Parameters Affecting the Synthesis of X and A Zeolites from Coal Fly Ash

This paper summarizes the investigation results on the main parameters affecting the synthesis of type X and A zeolites using coal silicious fly ash (FA) as raw material. The synthesis was performed by dissolution of alkali-fused alumino-silicates, followed by hydrothermal treatment. The experimental data confirm that fly ash SiO2/Al2O3 ratio, NaOH/FA ratio, acid treatment of pre-fused fly ash, salinity of solution have a significant effect on type and properties of newly formed zeolites. In summary, the results show that A and X-type zeolite form with FA SiO2/Al2O3 ratio < 1.12 and > 1.86, respectively. Moreover, FA characterized by SiO2/Al2O3 mole ratio of 3.15 is suitable for X-type zeolite synthesis while A-type zeolite does not form without NaAlO2 addition. The crystallization occurs faster at higher temperatures although above 90°C X-type zeolite evolves into more stable phases whereas increasing the crystallization time from 1 to 72 hours, the yield of the synthetic products enhances from 60 to 75%. The use of seawater is responsible for the synthesis of X-type showing both lower purity and specific surface area. However, the synthetic products are characterized by high exchange capacity (> 320 meq/100 g), thus suggesting their successful application as adsorbents and catalysts in different types of wastewater and industrial waste treatments.

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Synthesis of Zeolite A from Mongolian Coal Fly Ash by Hydrothermal Treatment

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.271.1 ◽

2018 ◽

Vol 271 ◽

pp. 1-8 ◽

Cited By ~ 4

Author(s):

Ulambayar Rentsenorov ◽

Batmunkh Davaabal ◽

Jadambaa Temuujin

Keyword(s):

Fly Ash ◽

Hydrothermal Treatment ◽

Cation Exchange Capacity ◽

Coal Fly Ash ◽

Batch Composition ◽

Exchange Capacity ◽

Zeolite Synthesis ◽

Zeolite A ◽

Acid Pretreatment ◽

Type Zeolite

Raw coal fly ash and acid pretreated fly ash were used to synthesize A-type zeolite by hydrothermal treatment. In order to synthesize zeolite A an aqueous gel having a molar batch composition of Na2O:Al2O3:1.926SiO2:128H2O was utilized. Fly ash and zeolitic products were characterized by SEM, XRF, XRD and cation exchange capacity (CEC). After hydrothermal treatment, several types of zeolites were formed: zeolite A, analcime, faujasite and hydroxy-sodalite. The highest content of zeolite A was formed in the mixture treated at 80°C for 8 hours. CEC values of the zeolitic products were 28-38 times higher than that of in raw fly ash. Acid pretreatment which leads to low calcium and iron content is preferable method for processing of fly ash for the zeolite synthesis. Synthesized zeolite can be used for ion exchangers for water treatment.

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4A-Molecular Sieve Synthesis by Microwave Heating with Silicon and Aluminum Materials Produced from the Coal Fly Ash

Materials Science Forum ◽

10.4028/www.scientific.net/msf.675-677.219 ◽

2011 ◽

Vol 675-677 ◽

pp. 219-222 ◽

Cited By ~ 1

Author(s):

Guang Hui Bai ◽

Peng Cheng Li ◽

Peng Xu ◽

Shuang Li Chen

Keyword(s):

Fly Ash ◽

Pore Size ◽

Sodium Silicate ◽

Molecular Sieve ◽

Coal Fly Ash ◽

Sodium Aluminate ◽

Raw Material ◽

Crystallization Time ◽

Microwave Technology ◽

Practical Applications

A new method, using sodium silicate and sodium aluminate synthesize 4A-molecular sieve, was developed by using microwave technology. The sodium silicate was a high modulus liquor by-product of nano-silica production from coal fly ash. Meanwhile, the sodium aluminate was a process by-product of alumina extraction from coal fly ash. Reaction mixture composition was defined as follow:SiO2/Al2O3 ratio in 2.0, Na2O/SiO2 ratio in 1.5, and H2O/Na2O ratio in 65. The gelation process was completed in 1 hr. Microwave crystallization power was (800w) 30%. Microwave crystallization period can last 25 mins. The 4A-molecular sieve was obtained by collecting crystals from the reaction mixture through filtration after washing with water to pH 11-12 and drying inside isotherm oven. The calcium exchange capacity and effective pore size of the product were 316mg/g and 0.4nm respectively. Over 90% of surface pore size reached in sizes of less than or equal to 8μm. Purity of 4A-molecular sieve up to 99%. This method significantly reduced the raw material costs for sodium silicate and sodium aluminate. In addition, the adoption of microwave technology also lowered the energy usage and shortened crystallization time. All these contributed final low costs of 4A-molecular sieve product, which made it possible for many practical applications.

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Evaluation of Coal Fly Ash and Incineration Ash as Raw Material for Zeolite Synthesis.

Shigen-to-Sozai ◽

10.2473/shigentosozai.117.501 ◽

2001 ◽

Vol 117 (6) ◽

pp. 501-505 ◽

Cited By ~ 10

Author(s):

Norihiro MURAYAMA ◽

Yousuke YAMAKAWA ◽

Kazuo OGAWA ◽

Hideki YAMAMOTO ◽

Junji SHIBATA

Keyword(s):

Fly Ash ◽

Coal Fly Ash ◽

Raw Material ◽

Zeolite Synthesis

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Synthesis of Coal Fly Ash Zeolite with Copper Oxide Load for Acid Red GR Wastewater Treatment

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.356-360.391 ◽

2011 ◽

Vol 356-360 ◽

pp. 391-394

Author(s):

Bo Quan Jiang ◽

Zheng Qiang Xiao

Keyword(s):

Fly Ash ◽

Copper Oxide ◽

Coal Fly Ash ◽

Orthogonal Test ◽

Crystallization Time ◽

Fusion Method ◽

Xrd Pattern ◽

Type Zeolite ◽

Color And Cod Removal ◽

Waste Coal

The waste coal fly ash was utilized to synthesize zeolite by alkaline fusion method through orthogonal test. The copper oxide was loaded on the zeolite by dipping method. The optimal ratio of coal fly ash to sodium hydroxide, ratio of liquid to solid, calcining temperature and crystallization time were determined to be 1.2, 9, 700°C and 10 h, respectively. The CuO dipped zeolite was applied to treat the acid red GR wastewater and the obtained color and COD removal rates were 83.80% and 99.88%, respectively. The XRD pattern showed that the NaA type zeolite phase was formed in the experiment.

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Removal of Pb2+ from Aqueous Solutions Using K-Type Zeolite Synthesized from Coal Fly Ash

Water ◽

10.3390/w12092375 ◽

2020 ◽

Vol 12 (9) ◽

pp. 2375

Author(s):

Yuhei Kobayashi ◽

Fumihiko Ogata ◽

Chalermpong Saenjum ◽

Takehiro Nakamura ◽

Naohito Kawasaki

Keyword(s):

Fly Ash ◽

Cation Exchange Capacity ◽

Binary Solution ◽

Coal Fly Ash ◽

Aqueous Media ◽

Surface Characteristics ◽

Exchange Capacity ◽

Binding Energies ◽

Surface Functional Groups ◽

Type Zeolite

In this study, a novel zeolite (K-type zeolite) was synthesized from coal fly ash (FA), and adsorption capacity on Pb2+ was assessed. Six types of zeolite (FA1, FA3, FA6, FA12, FA24, and FA48) were prepared, and their physicochemical properties, such as surface functional groups, cation exchange capacity, pHpzc, specific surface area, and pore volume, were evaluated. The quantity of Pb2+ adsorbed by the prepared zeolites followed the order FA < FA1 < FA3 < FA6 < FA12 < FA24 < FA48. Current results indicate that the level of Pb2+ adsorbed was strongly related to the surface characteristics of the adsorbent. Additionally, the correlation coefficient between the amounts of Pb2+ adsorbed and K+ released from FA48 was 0.958. Thus, ion exchange with K+ in the interlayer of FA48 is critical for the removal of Pb2+ from aqueous media. The new binding energies of Pb(4f) at 135 and 140 eV were detected after adsorption. Moreover, FA48 showed selectivity for Pb2+ adsorption in binary solution systems containing cations. The results revealed that FA48 could be useful for removing Pb2+ from aqueous media.

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Synthesis of Zeolite from Fly Ash and Removal of Heavy Metal Ions from Newly Synthesized Zeolite

E-Journal of Chemistry ◽

10.1155/2010/356150 ◽

2010 ◽

Vol 7 (4) ◽

pp. 1200-1205 ◽

Cited By ~ 3

Author(s):

Parag Solanki ◽

Vikal Gupta ◽

Ruchi Kulshrestha

Keyword(s):

Heavy Metal ◽

Fly Ash ◽

Metal Ions ◽

Heavy Metal Ions ◽

Coal Fly Ash ◽

Proximate Analysis ◽

13X Zeolite ◽

Alkali Fusion ◽

Type Zeolite ◽

The Cost

Coal fly ash was used to synthesize X-type zeolite by alkali fusion followed by hydrothermal treatment. Characteristics of the various Fly ash samples were carried out. Coal proximate analysis was done. Batch experiment was carried out for the adsorption of some heavy metal ions on to synthesized Zeolite. The cost of synthesized zeolite was estimated to be almost one-fifth of that of commercial 13X zeolite available in the market.

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Recovery of Cenospheres and Fine Fraction from Coal Fly Ash by a Novel Dry Separation Method

Energies ◽

10.3390/en13143576 ◽

2020 ◽

Vol 13 (14) ◽

pp. 3576

Author(s):

Jan Wrona ◽

Witold Żukowski ◽

Dariusz Bradło ◽

Piotr Czupryński

Keyword(s):

Fly Ash ◽

Coal Fly Ash ◽

Fine Fraction ◽

Free Fall ◽

Raw Material ◽

Fluidised Bed ◽

Air Chamber ◽

Pneumatic Separation ◽

Bed Separation ◽

Separation Product

Aluminosilicate microspheres are a valuable fraction of coal fly ash with diverse applications due to their low density. Currently, there is no efficient and ecologically rational method of cenosphere recovery from fly ash. A combination of dry methods for the recovery of both fine ash particles and aluminosilicate microspheres from coal fly ash is presented. It is comprised of fluidised bed separation followed by screening and pneumatic separation in a free-fall air chamber. Fluidised bed separation was assisted by a mechanical activator to prevent agglomeration. This step reduced the portion of material that required further treatment by 52–55 wt.%, with the recovery of microspheres exceeding 97%. Then, the concentrates were individually subjected to pneumatic separation. The final separation product for the fly ash containing 0.64 wt.% cenospheres was a cenosphere concentrate that constituted about 17 wt.% of the initial fly ash. The recovery of cenospheres was around 81%. Usage of a combination of dry methods allowed for maintaining almost 83 wt.% of the raw material in its dry form. Furthermore, the produced fly ash grain fractions could be used for different industrial purposes.

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