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The paper considers technologies for the synthesis of amino-formaldehyde resins of KF-MT-NP and AFK-10 grades obtained using the peptization procedure, which could result in the complete elimination of vacuum drying and contribute to the ecologization of the process of synthetic resins production. A modifying additive, which is an inorganic polymer (IP) capable of efficient binding of free formaldehyde in the resin and stabilizing its properties by extending its viability to 6–7 months, is used as a peptizer. [ABSTRACT FROM AUTHOR]

In this study, Si@TiO2 core‐shell nanoparticles are synthesized using the peptization technique, resulting in a thin and uniform TiO2 coating layer over silicon nanoparticles. This coating layer serves the purpose of controlling the structural degradation of the silicon nanoparticles. These core‐shell nanoparticles are then reinforced into the natural graphite with the potential to be used as a composite anode material (Graphite/Si@TiO2) for Li‐ion batteries. The developed composite material exhibits an initial specific capacity of ≈675 mAh/g at 0.5 A/g, and after 100 cycles it retains the capacity of 75 %. Compared with Graphite/Si composite anode, the developed composite anode material shows improved cyclic stability. The pre‐and post‐cycling morphological analysis of Graphite/Si and Graphite/Si@TiO2 composite anode reveals the degradation behavior. It is assumed that the TiO2 coating provides a protective shield for the silicon particles, preventing their interaction with the electrolyte and causing less material to deposit over the anode surface. Electrochemical Impedance Spectroscopy (EIS) analysis supports these findings, with the Graphite/Si composite anode exhibiting higher resistance than the Graphite/Si@TiO2 anode. In conclusion, the study demonstrates the potential of using Si@TiO2 core‐shell nanoparticles as a reinforcing agent for natural graphite to develop high‐performance composite anode material for Li‐ion batteries. [ABSTRACT FROM AUTHOR]

This study aims to synthesize stable colloidal silica via the peptization method as a green and low-cost route. It is crucial to adopt a proper synthesis procedure and choose an appropriate raw material. To achieve this purpose, kaolin was employed as a silica rich source that occurs abundantly in nature. The process involves synthesis of the wet gel through the succession of calcination, acid leaching, alkaline treatment, sodium silicate precipitation, and then peptization of the wet gel. Effect of the acid type on acid leaching was evaluated. Effective factors affecting the gel purity such ad acid concentration, pH of gelation, and temperature of alkaline treatment, were studied and optimized via a statistical design of the experiments. Subsequently, the influential parameters on stability and particle size of the obtained colloidal silica, including the temperature of the gel formation, pH of sol medium, concentration of silica gel, and type of stabilizing base, were investigated via one-facto-at-a-time. The samples were characterized by X-ray fluorescence analysis (XRF), dynamic laser light scattering analysis (DLS), X-ray Diffraction (XRD), Fourier transform infrared (FTIR), Brunauer–Emmett–Teller (BET), and Field emission scanning electron microscopy (FESEM) analyses. Results showed that under optimum conditions, ultra-pure silica gel with a silica content of 99.34 % was obtained. The colloidal sample with the highest stability (zeta potential of −75.6 mV), had nanoparticles showing sizes in the range of 21–66 nm.

Peptized titania sols offer numerous advantages, including uniform distribution, small particle size, good dispersibility in aqueous solutions, and strong interfacial adsorption capabilities. In this study, a novel insight into the systematic analysis of key parameters influencing the characteristics of peptized titania sols synthesized from the hydrolysis-peptization of titanium iso-propoxide (TIP) is presented. The article focuses on electrostatic stabilization, surface area dependent on various modifying conditions including H+/Ti molar ratio, solvent, pH, particle size distribution, peptizing temperature and ageing. The study also establishes the mobility of charges, facilitating charge accumulation on particle surfaces under different conditions. This resulting in enhancing electrostatic potential development in the solution, as indicated by the zeta potential value. Furthermore, the synthesized sols were used to investigate its photocatalytic performance by Methyl Violet and Rhodamine 6G organic dye degradation and other characterizations were performed to validate its properties. [Display omitted] • Anatase TiO 2 has been prepared by acid catalyzed peptization method. • Photocatalytic activity of synthesized nano TiO 2 sol have been studied. • pH, zeta potential, and optical density studies of TiO 2 has been analyzed. • Enhanced zeta potential observed in solution but reverse phenomena in alcohol. • H+/Ti mole ratio of 0.30 have shown best methyl violet degradation efficiency. [ABSTRACT FROM AUTHOR]

Industrial olive oil production is of fundamental economic importance for many Mediterranean countries. However, this industry generates huge amounts of toxic olive mill wastewater (OMW), which could represent a serious threat to human health and environmental biodiversity. In the current study, calcined layered double hydroxides (LDHs) were synthesized through a mechanochemical process involving the manual grinding of magnesium or zinc- and aluminum-nitrate salts in an agate mortar, followed or not by a peptization process. The experimental results showed that non-peptized LDHs have a layered structure with relatively low crystallinity. However, the peptization process resulted in LDHs with regular particles exhibiting high crystallinity and thermal stability. These LDHs achieved a significant improvement in the quality of OMW. Indeed, after 44 h of contact time, the removed amounts of chemical oxygen demand (COD) and biological oxygen demand (BOD) were assessed at approximately 300 and 100 mg·g-1, respectively. Moreover, the discoloration rate of this effluent was more than 90%. Overall, the results demonstrate the convenience of the mechanosynthesis of hydrotalcite and the high efficiency of OMW treatment, which is promising for the potential applications of calcined LDH in environmental clean-up and remediation of contaminated water. [ABSTRACT FROM AUTHOR]

One of the most extensively studied silicate systems with complete miscibility in the solid and liquid state – albite (Ab)-anorthite (An) system – has been analyzed in detail. It has been established that the commonly accepted system and interpretation rules for these diagrams do not match their graphic representation. Calculations have proved the colloidal state of the “solid” phase on the solidus. Actual data support the colloidal (liquid) state of the solidus phase below the solidus and eutectic point. Crystallization in multicomponent systems, at least in silicate melts, has been shown to be based on the sol coagulation mechanism. Thus, silicate solid phases, even those of fixed composition, have no particular melting point. They consolidate and melt within a temperature band. The bandwidth is subject to the system composition that predetermines the micelle structure and directly affects coagulation and peptization processes.

Compared to traditional membrane materials, alumina membranes are particularly beneficial for industrial wastewater treatment. However, the development of mesoporous α-alumina membranes for ultrafiltration applications is still a challenge due to uncontrolled pore size. In this study, we optimized the sol-gel method for the fabrication of a high-performance mesoporous α-alumina membrane. The peptization conditions (pH and peptization time) and phase transformation of boehmite were investigated to achieve better properties of the α-alumina membrane. The surface properties of the membrane were observed to be improved by reducing the system pH to 3.5 and increasing the peptization time to 24 h. The effect of sintering temperature on the phase transformation behavior, microstructures and performance of the membranes was also elucidated. An α-alumina ultrafiltration membrane with an average thickness of 2 μm was obtained after sintering at 1100 °C. The molecular weight cut-off of the α-alumina membrane, as obtained by the filtration of aqueous PEG solution, was approximately 163 kDa (12.5 nm). This is the smallest pore size ever reported for pure α-alumina membranes.

This study was aimed at the development of a better understanding of the agglomeration behavior of sulfated cellulose nanocrystals (CNCs) in the presence of sulfates with monovalent (NH4+, K+, Na+) and divalent (Ca2+) cations, and to demonstrate their potential in simple and efficient product separation. Protonated CNCs were counterion-exchanged and their ionic strength was increased by adding sulfates of the respective cation to trigger agglomeration. The critical concentrations of agglomeration (CAC) and peptization (CPC) were determined. We found that the agglomeration behavior of CNCs could be attributed to matching affinities between the cations and the sulfate half-ester groups on the CNC surfaces. Based on these findings, a facile and efficient downstream process was designed to separate CNCs from neutralized reactant solutions using CAC and CPC. This method provides colloidally stable CNCs at high yield provided by centrifugation. When salt concentrations in the product are maintained below the CAC, as prepared CNCs from neutralized reactant solutions might be used in hydrogels and emulsions. [ABSTRACT FROM AUTHOR]

In the Eastern Jin Dynasty, influenced by the politics, economy and culture, the intellectuals travelled in the scenic and facing the landscape in a metaphysics way, which promoted the development of the landscape Fu. The metaphysical nature, the changes of the expressing space and lyric style of the landscape Fu in that time reflected the poetization tendency of Fu. [ABSTRACT FROM AUTHOR]

This work reviews an eco-friendly process for producing TiO2 via colloidal aqueous sol–gel synthesis, resulting in crystalline materials without a calcination step. Three types of colloidal aqueous TiO2 are reviewed: the as-synthesized type obtained directly after synthesis, without any specific treatment; the calcined, obtained after a subsequent calcination step; and the hydrothermal, obtained after a specific autoclave treatment. This eco-friendly process is based on the hydrolysis of a Ti precursor in excess of water, followed by the peptization of the precipitated TiO2. Compared to classical TiO2 synthesis, this method results in crystalline TiO2 nanoparticles without any thermal treatment and uses only small amounts of organic chemicals. Depending on the synthesis parameters, the three crystalline phases of TiO2 (anatase, brookite, and rutile) can be obtained. The morphology of the nanoparticles can also be tailored by the synthesis parameters. The most important parameter is the peptizing agent. Indeed, depending on its acidic or basic character and also on its amount, it can modulate the crystallinity and morphology of TiO2. Colloidal aqueous TiO2 photocatalysts are mainly being used in various photocatalytic reactions for organic pollutant degradation. The as-synthesized materials seem to have equivalent photocatalytic efficiency to the photocatalysts post-treated with thermal treatments and the commercial Evonik Aeroxide P25, which is produced by a high-temperature process. Indeed, as-prepared, the TiO2 photocatalysts present a high specific surface area and crystalline phases. Emerging applications are also referenced, such as elaborating catalysts for fuel cells, nanocomposite drug delivery systems, or the inkjet printing of microstructures. Only a few works have explored these new properties, giving a lot of potential avenues for studying this eco-friendly TiO2 synthesis method for innovative implementations.

This paper reports a method for producing α-Al2O3 at low temperatures by using a hydrothermal process and a seeding technique. White aluminum hydroxide precipitate prepared through a homogeneous precipitation method using aluminum nitrate and urea was peptized by using formic acid at room temperature to transform it into a transparent alumina sol. After the sol was hydrothermally treated, α-Al2O3 nanoparticle seeds were added to the sol. The sol containing the α-Al2O3 nanoparticles was transformed into an α-Al2O3-seeded alumina gel by drying at room temperature. The non-seeded alumina gel began to crystallize into α-Al2O3 at 500 °C. The α-Al2O3-seeding promoted the crystallization of the alumina gel to α-Al2O3. A remarkable α-Al2O3 crystallinity was achieved with an increase in α-Al2O3 content by weight in the final seeded alumina gel. Even with a content as low as 1%, the seeded alumina gel was partially crystallized to α-Al2O3 at a temperature as low as 400 °C. [ABSTRACT FROM AUTHOR]

A sintering-CO2 decomposition process for preparation of pseudo-boehmite is proposed for clean valorization of high-alumina fly ash. The effects of different synthesis conditions on the crystal structure and textual properties of the pseudo-boehmite were studied systematically. The results showed that the main product was NaAlCO3(OH)2 when the decomposition terminal pH was below 9.5, and the optimal terminal pH for the pseudo-boehmite (PB) product was 10.5. The optimal aging time was 4 h, and the peptization ratio of PB reached 97.5% when the aging temperature was 90°C. Under decomposition conditions of 30 g/L initial alumina concentration in liquid phase and temperature of 40°C, followed by 4 h of aging treatment, the specific surface area of PB was 425 m2/g. The pore volume of PB product reached 0.6920 cm3/g at decomposition conditions of 40 g/L and 30°C. [ABSTRACT FROM AUTHOR]

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Abstract Waste glass powder was used as a low cost precursor for production of colloidal nanosilica for the first time. The process includes production of wet silica gel and thermal peptization of the wet gel. Purification of the glass powder and wet gel production were initiated by acid washing. The obtained powder was reacted with sodium hydroxide to produce wet silica gel. Type of the applied acid was examined in one factor at a time route. Temperature of the alkaline step and concentrations of the applied acid and base were investigated using Taguchi design of experiments. After finding the best combination of the investigated factor levels in production of the wet gel, time of the stabilization in thermal peptization was studied. Characterizations of the wet gel and colloidal silica were performed by XRF, DLS, FESEM, TEM, FTIR and N 2 sorption evaluation. Accordingly pure and stable colloidal nanosilica (98.50%) with average particle size of 21.9 nm was produced from the glass powder successfully. Specific surface area of the dried porous optimum sample was 83.63 m2/g. [ABSTRACT FROM AUTHOR]

Abstract In the operation of biological wastewater treatment processes, fast sludge settling during liquid-solids disengagement is preferred as it affects effluent quality, treatment efficiency and plant operation economy. An important property of fast settling biological sludge is the ability to spontaneously form big and dense flocs (flocculation) that readily separates from water. Therefore, there had been much research to study the conditions that promote biological sludge flocculation. However, reported findings have often been inconsistent and this has possibly been due to the complex nature of the biological flocculation process. Thus, it has been challenging for wastewater treatment plant operators to extract practical information from the literature. The aim of this review is to summarize the current state of understanding of the factors that affect sludge flocculation so that evaluation of such information can be facilitated and strategize for intervention in the sludge flocculation and deflocculation process. Highlights • Flocculation is complex and holistic understanding is needed to predict its direction. • Microbial EPS act as the indispensable glue stabilizing the floc structure. • Biological and physicochemical factors affect EPS production and interactions. • Optimal flocculation measures are unique for a given sludge at given conditions. • Frequent wastewater and sludge characterization help maintain consistent flocculation. [ABSTRACT FROM AUTHOR]

Novel eco-friendly method for preparation of mesoporous alumina from the product of rapid thermal treatment of gibbsite (CTA product) without “reprecipitation” stage is described. Compared with the nitrate-ammonia technology of “reprecipitation” of gibbsite to boehmite and its further calcination to γ-Al 2 O 3 , the new method consumed less amount of HNO 3 per 1 kg of Al 2 O 3 (by 30 times), while the amount of effluents is twice lower. Effluents do not contain ammonium nitrate, since the preparation of boehmite does not include ammonia. It is shown that the method makes it possible to obtain boehmite with needle-shaped particle morphology. The particle size of boehmite and the textural characteristics of alumina are easily adjusted over a wide range by changing the temperature, aging time or peptizing agent. Thus, the pore volume of alumina may be 0.45–0.95 cm 3 /g with an average pore diameter of 81–256 Å and S BET  = 140–240 m 2 /g. [ABSTRACT FROM AUTHOR]

A Portland cement is a basic initial component for concrete and reinforced concrete manufacture, which defines their technical-economic and operational properties. One of a perspective ways of increase in the efficiency of cement production without essential change of its technology is inclusion of various mineral additives influencing on a structure and properties of a cement stone. As power inputs make the most part of the costs necessary for cement manufacture, the cement industry is interested in decrease in fuel and electric power expenditures per 1 tonne of cement. To reach the decrease in power inputs and at the same time to raise the environmental safety of cement production the cement industry is recently focused on increase in output of composite cements. Composite cements not only promote optimization of the production in terms of ecology, but also can provide such technical advantages as lower hydration heat, higher chemical resistance and placeability. [ABSTRACT FROM AUTHOR]

The present study elucidates the creaming phenomenon of mineral oil-in-water macroemulsion using a new noninvasive method based on turbidimetry. Additionally, microscopic observation of the phenomenon is carried out to derive an in-depth understanding of the mechanisms. Accumulation of the particles in the emulsions under the formed cream is monitored during a relatively prolonged period of time. Backflow of continuous and dispersed phases in temporary channels is observed at the proximity of the cream. In addition to the backflow, a high traffic density of the dispersed particles and deflocculation of the cream are the main reasons for the accumulation of the dispersed phase particles and a temporary stability against creaming. The deflocculation hinders cream growth and increases the stratification of the cream. A low concentration zone of the dispersed phase with the width of ∼100 µm is observed under the cream. [ABSTRACT FROM AUTHOR]

A Portland cement is a basic initial component for concrete and reinforced concrete manufacture, which defines their technical-economic and operational properties. One of a perspective ways of increase in the efficiency of cement production without essential change of its technology is inclusion of various mineral additives influencing on a structure and properties of a cement stone. As power inputs make the most part of the costs necessary for cement manufacture, the cement industry is interested in decrease in fuel and electric power expenditures per 1 tonne of cement. To reach the decrease in power inputs and at the same time to raise the environmental safety of cement production the cement industry is recently focused on increase in output of composite cements. Composite cements not only promote optimization of the production in terms of ecology, but also can provide such technical advantages as lower hydration heat, higher chemical resistance and placeability. [ABSTRACT FROM AUTHOR]

The aims of this paper are to identify the driving mechanisms at the origin of the deflocculating action of inorganic dispersants and to study their consequences on the behaviour of a dense clay paste over time. Considering that the flow behaviour of clays is controlled by their surface charge, an extensive set of rheological experiments and zeta potential measurements are carried out. We first show that sodium hexametaphosphate disperses via electrostatic repulsive forces while sodium silicate acts through electrosteric repulsive forces. We show that this deflocculation can be achieved without reaching full coverage of positive charge with the dispersant. We then highlight that the stability of the deflocculated clay paste can be controlled by the proportion of introduced dispersant within the matrix. Finally, these results reveal that the re-arrangement of clay particles and the availability of residual positive charge are at the origin of the thixotropic behaviour and rigidification of the system over time. [ABSTRACT FROM AUTHOR]

The anionic surfactant sodium dodecylsulfate (SDS) has improved the physical stability of flurbiprofen (FBP) suspension, which was suspended by 0.2% (w/v) hydroxypropylmethyl cellulose (HPMC, K4M). Therefore, the physical stability of FBP suspensions and the interaction of HPMC/SDS were studied, and a certain association between them was revealed. The antisolvent precipitation method was used to prepare suspensions. The apparent drug concentration from different sites was evaluated to get the dispersion of drug actually. The process of flocculation and deflocculation with the addition of SDS was caught by analyzing the morphology of the suspended particles.The physical stability of the FBP suspensions was characterized mainly by measuring the re-dispersion time, the zeta potential and particle size. Meanwhile, conductivity measurements were carried out to obtain the characteristic concentrations of SDS in HPMC/SDS system. The viscosities, the abilities for improving the solubility and wettability of FBP in the separate and mixed HPMC/SDS solutions were also contrasted respectively. The suspensions prepared with HPMC/SDS possessed better physical stability. The suspensions were uniform when the concentration of SDS was between the critical adsorption concentration (CAC) and the polymer saturation point (PSP). After PSP, the uniformity became worse and worse until the SDS was enough to form a deflocculation state. Besides, the re-dispersion time of FBP suspensions was longest when the concentration of SDS around CAC and shorter by shorter after the critical micelle concentration (CMC). The article provided a new sight on the relation between the interaction of excipient matrix and pharmaceutical preparations. [ABSTRACT FROM AUTHOR]

CaTiO 3 and CaTiO 3 /TiO 2 nanocompounds have been synthesized through a colloidal sol-gel route using Ca 2+ /TiO 2 nanoparticulate sols. The peptization time was determined so that as higher is the Ca 2+ concentration, shorter is the peptization time. The obtained cryogels from the respective sols were calcined at different temperatures (300–900 °C) and the structural and morphological changes were characterized mainly by X-ray diffraction and transmission electron microscopy. In all cases, the formation of the CaTiO 3 phase was observed after calcination at temperatures as low as 500 °C. Mesoporous cryogels with nanoparticles with sizes below 50 nm were obtained and their photocatalytic activity changes as a function of the calcination temperature and the applied wavelength were determined. Quantum yield values revealed that either CaTiO 3 or the CaTiO 3 /TiO 2 (0.4 M ratio) compound can be chosen as the most efficient photocatalyst at higher calcination temperatures and longer wavelengths, while TiO 2 is more effective at low calcination temperatures and shorter wavelengths. [ABSTRACT FROM AUTHOR]

The relationships of the formation of aluminum oxide from aluminum hydroxide peptized with organic acids (propionic, maleic, malonic, tartaric) were studied. The pore structure parameters of the hydroxide samples and of aluminum oxide samples obtained from them are strongly influenced by acid peptization. The nature of the acid influences the extent of defectiveness of the γ-Al2O3 structure, manifested in the density of aluminum oxide, measured by helium pycnometry. The possibility and conditions for preparing mesoporous γ-Al2O3 suitable for use in chemical and petrochemical processes were determined. [ABSTRACT FROM AUTHOR]

• The CZA3 material shows relatively Ce-rich surface and highly dispersed CZ nanoparticles. • The Pd species in Pd/CZA3 were stabilized in oxidation states and smaller particle size. • Both fresh and aged Pd/CZA3 catalyst exhibited the best activity for CO, NO, C 3 H 6 and C 3 H 8. The sintering of Pd under high temperature operation conditions usually leads to serious deactivation of Pd-based TWCs. As the stronger Pd-CeO 2 -ZrO 2 (Pd-CZ) interaction in the form of Pd-O-Ce bond favors to anchor Pd species than that of Pd-Al 2 O 3 , to construct a CeO 2 -ZrO 2 -Al 2 O 3 (CZA) support with a relative CZ-rich surface is beneficial to selectively enlarger the Pd-CZ interface to maintain the excellent catalytic function of Pd/CZA TWCs. For the purpose, a facile one step peptizing method has been put forward to achieve the CZA material to stabilize Pd species. By XRD, TEM and Mapping, it could be inferred that comparing with the conventional precipitation method and peptization-precipitation method, the CZ nanoparticles could be homogeneously distributed on the network structure of porous Al 2 O 3 by in-situ growth in the peptization method. Then the CZA with a relative CZ-rich surface could be obtained, which interacted strongly with the supported Pd species and thus stabilized the Pd species in oxidation states and smaller particle size. As a result, the Pd/CZA catalyst from peptization method exhibited the best activity for CO, NO, C 3 H 6 and C 3 H 8 , the T 90 (complete conversion temperature at 90% conversion) of which was reduced by 40 °C, 50 °C, 40 °C and 20 °C comparing with that of Pd/CZA derived from conventional precipitation method even being thermal aged at 900 ℃/3 h, respectively. [Display omitted] [ABSTRACT FROM AUTHOR]

Irradiation effect of low-energy ion beam has been investigated on nanocoating developed with silica, titania and silica–titania core–shell nanoparticles embedded in an organic binder for nanopaint application. In this work, we have taken polyurethane as a model organic binder. Silica nanoparticles have been prepared through sol–gel synthesis with a particle size of 85 nm. Titania and core–shell nanoparticles have been prepared through both sol–gel and peptization process. Particle sizes obtained were 107 nm for titania and 240 nm for core–shell nanoparticles prepared through sol–gel process and 75 nm for TiO2and 144 nm for core–shell nanoparticles prepared through peptization process. The coating formulations were developed with the above nanoparticles individually and nanoparticle concentration was varied from 1 to 6 wt% and the best performance in terms of hydrophobicity was obtained with 4 wt % of the nanoparticles in polyurethane coating formulation. All the coating formulations prepared were applied on a glass substrate and dried at 100°C. The dry film thickness obtained was around 100 µm in each case. These films dried on glass substrate were irradiated by nitrogen and argon ion beam with energy of 26 keV at fluences of 1014to 1016 ions/cm2. The anti-algal property of the irradiated samples was improved and hydrophobicity was reduced. [ABSTRACT FROM PUBLISHER]

The effect of two deflocculants - sodium tripolyphosphate (PP) and Castament FS 20 (C1) based on polycarboxylate ester-effectively lowering the viscosity of cement paste and their mixtures on the structure of cement rock with microsilica after soaking at 65°C, drying, and firing was investigated. The mineral stratlingite forms additionally in the samples with C1 during soaking. It was found that C1 promotes active formation of the mineral anorthite and PP promotes crystallization of gehlenite during firing. In using a mixture of PP and C1 crystallization of anorthite predominates in the sample. The resulting density and strength of the samples of concrete with PP are higher than in samples with C1, but shrinkage phenomena are highest in them. Adifferent ratio of PP and C1 in the mixture decreases shrinkage, making it possible to obtain the highest strength and density of concrete after firing at temperature 1200°C. [ABSTRACT FROM AUTHOR]

In the present study, the deflocculated sludge was disintegrated through thin layer immobilized titanium dioxide (TiO 2 ) as photocatalyst under solar irradiation. The deflocculation of sludge was carried out by 0.05 g/g SS of sodium citrate aiming to facilitate more surface area for subsequent TiO 2 mediated disintegration. The proposed mode of disintegration was investigated by varying TiO 2 dosage, pH and time. The maximum COD solubilization of 18.4% was obtained in the optimum 0.4 g/L of TiO 2 dosage with 5.5 pH and exposure time of 40 min. Anaerobic assay of disintegrated samples confirms the role of deflocculation as methane yield was found to be higher in deflocculated (235.6 mL/gVS) than the flocculated sludge (146.8 mL/gVS). Moreover, the proposed method (Net cost for control – Net cost for deflocculation) saves sludge management cost of about $132 with 53.8% of suspended solids (SS) reduction. [ABSTRACT FROM AUTHOR]

The possibility to fabricate nanoceramic materials by techniques based on colloidal processing requires the use of effectively working deflocculants (dispersing agents) which are able to stabilize and decrease the viscosity of aqueous nanopowders suspensions. Galacturonic and lactobionic acids have been used in the research as deffloculants for nanoalumina; they allowed to obtain ceramic suspensions of high solid loading (50 vol%) and relatively low viscosity (ca. 4 Pa s at a shear rate 10 s −1 ). High solid loading could be achieved through combining three factors: the application of sugar acids as deflocculants, water leaching of the nanopowders from the surface impurities and precise defoaming of the slurries. Density of sintered bodies equalled 98% TD. [ABSTRACT FROM AUTHOR]

Colloidal nanosilica was prepared from perlite in two stages: production of wet gel and thermal peptization. The influence of acidic and alkaline solutions concentration, temperature and pH of the gel were investigated in wet gel production using Taguchi design of experiments. Effect of the temperature of the peptization process was studied by full factorial design. The purity of the obtained silica gel was analyzed using X-ray fluorescence (XRF) and the colloidal silica was characterized by dynamic laser scattering (DLS), field emission scanning electron microscope (FESEM) and N 2 sorption analyses. Results showed that pure colloidal nanosilica with purity of 99% was produced and the particle size of the product was in the range of 8 nm and 74 nm. Specific surface area of dried optimized mesoporous sample was 74.28 m 2 /g. [ABSTRACT FROM AUTHOR]

Hydrosols of hydrated tungsten trioxide WO • nHO have been synthesized via peptization of a precipitate obtained by hydrolysis of potassium tungstate. It has been shown that the resulting sols are stable to aggregation in a pH range of 3.0-4.5. Hydrodynamic diameters and ζ potentials of WO • nHO particles have been determined as functions of dispersion medium pH. In addition, their density and degree of hydration have been found for the stable sols. The thickness of particle surface layers has been estimated. [ABSTRACT FROM AUTHOR]

A method has been developed for the synthesis of hydrated tungsten oxide hydrosols, with this method being based on potassium tungstate hydrolysis followed by peptization of the formed precipitate. The influence of the conditions of precipitation, aging, and washing of the precipitate on the particle phase composition and shape and the degree of precipitate peptization has been studied. Hydrosol-particle sizes have been determined by different methods. It has been found that the dispersed phase of the hydrosols consists mainly of platelike particles of hydrated tungsten oxide WO · 2HO with a number-average size of 52 nm. The sols are stable to aggregation in a pH range of 3.0-4.5. The zeta potential of the particles ranges from-33 to-38 mV. [ABSTRACT FROM AUTHOR]

The excluded volume effect, or depletion attraction, is the phenomenon describing induced aggregation of colloidal particles suspended in a densely crowded macromolecule solution. In this work, we attempted to utilize this effect for the self-assembly of artificially manufactured microcomponents on a 10–100 μm scale. The bonding energy does not originate from the nature of the surfaces, but is generated by an increase of the translational entropy of macromolecules in solution. Thus, simple immersion of the microcomponents in the macromolecule solution allowed us to observe their assembly, based on shape complementarity, to minimize the free energy of the system. However, it became apparent that elaborate design is required for specific bonding between complementary shapes, in addition to merely increasing the contact surface area. [ABSTRACT FROM AUTHOR]

In the presence of additives such as etidronic acid (1-hydroxyethane-1,1-diphosphonic acid, HEDP), a process of peptizing of Laponite clay gels takes place. The peptizing process at the molecular level was directly revealed by 31P and ¹H high-resolution magic-angle sample spinning (HRMAS) NMR spectroscopy. Two NMR spectral components were detected and assigned to free etidronic acid and bound to the Laponite disk edges. Furthermore, with increase of temperature the ratio of bound-to-free etidronic acid increases. This thermal activation process could be explained by the increase in electrical polarization of the hydroxyl group at the edges and by the exfoliation of the tactoids that leads to more access to the additive molecules to the electrical charges of platelet edges. 31P HRNMR spectroscopy on sodium fluorohectorite with an aspect ratio of ∼750 shows a reduction of the bound etidronic acid molecules. Transmission electron microscopy (TEM), field-emission scanning microscopy (FESEM), UV-vis spectrophotometry, dynamic light scattering (DLS), and zeta potential results support the proposed peptizing mechanisms. [ABSTRACT FROM AUTHOR]

This paper discusses issues of aggregative and structural stability of high-concentration colloid dispersed systems taking into account their properties of high particle packing density and limited possibility of their participation in heat Brownian motion. The section on aggregative dynamic stability substantiates the methods of peptization of systems. The second part of the paper is dedicated to the method of achieving structural stability of such systems, their strength and elasticity combined with a degree of structural uniformity. [ABSTRACT FROM AUTHOR]

The effect of three different types of deflocculants and their amounts on high-alumina low-cement castables is studied. Castable formulations were done as per continuous particle size distribution of a Dinger-Funk model using a distribution coefficient of q = 0.21. Castable compositions were processed as per conventional processing techniques and variation in properties were evaluated regarding flowability of the mix and densification and strength development after drying and firing at 900 and 1500 °C. Phase analysis of the matrix phase was also done for the 1500 °C compositions to evaluate the phase formations at high temperature in the presence of cement. The alumina-based dispersant was found to have resulted in better properties in the castable. [ABSTRACT FROM AUTHOR]

Shear-induced particle migration is widely recognized to be a challenge in characterizing the rheological properties of fresh cement-based mortars. In this study, we aim to quantify shear-induced particle migration by characterizing the stress decay process during constant shear flow with the aid of a modified thixotropy/migration model. It is found that a conventionally used single exponential model is not sufficient to fit the stress decay and describe the destructuration and sand migration of mortar under shear. Instead, a two exponential model is needed to capture the interaction of sand particles and the suspending cement paste phase. Model parameters are used to quantify the effect of sand volume fraction, clay addition, and applied shear rate on the kinetics and intensity of colloidal deflocculation and sand migration. Results provide evidence that the colloidal and granular contributions to the overall stress decay of mortars can be represented by each of the two exponentials. [ABSTRACT FROM AUTHOR]