% (3rd domain), emulsion stability increased sharply, probably due to the development of interactions between surfactant molecules as they came closer to their gelling concentration. The effect of clay addition to the aqueous phase (up to 10% (w/w)) on the physicochemical properties of the studied emulsions was assessed from stability, drop size, interfacial tension, rheological and acido-basic analyses. A model based on the location of clay particles either in the bulk or at the interface could be proposed, in which clay particles would interact with surfactant molecules in the bulk phase, and form a mechanical barrier around the oil droplets, thus increasing emulsion stability.     

Effect of oil type on stability of high internal phase water-in-oil emulsions with super-cooled internal phase

This study considered the stability and rheology of a type of high internal phase water-in-oil emulsions (W/O) emulsion. The aqueous phase of the emulsions is a super-cooled inorganic salt solution. The oil phase is a mixture of industrial grade oils and stabilizer. Instability of these systems manifests as crystallization of the metastable dispersed droplets with time. This work focused on the effects of oil polarity and oil viscosity on the stability of these emulsions. Ten types of industrial oils, covering the viscosity range 1.4–53.2?cP, and with varying polarity, were used in combination with polymeric poly(isobutylene) succinic anhydride (PIBSA) and sorbitan monooleate (SMO)-based surfactants. The effect of oil relative polarity on rheological parameters of the emulsion was evident mainly in the emulsions stabilized using polymeric surfactant, whereas the oil viscosity did not show any significant effect. The optimum stability of the emulsions stabilized with SMO was achieved using high polar oils with a viscosity of 3?±?0.5?cP. However, when using the PIBSA surfactant, the best emulsion stability was achieved with low polar, high viscosity oils.     

地质聚合物及其在重金属废水处理中的应用

研究人员很早就发现了地质聚合反应终产物中存在类沸石结构。由于不同地质聚合物中硅铝比以及碱组分含量并不固定,因此很难确定地质聚合物中类沸石相的结构。从众多文献中可以看出,地质聚合物与低硅沸石具有组成和结构的相似性。本文阐述了地质聚合物与沸石之间的物质和结构遗传特性,为地质聚合物材料用于吸附和固化重金属离子的研究提供理论依据。目前,利用地质聚合物类分子筛结构来吸附、固定重金属离子以处理重金属废水成为一个研究热点。作为一种绿色、廉价的重金属吸附剂,地质聚合物对铅、铜、镍、铬、镉等重金属都有较好的吸附效果,重金属溶液的初始浓度、pH值、吸附温度、吸附剂用量均对吸附效果有着重要影响。通过对吸附过程中动力学和热力学进行研究发现,地质聚合物对重金属离子的吸附过程更符合二级动力学,且为Langmuir单分子层化学吸附。目前针对地质聚合物吸附重金属离子的吸附条件已有较详细的研究,在适宜条件下能达到较好的吸附效果,吸附量明显高于4A分子筛,这也表明了地质聚合物在去除废水中重金属离子的高效性。     

Formulation of Mechanochemically Evolved Fly Ash Based Hybrid Inorganic–Organic Geopolymers with Multilevel Characterization

In this research, advanced hybrid inorganic–organic geopolymeric material is developed by environmentally and user friendlier approach. The presented novel approach for geopolymer formation certainly overcomes the existing drawbacks of geopolymerization technology. The effect of rice husk ash and Na₂O/SiO₂ ratios on geopolymer gel formation and mechanical strength has been previously identified via solution chemistry route; however, development of geopolymeric material having hybrid inorganic–organic characters via together mechanochemical grinding of raw materials and effect of mechanochemically activated Na₂SiO₃ on geopolymeric properties via solid state route has never before been explored. Together mechanochemical grinding of raw materials of varying compositions in solid state resulted in the formation of ready to use geopolymeric precursors; which on just addition of water led to development of advanced hybrid inorganic–organic geopolymeric material with considerably enhanced properties. XRD, FTIR and SEM characterization data of developed geopolymeric precursor powder and hybrid inorganic–organic geopolymeric material are reported and discussed in detail. As the results of the investigations, the relationship between geopolymer composition, grinding mechanism and material properties established. The composition which exhibited synergistic effect of both rice husk and SMS is found to be excellent in performance. The study showed that it is practical and better to adopt this greener solid state approach for preparation of geopolymer instead of user-unfriendlier hazardous alkaline solution based approach, to achieve sustainable growth in geopolymers as like Portland cement.     

偏高岭石-磷酸基矿物键合材料的制备与结构特征

在室温条件下,通过偏高岭石与磷酸水溶液中低聚[PO4]n^3n-四面体基团的缩合,制备了脱水铝硅酸盐-磷酸基矿物键合材料,该反应产物具有二维Si-O-Al-O-P结构。采用X射线衍射分析（x-ray diffraction,XRD）、Fourier红外吸收光谱、29^Si和27^Al魔角旋转核磁共振（nudear magnetic resonance,NMR）对反应产物进行了结构和反应机理分析。结果表明：反应产物中的Al^3＋具有3种化学环境特征。29^Si NMR的化学位移只在-110处出现,预示着[SiO4]四面体以层状结构方式存在。反应产物的红外光谱中偏高岭石的表征Al-O层结构特征的800Cm^-1共振吸收峰消失。反应产物的XRD谱具有非晶结构特征。据此,对键合反应机理模型进行了推测。     

Synthesis and thermal behavior of inorganic–organic hybrid geopolymer composites

Inorganic geopolymer potassium aluminosilicate was prepared at room temperature by the reaction of kaolin, potassium silicate, and potassium hydroxide solution and was dispersed in situ into an epoxy matrix by various proportions to fabricate novel inorganic–organic hybrid geopolymer composites. The formation of inorganic geopolymer with respect to time was monitored by X‐ray diffraction and FT‐IR analysis and confirmed that 30 min is required to complete the geopolymerization. When geopolymers were properly mixed at different ratios with organic polymers such as epoxy and cured, these hybrid polymers exhibit significant thermal stability. Pure kaolin was also incorporated into the epoxy matrix to compare the change in chemical and thermal properties. Cone calorimetry results showed about 27% decreased in rate of heat release (RHR) on addition of 20% pure kaolin. However, about 57% of RHR was decreased on addition of only 20% geopolymer. Evaluation of CO₂ and CO were found to be minimum 2.0 and 0.7 kg/kg, respectively, for hybrid geopolymer composites compared to very high yield for epoxy at 3.5 kg/kg after 200 s of ignition. The current study shows that due to the high thermal stability of hybrid geopolymer composites, the novel hybrid geopolymer composites have the ability to be potential candidates to use in practical application where fire is of great concern. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 112–121, 2005     

三元复合驱体系的膜性质和乳状液的破乳动力学研究

三元复合驱 (ASP)溶液与原油的界面张力为任一组分NaOH或ORS -4 1浓度函数。表面活性剂ORS -4 1分子膜性质随碱浓度变化表明 ,碱与表面活性剂间存在相互作用。在高表面压下 ,聚丙烯酰胺对表面活性剂单分子膜影响极小 ,在低表面压下影响显著。破乳剂对ASP膜影响较大。使用常规瓶试法测定了W /O原油乳状液的破乳动力学。碱与表面活性剂浓度对乳状液破乳影响较大 ,当ORS -4 1浓度较高时 ,聚合物影响变小。ASP乳状液破乳变化规律符合一级动力学方程     

Mechanical and microstructural characterization of geopolymers synthesized from FCC waste catalyst and silica fume

A FCC waste catalyst-based geopolymer was synthesized from FCC waste catalyst and silica fume, which were used as the main silicon-aluminum raw material and correction material, respectively. Meanwhile, NaOH and water glass composite were used as alkaline activator in the preparation process. Herein, the effects of silicon correction materials, alkaline activator modulus, and silica fume content on the compressive strength performance of prepared geopolymers were discussed. The microstructure was comprehensively analyzed by X-ray diffraction, fourier infrared spectroscopy, nuclear magnetic resonance spectroscopy and scanning electron microscope. The results showed that the prepared geopolymer has good early property when the silica fume content is 50% and the water glass modulus is 1.2. The 3d compressive strength of the obtained sample reaches 23.77 MPa. Microstructure and geopolymerization process analysis indicate that the FCC waste catalyst and silica fume have a good synergistic effect, which confirms the feasibility of preparing the geopolymer by using these industrial waste materials.     

Miniemulsion and conventional emulsion copolymerization of styrene and butadiene: A comparative kinetic study

The kinetics of conventional and miniemulsion copolymerizations of styrene and butadiene were compared using the Mettler RC1 calorimeter. A two‐step homogenization procedure was applied to obtain miniemulsions of these monomers with hexadecane as the costabilizer. The results indicated that the miniemulsion polymerizations proceeded mainly by nucleation in the monomer droplets, while in the conventional emulsion polymerizations, particle formation occurred by a combination of micellar and homogeneous nucleation. The overall rate of miniemulsion polymerization was faster than the corresponding conventional emulsion system if the surfactant concentration was below the critical micelle concentration (cmc) and slower if the surfactant concentration was above the cmc. The homogenization process is important for making stable miniemulsion systems, but had no effect on the conventional emulsion system (without hexadecane), most likely because of the second stage addition of the butadiene monomer. The dependencies of the rate of polymerization (heat of reaction) and number of particles on the surfactant concentration differed for the two types of polymerization systems. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2304–2312, 2006     

乳化液膜法处理有机萘磺酸类废水的应用及稳定性

介绍了乳化液膜法处理含有机萘磺酸类工业废水的分离技术 ,分析了萃取过程中表面活性剂种类和浓度、内相浓度、外相pH等因素对膜稳定性的影响 ,论述了增强液膜稳定性的措施 ,并提出了该技术的研究进展和应用前景     

Status of aqueous surfactant phase science

Recent phase studies of several surfactant-water systems, using new or refined methods, have revealed significant errors in earlier phase diagrams. These diagrams had been determined largely using methods based on the isoplethal phase studies principle. This principle has inherent limitations which do not exist in isothermal methods. Isothermal nuclear magnetic resonance and refined calorimetric methods have been extensively used in recent surfactant phase studies. Methods based on the new lyotrope gradient (swelling) principle show great promise as a means of improving the efficiency and quality of surfactant phase studies.     

Influence of steel and PP fibers on mechanical and microstructural properties of fly ash-GGBFS based geopolymer composites

In this study, experimental investigations were carried out to estimate the mechanical and microstructural properties of polypropylene (PP) and steel fiber reinforced geopolymer mortar. Two industrial by-products are used as binders to produce the geopolymer composites, i.e., fly ash (FA) and ground granulated blast furnace slag (GGBFS). Different percentages of PP and steel fibers are used in geopolymer mortars to find the mechanical properties such as compressive, splitting tensile and flexural strengths were investigated to understand the strength behavior. However, the compressive elastic modulus values were estimated through the proposed equation based on the compressive strength of the fiber reinforced geopolymer composite samples. Moreover, to understand the geopolymeic reaction, microstructural studies, i.e., scanning electron microscopy (SEM), were conducted. The experimental results revealed that the addition of PP fibers up to 2.0% (volume fraction) enhanced the flexural properties of geopolymer mortar samples. The compressive strength of the steel fiber-reinforced geopolymer composite reached a maximum of 2.5% volume fraction, being a 13.26% improvement over the control mix. The flexural toughness index of the PP and steel fiber reinforced composites improved with increasing the fraction. However, steel fiber reinforced geopolymer samples are shown better flexural toughness compared to PP fibers. The SEM analysis of the geopolymer control mix achieved a good degree of geopolymerization and both the fibers yielded a considerable interfacial bonding with the geopolymer paste.     

New Interfacial Rheology Characteristics Measured using a Spinning‐Drop Rheometer at the Optimum Formulation of a Simple Surfactant–Oil–Water System

A new spinning‐drop tensiometer with an oscillating rotation velocity was used to measure the interfacial rheological properties of systems with very low interfacial tensions in the zone close to the so‐called optimum formulation of surfactant–oil–water systems. 2 simple formulation scans were selected: One with an extended anionic surfactant using a salinity variation in the water phase, and another with a mixture of 2 nonionic surfactants in a scan produced by changing their proportion. With both systems it was corroborated that at optimum formulation (i.e., at hydrophilic–lipophilic deviation (HLD) = 0), both the interfacial tension and the emulsion stability exhibit a deep minimum. A clear relationship was also found between the phase behavior and the interfacial rheological properties (dilational elasticity and viscosity). For the very first time and in both kinds of scans (salinity or average ethylene oxide number), it was found that the interfacial elastic modulus E and the interfacial viscosity, as well as the phase angle also exhibit a minimum at optimum formulation. These groundbreaking findings could be applied to emulsion instability at optimum formulation and to its applications in emulsion breaking.     

矿聚物及其复合材料研究进展

系统介绍了周内外关于矿聚物的组织结构、性能及影响因素、制备工艺及特点、矿聚物的反应过程与聚合机理。评述了矿聚物的陶瓷化、先进矿聚物基复合材料、矿聚物及其复合材料的应用等方面的研究进展,指出了今后矿聚物及其复合材料的研究方向。     

Preparation and characterization of tungsten tailing-based geopolymers

Using tailings to prepare constructive materials is of great significance for sustainable development of mineral processing industry. In this study, the possibility of preparing tungsten tailing-based geopolymers was explored in detail. XRD, FTIR, PLM, SEM and XPS analyses were carried out to characterize the phase composition, chemical bonding, microstructure, chemical state, and interface properties of tungsten tailing-based geopolymers. Results showed tungsten tailings presented little activity using NaOH as activator, while geopolymers with 60% non-pretreatment tungsten tailing and 40% metakaolin presented a 3-day compressive strength of 8.4 MPa and 28-day compressive strength of 9.1 MPa. The geopolymerization products of tungsten tailing-based geopolymers were N-A-S-H gels and aluminosilicate zeolite crystals, while tungsten tailings were wrapped by metakaolin-derived geopolymerization phases as aggregates with interfaces containing Si–O–Si bonding between quartz in tungsten tailings and zeolite and/or gel phase in metakaolin-derived geopolymer in the geopolymerization process. Besides, the leaching test results indicated that the immobilization efficiency of T6M4 geopolymers for Mn and Pb derived from tungsten tailings reached up to 97.28% and 99.95%, respectively. This research results provide a new idea for utilization of tungsten tailings on a large scale.     

矿渣-粉煤灰地聚物固化淤泥力学性能和路用性能研究

为实现河底淤泥的资源化处置,常采用水泥等胶凝材料固化淤泥提高承载力作为路基材料。传统固化材料能耗大、碳排放量高。为开发可持续性固化材料,本研究采用矿渣-粉煤灰二元地聚物固化淤泥,研究其力学性能及路用性能。通过研究Si/Al摩尔比、Na/Al摩尔比对地聚物凝结时间和抗压强度的影响规律,确定地聚物配合比设计。依据优化配合比固化淤泥,研究地聚物掺量、养护龄期对固化淤泥力学性能的影响,并对固化淤泥进行水稳性、加州承载比、干缩和温缩试验,以评估其路用性能;采用扫描电镜和X射线衍射等试验方法对固化淤泥进行微观分析,揭示其固化机制。试验结果表明,矿渣-粉煤灰基地聚物地质聚合产物为无定形地聚物凝胶、水化硅酸钙、水化铝酸钙等,增强了土颗粒之间的胶结并且填充了孔隙,提高了固化淤泥的力学性能和路用性能。研究结果为地聚物固化淤泥土工程应用提供了实验基础。     

Geopolymer foams by gelcasting

Highly porous geopolymers, with homogeneous microstructure, open cells and porosity up to 80 vol%, were fabricated by gel-casting, a process commonly used to produce ceramic foams. Geopolymer foams were prepared by stirring an activated blend of metakaolin and fly ash with a mixture of potassium hydroxide and potassium silicate with Si/K=1.66. The cell size and size distribution of the geopolymer foams could be efficiently adjusted by the control of some parameters such as solid content, surfactant type and content and mixing speed. The influence of each parameter on the porosity and other characteristics of the geopolymer foams were investigated. The foams were evaluated only after heat treatment at 80 °C, which was conducted in order to complete the geopolymerization reactions. The produced components could be heat treated up to 1200 °C in air without melting, if desired.The characteristics (morphology, strength, chemical and thermal resistance) of the geopolymer foams suggest that they could be employed as low cost replacement for highly porous ceramics in applications such as catalysis supports, adsorption and separation, filtration of hot gases and refractory insulation of furnaces. In addition, these components could be considered sustainable, because they reach their final properties after processing at temperatures not exceeding 100 °C and part of the raw materials employed are industrial waste.     

Geopolymerization kinetics of fly ash based geopolymers using JMAK model

Geopolymers are versatile materials possessing excellent mechanical properties and resistance against aggressive environments, these materials present a benefit of improving simultaneously both the environmental and engineering performance as compared to classical conventional materials. This paper determines the geopolymerization kinetics of fly ash based geopolymers using Johnson-Mehl-Avrami-Kolmogorov (JMAK) model. The experiments were designed using Taguchi method by varying four factors (Si/Al ratio, Na/Al ratio, W/S ratio, and curing temperature). The degree of reaction of fly ash (α) was used as a measure of the changes occurring during geopolymerization reaction. The characterization of the cured geopolymers was also carried out. The values of n were in the range of 0.0931–0.2321 while the values of k were in the range of 0.366–0.671. According to the JMAK model results, geopolymerization of fly ash based geopolymers is a one dimensional diffusion controlled reaction and its growth follows the mechanism of thickening of large product layers. The mechanism of geopolymerization consists of initial dissolution which is a first order chemical reaction, and further reactions including dissolution, gelation, and polycondensation are the diffusion controlled reactions. The asymmetric stretching band of Si-O-T shifted to 992 cm⁻¹ and increased in intensity indicating the formation of geopolymer. Microstructural analysis showed the heterogeneous nature of geopolymers consisting of geopolymer, unreacted fly ash, and different types of needle like structures while one sample showed plate like morphology consistent with the JMAK model results. The geopolymer was found to be an amorphous material with only few peaks due to unreacted crystalline fly ash.