Neutralization of solvent vapors of brand 650 by the adsorption‑catalytic method

The purpose of this work is to study the process of neutralization of vapors of a mixed solvent of the brand 650 by the adsorption‑catalytic method. The essence of the method consists in the concentration of solvent components on the sorbent, thermal desorption followed by periodic flameless catalytic oxidation of accumulated organic substances to carbon dioxide and water. Synthetic zeolite of the NaX brand was used as a sorbent, and a porous material based on foam ceramics of the Al2O3/SiO2 composition with a highly developed modified surface with an active catalytic phase was used as a catalyst. The mixed solvent contains, xylenes, ethylcellosol, n‑butanol. It is shown that the value of the sorption volume of zeolite for each class of the considered compounds is influenced by certain factors: the length and structure of the carbon skeleton, the position of the hydroxyl group (for alcohols and esters), the number of methyl groups in the composition of molecules (for the production of benzene). The conversion rate of the mixed solvent components was 65.4–90.1 %.

REDUCTION OF METAL CATIONS CONTENT FROM THE AQUEOUS SOLUTIONS BY SORBENTS

The article presents the results of research on reducing the concentration of heavy metals, such as copper and nickel, on natural zeolite in comparison with synthetic zeolite and chemically treated natural zeolite. The reduction of the content of specific types of heavy metals from aqueous solutions was investigated by the method of sorption kinetics. The results indicate the ability of natural zeolites to compete with synthetic zeolites.

Modified Zeolite as Purification Material in Wastewater Treatment: A Review

Natural zeolite is a hydrated aluminosilicate substance that has excellent ion exchange and adsorption properties and is environmentally and economically friendly. This review describes the current application and modification of zeolite in wastewater treatment using acid and surfactants, zeolite composites (such as zeolite membranes), permeable reactive barriers and photocatalysts. The properties of zeolite as well as the regeneration and desorption of cast-off zeolite are briefly reviewed. Modifications are made to improve the capability of zeolite in wastewater treatment facilities. Furthermore, this review proposes the integration of zeolite and other available technologies to treat emerging pollutants in wastewater. Different types of zeolite (natural and synthetic zeolite of different origins) are compared, and their properties are evaluated. Different type of pollutants and treatment methods involving zeolite are also discussed. Zeolite is enhanced to solve the problem of various pollutants in wastewater.

Adsorption Performance of Dyes Over Zeolite for Textile Wastewater Treatment

Removal of textile dyes from wastewater have recently attracted much attention, due to the toxicity, difficult visibility, and thereby the negative consequences on the aqueous environment. Therefore, there have been diverse promising new techniques such as adsorption for dyes removal from industrial wastewater. Compared to the highly cost treatment techniques, removal of dyes using the adsorption process is relatively simple and requires less cost. Synthetic zeolite was used in this research as a high capacity nano-adsorbent for the removal of reactive dyes from coloured wastewater. The impact of main parameters: dose of adsorbent (0.0025 to 0.02 g), pollutant concentration (25 to 200 mg/L), contact time (10 to 120 minutes), degree of agitation (25 and 300 rpm), and solution pH (2 to 8) on adsorption performance of the synthesised zeolite was investigated. The optimum values of these parameters to remove dyes efficiently at 90 % removal were 0.02 g, 200 mg/L, 80 min, 300 rpm, and 6-7 respectively. Also, two models were evaluated, the Langmuir and Freundlich isotherms. Langmuir isotherm was more efficient for representing the data than the Freundlich. The results of the Langmuir isotherm gave KL = 0.08 L/mg, qm = 6.02 mg/g, and R 2 = 0.98, which fitted to the adsorption data of zeolite. Reactive dye adsorption by synthetic zeolite is a vital tool in identifying the fate of dye removal from industrial wastewater treatment plants.

Comparison of Synthetic and Natural Zeolite Catalysts’ Behavior in the Production of Lactic Acid and Ethyl Lactate from Biomass-Derived Dihydroxyacetone

This article presents the results of the conversion of dihydroxyacetone (DHA) to lactic acid (LA) with the use of zeolite catalysts. For this purpose, synthetic zeolite beta (BEA) and natural clinoptilolite (CLI) were used as a matrix. The zeolites were modified with various metals (Sn, Fe, Cu and Zn) during ion exchange under hydrothermal conditions. The DHA conversion process with the participation of metal-functionalized zeolites allowed us to obtain intermediates, i.e., pyruvic aldehyde (PAL), which during the further reaction was transformed into a mixture of products such as ethyl lactate (EL), pyruvic aldehyde (PA), lactic acid and ethyl acetate (EA). The best selectivity towards lactic acid was achieved using Sn-CLI (100%) > Na-BEA (98.7%) > Sn-BEA (95.9%) > Cu-BEA (92.9%), ethyl lactate using Cu-CLI, and pyruvic aldehyde using the Zn-BEA catalyst. In the case of a natural zeolite, modification with Sn is promising for obtaining a pure lactic acid with a relatively good carbon balance.