Synthesis of Bulk Zeolites by Hydrothermal Treatment of Geopolymers

Synthesis of zeolites from mechanically activated kaolin clays

Steel slag, commercial waste material containing silica and alumina which are the chemical components elements of zeolite, was used as a source for synthesis of FAU zeolite (Y-zeolite, X-zeolite). Through acid-treatment to remove CaO species from steel slag and hydrothermal treatment, well-crystallized Na type FAU zeolite was obtained. Furthermore the synthesized FAU zeolite was applied as a support of photocatalyst. It was found that hydrophobic surface property of zeolite enhances photocatalytic activity for decomposition of organic pollutants and the zeolite synthesized from steel slag would be applicable as promising support of TiO2 photocatalyst.

Synthesis of zeolite A using the waste of iron mine tailings dam and its application for industrial effluent treatment

In November 2015, a dam from iron mining collapsed, which is considered as the largest environmental accident in Brazil. Over than 50 million m³ were released reaching the Doce River and killed 20 people in Mariana. The literature review shows that the mining tailings can be used as raw material to the synthesis of zeolites, which can be used for the wastewater treatment. The aim of this work was the synthesis of zeolites from the Samarco tailings and its application for the treatment of electroplating effluent. The residue was characterized which identified high-iron content for the synthesis of zeolites. The residue was mixed with NaOH (1:1) and the reaction temperature was evaluated from 350 °C to 650 °C. Then, the material was mixed with aluminum source and the effect of time was evaluated. The zeolite was applied to the wastewater treatment from electroplating industry. Results showed that the synthesis of zeolite A was carried out with a fusion step at 450 °C for 1 h using RAS: NaOH ratio 1:1, and further hydrothermal treatment at 100 °C during 4 h. The zinc removal from the wastewater was up to 98% using 50 mL of the solution, 2.5 g zeolite A, 60min and pH 6.4. The main metals presented in the solution were adsorbed up to 90% by the zeolite synthesized. Zinc adsorption by the zeolite fitted better on Langmuir isotherm. The zeolite was used four times in a row and zinc removal declined 98–68%.

Green synthesis of Cu-SSZ-13 zeolite by seed-assisted route for effective reduction of nitric oxide

Zeolite Y was synthesised, for the first time, using Nigerian Ahoko kaolin. In addition, a novel metakaolinization technique was used to produce the necessary reactant phase. The first step involves the refining of the raw kaolin sample, which removes a substantial amount of quartz, a major impurity present in all kaolin including Ahoko kaolin. The second step, metakaolinization, was carried out at a significantly lower temperature and for a shorter time than in previous studies. The method for the production of metakaolin, based on rapidly exposing a sample of refined kaolin to elevated temperature was investigated in this work. Metakaolin was obtained after 6 min of exposure at 600 °C. The metakaolin produced was then used to synthesis zeolite Y and ZSM-5 using conventional hydrothermal treatment and the shortened thermal treatment cycle was shown to be effective for commercial kaolin as demonstrated by the synthesis of zeolite A.

Synthesis of zeolite A from aluminoborosilicate glass used in liquid crystal display ( LCD ) panel glass substrate was attempted. Mixture of aluminoborosilicate glass and sodium aluminate was hydrothermally treated with sodium hydroxide solution for 10.8–345.6 ks at 368–423 K. Aluminoborosilicate glass was also acid treated with nitric acid before hydrothermal treatment. Obtained samples were characterized by X‐ray diffraction and scanning electron microscope observation. Zeolite A, hydroxysodalite, and zeolite P were synthesized, and with the specific conditions of hydrothermal treatment, a single phase of zeolite A was successfully obtained. Acid treatment was effective for synthesis of a single phase of zeolite A, because the components of aluminoborosilicate other than SiO 2 preferentially eluted for acid solution and during following hydrothermal treatment SiO 2 was supposed to elute for alkaline solution. Cation‐exchange capacities (CECs) were investigated for these products. It was clarified that CEC of the product with a single phase of zeolite A obtained from aluminoborosilicae glass was 4.2 mol/kg. CEC of the product consisted of zeolite A and hydroxysodalite was 3.9 mol/kg, and the one consisted of zeolite A, hydroxysodalite, and zeolite P was 2.6 mol/kg. This results shows that aluminoborosilicate glass could be expected to be recycled in zeolite A with good CEC by the appropriate process.

Bulk crystal seeding in hierarchical zeolite synthesis using organosilane surfactants – widening the mesopore-generating region and zeolite structures.

The objective of this work is to obtain synthesis of ZSM-5 zeolite using kaolin as Si and Al alternative source. Kaolin powder was dispersed under constant stirring into the sílica sol where the mass ratio of kaolin to silica was 1:2. After stirring for 2 hours, the dispersion was dried at 160 °C and calcined at 700 °C/2 hours. The synthesis of ZSM-5 zeolite was by hydrothermal treatment at 170 °C/48 hours under autogenous pressure. The materials were characterized by XRD, SEM, EDX, BET. According to the XRD, was possible to observe the formation of ZSM-5 zeolite with intense and well defined peaks set located between 2θ = 7-9° and 23-25°, typical of a crystalline material. The SEM showed the formation of particles clusters with orthorhombic shape characteristic of MFI structure. The results show that the hydrothermal treatment was efficient to produce ZSM-5 using calcined kaolin as alternative source.

As discussed in the previous chapters, conventional techniques of synthesis of fly ash zeolites have not been found successful in synthesizing zeolites of higher grades (i.e., zeolites possessing high cation exchange capacity), mainly due to incomplete zeolitization of the fly ash, the complexities associated with the liquid by-product and the impurities present in the activated residues. The degree of activation of the type fly ash may also depend on its zeolitization potential and hence identification of the most suitable fly ash which would yield products of improved grade becomes a prime focus. In this context, out of the two types of the fly ashes (viz., hopper ash and lagoon ash, available as dry powder at the electrostatic precipitator and as wet powder at lagoons, respectively), which have different characteristics (viz., physical, chemical, mineralogical and morphological), depending upon their disposal site conditions (dry and wet) were used in this study. Based on detailed experimentation, hopper ash has been ascertained to have faster reaction with NaOH and thus yields superior residue with higher cation exchange capacity than the lagoon ash. This could be observed from the X-ray fluorescence results, X-ray diffractograms and micrographs of the two ashes and their products, after hydrothermal treatment. Finally, it has been demonstrated that the hopper ash exhibits better zeolitization potential than the lagoon ash. Furthermore, to synthesize higher grade fly ash zeolites from the hopper ash, a technique which involves a very innovative synthesis process, has been developed and its details are presented in this chapter. Contrary to the conventional hydrothermal technique, this novel technique is based on ‘three-step activation’ of the hopper fly ash by employing hydrothermal as well as fusion activation and hence results in synthesis of zeolites of very high cation-exchange capacity.

The present study deals with the production and characterization of ZSM-5 zeolite under low temperature using amorphous rice husk ash as an alternative cheap silica source. Rice husk was combusted at various temperatures for the production of amorphous silica. The resulted amorphous silica ash was then utilized without any other treatment as a starting material for the synthesis of ZSM-5 zeolite using low temperature and under atmospheric pressure. For comparison, the high-temperature synthetic approach, the hydrothermal treatment under high temperature and autogenous pressure with the autoclave process, was also applied for the synthesis of ZSM-5 zeolite. The low-temperature method led successfully to the synthesis of highly siliceous zeolite of type ZSM-5. The produced materials were characterized using a variety of analytical techniques, including X-ray diffraction, Fourier transformation infrared spectroscopy, thermogravimetry–differential thermogravimetry analyses, scanning electron microscopy, electron dispersion X-ray analysis and nitrogen porosimetry. The results show that the utilization of an industrial by-product in abundance as a starting material can lead through a simple inexpensive technique to the synthesis of a high value added microporous material with many potential applications.

Synthesis of phosphorus-modified small-pore zeolites utilizing tetraalkyl phosphonium cations as both structure-directing and phosphorous modification agents

Coal fly ash (CFA) was utilized as a raw material for the synthesis of zeolite X. Zeolite of X-type was synthesised from CFA through alkali fusion tailed by hydrothermal treatment. The main crystal-like stage of fly ash, quartz could be also converted to pure X-type through hydrothermal suitable treatment using SiO2/Al2O3 components of the amorphous stage in coal fly ash along with the gel composition of 14.76 Na2O: 1 Al2O3: 3.5 SiO2: 454 H2O. The properties of zeolite X formed strongly depends on the treatment circumstances and concentrations of raw materials. The synthesised zeolite X from CFA was characterized by XRD, SEM-EDS, HR-TEM, SAED and FTIR which represents the appearance of crystalline quartz and mullite with spherical/hexagonal morphology. The predominant morphology was spherical particle with diameters ranging between 23.80 nm to 190.5 nm. By rising the SiO2/Al2O3 ratio of preliminary material, degree of crystallinity also increased maximum at SiO2/Al2O3 is 1.7. The cytotoxic influence of zeolite X on cancer cell lines like HEP2, HT-29, HEPG2 and A549 were evaluated. General outcomes exhibited that cancer cell lines treated with 200 μg ml−1 of zeolite X showed the greatest inhibition of cell proliferation and reduction in cell viability. These findings provides preliminary information to determine the prospective utilization of zeolite X as anticancer agent for alternate or complementary therapy.

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

The treated oil palm ash and kaolin powder are used as the starting material for the synthesis of zeolites materials. The method chose for the zeolites conversion is alkaline hydrothermal treatment. The chemical composition and crystalline phases of treated oil palm ash and as-synthesized samples were characterized and studied. From the analysis, the treated palm ash was a fertile source of silica and exists as quartz phase. The zeolite synthesis was carried out under hydrothermal conditions by activation with sodium hydroxide (NaOH) solution. The results indicated that the synthesized zeolite products obtained from 2 M NaOH concentrations contain zeolite gismondine as major constituent phase, whereas quartz was found as minor phase. The outcomes have significant motivation for the production of zeolites by using low cost material such as treated palm ash.