Synthesis of pure Na–X and Na–A zeolite from bagasse fly ash (original) (raw)
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Synthesis of NaA and faujasitic zeolites from high silicon fly ash
Materials Research Bulletin, 2009
High silicon fly ash (HSFA) utilized as a source of silicon in synthesizing of Na-A, -X and -Y zeolites through alkali fusion followed by hydrothermal treatment at 100 °C for 12 h. Various types of zeolites with different degrees of purity were prepared by changing Si/Al ratio of the reaction mixture from 1.6 to 3.0. In addition, exact boundaries of this ratio for synthesis of each zeolite type were determined. Furthermore, the effect of NaOH amount utilized in alkaline fusion step on crystalinity of samples investigated. The synthesized zeolites were characterized using various techniques including; XRD, TGA, FTIR, SEM and BET. The ion-exchange behaviors of zeolitic samples tested with Co2+. The obtained Na-X zeolite was crystaline, had a very high cation-exchange capability of 4.9 mequiv. g−1 and possessed relatively high specific surface area of about 434 m2 g−1.
Siliceous Fly Ash Utilization Conditions for Zeolite Synthesis
Environmental Sciences Proceedings
Fly ash is a coal combustion product partly disposed of in landfills since it finds no other application. Recycling this solid is of great benefit in terms of quality, cost effectiveness and the environment. The chemical and mineralogical composition of siliceous fly ash makes it an attractive and economic raw material for the synthesis of zeolites. Zeolites are microporous, aluminosilicate minerals characterized by a three-dimensional network of tetrahedral units produced industrially on a large scale. In this work, synthetic X and A-type zeolite with high crystallinity and high value of surface area were synthesized by a pre-fusion method followed by a hydrothermal treatment under various conditions. The data indicate that zeolitic products were obtained using NaOH while no zeolitic material was crystallized using KOH and LiOH. Pre-treatment of fly ash with acid before being used in the synthesis of artificial zeolites is considered an important parameter for the purity phase of z...
Synthesis of zeolite NaA from sugarcane bagasse ash
Materials Letters, 2013
Zeolite NaA was synthesized using sugarcane bagasse as silica source under hydrothermal condition at 80 1C for 72-160 h. The silicon was extracted by alkaline fusion for 40 min, at 550 1C with an alkali:ash ratio of 1. Zeolite A was obtained without phase contamination. The ash and synthesized zeolite NaA were analyzed by granulometry, XRD, SEM, FTIR, XRF and TG/DTA. In XRD results, all signals were perfectly indexed to zeolite A. The vibration bands at ca. 557 cm −1 suggested the presence of double-fourring (D4R) zeolite A structure. The synthesized material has a potential application as a catalyst, as adsorbent, and as an ion exchanger.
Effect of Na2O/SiO2 mole ratio on the crystal type of zeolite synthesized from coal fly ash
Journal of the Serbian Chemical Society, 2003
Coal fly ash was modified to zeolitic materials by hydrothermal treatment at 90 ?C. The zeolite synthesis was studied as a function of the mole ratio of Na2O/SiO2 in the reaction mixtures. The results showed that NaP1 zeolite is obtained when the Na2O/SiO2 mole ratio was 0.7. Hydroxysodalite is the dominant zeolite phase in modified fly ash treated with a higher Na2O concentration solution (Na2O/SiO2 = 1.3). The IR and XRD methods were used to determine the phases present in the starting sample and in the zeolitic materials.
Synthesis of Zeolite-A Using Silica from Rice Husk Ash
JOURNAL OF CHEMICAL ENGINEERING OF JAPAN, 2009
We describe the synthesis of zeolite-A using rice husk ash (RHA) as starting material. Synthesis comprised alkali activation at low temperature (<100 • C) using NaOH as reagent. We investigated the effect of experimental conditions on zeolite synthesis from RHA. The process was studied as a function of NaAlO 2 addition, NaOH concentration, temperature, and reaction time. A stirred batch reactor was used under the following reaction conditions: SiO 2 /Al 2 O 3 molar ratio, 1.7-2.8; NaOH concentration, 2-6 M; temperature, 50-80 • C; reaction time, 0-48 h. The obtained solids were identified by X-ray diffraction and characterized by scanning electron microscopy; specific surface areas and cation exchange capacity values were also determined. Concentrations of Si and Al in the solution were analyzed to monitor the reaction process. Single zeolite-A can be synthesized from RHA under all our experimental conditions. We proposed the formation mechanism of zeolite-A from RHA. The silicate ion dissolves in NaOH solution from RHA and reacts with aluminate in the solution to form aluminosilicate, from which zeolite-A crystals are generated. The high crystallinity was obtained rapidly when SiO 2 /Al 2 O 3 ratio, NaOH concentration and temperate were high in this experimental conditions.
Journal of Advanced Agricultural Technologies, 2014
Rice husk ash (RHA), a solid waste from biomass power plant was used as a raw material to synthesize Na-A and Na-X zeolites. In fact, high silica content of this material opens a possibility for it to be used as a potential zeolite precursor. In this study, a medium size particle of RHA has been reused to prepare zeolite with high purity. After segregation by mechanical sieving, the medium size particle fraction of RHA was subjected to alkali fusion treatment followed by dissolution and then residue separation to produce clear silicate supernatant as the silica source for preparing the low-silica zeolites. High purity Na-A and Na-X zeolites were prepared using hydrothermal treatment by optimizing the process condition, curing time, hydrothermal temperature and Si/Al molar ratio in the reaction mixture. The utilization of zeolite for adsorption of cadmium using batch technique was investigated. The effect of time, dosage and initial concentration of solutions on the adsorption was investigated. The result showed that adsorption capacity of Na-A zeolite was much higher than that of Na-X zeolite. The equilibrium data were fitted by the Langmuir model. Na-A and Na-X zeolites synthesized with the optimal condition possessed a maximum value of cation exchange capacity (CEC) of 470 meq/100 g and 503 meq/100g, respectively.
Synthesis and characterization of zeolites prepared from industrial fly ash
Environmental Monitoring and Assessment, 2014
In this paper, we present the possibility of using fly ash to produce synthetic zeolites. The synthesis class F fly ash from the Stalowa Wola SA heat and power plant was subjected to 24 h hydrothermal reaction with sodium hydroxide. Depending on the reaction conditions, three types of synthetic zeolites were formed: Na-X (20 g fly ash, 0.5 dm 3 of 3 mol•dm −3 NaOH, 75°C), Na-P1 (20 g fly ash, 0.5 dm 3 of 3 mol•dm −3 NaOH, 95°C), and sodalite (20 g fly ash, 0.8 dm 3 of 5 mol•dm −3 NaOH+0.4 dm 3 of 3 mol•dm −3 NaCl, 95°C). As synthesized materials were characterized to obtain mineral composition (X-ray diffractometry, Scanning electron microscopy-energy dispersive spectrometry), adsorption properties (Brunauer-Emmett-Teller surface area, N 2 isotherm adsorption/ desorption), and ion exchange capacity. The most effective reaction for zeolite preparation was when sodalite was formed and the quantitative content of zeolite from X-ray diffractometry was 90 wt%, compared with 70 wt% for the Na-X and 75 wt% for the Na-P1. Residues from each synthesis reaction were the following: mullite, quartz, and the remains of amorphous aluminosilicate glass. The best zeolitic material as characterized by highest specific surface area was Na-X at almost 166 m 2 •g −1 , while for the Na-P1 and sodalite it was 71 and 33 m 2 •g −1 , respectively. The ion exchange capacity decreased in the following order: Na-X at 1.8 meq•g −1 , Na-P1 at 0.72 meq•g −1 , and sodalite at 0.56 meq•g −1. The resulting zeolites are competitive for commercially available materials and are used as ion exchangers in industrial wastewater and soil decontamination.
Synthesis of Na-zeolites from fly ash
Fuel, 1997
The present study focuses on the synthesis of zeolites after fly ash activation, the major objectives being: (a) to study the activation processes; (b) to elucidate the activation conditions for maximum synthesis efficiency; (c) to optimize the conditions for the monomineral synthesis; and (d) to test synthesis efficiencies for different fly ash types. Fly ash was activated by NaOH and KOH solutions in a closed system. The zeolite conversion was studied as a function of temperature (150-200°C), reaction time (8-100 h) and solution concentration (0.1-1 M). The estimated pressure during activation ranged from 0.48MPa at 150°C to 1.55MPa at 200°C. The activation was performed using a sample concentration of 0.055gmL l. The zeolites synthesized were NAP1, NaP derivatives (mainly sodalite hydrate), analcime, gmelinite and nepheline hydrate after NaOH activation, and phillipsite after KOH activation. Subsequent experiments focused on short reaction times for high conversion efficiencies and monomineral synthesis of zeolites. High synthesis efficiencies for NaP 1 zeolite and analcime were obtained with the fly ash types studied. The results highlight the importance of the mineralogical composition of the fly ash. Fly ashes with very similar SiO2/ A1203 ratios show different zeolites synthesis behaviour under the same activation conditons. These differences could be attributed to different SIO2/A1203 ratios of the glass matrix inferred from the differences in mineralogy at the same bulk chemical composition.
Alkaline Hydrothermal Zeolites Synthesized From Fly Ash SIO2 and AL2O3
A co-disposal reaction was used wherein fly ash (FA) was reacted with acid mine drainage (AMD), to collect filtrates for zeolite synthesis. The Si and Al contents of the fly ash (FA) filtrates were used as precursor species for the alkaline hydrothermal conversion of the fly ash filtrates into zeolites. These filtrates were then analysed by XRF spectrometry for quantitative determination of SiO 2 and Al 2 O 3 . The [SiO 2 ]/[Al 2 O 3 ] ratio obtained in the filtrates range from 1.4 to 2.5. The [SiO 2 ]/[Al 2 O 3 ] ratio was used to predict whether the fly ash filtrates could successfully be converted into faujasite zeolitic material by the synthetic method of Rayalu et al. (1). If the [SiO 2 ]/[Al 2 O 3 ] ratio is higher than 1.5 in the co-disposal filtrates, it favours the formation of faujasite. The zeolite synthesis included an alkaline fusion of the co-disposal filtrates, followed by aging for eight hours and hydrothermal conversion by crystallisation at 100 ºC. Different variables were investigated during the synthesis of zeolite to ascertain their influence on the end product. These variables include the amount of water in the starting material, composition of fly ash related starting material and the FA:NaOH ratio used for fusing the starting material (2,3).