The Effect of Modification on the Structural,Acidic, and Catalytic Properties of a Layered Aluminosilicate

The effect of modification on the structural, acidic, and catalytic properties of a natural layered aluminosilicate containing 90% montmorillonite was studied. With the use of low-temperature nitrogen adsorption and XRD analysis, it was found that the addition of hydroxo complexes of aluminum prevents the silicate layers of the layered aluminosilicate from closing upon heating and results both in the formation of stable micropores and in a considerable increase in the specific surface area. The acidic properties of the H, Na, and Al forms of the layered aluminosilicate were studied by IR spectroscopy of adsorbed CO molecules and by the indicator method. After modification with hydroxo complexes of aluminum, the number of Lewis acid sites and the accessibility of acidic OH groups to CO adsorption increased. The total number and strength of acid sites increased as the calcination temperature of the layered aluminosilicate was increased. A correlation between catalytic activity in the reaction of acetone dimerization and the number of acid sites in different forms of the layered aluminosilicate was obtained.     

Use of intercalated clays in oxidation of organic dyes

Intercalated materials based on natural montmorillonite and Fe- and mixed Fe/Al-polyhydroxo complex were obtained and their texture properties were studied. The catalytic properties of these materials were examined in the reaction of oxidation of an organic dye, Direct Pure Blue, with hydrogen peroxide in aqueous solutions. The optimal conditions of oxidation of azo dyes in the presence of intercalated clays were determined. In these conditions, a 100% oxidation of dye solutions can be achieved, with the stability of catalysts preserved.     

Production of Adsorption Materials from Bentonite Clay Containing an Organic Dye

Russian Journal of Applied Chemistry - Carbon-containing materials were produced from a mixture of bentonite clay and Crystal Violet dye adsorbed on the clay. X-ray diffraction analysis and IR...     

Regulating the physicochemical and catalytic properties of layered aluminosilicates

Basic methods of the introduction of metal ions into the interlayer space of natural layered aluminosilicate (LAS) are considered. The physicochemical and structural properties of pillared LAS’s depend on the nature of the cation, as well as on the cation intercalation method and conditions. The catalytic properties and stability of an LAS in acid-catalyzed and oxidation reactions may depend on its textural and physicochemical properties.     

Influence of preparation conditions on the catalytic activity of Fe-montmorillonites in phenol oxidation in aqueous solutions

The influence of preparation conditions on the catalytic activity of Fe-containing montmorillonites in phenol oxidation with hydrogen peroxide in aqueous solutions and on their resistance to washout of iron ions was examined.     

Adsorption of Triarylmethane Dye on Ca-Montmorillonite: Equilibrium,Kinetics, and Thermodynamics

The equilibrium, kinetics, and thermodynamics of adsorption of triarylmethane dye, crystalline violet, from aqueous solutions on Ca-montmorillonite have been studied. The regularities of the influence of the physicochemical parameters (suspension pH, clay and dye concentrations, temperature, and contact time) on the specific adsorption value of the dye have been found. It has been shown that Ca-montmorillonite is capable of removing the dye from aqueous solutions in a wide range of concentrations with an efficiency of up to 99.8%. The adsorption of crystalline violet obeys the Langmuir model (the correlation coefficient is 0.999), which corresponds to monolayer adsorption on a homogeneous surface. The kinetics of dye adsorption is described by a pseudo-second-order equation, which is characteristic of chemisorption. The thermodynamic parameters of adsorption, ΔH = 40.42 kJ/mol, ΔS = 139.6 J/mol, and ΔG =–4.68 kJ/mol (323 K), have been determined and lead to the conclusion that the dye adsorption is a spontaneous endothermic process.     

Effect of parameters of the Fe3+/H2O2 catalytic system on the efficiency of oxidative destruction of azo dye acid chrome dark blue

Effect of physicochemical parameters on the rate and efficiency of oxidative destruction of the Acid chrome dark blue azo dye in aqueous solutions was studied. The reaction orders with respect to reagents and the optimal conditions of oxidative destruction of the azo dye in the Fe³⁺/H₂O₂ catalytic system were determined.     

Catalytic properties of Fe-Cu-Al-montmorillonites in the oxidation of acid chrome dark blue azo dye

Interlayer cations in the sodium form of the aluminosilicate montmorillonite (Mt) have been exchanged by mixed, bulky, polynuclear hydroxo cations (Al: (Fe + Cu) = 10, Cu: Fe = 0–1, OH: (Fe + Cu + Al) = 2), and the product has been heat-treated to obtain Fe-, Fe-Al-, and Fe-Cu-Al-containing materials (Fe-Cu-Al-Mt). The chemical composition and textural characteristics of the materials depend on the Cu: Fe molar ratio. The catalytic properties of the materials in the oxidation of acid chrome dark blue (ACDB) azo dye with hydrogen peroxide have been investigated. The activity and stability of the Fe-Cu-Al-Mt systems are determined by the quantity of copper and iron atoms introduced into the structure of the material. As the iron ion content is increased, the specific catalytic activity of the system increases and the system becomes less resistant to the leaching of iron ions into the solution. Raising the copper content of the system above 0.07 wt % reduces its activity and stability. The effects of the catalyst content, pH of the solution being oxidized, and reactant ratio (H₂O₂: ACDB) on the reaction rate have been studied. The ACDB oxidation conditions have been optimized.