Sodium Aluminate Research Articles

Synthesis of inorganic polymer sodium aluminum silicate system based on sodium silicate and application as film forming agent for silicate paint

In this study, sodium aluminum silicate inorganic polymer was synthesized by sol-gel method. The parameters affecting the polymer formation were also investigated. Polymers with optimal parameters have been applied to make high temperature resistant inorganic paints. Modified infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and X-ray diffraction (XRD) methods were used to investigate the characteristics of the paint film. Furthermore, the mechanical and mechanical properties of heat-resistant inorganic paints and their heat resistance were also investigated.

Effect of electrolyte systems on plasma electrolytic oxidation coatings characteristics on LPSO Mg-Gd-Y-Zn alloy

In order to solve the problem of poor corrosion resistance of Mg-Gd-Y-Zn alloy with high strength and high toughness. In this paper, two-step plasma electrolytic oxidation (PEO) was implemented on Mg-Gd-Y-Zn alloy with long period stacking ordered (LPSO) phase in seven different electrolyte systems. Optical microscope (OM), Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) were used to characterize the structure distribution and composition of the LPSO phase. X-ray diffraction (XRD), SEM, EDS, Mott-Schottky test (M-S), potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and immersion hydrogen evolution were used to study the morphology, composition, structure and corrosion resistance of the PEO coatings prepared using the various electrolytes. The PEO coating prepared by the mixed electrolyte of sodium aluminate, sodium phosphate and sodium silicate, referred to as PEO-APS coating, had the most excellent structure and corrosion resistance. The coating was dense and uniform, the coating thickness was 3.5 μm, the open porosity was 4.4 %, the average pore size was 0.12 μm, and the corrosion current density icorr was 2.09 × 10−8 A cm−2. In addition, the formation mechanism and corrosion resistance mechanism of the PEO-APS coating were discussed, and the effect of LPSO phase on the PEO-APS coating was proposed.

Effect of redox agents on the reaction behavior of pyrite in sodium aluminate solution at elevated temperatures

As the main sulfide mineral in diasporic bauxite, pyrite readily reacts with sodium aluminate solution in Bayer digestion at elevated temperatures, adversely affecting the utilization of high-sulfur bauxite for alumina production by the Bayer process. For better understanding of the reaction mechanism during Bayer digestion, this paper focuses on the impacts of oxidant and reductant on the reaction extents of pyrite at elevated temperatures. The extents of reaction between pyrite and sodium aluminate solution are 57.9, 38.3 and 99.0 % at 260 °C for 40 min with no, oxidant and reductant addition, respectively. In the presence of oxidant, a dense layer formed on the surface of unreacted pyrite retarding the reaction with sodium aluminate solution, which follows the Kröger and Ziegler diffusion control model at 240–260 °C. However, the presence of reductant favors the decomposition of pyrite due to the formation of hematite and then transformation to magnetite, and the development of “chemical etching channel”. Finally, the above results were experimentally verified by digesting high-sulfur diasporic bauxite at 260 °C for 60 min, in which the inhibition of pyrite reaction with oxidant addition is affected by the organic content of the bauxite. These results may facilitate the development of a technique for directly treating the high-sulfur diasporic bauxite for alumina production with the Bayer process bypassing desulfurization pretreatment.

High-temperature behavior of geopolymer mortar containing nano-silica

Nano-silica (NS) can significantly improve the microstructure, mechanical properties, and durability of metakaolin/fly ash-based geopolymer mortar (GPM). To investigate the high-temperature behavior of GPM containing NS, cubic compressive strength test, prism compressive strength test, flexural strength test, visual appearance analysis, thermal strain test, thermogravimetric and differential thermal analyses, bubble parameter test, scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy were conducted. The NS weight contents were 0 %, 0.5 %, 1.0 %, 1.5 %, 2.0 %, and 2.5 %, and the exposure temperatures were 25, 100, 200, 400, and 600 ℃. The results revealed that the sand in mortar constrained the development of cracks when the exposure temperature was 25–200 ℃, whereas cracks formed when the temperature was 200–600 ℃. From 25 to 200 ℃, a significant mass loss with slight geopolymer shrinkage was observed. In contrast, from 200 to 600 ℃, a slight mass loss with evident shrinkage occurred. The compressive and flexural strengths of the GPM first increased when the temperature was 25–200 ℃ and then decreased when the temperature was 200–600 ℃. When the temperature was less than 200 °C, NS improved the GPM strength; however, the strength decreased when the temperature exceeded 200 ℃. The latter occurred because NS enhanced the compactness of the GPM, resulting in increased pore pressure. Additionally, the thermal stability of the phases and sodium alumina silicate hydrate structure in the geopolymer was observed. The compactness and stability of the microstructure in the GPM were enhanced by NS. A damage model based on the cubic compressive strength that well describes the relationship between the exposure temperature and degree of damage was proposed.

Synthesis and Characterization of Nanozeolite from Sugarcane Bagasse Ash and Its Nutrient Loading Potential

Sugarcane bagasse, a known agricultural waste product in the Philippines with 88% silica (SiO2) content based on elemental analysis, is a viable starting material for zeolite synthesis. In this study, silica derived from sugarcane bagasse ash (SBA) collected from La Carlota, Negros Occidental, Philippines, was extracted via an alkaline extraction method using 2M NaOH and precipitation with 5 N H2SO4 under constant stirring at elevated temperature. Sodium aluminate was added as aluminum source then subjected to ageing at 80°C for 72 h to form the clinoptilolite-type zeolite crystals. Characterization using Scanning Electron Microscopy – Energy Dispersive X-ray Spectroscopy and X-Ray Diffractometry confirmed the successful synthesis of the SBA silica and clinoptilolite, with an Si/Al ratio of 1.59 and average pore diameter of 85.77 nm. Surface modification was done by adding CTAB, a cationic surfactant. Nutrient loading was performed using synthesized nanozeolite (SNZ) for N and K loading and surface modified synthesized nanozeolite (SMSNZ) for PK loading which was compared with nutrient loading performance of commercial natural zeolite. The nanozeolite was added to 1 M urea for N loading, 1 M potassium chloride (KCl) for K loading, and 1 M potassium dihydrogen phosphate (KH2PO4) for PK loading at 1:10 (solid: liquid) solution ratio for 8 h under constant stirring followed by filtration and air drying. Chemical characterization of the synthesized nanozeolite revealed that it has a total CEC of 199.30 meq 100 g-1, ICEC of 182.51 meq 100 g-1, and ECEC of 16.79 meq 100 g-1. Nutrient loading resulted in a 9.62% N and 17.01% K2O content using SNZ and a 13.35% P2O5 and 16.26% K2O content using SMSNZ, which were relatively higher compared to using a commercial natural zeolite. These can be attributed to the high internal CEC due to the high quantity of nanopores in the zeolite, which can capture and store the K+ and NH4+ ions via geometric fit, then release them to the soil on-demand via ion-exchange or occlusion. The surface modification with a surfactant drastically alters the surface chemistry of zeolite allowing simultaneous adsorption of anions (PO4-) externally and cations (K+) internally. The chemical characterization confirmed successful loading of N, K, and PK to synthesize nanozeolite from SBA-derived silica, and its potential as a controlled release fertilizer can be tested in further studies.

Sodium aluminate activated geopolymers based on natural zeolite clinoptilolite

Geopolymers based on natural zeolite clinoptilolite were activated with different concentration of sodium aluminate and potassium hydroxide and the influence on compressive strength, density and water absorption were evaluated. The microstructure was analyzed by XRD, FTIR and SEM. The obtained geopolymers are comprised of newly formed zeolite phases – phillipsite, zeolite A.

A Review: To Investigate the Properties of Geopolymer Concrete with Fly Ash in Place of Cement

Abstract: A novel type of concrete called geopolymer concrete is created by reacting sodium silicate containing minerals with sodium aluminate and a caustic activator, such as fly ash or slag from the production of iron and metal. It can serve as a viable replacement for regular portland cement. In addition to having outstanding mechanical qualities, geopolymer concrete also possesses a number of extremely high-end qualities, including corrosion and fire resistance. The majority of industrial solid waste and bottom ash from waste incineration are stacked up at random, which not only uses up land resources but also negatively affects the ecosystem. They can be recycled and utilised as raw materials to make geopolymer concrete. Geopolymer concrete has the ability to absorb pollutants like heavy metals and other radioactive chemicals, so that its stability, elasticity, and thermal qualities are unaffected. However, geopolymer concrete's use goes beyond that because of its superior qualities. The geopolymerization of concrete, the origin of the raw materials, the numerous categories of activators, the development processes, and the diverse applications of geopolymer concrete in various fields are all covered in this paper. In this section, the factors that affect the mechanical and abrasion resistance of geopolymer concrete. In order to establish a hypothesis that will be used to develop geopolymer concrete for future development, the disadvantages and application quantification of geopolymer concrete, as well as its mix design, will be summarised in this paper.

Structural characterization of three hydride-bridged sodium aluminate compounds

The synthesis and single-crystal structures of three hydride-bridged sodium aluminate compounds containing the utility amide HMDS [N(SiMe3)2 or C6H18NSi2] are reported. Both bis[bis(trimethylsilyl)amido-2κN]-μ-hydrido-hydrido-2κH-(N,N,N′,N′′,N′′-pentamethyldiethylenetriamine-1κ3 N,N′,N′′)(tetrahydrofuran-1κO)aluminiumsodium, [AlNa(C6H18NSi2)2H2(C4H8O)(C9H23N3)] or (HMDS)2Al(H)2Na(THF)(PMDETA), (1) (THF = tetrahydrofuran, C4H8O; PMDETA = N,N,N′,N′′,N′′-pentamethyldiethylenetriamine, C9H23N3) and tetrakis[bis(trimethylsilyl)amido]-3κ2 N,4κ2 N-tetra-μ-hydrido-tetrakis(tetrahydrofuran)-1κ2 O,2κ2 O-dialuminiumdisodium, [Al2Na2(C6H18NSi2)4H4(C4H8O)4] or [(HMDS)2Al(H)2Na(THF)2]2 (2), are dihydrides. However, 1 is a dinuclear Al—H—Na monomer with one bridging and one terminal hydride ligand whilst in 2 all the hydride ligands bridge between Al and Na atoms to give a dimeric structure with a core (AlHNaH)2 eight-membered ring. In contrast, the structure of bis[bis(trimethylsilyl)amido]-3κN,4κN-dihydrido-3κH,4κH-tetra-μ-hydrido-bis(N,N,N′,N′′,N′′-pentamethyldiethylenetriamine)-1κ3 N,N′,N′′;2κ3 N,N′,N′′-dialuminiumdisodium, [Al2Na2(C6H18NSi2)2H6(C9H23N3)2] or [(HMDS)Al(H)3Na(PMDETA)]2 (3), also contains a (AlHNaH)2 eight-membered ring but is a trihydride with two bridging and one terminal hydride ligand per Al centre. The (AlHNaH)2 eight-membered rings of 2 and 3 differ in their structural details. That of 2 is based around a twofold axis and has a larger Al...Al intra-ring distance than that found in centrosymmetric 3.

Effects of sodium aluminate and reverse osmosis brine on hydration and mechanical properties of slag

In this study, reverse osmosis brine (ROB) and sodium aluminate (NA) were used as mix water and an activator for ground granulated blast furnace slag (GGBFS), respectively, to investigate the hydration reaction and mechanical properties of the GGBFS. Samples with NA alone and a combination of NA and 5% and 10% CaO were fabricated using tap water (TW) and ROB as mix water. The addition of CaO enhanced the effect of the NA activator in increasing the strength of the samples. With the NA–CaO combination, TW samples promoted the formation of C2ASH8 and C3AH6 phases more than the ROB samples. In the ROB samples, Friedel’s salt was formed. The strength of the TW samples was lower than that of the ROB samples, attributed to the abundantly formed C3AH6 phase in the TW samples. The NA–CaO–ROB samples improved the chloride ion adsorption capacity by increasing the Ca/Si ratio of the hydration reactant. However, in the ROB samples, Friedel's salt was decomposed due to carbonation by air exposure, increasing the concentration of chloride ions in the pore solution and promoting calcite formation. The NA–CaO–ROB samples confirmed the effectiveness of NA as a new GGBFS activator and the potential of ROB as a building material.

Strength optimization and key factors correlation of one-part fly ash/ladle furnace slag (FA/LFS) geopolymer using statistical approach

The utilization of ladle furnace slag (LFS) in one-part geopolymer technology has not been reported. The study of the cause-and-effect relationship between the mixing ratio is therefore important. The present work optimized one-part fly ash (FA)/LFS geopolymer with 33 full factorial design using variance analysis (ANOVA) to predict the key engineering properties of the one-part geopolymer with satisfactory precision. Three factors, which are alkali activator to aluminosilicate sources (AA/AS), sodium metasilicate to sodium hydroxide, Na2SiO3 to NaOH (SM/SH) and water to binder (W/B) ratios, were considered. The AA/AS, W/B and interrelationship between AA/AS and W/B ratios were the most significant factors influencing the key engineering properties. The one-part geopolymer with AA/AS, SM/SH and W/B ratios of 0.20, 5.0 and 0.25 were concluded as an optimal response to achieve a good compressive strength of 38.8 MPa after 28 days. The microstructural and phase analysis indicated that the LFS participated moderately in geopolymerization reaction with the formation of calcium silicate hydrate (C–S–H) and sodium aluminate silicate hydrate (N-A-S-H). The optimized one-part FA/LFS geopolymer met the minimum requirement of ASTM C1157 (>28.0 MPa) for a functional construction binder. The outcome of the paper offers a guideline to the construction industry to maximize the use of LFS to prepare green construction binder.

Development of surface-modified galvanised steel as an immobilised photocatalyst for textile wastewater treatment

The quest for cost-effective photocatalytic material and a simple process for wastewater degradation has inspired the development of immobilised ZnO photocatalyst by surface-modifying the commercial galvanised steel via plasma electrolytic oxidation process (PEO). In this work, galvanised steel underwent oxidation via PEO using a suitable base electrolyte system (borax and sodium aluminate). The optimum time for effectively converting zinc in the galvanised steel to ZnO is investigated. The 90 s PEO process effectively converted ZnO with the bandgap value of 3.30 eV. Additionally, vanadium was doped into the ZnO by adding sodium metavanadate (0.3 to 1.2 g/L) to the base electrolyte to reduce the bandgap. The effect of dopant concentration on the surface morphology, phase analysis, optical properties, recombination rate and separation efficiency of charge carriers were investigated. Also, the photocatalytic efficiency was measured by evaluating methylene blue dye's degradation under UV light irradiation. It was found that 0.9 g/L of sodium meta vanadate addition to the base electrolyte system was shown crystalline ZnO with near-visible light absorption (3.15 eV) along with reduced electron-hole recombination. Finally, the vanadium-doped ZnO photocatalyst showed 95 % MB dye degradation with a rate constant K = 0.014 min−1 under UV light.

Comparative study of the isothermal solid-state reaction systems of kaolinite–Na2CO3 and kaolinite–quartz–Na2CO3 for coal gangue activation

A clear understanding of the solid-state reaction of kaolinite (Kln), quartz (Qtz), and sodium carbonate (Na2CO3) is of great significance for the process optimization of coal gangue calcined with Na2CO3. In this work, a comparative study of the isothermal solid-state reaction systems of Kln–Na2CO3 and Kln–Qtz–Na2CO3 was performed by means of X-ray diffraction (XRD), scanning electron microscope, and energy dispersion spectroscopy (SEM-EDS). The results showed that the calcined products both for these reaction systems mainly contain different kinds of sodium aluminum silicates (e.g., NaAlSiO4, Na1.55Al1.55Si0.45O4, and Na1.95Al1.95Si0.05O4) and various kinds of sodium silicates (e.g., Na2Si3O7, Na2SiO3, and Na6Si2O7). The mass percentage of Na2CO3 played a key role in the phase transformation, determining the Na/Al/Si molar ratio of the formed sodium aluminum silicates. Compared with the reaction system of Kln–Na2CO3, the existence of Qtz inhibited the formation of sodium aluminum silicates in the reaction system of Kln–Qtz–Na2CO3. It should be noted that the formed phases both for these reaction systems were slightly different from that of the thermodynamical calculated results of Na2O–SiO2–Al2O3 using FactSage™ software. According to both the experimental and calculated results, a reasonable batching area for coal gangue activation was proposed that the addition of Na2CO3 should be in the range of 20–50% of the total mass of Kln, Qtz, and Na2CO3.

Ex Situ Upgrading of Extra Heavy Oil: The Effect of Pore Shape of Co-Mo/γ-Al2O3 Catalysts

Co-Mo/γ-Al2O3 catalysts with different pore shapes were synthesized for the ex situ upgrading of extra heavy oils by hydrodesulfurization (HDS), hydrodemetallization (HDM), and hydrodeasphaltization (HDA). The catalysts were synthesized using aluminum oxides that were prepared by various methods. It was found that using the product obtained by the thermochemical activation of gibbsite leads to the formation of slit-shaped pores in aluminum oxide, while the application of the hydroxide deposition method by the precipitation of sodium aluminate and nitric acid gives cylindrical pores in aluminum oxide. Co-Mo catalysts synthesized using these two types of pores exhibit different catalytic activities. The catalyst synthesized on a carrier with cylindrical pores exhibited a higher catalytic activity in sulfur, heavy metals, and asphaltenes removal reactions that are synthesized on a carrier with slit-like pores. This is because the presence of cylindrical pores leads to a decrease in diffusion restrictions when removing large molecules of asphaltenes and sulfur-containing and metal-containing compounds.

Geopolymer synthesized from electrolytic manganese residue and lead-zinc smelting slag: Compressive strength and heavy metal immobilization

In order to follow the growing trend towards waste re-utilization and clean production, geopolymers were synthesized to immobilize Pb2+ and Zn2+ by simultaneously using electrolytic manganese residue (EMR) and lead-zinc smelting slag (LZSS) as raw aluminosilicate materials. Different contents of supplementary cementitious materials (i.e., blast furnace slag, sodium aluminate and silica-gel powder) were respectively employed to study the influences of Ca, Al and Si on compressive strengths of geopolymers. Moreover, the geopolymers can be used to immobilize heavy metals including Pb and Zn. The effects of heavy metals on compressive strength and leaching concentration were explored. Results showed that, geopolymers with 1% Pb(NO3)2 loading had a highest 7-day compressive strength of 28.5 MPa and a low heavy metal leaching concentration below the limit (total Pb < 5 mg/L, total Zn < 100 mg/L). Proved by XRD, FTIR, SEM-EDS, XPS analyses and theoretical calculation, the immobilization of Pb/Zn in EMR/LZSS based geopolymers was realized by physical encapsulation and chemical bonding. The proposed technology can be potentially used to convert Pb/Zn-containing solid wastes into less hazardous or nonhazardous solids for environmentally acceptable construction applications.

Modification of sodium aluminum silicate hydrate by thioglycolic acid as a new composite capable of removing and preconcentrating Pb(II), Cu(II), and Zn(II) ions from food and water samples

In this paper, sodium aluminum silicate hydrate was synthesized using rice husk as a silicon source and scrap aluminum cans as an aluminum source. Afterward, with the aid of microwave heating, a composite of sodium aluminum silicate hydrate and (3-aminopropyl)trimethoxysilane was facilely synthesized then modified by thioglycolic acid to produce a new composite. Besides, characterization of the synthesized composite was carried out using XRD, FT-IR, TEM, CHN elemental analyzer, nitrogen gas sorption analyzer, and SEM. The XRD pattern of the produced composite shows that there is a halo at 2θ = 25.0°, which means that there is a crystalline structure that is combined with an amorphous background. The SEM and TEM studies indicate that the synthesized composite has a structure similar to cotton. The synthesized composite was utilized for the efficient removal and preconcentration of Pb(II), Cu(II), and Zn(II) ions from food and water samples prior to determination by flame atomic absorption spectrometry. The produced composite has a maximum adsorption capacity of 185.53, 168.92, and 125.94 mg/g for Pb(II), Cu(II), and Zn(II) ions, respectively. The recovery findings demonstrate that the process is accurate, adaptable, and resulted in quantitative separation (greater than95 percent). Furthermore, the % RSD was less than 3.5 percent, indicating good reproducibility. The Langmuir isotherm and pseudo-second-order model fit the experimental results well. The thermodynamic studies established that the adsorption process is spontaneous, chemical, and exothermic. The produced composite was successfully regenerated and used multiple times to remove the metal ions under investigation from aqueous solutions.

Sodium aluminum silicate composite ceramics with secondary caries prevention for dental crown restoration

Secondary caries caused by plaque accumulation at the edge of crown restorations is still a significant reason for crown restoration treatment failures. To prevent secondary caries, it is urgent to develop dental crown restorative materials with good antibacterial ability and mechanically stable properties. In this work, functionalized dental crown restorations were successfully prepared by doping the human trace element Zn into sodium aluminum silicate ceramics (NAS/Zn). The results demonstrated that the NAS/Zn composite ceramics killed Streptococcus mutans (S. mutans) effectively. The Zn ions released by NAS/Zn composite ceramics disrupted the bacterial membrane integrity and DNA proliferation, promoted the outflow of protein, and eventually led to bacterial death. Most notably, NAS/Zn composite ceramics exhibited excellent biocompatibility. This study will provide a new strategy to prevent the occurrence of secondary caries via the construction of dental crown restorative materials.

Effect of neutral activator on properties of steel slag powder-cement composite cementitious material

In this paper, the physical and mechanical properties of TISCO steel slag were tested by composite activators with different ratios. The optimal neutral composite activator was determined, and the properties of neutral activated steel slag power-cement composite cementitious material with 30% cement content were studied. The experimental results indicated that the best ratio of gypsum: silica fume: sodium sulfate: sodium aluminate: self-made activator was 2.5:2.5:1:0.5. By XRD, SEM and TG-DTG detection, it was found that the less stable periclase reduced in 30% cement content and activated steel slag slurry. After 28d curing, the micro morphology and compactness of hydration products were not different from that of cement, even no incompletely hydrated particles. The voids between hydration products and the interface of different hydration products were continuously filled with hydration products over age. C-S-H and AFt generated by 7d activated SSP cement composite powder was greater than that of cement. At 28d, a small amount of Ca(OH)2 was generated. The results show that the combination of self-made neutral activator and other activators can improve the properties of cement steel slag powder composite cementitious material and improve the utilization rate of steel slag.

Effect of black sand nanoparticles on physical-mechanical properties of butyl rubber compounds

A novel type of silica namely black sand (BS) with silane coupling agent was chosen as reinforcing filler in butyl rubber (IIR). BS was obtained from the beach area of Rosetta in Egypt. The filler was characterized by Fourier-transform infrared (FTIR), X-ray diffraction (XRD), and transmission electron microscope (TEM). The XRD analysis showed that BS is composed mainly of Albite (Sodium Aluminium Silicate) up to 64% approximately. Novel nanocomposites were prepared via a two-roll mill by incorporating different concentrations of BS nanoparticles (5,10, 15, 20,30 and 40 phr) in IIR. The effects of filler loading on shape factor, curing characteristics, and mechanical and dynamic properties of IIR vulcanizates were investigated. The modulus of IIR vulcanizates was used to predict the shape factor of BS aggregation in the polymer. The data indicated that cure time decreased with the increase in filler loading, and the change in scorch time is less. It was found that the shape factor is independent of the concentration. With an increase in the filler loading, tensile and elongation of the composites were significantly increased, especially at 30 phr. The bound rubber content increased with increasing BS content up to 30 phr exhibiting the rubber-filler interaction. The reinforcing factor, R (related to the difference in tan δ peak height at the glass transition temperature (Tg) for the filled and unfilled rubbers), also demonstrated that the BS-IIR interaction was stronger than for unfilled rubber. Since 30 phr black sand loaded IIR composite showed superior physical-mechanical properties. In general, the results indicated that the black sand filler was an effective reinforcement material for the butyl rubber.

Study on the opportunity to improve the quality of the flour for pastry by adding chemical leavening agents

Food products that do not require practices for processing, and are easy to prepare have attracted the attention of consumers. An example of this type of product is the premixes formulations for cake mix which allows the cake to be made easily and quickly. The consumer of this type of product has the expectation, when following the instructions, to obtain a uniform and quality product. There are many different chemical leavening agents available to the baker. These include baking soda (sodium bicarbonate), ammonium bicarbonate, potassium bicarbonate, baking powder (baking soda, calcium phosphate and sodium aluminum sulfate) and leavening acids. Generating CO2 and neutralizing sodium bicarbonate is the primary role of leavening acids, but, it is important not to forget their secondary role and their effects. Taking into consideration these facts, the objective of experiments was to establish the connection between quantity and quality of leavening agents and the quality of bakery products. As the chemical leavening agents get into flour, it is also important to comprehend how they influence the rheological parameters of flour with direct implication in the quality of the products made. For experiments, baking powder was used, which was added in specific quantities to wheat flour. The flour samples were made, and the samples obtained were sensory evaluated in the panel. Correlating Mixolab Profiler indices with the baking samples, and also with the legislation regarding, the best results were obtained for flour with 2% baking powder.

Structure and reactivity of sodium aluminate complexes in alkaline solutions

The underlying mechanism by which tetrahedrally-coordinated aluminate solution species react to precipitate octahedrally-coordinated Al3+ in gibbsite is unknown. Sodium aluminate solutions provide the opportunity to investigate the role of ion speciation and local structure in the reaction, as the solution metastability can be controlled by varying ratio of excess NaOD to Al3+. Here, capitalizing on this tunable precipitation behavior, aluminate speciation was investigated through a combination of Raman, infrared, and NMR spectroscopies, together with geometrical fitting of neutron and X-ray radial distribution functions. These techniques reveal a mixture of monomeric Al(OD)4− and dimeric Al2O(OD)62− in all compositions, but solutions avoiding precipitation for extended timescales (i.e. months to years) show an increased dimeric Al2O(OD)62− population formed at the expense of the Al(OD)4− monomer. Conversion between these species, as well the potential for further oligomerization and formation of larger pre-nucleation species is driven by the hydrogen/deuterium bonding (H/D-bonding) and proton/deuteron transfer reactions. Changes within the local environment around the aluminate anions, including solvation and the presence of solvent-shared ion pairs or contact ion pairs, will consequently govern the reactivity of these aluminate species to either promote or inhibit precipitation.