Zeolite Particle Size Research Articles

Comparative study on dehydration of isopropanol and acetonitrile by pervaporation using PEBA/PANI/zeolite mixed matrix membranes

ABSTRACT Isopropanol (IPA) and Acetonitrile (ACN) solvents form azeotrope with water and separation by conventional processes is energy intensive. So, Pervaporation (PV) process became quite prominent and an alternative technique for dehydration of azeotropic mixtures. The selection of membrane places a crucial role in pervaporative separation and Mixed Matrix Membranes (MMMs) were widely employed. In this context, MMMs designated as PEBA-PANI and PEBA-PANI-4A were prepared by embedding PANI, zeolite 4A fillers in PEBA matrix. The synthesised zeolite particles, pristine PEBA and MMMs were characterised by XRD, FTIR, as well as contact angle measurements. Further, surface morphology and average particle size of zeolite particles are observed using SEM. Sorption studies with varying composition of isopropanol, and acetonitrile aqueous mixtures were correlated with their PV performances. The PEBA-PANI-4A MMMs showed higher % sorption of 11.34 and 8.57 for IPA–Water and ACN–Water systems respectively. Similarly greater pervaporation flux and selectivity of 0.28 kg/m2h and 720 were obtained for IPA–Water and 0.068 kg/m2h and 564 for ACN–Water systems at 10 wt. % water concentration. The PV results revealed that the MMMs exhibited better performance than pristine PEBA. All three membranes showed greater sorption, flux and selectivity for IPA-Water system than ACN-Water system.

Improving the Thermo-Physical Properties of Plam Oil with Zeolite Nanoparticles

This research aimed to improve the thermo-physical properties of plam oil with NaA zeolite. Palm oil was selected for heating oil due to its high flash point and environmental friendliness compared to synthetic or mineral oil. The effect of NaA zeolite concentration suspended in palm oil was investigated in terms of the specific heat capacity (Cp), viscosity (μ), viscosity index (VI), thermal analysis (TGA) and density (ρ) of palm oil. The NaA zeolite was synthesized by crystallization technique, and X-ray diffraction analysis was performed to determine NaA zeolite crystallinity. The size of NaA zeolite was measured using a particle size analyzer. The average size of the synthesized NaA zeolite was 4767 nm. After grinding process for 180 min, the average size of zeolite decreased to 632 nm. An average 632 nm NaA zeolite particle size was added to palm oil at 0.25, 0.5, 0.75 and 1 wt%. The results showed that when the NaA zeolite concentration increased, the nanofluid’s viscosity at 40 °C and 100 °C was increased. The addition of 1 wt% NaA zeolite resulted in the nanofluid having a maximum viscosity of 41.31 and 8.47 cSt at 40 °C and 100 °C, respectively. The highest viscosity index was 195 cSt when added with 0.5 wt% NaA zeolite. The density of palm oil slightly increased with increasing NaA zeolite concentrations. The specific heat capacity of palm oil increased when NaA zeolite was added. The results showed that NaA zeolite allowed palm oil to store heat energy better than palm oil, enabling it to release and absorb more heat during heat transfer. Thermogravimetric analysis, palm oil initiated to degrade at 263 °C, while the addition NaA zeolite in palm oil indicated that palm oil initiated to degrade at 350 °C. The shift in the degradation curve demonstrated that the nanofluid could withstand high temperatures. Adding NaA zeolite to palm oil showed that palm oil could endure more heat and has a long service life.

Učinkovitost obrade elektrokoagulacije kombinirane s različitim veličinama čestica prirodnog zeolita

In a previous study, the larger size of synthetic zeolite particles was highlighted as better choice for electrocoagulation combined with zeolite (ECZ). This choice resulted in a smaller rise in pH and temperature, a more significant decline in turbidity as well as chemical oxygen demand (COD), and lower electrode wastage, but with greater damage to the electrode surface. The focus of this study was to determine whether natural zeolite of three different particle sizes has the same effect on the ECZ process. The Taguchi method L9 was employed in planning the experiments, with particle sizes of natural zeolite ranging up to 600 μm, three different electrode materials (carbon steel, aluminium alloy, and sacrificial zinc anode), current density in the range of 0.003–0.018 A cm<sup>–2</sup>, and contact time in the range 10–30 min. The Taguchi optimisation results revealed a more significant decrease in COD and turbidity with the smallest particle size of natural zeolite used (90 µm) and with Al electrodes. Evidently, the zeolite particle size, together with the zeolite composition, had a significant influence on the reduction in COD and turbidity. Anode consumption ranged from 0.0172 to 0.6469 g, with minor cathode consumption evident on all electrode materials. Optical microscopy analysis indicated significant corrosion of the anodes, particularly with the largest natural zeolite particle size of 160–600 µm, while minor corrosion damage was also observed on the cathodes.

Crystal growth regulation of Cu-SSZ-13 zeolites for effective catalytic reduction of NOx from automotive exhausts

In this study, glucose was used in the synthesis of SSZ-13 zeolites; it acted as a zeolite growth regulator to successfully change the morphology of SSZ-13 zeolites. The particle size of the SSZ-13 zeolites reduced from 10 to 3 μm, and the morphology of the zeolite surface changed from rough and irregular spherical to smooth and uniform cubic. The glucose-modified SSZ-13 zeolites were ion-exchanged with Cu2+ ions (named as Cu-SSZ-13-Glu) and tested for the catalytic reduction of NOx with NH3 (NH3–SCR). The results demonstrated that the catalyst Cu-SSZ-13-Glu exhibited better NH3–SCR catalytic performance than that of conventional Cu-SSZ-13, with a wider effective reaction window, superior low-temperature SCR performance, favorable anti-SO2 poisoning ability, and excellent hydrothermal stability. The characterization results of the Cu-SSZ-13-Glu sample revealed an increase in crystallinity as well as acidic sites, and an improvement in the redox properties. After hydrothermal aging, compared with traditional Cu-SSZ-13, the Cu-SSZ-13-Glu zeolites exhibited a more stable structure and maintained higher crystallinity, larger specific surface area, and microporous volume. Moreover, the Cu2+ ions in the Cu-SSZ-13-Glu zeolites were more stable, and fewer CuOx species were generated after hydrothermal aging, retaining more Cu2+ ions species and acidic sites. To summarize, the simply prepared Cu-SSZ-13-Glu zeolites exhibited excellent catalytic activity and hydrothermal stability, showing broad application prospects in the field of nitrogen oxide removal from automotive exhausts.

Particle size effect of pre-wet zeolites on autogenous shrinkage and mechanical properties of LECC

The conservation effects can vary significantly when utilizing zeolite internal curing (IC) agents of different particle sizes in Lightweight Engineered Cementitious Composites (LECC). This paper addresses this issue by investigating the impact of zeolites with varying particle sizes (with average particle sizes of 90 μm, 240 μm, and 410 μm) on the mechanical and shrinkage properties of LECC. Furthermore, it delves into the intrinsic influencing mechanisms through pore characterization parameters and quantitative techniques for assessing the degree of hydration. The results demonstrate that the particle size of zeolite exerts a substantial influence on the conservation efficiency of LECC. Specifically, small-sized zeolite effectively eliminates pores larger than 200 μm within the LECC matrix, resulting in significant enhancements in its mechanical properties (a 16% increase in compressive strength) and shrinkage resistance (a 54% reduction in shrinkage). Conversely, large-sized zeolite diminishes the mechanical properties of LECC, albeit contributing to some extent to improved shrinkage properties (a 32% reduction in shrinkage). The improved conservation effect of small-sized zeolite stems from the refined pore structure and the filling effect of volcanic ash. Pore structure analysis reveals that small-sized zeolite yields a finer pore structure, primarily distributed within the 12 μm range. This enhances water absorption and release, consequently improving conservation efficiency. Additionally, hydration product analysis indicates that small-sized zeolite promotes cement hydration, resulting in a 9% increase in the degree of cement hydration.

Influence of impeller clearance, impeller size and baffles on copper sorption on zeolite NaX: Do the size and position really matter?

Even though optimal mixing parameters may significantly influence the sorption process and its costs, the influence of hydrodynamics on sorption in a batch reactor hasn't yet been adequately studied. In this study, the hydrodynamic conditions produced by pitched blade turbine (PBT) impellers of various diameters and positions in baffled and unbaffled reactors were investigated. The objective was to investigate their influence on the just suspended impeller speed (NJS), power consumption per zeolite mass and the sorption process at the same temperature, initial copper solution concentration, and zeolite particle size in all the experiments conducted. The results show that NJS generally decreases as impeller diameter increases and is lower in the reactor without baffles. A transient multiphase computational fluid dynamics model was developed to provide valuable insight into the complex flow kinetics and it was found that the further the impeller is from the bottom of the baffled reactor the wider is the secondary suspension flow and the intensity of the flow below the impeller decreases. For this reason, complete suspension of the NaX zeolite particles in the solution was achieved at a higher PBT impeller speed. Due to the swirling motion of the suspension, this phenomenon is not observed in the unbaffled reactor for all the impellers used besides the smallest one. The power consumption per zeolite mass, at the state of complete zeolite suspension, increases in baffled reactor and decreases in unbaffled reactor with increasing impeller diameter having significantly lower values in the unbaffled reactor. The significantly lower power consumption per zeolite mass in an unbaffled system could be attributed to, not only the generally lower NJS values, but also to the resistance force which baffles make to the tangential fluid flow. The Ritchie model and Mixed surface reaction and diffusion controlled adsorption kinetic model were used for the kinetic analysis of the experimental kinetic data. The kinetic results indicate that the process is faster when the impeller is at the standard of bottom clearance, regardless of the presence of the baffles.

Modification of crystal growth of NaA zeolite with steric hindrance agents for removing ammonium ion from aqueous solution

The incorporation of steric effects into the hydrothermal synthesis system of NaA zeolite proves to be an effective method for modifying grain size, enhancing grain dispersion and obtaining single crystal products. In this study, three different molecular configurations, namely short-chain ethanolamine (MEA), long-chain polyethylene glycol (PEG), and ring-chain cyclohexanol (CyOH), were employed to investigate the impact of steric effects on the crystal growth of NaA zeolite. The crystal form, morphology, and particle size of NaA zeolite were characterized using XRD, FT-IR, and SEM techniques. The order of steric hindrance in terms of molecular configuration was found to be as follows: CyOH > PEG > MEA. NaA-CyOH exhibited a high dispersion of single crystal particles, the smallest grain size, and the largest specific surface area and pore volume. To evaluate the ammonium ion adsorption performance, NaA-CyOH-31, the zeolite with the best performance, was utilized for studying the reaction kinetics. The results indicated that the adsorption behavior of NaA zeolite towards ammonium ion could be better described by the quasi second-order equation and the Langmuir model. Furthermore, the evaluation of the regeneration ability of NaA-CyOH zeolite demonstrated that the recovered adsorbent still maintained a high level of adsorption performance.

Electrocoagulation Combined with Synthetic Zeolite—Does the Size of Zeolite Particles Matter?

Although electrocoagulation combined with zeolite (ECZ) shows higher efficiency in wastewater treatment, the actual contribution of zeolite particle size has not been fully explored. In this work, the influence of particle size of synthetic zeolite SZ (<90, 90–160, and 160–600 μm) on ECZ treatment of compost leachate with very high organic load is investigated together with different electrode materials (Fe, Al, and Zn), current densities (0.003, 0.009 and 0.018 A/cm2), and contact times (10, 20 and 30 min). The results positively highlight that the largest particle size should be used in ECZ, as it leads to a lower increase in pH and temperature, a higher decrease of chemical oxygen demand (COD) and turbidity, and a lower electrode consumption, while causing more damage to the electrode surface. The estimated energy costs ranged from 3.960 kW/m3–1313.657 kW/m3. The Taguchi L9 orthogonal configuration showed the highest COD and turbidity decrease under the conditions of 160–600 µm zeolite particles. The powder X-ray diffractometer (PXRD) analysis shows that interplanar spacing decreases when smaller and medium SZ particle sizes are used, while this effect was not observed with larger zeolite particle size. SEM-EDS shows that oxygen, silicon, and aluminium are the predominant elements in electrogenerated sludge coupled with zeolite.

Using Natural Zeolite as a Feed Additive in Broilers' Diets for Enhancing Growth Performance, Carcass Characteristics, and Meat Quality Traits.

Using natural zeolites as a food additive in poultry diets offers an intriguing perspective. The objective of this study was to investigate the effects of zeolite addition and particle size on broiler performance, carcass characteristics, meat quality, moisture of excreta and litter, and intestinal measurements during 35 days. A total of 560 1-day-old female Ross-308 broilers were divided into five treatment levels (0, 5, 10, 15, and 20 g zeolite/kg diet) (n = 16 replicates/treatment, n = 8 replicates /particle size of each treatment). Performance was calculated weekly. Carcass characteristics, meat quality, small intestine (SI) measurements, litter pH, and moisture content were determined on day 35. Litter pH, breast redness, cooking loss, chewiness, total weight, and SI length were all affected by zeolite treatments (p < 0.05). Particle size had an impact on the gastric pH and texture analysis. Their interaction had an effect on color redness, litter pH, and cooking loss. Performance was unaffected by either the main or interaction effects. Zeolite as a feed additive may be useful in broiler diets, particularly large particles. The performance and production efficiency factor improved numerically (p > 0.05) with increasing zeolite doses up to 10 g zeolite/kg diet.

Correlation between zeolitic particle size and the low-temperature NOx storage capacity of Pd/ZSM-11 passive NOx adsorber

The effect of zeolitic particle size on the NOx adsorption and desorption was investigated by synthesizing ZSM-11 zeolites with different particle sizes (0.5∼0.8, 1∼2, and 5∼6 μm) for doping Pd as passive NOx adsorbers (PNAs). Several characteristic techniques of XRD, HAADF-STEM, H2-TPR, CO-DRIFT, XPS and NH3-TPD were applied to clarify the essential association of the PNAs performance of Pd/ZSM-11 zeolites with the support zeolite properties and Pd active species. It was found that both the efficient Pd(II) species for assisting NOx adsorption-release and the acid amount (especially the strong acid sites) for facilitating Pd dispersion have positive correlation with the decrease of zeolite particle size. Differently, in addition to the active Pd species, meso-macroporosity properties are another key factors to determine the NOx adsorption ability of PNAs. The meso-macroporosity properties of Pd/Z11-1.5 show a negative correlation with the decrease of zeolite particle size while Pd/Z11-0.7's show the positive correlation with the decrease of zeolite particle size. As a consequence, Pd/Z11-1.5 with higher Pd(II) content but weaker meso-macroporosity properties than Pd/Z11-5.0 shows comparable adsorption capacity to Pd/Z11-5.0, while Pd/Z11-0.7 with both high Pd(II) content and good meso-macroporosity properties not only exhibits the highest NOx storage capacity, but also can release the NOx at the lowest temperature of less than 300 °C, indicating to be a good candidate for purifying NOx at the actual exhaust temperature of diesel vehicles.

Fluoride Adsorption from Aqueous Solution by Modified Zeolite-Kinetic and Isotherm Studies.

Fluorine is a very common element in the Earth's crust and is present in the air, food, and in natural waters. It never meets in the free state in nature due to its high reactivity, and it comes in the form of fluorides. Depending on the concentration of fluorine absorbed, it may be beneficial or harmful to human health. Similar to any trace element, fluoride ion is beneficial for the human body at low levels, but as soon as its concentration becomes too high, it is toxic, inducing dental and bone fluorosis. The lowering of fluoride concentrations that exceed the recommended standards in drinking water is practiced in various ways around the world. The adsorption process has been classified as one of the most efficient methods for the removal of fluoride from water as it is environmentally friendly, easy to operate, and cost-effective. The present study deals with fluoride ion adsorption on modified zeolite. There are several influential parameters, such as zeolite particle size, stirring rate, solution pH, initial concentration of fluoride, contact time, and solution temperature. The maximum removal efficiency of the modified zeolite adsorbent was 94% at 5 mg/L fluoride initial concentration, pH 6.3, and 0.5 g modified zeolite mass. The adsorption rate increases accordingly with increases in the stirring rate and pH value and decreases when the initial fluoride concentration is increased. The evaluation was enhanced by the study of adsorption isotherms using the Langmuir and Freundlich models. The Langmuir isotherm corresponds with the experimental results of the fluoride ions adsorption with a correlation value of 0.994. The kinetic analysis results of the fluoride ions adsorption on modified zeolite allowed us to demonstrate that the process primarily follows a pseudo-second-order and then, in the next step, follows a pseudo-first-order model. Thermodynamic parameters were calculated, and the ΔG° value is found to be in the range of -0.266 kJ/mol up to 1.613 kJ/mol amidst an increase in temperature from 298.2 to 331.7 K. The negative values of the free enthalpy ΔG° mean that the adsorption of fluoride ions on the modified zeolite is spontaneous, and the positive value of the enthalpy ∆H° shows that the adsorption process is endothermic. The ∆S° values of entropy indicate the fluoride adsorption randomness characteristics at the zeolite-solution interface.

Investigation of the microstructure and corrosion resistance of hydrothermal-synthesized MFI zeolite coating on H13 steel

Three different processes (non-3-aminopropyltriethoxysilane (APTES) pretreatment followed by one-step hydrothermal synthesis, APTES pretreatment followed by one-step hydrothermal synthesis, APTES pretreatment followed by two-step hydrothermal synthesis) were used to synthesize an MFI zeolite coating on mechanically polished H13 steel to improve corrosion resistance. The coatings synthesized by the different processes were remarkably different in terms of zeolite particle size, thickness, density, and corrosion resistance. In the case of the MFI zeolite coating synthesized on non-APTES-pretreated H13 steel, a non-dense gel layer and poorly intergrown zeolite particle layer lowered adhesion strength and corrosion ability, whereas the presence of the APTES film increased the density of the gel layer. Consequently, it showed better adhesion strength, and corrosion resistance with a lower corrosion current density (Icorr) and higher impedance value at 0.01 Hz. The adhesion strength and corrosion resistance of the MFI zeolite coating was further enhanced by two-step hydrothermal synthesis because the gel layer became denser and thicker in the early stages of secondary synthesis. The molten immersion test also indicated that the MFI zeolite coating had a high corrosion resistance in molten aluminum.

Silicalite-1 zeolites for toluene sorption: Effects of the particle size and intracrystalline mesopores

The diffusion limitation of conventional silicalite-1 zeolites was addressed by particle size modulation and intracrystalline mesopore introduction, and the two effects on toluene sorption over silicalite-1 zeolites were systematically investigated. The diffusion rate of toluene increases as the particle size of silicalite-1 zeolites decreases, while the introduction of mesopores into zeolite crystals can further increase the diffusion rate. However, higher diffusion rates of toluene do not always result in better adsorption capacity. The breakthrough time of silicalite-1 zeolites with different particle sizes shows a “volcano” shape. And the breakthrough time decreases after the introduction of intracrystalline mesopores into silicalite-1 zeolites. For toluene adsorption capacity, the microporous structure plays the main role, the mesoporous structure mainly diminishes diffusion limitation and improves the utilization of micropores. The nanosized zeolites with dispersed intracrystalline mesopores exhibit the best dynamic adsorption capacity with the lowest diffusion limitation. The short microporous diffusion path and abundant micropore structure are the vital parameters for silicalite-1 zeolite adsorbents with high performance.

Tunable Luminescence of Silver Nanoclusters Confined in SOD/FAU Zeolites and Selective Sensing for Organic Amine

A series of Ag-zeolite luminescent composites are prepared based on SOD and FAUY zeolites, and the effect of zeolite host particle size on their dynamic luminescent emission properties was discussed for the first time. The relationship between zeolite particle size and the nucleation of silver nanoclusters (AgNCs) is revealed. With the increase of zeolite particle size from nanometers to microns, the luminescent color of both Ag-SOD and Ag-Y composites shows significant blue shift. The observed tunable luminescence can be accounted for the slower nucleation rate of AgNCs in micron-scale zeolites with longer channels, resulting in smaller nuclearity of AgNCs within large-size zeolites, through the characterization of extended X-ray absorption fine structure, implying the important roles played by the zeolite themselves in determining the luminescence properties. Moreover, the composites prepared by us feature simple signal transduction, fast response (30 s), and excellent selectivity and sensitivity for discriminative luminescence detection of triethylamine and ethylamine, and they have good reversible luminescence response after sensing HAc gas, which might imply the potential applications in the volatile organic amine detection and information encryption field.

Equilibrium studies for the removal of manganese (Mn) from aqueous solution using natural zeolite from West Java, Indonesia

Manganese (Mn) is one of the heavy metals found in industrial wastewater, such as acid mine drainage, which has caused serious environmental problems worldwide. This equilibrium study was carried out to determine the maximum capacity of natural zeolite towards manganese removal from made aqueous solution as affected by zeolite quantity, particle size, activation temperature, and initial pH of the solution. The natural zeolites obtained from Tasikmalaya, West Java, Indonesia, were crushed and filtered into three groups of diameters: &amp;lt;0.5, 1-2, and 2-4 mm. Each group was divided into two sub-groups, one sub-group was heated in a muffle furnace at 250 &lt;sup&gt;o&lt;/sup&gt;C for two hours, and the other sub-group was left at room temperature (25 &lt;sup&gt;o&lt;/sup&gt;C). This experiment consisted of two sections. Section one was physical and chemical characterizations of the natural zeolite, using Scanning Electron Microscopy (SEM), X-Ray Diffraction, and X-Ray Fluorescence techniques. The second section was equilibrium studies using two series of 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, and 5 g of natural zeolites of each sub-groups, then respectively added with 50 mL of a solution containing 50 ppm Mn having pH of 5.5 and 7.0. All suspensions were shaken for 24 h and filtered. The filtrates were red for total dissolved Mn using Atomic Adsorption Spectrophotometer (AAS). Freundlich and Langmuir isothermic models were fitted to the collected data to describe the adsorptive behaviour of Mn toward natural zeolites. Data showed that 0.5 g of natural zeolite had removed the remarkably highest Mn from the solution, regardless of the size of the particles, thermal treatment, and initial solution pH. The smallest size of zeolite particle and higher initial solution pH tended to increase the adsorptive capacity of the natural zeolite toward Mn. The Freundlich isothermic model fitted better to Mn adsorption behaviour than the Langmuir model.

Effect of particle size of zeolite clay included in high-energy diets for feedlot lambs: Growth performance, dietary energy, carcass traits, and visceral mass.

Several reports on the effects of zeolite (ZEO) inclusion in diets for feedlot lamb diets have indicated improvements in dietary energy efficiency and decreases in internal fat. Inclusion levels and the type of zeolite used have been the main focus of those reports. However, the possible effect of the zeolite particle size on the growth performance and carcass characteristics has not yet been investigated. Forty-eight male intact Pelibuey × Katahdin lambs were fed for 67 days with a high-energy diet supplemented with ZEO as follows: 1) basal diet 0% ZEO (control); 2) basal diet 3% ZEO particle size 250 µM (sieve 60); 3) basal diet 3% ZEO particle size 149 µM (sieve 100); and 4) basal diet 3% ZEO particle size 74 µM (sieve 200). ZEO replaced corn grain and soybean meal in equal parts. At the end of feeding, lambs were slaughtered, and variables such as carcass characteristics and visceral mass were evaluated. Particle size did not affect growth performance, carcass characteristics, or visceral mass. The inclusion of ZEO reduced 3.4% of dietary net energy in diets but did not affect dry matter intake or average daily gain, thus improving (p ≤ 0.05) dietary energy efficiency by 2.9%. Except for an 18.9% reduction (p = 0.02) in visceral mass fat, ZEO did not affect other carcass characteristics or visceral organ mass. The particle size studied in the present experiment has not affected any of the variables of growth performance or carcass characteristics. ZEO inclusion could be a strategy to reduce the visceral fat in finishing lambs.

Optimal zeolite structure design for VOC emission reduction in asphalt materials

Asphalt releases a large amount of VOC when it is being heated, which is harmful to both workers and environment. Literatures indicates that porous materials might reduce asphalt VOC through physical adsorption and chemical adsorption, so that zeolite material is promoted to reduce the asphalt VOC due to its adsorption and catalytic properties. In this study, the VOC from zeolite-modified asphalt with different Si/Al ratio, particle size and crystal form were compared to explore the influence law of three zeolite structural characteristics on VOC reduction effect. Results show that Si/Al ratio influence the released VOC types. Small Si/Al ratio leads to inhibit branched alkanes, while large Si/Al ratios leads to inhibit alkenes and cyclic substances. Zeolite particle size has a greater impact on VOC emission amount than that of Si/Al ratio. Larger particle size has a better VOC reduction effect. Nano polycrystalline zeolite has stronger VOC reduction effect than single crystal zeolite. Above all, nano-polycrystalline zeolite with large particle size is a better choice to reduce benzene series.

The effects of dry grinding and wet grinding on synthesizing iodosodalite

How to dispose of radioactive iodine waste in a green and safe way has become a hot spot for research institutions around the world. In this study, we mainly compare the effects of wet grinding - hydrolysis transformation - sintering (wet grinding) and dry grinding - cold pressing - sintering (dry grinding) on the synthesis of iodosodalite. The analysis results show that the particle size of 4A zeolite treated by wet grinding for 2.5 ​h is approximately 5.5 ​μm. The results of in situ XRD, infrared spectroscopy, and in situ Raman show that the effect of wet grinding and refining treatment is more obvious for iodosodalite synthesis at 900 ​°C. TEM-EDS shows that the morphology of iodosodalite prepared by the wet method is more intact. Based on the above results, it is demonstrated that the wet milling treatment method is more favorable for the synthesis of iodosodalite.

Nano and natural zeolite feed supplements for dairy goats: Feed intake, ruminal fermentation, blood metabolites, and milk yield and fatty acids profile

Zeolite particle size can affect its characteristics as a rumen modifier, thus its form may not only affects the goats' health during the transition period but also their milk quantity and quality. Our objectives of this study were to evaluate the effects of zeolite supplementation either in its natural or nano form on ruminal fermentation characteristics, blood biochemical parameters, and milk production and chemical composition of dairy goats. Thirty-nine late pregnant Damascus goats (initial body waight: 26.1 ± 0.93 kg, mean ± SD) were randomly assigned to three experimental dietary treatments (n = 13/ treatment) for 90 days of an experimental period: The control treatment was fed a basal diet without feed additives, natural zeolite [supplemented at 20 g/kg of dry matter (DM) to the basal diet], and nano zeolite (supplemented at 0.4 g/kg DM to the basal diet). Both zeolite forms increased (P < 0.05) ruminal pH, total protozoal count, Diplodinium spp ciliates, and reduced (P < 0.01) ammonia, while nano zeolite enhanced the total short-chain fatty acids concentration compared to the control. Supplementation of nano zeolite increased (P = 0.01) the blood calcium and reduced (P < 0.05) total cholesterol, total lipids, aspartate aminotransferase, alanine aminotransferase activities compared to other diets. Goats fed nano zeolite produced higher (P < 0.01) milk yield without affecting the feed intake, while both zeolite forms resulted in similar reductions (P < 0.05) in milk fat, protein, lactose, solid not fat, and somatic cell count. No differences were detected in milk total saturated fatty acids and total odd and branched-chain fatty acids among treatments while, nano zeolite reduced (P = 0.03) milk concentration of eicosanoic acid (C20:0). Natural zeolite tended to reduce (P = 0.08) the concentrations of total mono-unsaturated fatty acids in milk, while nano zeolite resulted in higher (P = 0.04) miristoleic (C14:1-Cis9; omega 5) than the control. No differences were detected in the total and individual polyunsaturated fatty acids compared to the control. In conclusion, nano zeolite was more pronounced as a feed additive than its natural form to support goats through late pregnancy to early lactation and to enhance milk quality.

Selective production of light olefins over zeolite catalysts: Impacts of topology, acidity, and particle size

Compared to conventional steam cracking, catalytic cracking of naphtha and methanol-to-olefins (MTO) over zeolite catalysts have been proved as the most successful processes for producing light olefins. To achieve the maximum light olefins yield and the longest lifetime, zeolite catalysts with excellent catalytic performance should be designed, by choosing suitable structure and regulating their physicochemical properties. In this review, the impacts of topology, acidity, and particle size of zeolites on the catalytic performance of naphtha cracking and MTO reactions, especially the light olefins selectivity and lifetime are systematically discussed. We hope that this review can be helpful not only to deeply understand the structure–property-performance relationship of various zeolite catalysts, but also to design more excellent zeolite catalysts for these two processes.