Zeolite synthesis from coal fly ash for the removal of lead ions from aqueous solution

Fly ash samples from the Bayswater and Eraring power plants, located in New South Wales, Australia, were used in a preliminary study on zeolite synthesis by hydrothermal treatment with sodium hydroxide under various conditions. The treated fly ash was tested for the ability to remove lead ions from aqueous solution. Both fly ashes were partially converted to zeolite. The zeolites formed under the experimental conditions were zeolite Na‐P1 and sodalite octahydrate for the Bayswater ash and phillipsite, zeolite X, zeolite Na‐P1 and sodalite octahydrate for the Eraring ash. The type of zeolite formed was dependent on the treatment time and sodium hydroxide concentration. In the case of the Bayswater ash, zeolite Na‐P1 was formed by treatment with 4 mol dm^?3 NaOH for 48 h while treatment with 5 mol dm^?3 NaOH for 96 h produced sodalite octahydrate at the expense of zeolite Na‐P1. In the case of the Eraring ash, phillipsite was formed following treatment with 3 mol dm^?3 NaOH, zeolite X and zeolite Na‐P1 were formed following treatment with 4 mol dm^?3 NaOH and sodalite octahydrate was formed following treatment with 5 mol dm^?3 NaOH. A maximum cation exchange capacity of ～400 meq/100 g was achieved by both treated ash samples. Treatment of a solution with a lead ion concentration of 120 ppm using 0.5 g of both treated ash samples (S/L ratio = 0.25 g/100 cm³) achieved complete removal in 5 min, whereas treatment with 0.1 g of each material (S/L ratio = 0.05 g/100 cm³) achieved complete lead ion removal after 24 h. © 2001 Society of Chemical Industry     

Synthesis of zeolite from coal fly ashes with different silica–alumina composition

Coal fly ashes can be converted into zeolites by hydrothermal alkaline treatment. This study focuses on the effect of Si/Al molar ratio of the fly ash source on the type of formed zeolite, which also is affected by the alkaline condition. The fly ashes were mixed with an aqueous NaOH solution and hydrothermally treated at about 100 °C. Zeolite Na–P1 and/or hydroxy-sodalite appeared after the treatment. Zeolite Na–P1 predominantly formed from silica-rich fly ash at a low-NaOH concentration. The cation exchange capacity of the product with a large content of zeolite Na–P1 reached a value of 300 meq/100 g. The type of the product was controlled by addition of aerosil silica or alumina. It was found that silica addition effectively enhances the formation of zeolite Na–P1, even at a high-NaOH concentration. These results were discussed on the basis of a formation mechanism of zeolite from coal fly ash through dissolution–precipitation process.     

High capacity cation exchanger by hydrothermal zeolitization of coal fly ash

During; hydrothermal treatment in NaOH medium coal fly ash partially transformed to zeolite P and/or hydroxysodalite, while quartz slowly dissolved and mullite remained stable. Residual coal favored the formation of zeolite P. The relative proportion of the two zeolites could be changed by seeding. During fusion of fly ash with NaOH an endothermic reaction at 170–180°C occurred, resulting in formation of an unreported Na aluminosilicate with approximate composition Na₁₅Si₄Al₃0₂₀ and major XIRD reflections at 4.793, 3.828, 3.000, 2.854, 2.578, and 2.524 Å. The product of fusion interacted with water giving aluminosilicate gel, which yielded zeolite P upon hydrothermal treatment at 100°C without aging and zeolite X after aging in water for 12 hours at room temperature. Cation exchange capacity was 420 and 400 meq/ 100 g for zeolite P and zeolite X respectively.     

Processing of urea‐formaldehyde‐based particleboard from hazelnut shell and improvement of its fire and water resistance

The purpose of this study was to manufacture urea‐formaldehyde‐based particleboard from hazelnut shell and eliminate its disadvantages such as flammability, water absorption, swelling thickness by using fly ash and phenol‐formaldehyde. Synthesized urea‐formaldehyde and grained hazelnut shells were blended at different ratios ranging from 0.8 to 3.2 hazelnut shell/urea‐formaldehyde and dried at 70°C in an oven until constant weight was reached. In addition, other parameters affecting polymer composite particleboard from hazelnut shell and urea‐formaldehyde were investigated to be the amount of fly ash, amount of phenol formaldehyde and the effects of these parameters on bending stress, limit oxygen index, water absorption capacity and swelling in the thickness. The optimization results showed that the maximum bending strength was 4.1N/mm², at urea‐formaldehyde ratio of 1.0, reaction temperature of 70°C, reaction time of 25 min, hazelnut shell/urea‐formaldehyde resin of 2.4 and mean particle size of 0.1 mm. Although the limited oxygen index and smoke density of composite particleboard without fly ash has 22.3 and 1.62, with fly ash of 16% (w/w) according to the filler has 38.2 and 1.47, respectively. Water absorption and increase in the swelling thickness exponentially decreased with increasing phenol formaldehyde. Copyright © 2009 John Wiley & Sons, Ltd.     

Zeolite synthesis from paper sludge ash with addition of diatomite

BACKGROUND: This study aimed to investigate the synthesis of zeolites from paper sludge ash (PSA) with added diatomite to remove both NH₄⁺ and PO₄^3? for water purification. The PSA had low Si and significant Ca contents. Four types of diatomite: white (T‐W) and brown (T‐B) from deposits of marine origin in Takanosu, and white (S‐W) and gray (S‐G) from lacustrine deposits in Shonai, were added to NaOH solution to increase the Si content and thereby synthesize zeolites with high cation exchange capacity (CEC). RESULTS: The order of the amounts of Si extracted from the diatomite to the alkali solution was S‐W > T‐W = T‐B > S‐G, which correlates with the amorphous SiO₂ content of diatomite. The original ash without addition of diatomite yielded hydroxysodalite with CEC of about 1.0 mmol g^?1. For all samples, the addition of diatomite to the solution yielded zeolite‐P with a higher CEC, but the addition of excess Si inhibited the synthesis of zeolite‐P, and the CEC of the product was low. A product with high CEC including zeolite‐P was obtained in a solution with around 500 mmol L^?1 of Si concentration, and had the ability to remove both NH₄⁺ and PO₄^3?. CONCLUSION: Diatomite has the potential for used as an additive for the synthesis of high CEC zeolite from PSA. The product with zeolite‐P exhibited relatively high CEC, capacity for NH₄⁺ uptake, and the ability to remove PO₄^3? by precipitation, which is preferable for water purification applications. Copyright © 2008 Society of Chemical Industry     

Properties and potential applications of zeolitic materials produced from fly ash using simple method of synthesis

Very low energy-consuming procedure is proposed for synthesis of zeolitic materials from fly ash. Three different zeolite materials (X, P and S), rich in zeolite phases, Na-X (FAU), NaP1 (GIS) and sodalite (SOD) were produced from F-class fly ash, using NaOH and NaCl solutions under atmospheric pressure at temperature below 110 °C.Obtained zeolitic products were analysed for their composition and physicochemical properties then compared to the raw fly ash and commercial adsorbents. The zeolitization results in a significant increase of CEC (from 5.5 up to 239 meq 100 g^− 1), and the high ability to adsorb heavy metal ions (over 40 mg g^− 1) and retain complex and organic molecules (EGME), mostly evident for material X. Adsorptive purification of waste and working lubricating oils using zeolitic products allow to provide their commercial applications in petroleum industry. Leachability of toxic elements after standard post-reaction washing is environmentally safe.     

Preparation of zeolitic adsorbents from waste coal fly ash

Power plants burning coal generate a large amount of fly ash as waste matter. The objective of this study is to produce zeolitic adsorbents that possesses high adsorptive capacity for toxic cations. The sample was first pretreated with a High Intensity Magnetic Separator for the removal of iron and magnetic materials (mainly Fe₂O₃ and TiO₂). The zeolitic adsorbents were prepared under the various conditions of NaOH concentration (1–5 N), reaction time from 3 to 96 hours and at the various temperatures of 60, 80 and 100°C. The results of the experiment showed that the coal fly ash should be synthesized with 4 N NaOH for 48 hours at 100°C in order to have good adsorptive capacity. The zeolitic adsorbents showed higher cation exchange capacity values than the natural zeolite in removing NH ₄ ⁺ , Pb²⁺, Ca²⁺and Cd²⁺ions.     

Effects of Ageing and Seeding on the Formation of Zeolite Y from Coal Fly Ash

Zeolite Y was selectively synthesised by treating Tarong fly ash in a hydrothermal system. The effects of ageing and seeding on the formation of the resultant phases, crystallisation kinetics, and gel chemistry of Si and Al were investigated. Most of the Si and Al components in the Tarong fly ash could be effectively transformed into zeolite Y in the presence of seeds but not the mineral phase, like mullite. The maximum crystallinity of zeolite Y obtained was 72%. The cation-exchange capacity (CEC) of the fly ash was 0.08 mmol/g but increased to 3.2 mmol/g after a proper treatment. Crystallisation of zeolite materials from fly ash is quite different from that of normal zeolite synthesis because the sources of Si and Al are relatively less reactive and other cation ions (e.g., K⁺, Mg²⁺) are present in fly ash. Zeolite P is a competitive phase present in the resulting products that could be eliminated by employing the seeding method. NMR study demonstrated that ageing plays an important role in enhancing the hydrothermal condition during which both Si and Al in fly ash dissolved into a basic solution and reacted to form ring-like structures, and further to zeolite materials. Seeding can selectively induce the formation of zeolite Y and eliminate the processes of induction and nucleation.     

Immobilization of Cs,Cd, Pb and Cr by synthetic zeolites from Spanish low-calcium coal fly ash

This report describes a study of the immobilization of Cs⁺, Cd²⁺, Pb²⁺ and Cr³⁺ by synthetic zeolites formed as a result of the hydrothermal treatment of Spanish class F coal fly ash in a 1 M solution of NaOH. The majority zeolite formed at 150 °C was a gismondine-type P1-Na species (Na₆Al₆Si₁₀O₃₂·12H₂O), which at 200 °C transformed into analcime-C zeolite (Na(Si₂Al)O₆H₂O). The shift in pore size distribution towards pores with diameters of about 2.2 nm observed after the zeolites were washed entailed an increase in the specific surface area, to values nearly double the figures recorded prior to washing. With a high selectivity for Cs, the gismondine type Na zeolite P was found to be the best candidate for immobilizing radioactive waste. Gismondine and analcime-C zeolites also exhibited high Cd selectivity.     

Alkylation of phenol with tert‐butyl alcohol over a catalyst synthesized from coal fly ash

The alkylation of phenol with tert‐butyl alcohol was carried out in a continuous flow reactor over a catalyst synthesized from fly ash. The activity of the synthesized catalyst was compared with those of other conventional zeolite catalysts such as 13X (NaX) and Hβ. Of all the catalysts tested, zeolite Hβ showed the highest activity in phenol conversion followed by the synthesized zeolite (HZOP‐31). The activity of commercial 13X zeolite was found to be same as that of HZOP‐31. Ce‐exchanged catalyst (CeZOP‐31) showed even better performance than 13X in the alkylation of phenol. The effects of different parameters such as reactant mole ratio, temperature and space velocity on phenol conversion and tert‐butyl phenol selectivity were studied. The effect of mass transfer resistance was found to be negligible within the feed rate range and particle size range studied. The apparent activation energy for the reaction of tert‐butyl alcohol over HZOP‐31 was determined as 30.1 kJ mol^?1. Copyright © 2006 Society of Chemical Industry     

Conducting composites of poly(N‐vinylcarbazole), polypyrrole,and polyaniline with 13X‐zeolite

N‐vinylcarbazole (NVC) was polymerized by 13X zeolite alone in melt (65°C) or in toluene (110°C) and a poly(N‐vinylcarbazole) (PNVC)‐13X composite was isolated. Composites of polypyrrole (PPY) and polyaniline(PANI) with 13X zeolite were prepared via polymerization of the respective monomers in the presence of dispersion of 13X zeolite in water (CuCl₂ oxidant) and in CHCl₃ (FeCl₃ oxidant) at an ambient temperature. The composites were characterized by Fourier transform infrared analyses. Scanning electron microscopic analyses of various composites indicated the formation of lumpy aggregates of irregular sizes distinct from the morphology of unmodified 13X zeolite. X‐ray diffraction analysis revealed some typical differences between the various composites, depending upon the nature of the polymer incorporated. Thermogravimetric analyses revealed the stability order as: 13X‐zeolite > polymer‐13X‐zeolite > polymer. PNVC‐13X composite was essentially a nonconductor, while PPY‐13X and PANI‐13X composites showed direct current conductivity in the order of 10^?4 S/cm in either system. However, the conductivity of PNVC‐ 13X composite could be improved to 10^?5 and 10^?6 S/cm by loading PPY and PANI, respectively. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 913–921, 2006     

Zeolite A‐polypropylene and silver‐zeolite A‐polypropylene composite films for antibacterial and breathable applications

Polypropylene (PP) composite films were successfully prepared using melt blending by directly mixing PP pellets with zeolite A or silver‐zeolite A powder and then blowing. All the prepared films were characterized in terms of their physical, mechanical, optical, and gas permeability properties. The structure of each composite film was similar to that of the pure PP film. The crystallinity and glossy quality of the composite films were increased by the addition of silver, zeolite, and maleic anhydride grafted PP (PP‐g ‐MA). The composite PP film with zeolite A and PP‐g ‐MA exhibited a level of oxygen and carbon dioxide permeation (6438 and 15,087 cc m^?2 day^?1 atm^?1, respectively). Finally, all the films were evaluated for their antibacterial activity and fruit packaging applications. Silver‐zeolite A‐PP composite films exhibited a bactericidal activity of 79% against Staphylococcus aureus and 52% against Escherichia coli , while the zeolite A‐PP film could extend the shelf‐life of bananas for over a week. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45450.     

Graft copolymerization of 2‐acrylamido‐2‐methyl‐1‐propanesulphonic acid onto carboxymethylcellulose (sodium salt) using bromate/thiourea redox pair

Unreported graft copolymer of 2‐acrylamido‐2‐methyl‐1‐propanesulphonic acid (AMPS) with sodium carboxymethylcellulose (Na‐CMC) was synthesized and reaction conditions were optimized using a bromate/thiourea redox pair under an inert atmosphere at 40°C. Grafting ratio, add on, and conversion increase as the concentration of thiourea and [H⁺] increases up to 3.6 × 10^?3 and 0.6 × 10^?2 mol dm^?3, respectively, while on increasing the concentration of bromate ion and Na‐CMC, grafting ratio, add on, and conversion decrease. The samples of Na‐CMC and grafted Na‐CMC with AMPS were subjected to thermogravimetric analysis, with the objective of studying the effect of grafting of AMPS on the thermal stability of graft copolymer. The graft copolymer was found to be more thermally stable than pure Na‐CMC. Comparing the IR spectra of pure with grafted Na‐CMC confirm the evidence of grafting. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 100: 26–34, 2006     

Modification of surface properties of wool fabric with linde type a nano‐zeolite

Wool is a naturally occurring composite fiber consisting of keratin and keratin‐associated proteins as the key molecular components. The outermost surface of wool comprises a lipid layer that renders the surface hydrophobic, which hinders certain fabric processing steps and moisture management properties of wool fabrics. In this study, Linde Type A (LTA) nano‐zeolite (a Na⁺‐, Ca²⁺‐, and K⁺‐exchanged type A zeolite) was integrated onto the surface of wool using 3‐mercaptopropyl trimethoxy silane as a bridging agent. The resultant surface morphology, hydrophilicity, and mechanical performance of the treated wool fabrics were evaluated. Notably, the surface hydrophilicity of wool increased dramatically. When wool was treated with a dispersion of 1 wt % zeolite and 0.2 wt % silane, the water contact angle decreased from an average value of 148° to 50° over a period of approximately 5 min. Scanning electron microscopic imaging indicated good coverage of the wool surface with zeolite particles, and infrared spectroscopic evaluation demonstrated strong bonding of the zeolite to wool keratins. The zeolite application showed no adverse effects on the tensile and other mechanical properties of the fabric. This study indicates that zeolite‐based treatment is potentially an efficient approach to increasing the surface hydrophilicity and modifying other key surface properties such as softness of wool and wool fabrics. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42392.     

A simple thermogravimetric method for the evaluation of the degree of fly ash conversion into zeolite material

The thermogravimetry was used for the evaluation of degree of conversion of fly ash into zeolite material alongside the CEC and XRD methods being currently proposed for this purpose. The present work proposes the calculation of the thermogravimetric fly ash-to-zeolite conversion factor, CF_TGA, based on the comparison of the mass loss of the commercial zeolite (standard) occurred during dehydration with that of the fly ash-derived zeolite. This mass loss is characteristic of a specific zeolite type, and the corresponding zeolite water content in the sample of zeolites indicates their degree of crystallinity and zeolite phase content. The use of the TGA method for the indirect determination of the fly ash-to-zeolite conversion factor would be preferable owing to its “speed” compared to other methods proposed for this purpose, as well as the capability to use a consistent procedure. Because of its short CF_TGA determination procedure, the thermogravimetric method can be used for the control and determination of the quality of fly ash-derived zeolite in an industrial plant.     

Synthesis and characterization of 2‐oxazoline‐benzoxazine compound and its polymer

A novel 2‐oxazoline‐benzoxazine (POB) was synthesized with 2‐(hydroxylphenyl)‐2‐oxazoline, 1,3,5‐triphenylhexahydro‐1,3,5‐triazine and paraformaldehyde. The chemical structure of the monomer was confirmed by FTIR, ¹H‐NMR, ¹³C‐NMR, and MS. The curing behavior of the monomer was studied by DSC and FTIR, and the ring opening reaction of the monomer was found to occur from 187.5°C. The results of DMA and TGA demonstrated that the thermal properties of polymer for POB monomer (P‐m) are better than polymer for POB precursor (P‐p), because that the oligomer in benzoxazine precursor decreased the perfection of the polymer's network structure; it was also found that the thermal properties of P‐m and P‐p are much better than the common polybenzoxazine and the composite material of benzoxazine and 2‐oxazoline. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci , 2008.     

粉煤灰两步法水热合成NaA沸石工艺研究

研究了粉煤灰两步法水热合成沸石过程中,粉煤灰中Si和Al在不同NaOH浓度溶液下的溶出规律及溶出浓度;采用XRD和CEC测试手段探讨了晶化过程中的温度、时间和NaOH浓度三个参数对晶化产物的影响,得到了最佳的工艺参数:晶化温度为100℃,时间为4h,NaOH浓度为2.5M.在此条件下,合成出了结晶良好且纯度较高的NaA沸石,其CEC值为4.3mmol/g.     

Determining suitability of a fly ash for silica extraction and zeolite synthesis

Zeolitic material is obtained from fly ash both by direct conversion of the ash or from SiO₂ extracts obtained from fly ash. This study focuses on determining the suitability of a fly ash for SiO₂ extraction and for zeolite synthesis by direct conversion. The SiO₂ extraction experiments from different fly ashes show that the main parameters governing the SiO₂ extraction are: (a) a high bulk SiO₂ content (>52%, for obtaining an extraction yield of 100 g SiO₂ kg^?1) in the starting fly ash, (b) a high proportion (>55%) of the bulk SiO₂ present in the degradable glass matrix and the highly soluble opaline fraction, and (c) a high bulk SiO₂/Al₂O₃ ratio (>2.0) of the fly ash. The results from experiments of zeolite synthesis by direct conversion demonstrate that the most important criteria for the selection of a fly ash for this process are: (a) a high content of Al₂O₃ and SiO₂(>65%) (b) a high glass content (>63%) and (c) relatively low SiO₂/Al₂O₃ ratio (<2.0). Multivariate analysis confirms the importance of the above‐mentioned variables and shows some additional variables that have influence on ash behaviour under alkaline conditions. It quantifies the use of those variables for determining the suitability of ashes for SiO₂ extraction and zeolite synthesis and is able to distinguish between the two. Copyright © 2004 Society of Chemical Industry     

Using Coal Fly Ash and Wastewater for Microwave Synthesis of LTA Zeolite

The reuse of industrial wastes from a coal‐fired power plant and a plasma electrolytic oxidation process was attempted to realize a zero discharge. The batch composition was adjusted by adding sodium hydroxide and sodium aluminate. A single‐mode microwave oven equipped with reflux condenser was used for crystallization under atmospheric pressure. The synthesized samples were characterized by X‐ray diffraction, scanning electron microscopy, BET, thermogravimetric analysis, and cation‐exchange capacity (CEC) measurement. Analytical results indicated that Na‐A zeolite with a defined maximum crystallinity could be successfully synthesized by hydrothermal treatment of fly ash with wastewater. Due to the high CEC, the product can be applied for gas purification and soil remediation processes.