Hydroxysodalite Zeolite Research Articles

Fusion-Assisted Hydrothermal Synthesis and Post-Synthesis Modification of Mesoporous Hydroxy Sodalite Zeolite Prepared from Waste Coal Fly Ash for Biodiesel Production

Increases in biodiesel prices remains a challenge, mainly due to the high cost of conventional oil feedstocks used during biodiesel production and the challenges associated with using homogeneous catalysts in the process. This study investigated the conversion of waste-derived black soldier fly (BSF) maggot oil feedstock over hydroxy sodalite (HS) zeolite synthesized from waste coal fly ash (CFA) in biodiesel production. The zeolite product prepared after fusion of CFA followed by hydrothermal synthesis (F-HS) resulted in a highly crystalline, mesoporous F-HS zeolite with a considerable surface area of 45 m2/g. The impact of post-synthesis modification of the parent HS catalyst (F-HS) by ion exchange with an alkali source (KOH) on its performance in biodiesel production was investigated. The parent F-HS zeolite catalyst resulted in a high biodiesel yield of 84.10%, with a good quality of 65% fatty acid methyl ester (FAME) content and fuel characteristics compliant with standard biodiesel specifications. After ion exchange, the modified HS zeolite catalyst (K/F-HS) decreased in crystallinity, mesoporosity and total surface area. The K/F-HS catalyst resulted in sub-standard biodiesel of 51.50% FAME content. Hence, contrary to various studies, the ion exchange modified zeolite was unfavorable as a catalyst for biodiesel production. Interestingly, the F-HS zeolite derived from waste CFA showed a favorable performance as a heterogeneous catalyst compared to the conventional sodium hydroxide (NaOH) homogeneous catalyst. The zeolite catalyst resulted in a more profitable process using BSF maggot oil and was economically comparable with NaOH for every kilogram of biodiesel produced. Furthermore, this study showed the potential to address the overall biodiesel production cost challenge via the development of waste-derived catalysts and BSF maggot oil as low-cost feedstock alternatives.

Cu(II) impregnated clay-derived HS zeolite: Synthesis, characterization and catalytic activity on catalytic wet peroxide oxidation (CWPO) of phenol

The majority of phenol-containing liquid industrial wastes are discharged into natural waters. As a result, several investigations, such as catalytic wet peroxide oxidation (CWPO), have been conducted to remediate these effluents. Copper-supported heterogeneous catalysts were prepared by an impregnation technique and tested in CWPO of phenol. Both the raw pyrophyllite clay and its zeolite form were used as supports. The samples were characterized by BET specific surface area analysis, X-ray diffraction, X-ray fluorescence, and X-ray photoelectron spectra. The effect of temperature (25–70 °C), the concentration of hydrogen peroxide (2–10 mmol·L−1), and the amount of catalyst (0.5–3 g·L−1) were selected for optimization of the catalytic system H2O2-2.5% Cu/ZP using the response surface methodology based on central composite design. The catalyst (2.5% Cu/ZP), with support of synthesized hydroxysodalite zeolite form, showed the best catalytic activity in comparison to that based on raw pyrophyllite support (2.5% Cu/RP). The maximized degradation was 100% after 4 h at optimum conditions (T = 50 °C, [H2O2] = 6.39 mmol·L−1, catalyst amount = 1.82 g·L−1) with 87.73% of mineralization.

Optimal synthesis of nanosize seeds for secondary growth of high performance hydroxy-sodalite (H-SOD) zeolite membranes for small gas and water separations

Nanosize H-SOD particles were hydrothermally synthesized as seeds for the secondary growth of hydroxy-sodalite (H-SOD) zeolite membrane. The size and phase purity of H-SOD zeolite particles were carefully controlled by changing several hydrothermal conditions. Especially, NaOH concentration in the hydrothermal solution made a significant effect on the phase purity and particle size. The high phase purity particles with a mean diameter of 80 nm were successfully synthesized at a 3 M NaOH concentration and applied for secondary growth. Overall, uniform H-SOD zeolite membranes with various thicknesses (3, 7, and 9.5 μm) were prepared by varying secondary growth time. The 9.5 μm thick H-SOD zeolite membrane exhibited high H 2 /N 2 permselectivity of 95 at 473 K and a transmembrane pressure of 0.3 MPa. And, the pervaporation performance was evaluated for 90 wt% methanol-water mixture at 423 K, an elevated temperature. It showed a high water/methanol separation performance; its water/methanol separation factor was 2726 and the total flux, 1.02 kg/m 2 h. The high small gases and water separation performances were because interparticular voids between the nano size seeds were small and the surface of seed layer was flat. Therefore, the secondary growth remained a continuous zeolite layer with few non-zeolitic pores. In the present work, it was well proven experimentally that application of nanosize seed is an effective option to prepare high performance zeolite membrane in H-SOD zeolite system. • High purity H-SOD zeolite particles with a mean diameter of 80 nm were carefully prepared for the secondary growth of H-SOD zeolite membranes. • Synthesis temperature, time and NaOH concentrations played major roles on the particle size. • The H-SOD zeolite membranes prepared by using the nanosize seeds showed excellent performances for H 2 /CO 2 , H 2 /N 2 and water/methanol separations. • The good performance was due to smaller interparticular voids between nano size seeds and the increased surface flatness of seed coating layer.

A Preliminary study of removal of some heavy metals from aqueous medium by a mesoporous hydroxysodalite zeolite prepared from basalt rich in calc-plagioclaseby alkali activation

This work presents an exploration of the use of hydroxysodalite zeolite prepared from basalt rich in calc-plagioclaseby alkali activation for removal of some heavy metals from aqueous medium. The preliminary results of batch and column experiments indicated a quantitative and fast removal of the three investigated ions, Cu 2+ , Pb 2+ and Zn 2+ from aqueous solutions. The data from the batch experiments and the column experiments jointly support the notion that hydroxysodalite zeolite prepared from basalt rich in calc-plagioclase is an efficient adsorbent for the investigated heavy metals. Almost quantitative removal of the ions was achieved within a period of 15 min of exposure of the solution to the adsorbent in batch experiments and through passing a small column filled with the adsorbent. The highest removal efficiency by the zeolite prepared from basalt rich in calc-plagioclase of the three tested heavy metal Cu 2+ , Pb 2+ and Zn 2+ were 99.98% ,99.76% and 99.93 % respectively. Keywords: hydroxysodalite zeolite, basalt utilization, heavy ions removal, pollution remediation DOI: 10.7176/CMR/12-7-09 Publication date: November 30 th 2020

Lithium Extraction and Hydroxysodalite Zeolite Synthesis by Hydrothermal Conversion of α-Spodumene

The continuously increasing demand for lithium has made it one of the strategic metals, rendering its exploitation of critical importance. Natural α-spodumene is still the primary resource of lithi...

A Tunable Template-Assisted Hydrothermal Synthesis of Hydroxysodalite Zeolite Nanoparticles Using Various Aliphatic Organic Acids for the Removal of Zinc(II) Ions from Aqueous Media

Hydroxysodalite zeolite nanoparticles with different crystallite sizes (37.61–64.88 nm) were synthesized using a hydrothermal method in the absence and presence of low-cost aliphatic organic acids as templates. The templates used were oxalic acid dihydrate, tartaric acid, citric acid monohydrate, succinic acid, maleic acid, and ethylenediaminetetraacetic acid (EDTA). The synthesized nanoparticles were characterized using HR-TEM, FE-SEM, FT-IR, and XRD techniques. The hydroxysodalite zeolite synthesized using ethylenediaminetetraacetic acid (EDTA) has the smallest crystallite size (37.61 nm) whereas the template free one has the largest crystallite size (64.88 nm). The synthesized nanoparticles could be effectively applied to purify polluted water from the zinc(II) ions, and the maximum adsorption capacity was 8.53 mg/g. Kinetic study displayed that the adsorption process of zinc(II) ions obeyed pseudo-second-order, intra-particle diffusion, liquid film diffusion, and pore diffusion models whereas the rate determining step of the adsorption is only controlled by the pore diffusion model. In addition, equilibrium study showed that the adsorption process fitted well with the Langmuir isotherm model compared to the Freundlich isotherm model. Besides, thermodynamic study showed that the adsorption process is exothermic, spontaneous, and chemisorption. Moreover, desorption and reusability study revealed that there is a slight decrease in both of the % removal and adsorption capacity of the hydroxysodalite adsorbent with progressing five cycles. Hence, we can infer that this new hydroxysodalite adsorbent can possibly be utilized repeatedly without sacrificing its adsorption capacity towards zinc(II) ions.

Single-step process to produce alumina supported hydroxy-sodalite zeolite membranes

Membranes based on zeolites have been extensively studied and used to purify/separate H2 or CO2 or other gases, depending on their composition. The deposition of zeolite films onto porous, chemically and thermally stable, substrates can increase their stability, but the production process may require lengthy two-step procedures. In this work, a single-step method was developed for the production of homogeneous hydroxy-sodalite (HS) zeolite films, without seeding and by direct deposition during hydrothermal treatment on cheap and porous alumina substrates. Alumina substrates have been developed with fine porosity (> 35% porosity, 500–600 nm of mean pore diameter), with low resistance to gas flow but reduced surface porosity to favour the deposition of dense films. The single-step growth of HS films with a thickness ranging from a few to 28 μm on alumina was successfully achieved. These membranes have been tested in hydrogen, methane, carbon dioxide and nitrogen, and good results in terms of hydrogen permeance and separation performance were achieved for 10–12-μm-thick HS films on alumina.

Preparation of Nanopore Hydroxysodalite Zeolite Membranes by Dry Gel Method

Hydroxysodalite (HS) Zeolite membrane was prepared onto seeded mullite supports using a new crystallization method called ‘Dry Gel Conversion Technique’. Molar composition of the starting gel of HS zeolite membrane was SiO2/Al2O3=1.0, Na2O/Al2O3=65, and H2O/Al2O3=1000. X-ray diffraction (XRD) patterns of the membranes exhibited peaks corresponding to the support and the zeolite. The crystal species were characterized by XRD and morphology of the supports subjected to crystallization was characterized by Scanning electron microscopy (SEM). Separation performance of HS zeolite membranes was studied for water-Ethanol mixtures using pervaporation (PV). The membranes showed good selectivity towards water in the water-Ethanol mixtures. Water permeates faster because of its preferential adsorption into the nano-pores of the hydrophilic zeolite membrane. In PV of water-Ethanol mixtures, the membrane exhibits a hydrophilic behavior, with a high selectivity towards water and a good flux. The best Flux and separation factor of the membranes were 2.05 kg/m2.h and 10000, respectively. In addition, these membranes used for hydrogen separation from CH4 and It shown high selectivity and permeability ratio to zeolite membrane preparated by conventional method. Keywords: nanopore, hydroxysodalite, pervaporation, dry gel, zeolite, membrane

Preparation of Nanopore Hydroxysodalite Zeolite Membranes by Dry Gel Method

Hydroxysodalite (HS) Zeolite membrane was prepared onto seeded mullite supports using a new crystallization method called ‘Dry Gel Conversion Technique’. Molar composition of the starting gel of HS zeolite membrane was SiO2/Al2O3=1.0, Na2O/Al2O3=65, and H2O/Al2O3=1000. X-ray diffraction (XRD) patterns of the membranes exhibited peaks corresponding to the support and the zeolite. The crystal species were characterized by XRD and morphology of the supports subjected to crystallization was characterized by Scanning electron microscopy (SEM). Separation performance of HS zeolite membranes was studied for water-Ethanol mixtures using pervaporation (PV). The membranes showed good selectivity towards water in the water-Ethanol mixtures. Water permeates faster because of its preferential adsorption into the nano-pores of the hydrophilic zeolite membrane. In PV of water-Ethanol mixtures, the membrane exhibits a hydrophilic behavior, with a high selectivity towards water and a good flux. The best Flux and separation factor of the membranes were 2.05 kg/m2.h and 10000, respectively. In addition, these membranes used for hydrogen separation from CH4 and It shown high selectivity and permeability ratio to zeolite membrane preparated by conventional method. Keywords: nanopore, hydroxysodalite, pervaporation, dry gel, zeolite, membrane

Synthesis of hydroxysodalite zeolite by alkali-activation of basalt powder rich in calc-plagioclase

Hydroxysodalite (H-SOD) microcrystalline particles were synthesized from basalt powder rich in calcic-plagioclase (anorthite) by alkali activation at 80°C/24h. Sodium hydroxide (NaOH) solution was used as alkaline activator. The reactivity of the natural solid precursor basalt was studied using differential scanning calorimetry (DSC), and a maximum reaction enthalpy of (−ΔH) of 170J/g was obtained. The chemical, mineralogical, and textural properties were obtained by using X-ray powder diffractometry (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and N2-adsorption-desorption measurements. The synthesized material has a specific BET surface area of 20.5m2g−1 approximately 200 times higher than raw basalt material (0.1m2g−1). The compressive strength of basalt based H-SOD/sand composite samples cured at 80°C for 24h upon using different amounts of the activator (NaOH) was evaluated under dry and saturated conditions. The dry samples with NaOH/basalt mass ratio of 0.12 have reached a compressive strength of 57MPa. Wet samples, on the other hand, showed a compressive strength of 25MPa after seven days of soaking in water and four episodes of wetting and drying. The present work illustrates that crystalline H-SOD could be synthesized from cheap basalt powder precursor.

Synthesis of nanostructure hydroxy sodalite composite membranes via hydrothermal method: support surface modification and synthesis method effects

AbstractMultilayer hydroxy sodalite zeolite membranes were synthesized on the outer surface of support with and without modification via in situ and secondary growth hydrothermal synthesis methods. The synthesized zeolite membranes were characterized by X‐ray diffraction, scanning electron microscopy, and single gas (H2, N2, and n‐pentane) permeation measurements at different pressure differences. The membranes synthesized by secondary growth method on the modified support were found to be highly intergrown, but the permeation results for hydrogen and n‐pentane at a temperature of 323 K were not repeatable, which can be related to the weak interaction between zeolite layer and substrate. High performance hydroxy sodalite zeolite membrane was successfully formed on a nonmodified α‐Al2O3 support by in situ hydrothermal synthesis method. No permeance of n‐pentane was measured for this membrane at 323 K and 2 bar so that infinite permselectivity of H2/n‐C5H12 could be obtained for the four‐layer synthesized membrane on the nonmodified support, verifying the synthesis of a good quality hydroxy sodalite zeolite membrane. © 2014 Curtin University of Technology and John Wiley & Sons, Ltd.

Hydrothermal synthesis of hydroxy sodalite zeolite membrane: Separation of H2/CH4

In this study, hydroxy sodalite (HS) zeolite was synthesized via hydrothermal method. As reported in the literature, the recommended molar composition of H2O/Al2O3 for HS zeolite synthesis is about 1000. However in our work, HS zeolite was synthesized using new molar compositions of H2O/Al2O3 for different synthesis times and their effects on morphology and crystallinity of the synthesized zeolites were investigated. Also, HS zeolite membranes were synthesized on seeded supports using synthesized powders and the effect of seed size was also investigated. The products were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Gas permeation through the membranes was also measured. First of all, it was found that synthesis time has a significant effect on crystallinity and crystal size of the synthesized zeolite. Also, water molar ratio can control crystal size of the synthesized zeolite.It was found out that with increasing the seed size, H2 and CH4 permeations decrease, from 3224 to 279 (Barrer) and from 611 to 45 (Barrer), respectively, while the H2/CH4 selectivity increases from 5.28 to 6.20. Finally, to obtain HS zeolite with desirable particle size, crystallinity and morphology, optimum synthesis conditions were proposed.

Synthesis of zeolites from coal fly ash using mine waters

In this study mine waters obtained from coal mining operations in South Africa were used as a substitute for pure water during the synthesis of zeolites from South African coal fly ash. Procedures that had been optimized to produce single phase zeolite Na-P1 and X using pure water were employed independently. The use of circumneutral mine water resulted in similar quality zeolite Na-P1 and X whereas the use of acidic mine drainage led to the formation of a single phase hydroxysodalite zeolite. Since these two wastes (fly ash and mine waters) are found in close proximity to each other, this study demonstrates that they can be used to ameliorate each other and at the same time produce saleable zeolitic products that can be used to offset their costs of disposal and treatment.

Characteristics of Brazilian coal fly ashes and their synthesized zeolites

Five different Brazilian fly ashes were used to synthesize zeolites by hydrothermal treatment. Raw fly ash materials and zeolitic products were characterized in terms of pH, conductivity, real density (Helium Pycnometry), specific surface area (BET method), morphological analysis (SEM), chemical composition (XRF), mineralogical composition (XRD) and cation exchange capacity (CEC). Humidity and loss of ignition (LOI) of the fly ashes were also evaluated. Results indicated that the fly ash sample from Figueira power plant (FG) has a high content of Pb. The fly ash from São Jerônimo power plant (SJ) presents a higher content of unburned carbon. Chemical composition analyses indicate that the content of SiO2 and Al2O3 is above 70wt.% in all fly ashes. After hydrothermal treatment, various zeolites such as hydroxy-sodalite, NaP1 and X zeolites were formed depending on sourced fly ash. Hydroxy-sodalite zeolite was formed in all samples. NaP1 zeolite was formed in fly ashes with high content of Ca while X zeolite was formed from the fly ashes with high content of Al. CEC values of the zeolitic materials are 40 times higher than fly ash samples, potential for use as ion exchangers.

Synthesis of hydroxy sodalite from coal fly ash using waste industrial brine solution

The effect of using industrial waste brine solution instead of ultra pure water was investigated during the synthesis of zeolites using three South African coal fly ashes as Si feedstock. The high halide brine was obtained from the retentate effluent of a reverse osmosis mine water treatment plant. Synthesis conditions applied were; ageing of fly ash was at 47°C for 48 hours, and while the hydrothermal treatment temperature was set at 140°C for 48 hours. The use of brine as a solvent resulted in the formation of hydroxy sodalite zeolite although unconverted mullite and hematite from the fly ash feedstock was also found in the synthesis product.

Zeolite Synthesis from Brazilian Coal Fly Ash for Removal of Zn<sup>2+</sup> and Cd<sup>2+</sup> from Water

A Brazilian fly ash sample (CM1) was used to synthesize zeolites by hydrothermal treatment. Products and raw materials were characterized in terms of real density (Helium Pycnometry), specific surface area (BET method), morphological analysis (SEM), chemical composition (XRF) and mineralogical composition (XRD). The zeolites (ZM1) from fly ash were used for metal ion removal from water. Results indicated that hydroxy-sodalite zeolite could be synthesized from fly ash sample. The zeolite presented higher specific surface area and lower SiO2/Al2O3 ratio than the ash precursor. The adsorption showed that cadmium is more preferentially adsorbed on ZM1 than zinc. The adsorption equilibrium time for both Zn2+ and Cd2+ was 20 hours in a batch process. The adsorption isotherms were better fitted by the Langmuir model and the highest percentages of removal using ZM1 were obtained at pH 6 and 5 and doses of 15 and 18 g L-1 for Zn 2+ and Cd2+ , respectively. Thermodynamic studies indicated that adsorption of Zn2+ and Cd2+ by ZM1 was a spontaneous, endothermic process and presented an increase of disorder at the interface solid/solution.

Preparation of nano pore hydroxysodalite zeolite membranes using of kaolin clay and chemical sources

Zeolite hydroxysodalite (HS) was synthesized successfully by hydrothermal method using the natural kaolin. In the first step, kaolin has been calcined at 700 °C to the metakaolinite phase. As a second step, the zeolitisation experiments have been carried out under hydrothermal conditions. The metakaolinite obtained has been reacted with NaOH solutions in autoclaves at 100 °C. The crystal species were characterized by X-ray diffraction (XRD) patterns and morphology of the supports subjected to crystallization was characterized by Scanning electron microscopy (SEM). Performance of the hydrophilic Nano zeolite membranes during separation of water/Ethanol mixtures was evaluated. These membranes showed very high selectivity of water for water/Ethanol mixtures. Separation factor as high as 10,000 was obtained for ethanol feed concentration of 90%. Total mass flux was also obtained 0.959 kg/m 2.h.

Preparation of nanopore HS zeolite membranes for reverse osmosis processes

Zeolite membranes have been studied extensively for more than 15 years, mainly focusing on gas separation and liquid pervaporation processes. Recently, molecular dynamic simulation has shown that zeolite membranes are theoretically suitable for ion removal from aqueous solutions by reverse osmosis (RO) processes. The separation mechanism of the zeolite membranes is the size exclusion of hydrated ions, which have kinetic sizes significantly larger than the aperture of the hydroxysodalite (HS) zeolite (diameter 0.3 nm). HS zeolite membrane indicates that it may be possible to simultaneously separate ions and dissolved organic compounds from water by RO processes. Zeolite membranes may be used as an alternative to polymeric membranes for desalination of seawater and wastewaters. HS zeolite membranes composed of a continuous intergrowth of HS zeolite crystals have been prepared hydrothermally on the surface of porous tubular supports. In this research, synthesis of zeolite HS membrane was investigated. SEM and XRD analysis have been used to confirm zeolite HS membrane formation. Membrane performance has been evaluated using an experimental pervaporation setup. Effects of operation condition (temperature, rate and pressure) on the membrane structure and performance have been investigated for HS zeolite membranes grown onto seeded mullite supports.

Mechanisms and experimental results of aqueous mixtures pervaporation using nanopore HS zeolite membranes

Dehydration of solvents using hydrophilic polyvinylalcohol pervaporation membranes is a well-established technology. However, these polymeric membranes may not be suitable for applications involving high water concentrations or applications containing harsh solvents like unsymmetrical dimethylhydrazine (UDMH) due to membrane stability problems and swelling effects. The recent development of solvent and temperature-resistant, hydrophilic zeolite Hydroxysodalite (HS) membranes has made it possible to overcome the above limitations of hydrophilic polymeric membranes. Zeolite membranes have uniform and molecular-sized pores, and they separate molecules based on differences in the molecules' adsorption and diffusion properties. Strong electrostatic interaction between ionic sites and water molecules (due to its highly polar nature) makes the zeolite HS membrane very hydrophilic. Zeolite HS membranes are thus well suited for separating liquid-phase mixtures by pervaporation. In this study, experiments were conducted with various UDMH–water mixtures (1–20 wt.%) at 25 °C. Total flux for UDMH–water mixtures was found to vary from 0.323 to 0.214 kg/m 2 h with increasing UDMH concentration from 1 to 20 wt.%. Ionic sites of the HS zeolite matrix play a very important role in water transport through the membrane. These sites act both as water sorption and transport sites. Surface diffusion of water occurs in an activated fashion through these sites. The precise nanoporous structure of the zeolite cage helps in a partial molecular sieving of the large solvent molecules leading to high separation factors. A comparison between experimental flux and calculated flux using Stephan Maxwell (S.M.) correlation was made and a linear trend was found to exist for water flux through the membrane with UDMH concentration.

New nanopore zeolite membranes for water treatment

Zeolite membranes have been studied extensively for more than fifteen years, mainly focusing on gas separation and liquid pervaporation processes. Recently, molecular dynamic simulation has shown that zeolite membranes are theoretically suitable for ion removal from aqueous solutions by reverse osmosis (RO) processes. The separation mechanism of the zeolite membranes is the size exclusion of hydrated ions, which have kinetic sizes significantly larger than the aperture of the Hydroxysodalite (HS) zeolite (diameter 0.4nm). HS zeolite membrane indicates that it may be possible to simultaneously separate ions and dissolved organic compounds from water by RO processes. Zeolite membranes may be used as an alternative to polymeric membranes for desalination of seawater and wastewaters. HS zeolite membranes composed of a continuous intergrowth of HS zeolite crystals have been prepared hydrothermally on the surface of porous tubular supports. In this research, synthesis of zeolite HS membrane was investigated. SEM and XRD analysis have been used to confirm zeolite HS membrane formation. Membrane performance has been evaluated using an experimental pervaporation setup. Effects of operation condition (temperature, rate and pressure) on the membrane structure and performance have been investigated for HS zeolite membranes grown onto seeded mullite supports.