Study of phase formation in heterogeneous synthesis of aluminum-ammonium hydroxocarbonate

Synthesis of ammonium aluminium carbonate hydroxide NH4AlCO3(OH)2 from hydrated alumina received by ammonization of ammonia alums NH4Al(SO4)2·12H2O was studied. It was found the synthesis of NH4AlCO3(OH)2 occurs without the formation of intermediate phases.

Study of production 500 kg/batch polyaluminum chloride from aluminum hydrate

Polyaluminum chloride (PAC) is commonly used as a chemical in the water treatment industry, deodorant and paper-making. The PAC is a complex inorganic substance between hydroxyl and aluminum ions that gradually takes place chlorination with its general formula of Alx(OH)yCl3x-y. It has the ability to coagulate suspended solid or dispersed colloid within water perform easily precipitated flock. The raw materials used for manufacturing liquid PAC consists of hydrated alumina (Al(OH)3), hydrochloric acid (HCl), sulfuric acid (H2SO4) and calcium carbonate (CaCO3). A pilot-scale experiment with a capacity of 500 kg/batch feed was conducted by reacting Al(OH)3 with HCl and H2SO4, then neutralized using CaCO3 to obtain liquid PAC and gypsum as a by-product. The variation of acid concentration as reactant and reaction time were conducted to determine its effect on the composition of PAC and the amount of gypsum produced. The optimum experiment produced liquid PAC with the highest Al2O3 composition of 11.96% and the lowest Cl− ion of 10.87% at 2 hours reaction time with a total acid concentration of 37.74%.

Yellow Lake Pigments from Weld in Art: Investigating the Winsor & Newton 19th Century Archive

Weld (Reseda luteola) was one of the main sources of yellow dyes used for dyeing textiles and to prepare artists’ pigments in Europe until the 19th century. For the first time, this work explores the technology of preparing weld lake pigments in the 19th century by Winsor & Newton (W&N), a renowned supplier of artists’ materials. Five recipes were discovered in the W&N 19th century Archive Database and reconstructed in the laboratory. W&N was extracting weld in neutral and basic media, and preparing the insoluble lake by complexation with Al3+ in the form of alum (KAl(SO4)2•12H2O) or hydrated alumina (Al(OH)3). Five yellow lake pigments were successfully obtained and characterized by High-Performance Liquid Chromatography-Diode Array Detector (HPLC-DAD) and Fourier Transform Infrared Spectroscopy (FTIR). Their chromatographic profiles display as main yellows, luteolin 7-O-glucoside (Lut-7-O-glu) or both Lut-7-O-glu plus luteolin 3′,7-O-glucoside (Lut-3’,7-O-glu). In two of the processes, the presence of gypsum (CaSO4•2H2O) was unequivocally detected by FTIR, being formed as a by-product. This work offers the first identification of weld lake pigments’ characteristic infrared bands. The W&N Database proved again to be a unique source of information on 19th-century artists’ materials and their commercial preparation. The knowledge gain is essential to ensure effective conservation and authentication procedures.

Treatment of Grey Water using Natural Zeolites

Water is the inevitable source for all living things. Due to rapid development in industrialization and urbanization leads to contamination of surface water as well as groundwater which results in water scarcity. Thus grey water which is easily available can be considered as an alternate source of water. Grey water is the waste water generated from office buildings or household appliances like bathrooms, kitchens, washing machines, etc. without fecal contamination. The usage of the soap solution in bathrooms, kitchen dish washing areas and detergents used in washing areas leads to the increasing carbonates and bicarbonates of calcium and magnesium ions in grey water. The present study deals with the treatment of grey water by boiling and zeolite process for the removal of hardness. Natural zeolites are environmentally and economically acceptable hydrated alumina-silicate materials for grey water and wastewater treatment. The treated water can be used for laundry purposes, toilet flushing and gardening thereby reducing the demand for fresh water.

Special Binding for Refractory Concretes

The paper shows data related to coexistence of various binding systems, which could be present during the hardening of special concretes. It is taken into account the Ultra Low Aluminous Cement Concretes additivated with different materials (phosphates and mineral ultra dispersed powders - Condensed Silica Fume, Hydrated Alumina etc). In correlation to the pH-value, these substances can favour the forming of new binding systems besides the hydraulic binder (which is not important in this case). The new system is the coagulation binding form. The coagulation binding system has a very important role in the advanced compactness and in the increasing mechanical strengths of concrete structures.

Research and simulation of hydrated alumina homogeneous precipitation and its application to obtain a carrier for catalysts in the petrochemical industry

The results of studies of the process of hydrated alumina homogeneous precipitation were presented in this work. The variants of this process are considered. The most convenient embodiment of this process is the precipitation of hydrated alumina from its salts with the use of auxiliary substances, such as urea. Urea hydrolysis allows a homogeneous precipitation process under the most mild conditions. It is shown that the process of hydrolytic precipitation in the aluminum salt-urea system proceeds according to the dissociative mechanism SN1. This article analyzes the regularities of precipitation of solid colloidal particles of hydrated metal oxides on the surface of various substrates. Two models of this process are proposed. The proposed α-model is a process of continuous nucleation of interaction centers, at random points of a free surface throughout the process. The proposed β-model provides for the instantaneous nucleation of these centers when they are randomly distributed over the entire surface of the substrate. Based on the proposed models, the average values of the following values are calculated: the thickness of the gel film; its roughness and specific surface area. The calculations carried out in the article showed that these parameters are universal functions of the degree of filling of the surface and do not depend on the specific model of the mechanism of the process. Studies have been conducted on the use of homogeneously precipitated aluminum hydroxide as a binder in the preparation of porous materials. The resulting materials have a developed specific surface area and porosity.

Mitigation of Alkali–Silica Reaction by Hydrated Alumina

Recent trends and forecasts on the availability of fly ash, slag, and lithium admixtures for use in concrete suggest a need to seek reliable alternatives for the mitigation of alkali–silica reaction (ASR). One such option may be aluminum-based admixtures. Past studies have shown that supplementary cementitious materials that contain alumina (Al2O3) are more effective at mitigating ASR than are supplementary cementitious materials purely rich in silica (SiO2). To establish the effectiveness and mechanisms of ASR mitigation by alumina, this research used pure hydrated alumina, Al(OH)3, as a cement replacement. The objectives of the study were to determine if Al(OH)3 can successfully mitigate ASR and to investigate five hypothesized mechanisms by which Al(OH)3 may mitigate ASR. The hypothesized mechanisms are ( a) reducing pH and alkalis in concrete pore solution, ( b) consuming and reducing portlandite and dissolved calcium in the pore solution, ( c) reducing silica dissolution and damage to aggregates at high pH, ( d) altering the composition of ASR gel and creating innocuous gels, and ( e) reducing water and ion transport by reducing the porosity and pore size of cement paste. The results show that Al(OH)3 can effectively mitigate ASR through mechanisms ( a), ( b), and primarily ( c).