Synthesis of zeolite Li-ABW from fly ash by fusion method

In-Situ Transformation of Li-ABW Zeolites Based on Li-Geopolymer

Lithium batteries, as energy storage devices, are playing an increasingly important role in human society. As a result of the low safety of the liquid electrolyte in batteries, more attention has been paid to solid electrolytes. Based on the application of lithium zeolite in a Li-air battery, a non-hydrothermal conversed lithium molecular sieve was prepared. In this paper, in-situ infrared spectroscopy, together with other methods, was used to characterize the transformation process of geopolymer-based zeolite. The results showed that Li/Al = 1.1 and 60 °C were the best transformation conditions for the Li-ABW zeolite. On this basis, the geopolymer was crystallized after 50 min of reaction. This study proves that the formation of geopolymer-based zeolite occurs earlier than the solidification of the geopolymer and shows that the geopolymer is a good precursor for zeolite conversion. At the same time, it comes to the conclusion that the formation of zeolite will have an impact on the geopolymer gel. This article provides a simple preparation process for lithium zeolite, explores the preparation process and mechanism, and provides a theoretical basis for future applications.

Electronic band structure and density of state modulation of amphetamine and ABW type-zeolite adsorption system: DFT-CASTEP analysis

The structured abstract is combined from two parts: CONTEXT: The adsorption behavior of amphetamine (AMP) on the surface of ABW-aluminum silicate zeolite was implemented with a computational depiction. Studies of the electronic band structure (EBS) and density of states (DOS) were conducted to demonstrate transition behavior attributed to aggregate-adsorption interaction. Thermodynamic illustration of the studied adsorbate was studied to investigate the structural behavior of the adsorbate on the surface of the zeolite adsorbent. The best investigated models were assessed with adsorption annealing calculations related to adsorption energy surface. The periodic adsorption-annealing calculation model predicted a highly stable energetic adsorption system based on total energy, adsorption energy, rigid adsorption energy, deformation energy, and dE_ad/d_Ni ratio. METHODS: Cambridge sequential total energy package (CASTEP) based on density functional theory (DFT), under Perdew-Burke-Ernzerhof (PBE) basis set, was used to depict the energetic levels of the adsorption mechanism between AMP and ABW-aluminum silicate zeolite surface. DFT-D dispersion correction function was postulated for weakly interacted systems. Structural and electronic elucidations were described with geometrical optimization, FMOs, and MEP analyses. Thermodynamic parameters such as entropy, enthalpy, Gibbs free energy, and heat capacity over temperature dependence studied the conductivity behavior over localized energetic states based on Fermi level and described the disorder degree of the system.

Preparation of Synthetic Zeolites from Coal Fly Ash by Hydrothermal Synthesis

Large amounts of coal combustion products (as solid products of thermal power plants) with different chemical and physical properties cause serious environmental problems. Even though coal fly ash is a coal combustion product, it has a wide range of applications (e.g., in construction, metallurgy, chemical production, reclamation etc.). One of its potential uses is in zeolitization to obtain a higher added value of the product. The aim of this paper is to produce a material with sufficient textural properties used, for example, for environmental purposes (an adsorbent) and/or storage material. In practice, the coal fly ash (No. 1 and No. 2) from Czech power plants was firstly characterized in detail (X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDX), particle size measurement, and textural analysis), and then it was hydrothermally treated to synthetize zeolites. Different concentrations of NaOH, LiCl, Al₂O₃, and aqueous glass; different temperature effects (90–120 °C); and different process lengths (6–48 h) were studied. Furthermore, most of the experiments were supplemented with a crystallization phase that was run for 16 h at 50 °C. After qualitative product analysis (SEM-EDX, XRD, and textural analytics), quantitative XRD evaluation with an internal standard was used for zeolitization process evaluation. Sodalite (SOD), phillipsite (PHI), chabazite (CHA), faujasite-Na (FAU-Na), and faujasite-Ca (FAU-Ca) were obtained as the zeolite phases. The content of these zeolite phases ranged from 2.09 to 43.79%. The best conditions for the zeolite phase formation were as follows: 4 M NaOH, 4 mL 10% LiCl, liquid/solid ratio of 30:1, silica/alumina ratio change from 2:1 to 1:1, temperature of 120 °C, process time of 24 h, and a crystallization phase for 16 h at 50 °C.

Low-cost and facile synthesis of geopolymer-zeolite composite membrane for chromium(VI) separation from aqueous solution

Inorganic membranes in wastewater treatment have captured increasing attention due to their numerous advantages. However, high cost and complicated producing process restricted their benign developments. This study proposed an novel inorganic geopolymer-zeolite composite membrane which was synthesized by using circulating fluidized bed fly ash (CFBFA) solid waste as initial material and via a low-cost and facile geopolymerization-hydrothermal treatment processes, further, the membrane was employed to separate Cr(VI) ion from aqueous solutions. X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectra results indicated that geopolymer-zeolite (Li-ABW) composite membrane was obtained successfully. Field emission scanning electron microscopy (FESEM) results demonstrated that the membrane had a compact zeolite layer with thickness about 1.5 μm. The effects of transmembrane pressures (TMP), Cr(VI) concentration, pH, ionic strength, and co-existing ions on Cr(VI) rejection were investigated, and the results revealed that the Cr(VI) rejection reached 85.45 % under 10 kPa of TMP, 1000 mg L^-1 of Cr(VI), and pH 7. The separation mechanism of Cr(VI) on the geopolymer-zeolite composite membrane was considered to be size exclusion and electrostatic interaction. These results suggested that the geopolymer-zeolite composite membrane had a potential application for the effective removal of Cr(VI) contaminants from wastewater.

Improvement in the Synthesis Conditions and Studying the Physicochemical Properties of the Zeolite Li-A(BW) Obtained from a Kaolinitic Rock

Crystallization of zeolite Li-A(BW) from kaolinite (Standard Porcelain by the IMERYS Minerals Ltd) through a conventional hydrothermal treatment is here achieved for the first time with no additives as reported in the literature. Moreover lower kaolin calcination temperatures and lower synthesis temperatures are tested and verified in this work. The synthesis process is rather simple as the reaction of kaolinite with alkali occurs very readily after calcination of at 650 °C. Metakaolin is mixed with calculated amount of aluminum hydroxide and lithium hydroxide and the experiment is performed at ambient pressure and 180 ± 0.1 °C. Li-A(BW) is characterized by powder X-ray diffraction, high temperature X-ray diffraction, scanning electron microscopy, inductively coupled plasma optical emission spectrometry, thermal analysis and infrared spectroscopy. Calculation of cell parameters (through Rietveld Refinement) and density, specific surface and pore size are also achieved. The amount of amorphous phase in the synthesis powders is estimated with quantitative phase analysis using the combined Rietveld and reference intensity ratio methods. The results become notably attractive in view of a possible industrial transfer of the synthesis protocol.

Fly Ash-Based Geopolymers as Sustainable Bifunctional Heterogeneous Catalysts and Their Reactivity in Friedel-Crafts Acylation Reactions

This study presents the synthesis, characteristics and catalytic reactivity of sustainable bifunctional heterogeneous catalysts derived from coal fly ash-based geopolymer, particularly those with a high Ca content (C-class) fly ash. The developed catalysts were synthesized at room temperature and pressure in a simple ecologically-benign procedure and their reactivity was evaluated in the Friedel-Crafts acylation of various arenes. These catalysts can be produced with multilevel porous architecture, and a combination of acidic and redox active sites allowing their use as bifunctional catalysts. The acidic sites (Lewis and Brønsted acidic sites) were generated within the catalyst framework by ion-exchange followed by thermal treatment, and redox sites that originated from the catalytically reactive fly ash components. The developed catalysts demonstrated higher reactivity than other commonly used solid catalysts such as Metal-zeolite and Metal-mesoporous silicate, heteropolyacids and zeolite imidazole frameworks (ZIF).

Immobilization and characterization of Fe(0) catalyst on NaOH-treated coal fly ash for catalytic reduction of p-nitrophenol

In this study, coal fly ash (CFA), i.e., an industrial waste product created in large quantities by thermoelectric power plants, was treated with sodium hydroxide to afford a novel Fe (0) catalyst supported on alkaline-treated CFA. The NaOH-treated CFA (NCFA) exhibited a morphological change from slick spheres to pointed, leaf-like spheres, which was accompanied by a noticeable increase in specific surface area from 1.2 to 7.5 m²/g. Sequential addition of an Fe(III) precursor and NaBH₄ solution to a suspension of NCFA resulted in the formation of Fe (0) particles on the surface of NCFA (Fe/NCFA). The catalytic activity of Fe/NCFA toward the reduction of p-nitrophenol (p-NP) was examined; among the Fe/NCFAs synthesized from different NCFAs (1, 3, and 7 M NaOH), the Fe/3 M NCFA sample displayed the highest activity owing to the highest Fe content on its surface, without leaching any toxic heavy metals. In addition, the effects of NaBH₄ concentration, Fe loading, and catalyst dosage on the catalytic reduction of p-NP by Fe/NCFA were comprehensively investigated. Finally, the recyclability and stability of Fe/NCFA were examined, demonstrating the complete reduction of p-NP over four continuous recycling cycles. The present results demonstrate the marked potential of CFA as a component in reactive catalysts for the removal of environmental pollutants from wastewater.

Synthesis of zeolite from multilayer food packing and sugar cane bagasse ash for CO2 adsorption

The X/A zeolite crystal mixtures were synthesized using sugar cane bagasse ash (SCBA) as a silicon source and multilayer food packing (MFP) as an aluminum source under hydrothermal conditions at 80 °C for 79–296 hours.