Quantity Of Zeolite Research Articles

Hydrodeoxygenation of linoleic acid using water as hydrogen source on Co/HB zeolite

Hydrodeoxygenation (HDO) is a critical step in upgrading biomass-derived feedstock to renewable fuels and valuable chemicals. Thus, preserving the environment through the use of agricultural waste. Water plays the role of solvent, reactant, or byproduct in biomass HDO reactions, which are catalyzed by Co/HB zeolite catalysts. In this investigation, The hydrodeoxygenation of linoleic acid was examined in a patch-packed-bed reactor with a beta zeolite range of (5-15) mg and catalyzed at a temperature range of 230-300 K for 2-3 h. Linoleic acid, an unsaturated fatty acid, was used in this work to create hydrocarbons in the diesel range, as well as to clarify the impact of zeolite quantity, temperature, and time on the yielded product, to produce biofuels from Linoleic acid by hydrodeoxygenation in the high-pressure reactor in the presence of the catalyst. The products are then characterized by gas chromatography-mass spectrometry (GC-MS). Based on the optimization results, it was determined that the hydrodeoxygenation reaction primarily eliminated the oxygen atoms from fatty acids. The yield of the intended products was 96.2% at the Co/HB zeolite amount (10% wt), high reaction temperature (270 ºC), and time (150 min) conditions.

Zeolite addition in microalgae Chlorella sp. for treatment of bacteria contaminated vinasse

AbstractChlorella pyrenoidosa has been grown in artificial vinasse digestate. The method being used is intended to gather data on kinetic parameters that govern the performance of C. pyrenoidosa cultivated in a medium containing bacterial components. This condition was developed by introducing 1000 μL of Bacillus cereus to the medium (5 ppm of vinasse: 15 ppm of NaHCO3 = 3:2), which was subsequently mixed with C. pyrenoidosa culture at a 1:1 v/v ratio. The cultivation was carried out in batch mode for 15 days. The photosynthesis process of C. pyrenoidosa was conducted in 14 h and supported by 2 mL L−1 Guillard, which was given every 5 days. The study additionally investigated how different amounts of Zeolite (30, 60, and 90 gL−1) affected the kinetic parameters of microalgae grown in artificial vinasse digestate. This study demonstrated that the utilization of artificial vinasse digestate as a growing medium for C. pyrenoidosa resulted in growth limitation symptoms of microalgae, as a consequence of unfavorable interaction between C. pyrenoidosa and bacteria that already existed in the medium. This is indicated by low values of growth kinetics parameters, including specific growth rate (0.0259 d−1) and biomass productivity (0.51774 gL−1d−1) as compared to the reactor without bacteria in the medium. Therefore, adding a certain quantity of Zeolite to the reactor is a promising alternative for mitigating the negative effects of bacterial presence. With the addition of 90 g L−1 of Zeolite to the reactor, the specific growth rate of C. pyrenoidosa increases by 71%, indicating an appropriate growth. In addition, the total yield of PHB formation and the Melanoidin degradation efficacy of this reactor improved by 70% and 98%, respectively.

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: <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 <sup>o</sup>C for two hours, and the other sub-group was left at room temperature (25 <sup>o</sup>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.

Enhanced crystallization and properties of poly(ethylene terephthalate) nanocomposites with zeolites from 3D to 2D topologies

To improve the low crystallization rate and long molding cycle of Poly(ethylene terephthalate) (PET), series of PET nanocomposites incorporated small quantities of zeolites with different topologies were blended by melt compounding. The nucleation influence of 3-dimensional zeolites Y, ZSM-5 and 2-dimensional zeolite MCM-22P on the crystallization manner of PET was analyzed by non-isothermal and isothermal crystallization, quantitative evaluation of nanoparticle dispersion and morphology of nanoparticles. The results show that all PET/zeolite nanocomposites exhibit higher crystallization temperature and faster crystallization rate than PET due to large specificsurfacearea of zeolites and their superior dispersion in the PET matrix. Among them, PET/MCM-22P nanocomposites remarkably improved the crystallization behavior, thermal stability and oxygen barrier properties, which is related to the layered morphology of MCM-22P and hydrogen bond interactions between MCM-22P and PET. It is revealed that MCM-22P can provide more heterogeneous nucleation sites for PET by exfoliation in melting compounding. Furthermore, the nucleation mechanism induced by MCM-22P was investigated by the means of Mozhishen method, Avrami equation and theory of Hoffman-Lauritzen. The results indicate that the incorporation of MCM-22P can decrease the free energy of nucleation and fold surface in PET crystallization process, thus improving the crystallinity.

Effects of Zeolitic Urea on Nitrogen Leaching (NH4-N and NO3-N) and Volatilization (NH3) in Spodosols and Alfisols

Global use of urea nitrogen (N) fertilizer is increasing, but N losses are still very high (40–70%). Zeolites have the capability of holding NH4+, thus reducing N losses when applied as a soil amendment. However, application of a large quantity of zeolite is costly and inconvenient. In this study, zeolitic fertilizers were evaluated to select the best formulation with reduced leaching of NH4-N and NO3-N and NH3 volatilization in agricultural soils (Alfisol and Spodosol). The treatments included the following: T0 = control, T1 = urea fertilizer, T2 = zeo-urea (1:1), T3 = zeo-urea (2:1), T4 = zeo-urea (3:1), T5 = zeo-urea (1:2), and T6 = zeo-urea (1:3). Leaching was performed at 4, 8, 12, 19, 25, 32, 39 and 45 days after the soils were treated with the designated fertilizers, including control, and packed into columns. Leachate samples were collected after each leaching event and analyzed for the concentrations of NH4-N and NO3-N and the quantity of leachate. Ammonia volatilization was recorded at days 1, 5, 9, 13 and 20 of soil treatments. Results indicate that zeolitic fertilizer formulations effectively reduced N losses. NH4-N loss was reduced by 13% and 28% by zeo-urea (1:1) in Alfisol and Spodosol soils, respectively, whereas zeo-urea (2:1) and zeo-urea (3:1) effectively decreased NO3-N leaching in Alfisol. Volatilization loss of NH3 was reduced by 47% in Spodosol and 32% in Alfisol soil with zeo-urea (1:1) as compared with that of urea fertilizer. The results suggest that zeo-urea (1:1) is an effective fertilizer formulation for reducing N losses, especially in Alfisol, as compared with conventional urea fertilizer.

Enhanced Nitrogen Removal and Anammox Bacteria Retention with Zeolite-Coated Membrane in Simulated Mainstream Wastewater

The anammox process has been used for side-stream nitrogen removal. Mainstream anammox is challenging, however, as a result of low ammonium concentrations and retention times that wash out slow-growing anammox bacteria. To overcome these challenges, hollow fiber membranes with zeolite-coated surfaces were prepared to create near-surface microenvironments that mimic attributes of side-stream treatment systems. Results showed that in mainstream-type media, zeolite-coated membranes enhanced the growth of anammox bacteria on the membranes and in the bulk liquid of the reactor compared to reactors containing uncoated control membranes. The zeolite-coated membranes also improved the average total nitrogen (TN) removal to 73 ± 10% compared to 1 ± 49% in the control reactors. Additional experiments containing zeolite particles demonstrated that increasing zeolite mass increased the number of anammox gene copies present and improved TN removal, with effluent TN concentrations decreasing from 51.8 ± 5.9 to 7.78 ± 2.6 mg-N/L (P = 0.00085) as zeolite increased from 0.05 to 1.0 g/reactor, respectively. These results suggest that membranes/surfaces containing a greater quantity of zeolite should further improve retention of anammox bacteria and TN removal. Application of such membranes in an integrated fixed-film activated sludge (IFAS)-type system or membrane-aerated biofilm reactor (MABR) with intermittent aeration and low bulk DO concentrations should facilitate mainstream anammox.

Sandstone Acidizing Using a Low-Reaction Acid System

Abstract Sandstone acidizing is the process of removing the damage from sandstone reservoirs to restore the well productivity/injectivity to its original or expected rates. It differs from carbonate acidizing in which a substantial portion of the rock is dissolved. Stimulating sandstone with mud acid HF/HCl may cause many problems as sandstone is a clastic sedimentary rock that consists mainly of quartz, silica minerals, feldspars, clays, and minor quantities of zeolite and chlorites. When conventional mud acid reacts with rock some sensitive components of sandstone get cemented by silica, calcite, or iron oxides. This happens due to the different precipitation reactions that take place and form fluosilicates, calcium fluorides, silica-gel filming, and even colloidal silica-gel compounds. In this work, two chelating agents, hydroxyethylenediaminetetraacetic acid (HEDTA) and diethylenetriaminepentaacetic acid (DTPA), were used to stimulate Berea sandstone cores. Berea sandstone cores were scanned using the XRD to quantify their mineralogical composition. Different pore volumes of 0.6M HEDTA and 0.6M DTPA were used as a preflush followed by different concentrations of HF as a main flush. For the post-flush stage, ammonium chloride was used to flow back the cores and measure their permeability. The levels of calcium, magnesium, aluminum, and iron ions in the effluent samples were measured using inductively coupled plasma (ICP) to assess the ability of each chemical to leach these different ions. Both HEDTA and DTPA showed a strong capability of chelating calcium, iron, and magnesium ions from the sandstone cores while the amounts of chelated aluminum ions were quite small. Once starting the injection of the used chelating agents, the permeability of the core got enhanced gradually. The higher amounts of the chelating agents resulted in better the cores permeability. However, DTPA showed a better permeability enhancement than HEDTA due to its stronger ability to chelate the calcium, iron, magnesium, and aluminum ions. Adding HF as the main flush initiates different reactions with the clay and silica minerals of the Berea sandstone cores. This caused a reduction in the permeability due to the formation of some precipitates such as fluosilicates and calcium fluorides. Therefore, it is recommended to use a very low concentration of HF while treating the Berea sandstone.

Kinetics and Equilibrium Studies for the Removal of Mn and Fe from Binary Metal Solution Systems Using a Romanian Thermally Activated Natural Zeolite

In the present study, the sorption behavior of iron (Fe) and manganese (Mn) from a binary metal solution system onto thermally activated natural zeolite was studied. Batch adsorption experiments were carried out to investigate the effects of zeolite quantity, particle size, and activation temperature. Equilibrium studies were carried out to evaluate the adsorption capacity of the thermally activated natural zeolite. The obtained results showed that the thermally activated natural zeolite favored the removal of Fe over Mn, due to competition between them. Elemental analysis of the activated zeolite samples obtained by energy-dispersive X-ray analysis (EDX) indicated a Si/Al ratio >4, which is specific for clinoptilolite-type zeolite. The removal of Fe and Mn was best described by the Langmuir model, indicating the formation of a monolayer on the surface of the activated natural zeolite. The kinetic results revealed that the experimental data were best fitted by the pseudo-second-order model for both metals. The results suggest that a new natural zeolite from Rupea quarry, Brașov County, Romania could be used as a potential adsorbent for removal of Fe and Mn from binary metal solution systems, addressing the lack of information about this material from this region.

Potential Application of Chilean Natural Zeolite as a Support Medium in Treatment Wetlands for Removing Ammonium and Phosphate from Wastewater

This study aims to evaluate the sorption characteristics of NH 4 + -N and PO 4 3 − -P onto the surface of natural zeolites coming from Chile and their potential application in the subsurface-flow treatment wetlands for wastewater treatment in rural areas. For this purpose, adsorption experiments onto the zeolite were developed in batch assays. The effects of the adsorbent quantity (20 g and 50 g) and particle size (0.2–1.0 mm; 1.5–3.0 mm, and 5.0–8.0 mm) were evaluated in terms of adsorption capacity at different NH4+-N and PO4−3-P concentrations. Then, the obtained laboratory results were adjusted to theoretical models: Saturation-growth-rate and Langmuir. The saturation adsorption of NH4+-N on the zeolite increases at the same time that the initial concentration increases for the same zeolite quantity; however, the saturation values were similar between the different zeolite sizes tested. For PO4−3-P, the adsorption did not have a direct relationship with the initial concentration nor zeolite quantity and better results were only achieved for zeolite sizes of 1.5–3.0 mm. Regarding the Langmuir model, sizes of 1.5–3.0 mm had the best adsorption characteristics, with the maximum adsorption capacity of up to 1.58 mg/g for NH4+-N and up to 0.08 mg/g for PO4−3-P. Therefore, a new material—a natural zeolite from the Maule Region of Chile—is described as a potential support medium for treatment wetlands.

Potentiality of the Use of Pyroclastic Volcanic Residues in the Production of Alkali Activated Material

Volcanic rocks have been used for building activity by the inhabitants of important cities located on the slopes of Mt. Etna, Italy. In this paper, the potential use of volcanic residues (code 20 03 03—“Municipal waste” residues from road cleaning in the European Waste Catalogue (EWC)) for the production of alkali activated material, especially devoted to the restoration of buildings belonging to the Baroque Sicilian architecture, was investigated. In particular, large volcanic pyroclastic deposits of recent eruptions considered waste materials were studied and a volcanic paleo-soil, locally named ghiara, widely used for mortars and plaster production in XVII–XVIII century with good pozzolanic features, was also considered. Both volcanic materials were activated using different mixtures of NaOH and Na2SiO3. Furthermore, formulations with different amount of metakaolin addition (10–25 wt%) were prepared due to low reactivity of volcanic materials and to allow the activation at room temperature. X ray diffraction revealed the formation of small quantities of zeolites as a result of the alkali activation process. The mechanical-physical results evidenced that the mechanical strength is strongly dependent on the metakaolin amount (10–38 MPa); accessible porosity average 25% and an average pore diameter of 0.06 µm; water absorption range 9–15%, eluates conductivity in the range 20–350 µS/m. These results confirm the occurring of alkali activation and the good potential for these pyroclastic wastes for valorization in the restoration field.Graphic

Use of Mechanochemical Activation and Ultrasonic Treatment for the Synthesis of LTA Zeolite

The processes of LTA zeolite synthesis from mixtures of metakaolin and solid sodium hydroxide with an overstoichiometric quantity of alumina (molar composition of the mixture Al2O3·2SiO2: NaOH: Al2O3 = 6: 12: 2) were examined in relation to the treatment method used in the first step (mechanochemical activation or ultrasonic treatment). Formation of cubic sodium aluminate in the first step was established in both cases. Subsequent heat treatment in the case of mechanical activation resulted in the synthesis of the LTA zeolite, and in the case of ultrasonic treatment, in the synthesis of sodium aluminosilicates. After final hydrothermal crystallization the LTA zeolite quantity exceeded 95 wt %. The zeolite phase morphology was shown to depend on the treatment method used in the first step of the synthesis.

Efecto de la inclusión de zeolita (clinoptilolita) en ovinos en etapa de finalización: Respuesta productiva y energética de la dieta

El objetivo de este estudio fue evaluar el efecto de la adición de diferentes niveles (0, 1,5, 3 y 4,5%) de zeolita en dietas integrales de finalización sobre la respuesta productiva y la eficiencia en la utilización de la energía neta de la dieta de ovinos de pelo. Para lo anterior, 40 ovinos machos ¾Katahdin × ¼Pelibuey (peso inicial = 32,28±2,34 kg) se asignaron a 20 corraletas (2 ovinos/corraleta, 5 corrales/tratamiento) alimentándose durante 75 días con alguno de los 4 tratamientos. Las dietas ofrecidas fueron tipo integral. La dieta testigo (sin zeolita) contenía 16,51% de proteína cruda (PC) y 1,39 McalENg/kg y la cantidad total de zeolita incluida en cada tratamiento sustituyó al maíz y a la pasta de soja en partes iguales. Por cada nivel de sustitución del maíz-pasta de soja se disminuyó la concentración de PC en 0,11 puntos porcentuales y la energía neta en 0,03 Mcal/kg. El sustituir maíz y pasta de soja por zeolita hasta un nivel de 1,5% en la dieta no afectó el consumo de materia seca (MS), la ganancia diaria, la eficiencia alimenticia, la utilización de la energía neta de la dieta (EN observada sobre la EN esperada) o la retención aparente de energía por unidad de MS consumida. El aumentar a el nivel de suplementación de zeolita por encima de 1,5% incrementó la eficiencia alimenticia, la utilización de la energía neta de la dieta y la retención aparente de energía por unidad de MS consumida siendo la respuesta máxima para el nivel de inclusión de 3% (componente cuadrático, p<0,01). Con respecto al grupo testigo, la inclusión de 3% de zeolita a la dieta mejoró (p<0,01) en 6,8% la eficiencia alimenticia, en 8.4% la utilización de la energía neta de la dieta y en 8,9% la retención aparente de energía por unidad de MS consumida. La inclusión de zeolita por encima de 1,5% a dieta de finalización mejora la utilización de la energía neta de la dieta. En base al rendimiento productivo y la eficiencia en la utilización de la energía neta de la dieta, la respuesta óptima observada para los corderosen el presente estudio fue con el 3% de inclusión de zeolita.

Influencia de la sustitución parcial del maíz y dela pasta de soja por zeolita en ovinos en etapa de finalización: Características de la canal, composición tisular y masa visceral

The aim of this study was to evaluate the effect of different supplemental levels (0, 1.5, 3 and 4.5%) of zeolite in partial substitution of dry rolled corn and soybean meal in a finishing diet formulated on dry-rolled corn basis (16.51% CP and 1.39 Mcal/kg NEg) on carcass characteristics, tissue composition and visceral organ mass in hairy lambs. Total quantity of zeolite included replaces corn and soybean meal in equal parts, so that, for each level of which corn and soybean meal were substituted, CP concentration decreased 0.11 percentage points and net energy decreased 0.03 Mcal NEg/kg. Feeding phase was performed with 40 lambs ¾ Kathadin × ¼ Pelibuey (initial weight = 32.28 ± 2.34 kg) which were assigned to 20 pens (2 lambs/pen, 5 pens/treatment) and were feeding for 75 days with one of the four treatments. Zeolite inclusion did not affect carcass characteristics, but tended to linearly increase (p=0.10) LM area. Zeolite inclusion linearly increased (p≤0.04) the quantity and the proportion of muscle, and decreased (p=0.02) the quantity and the proportion of fat in shoulder, thus increasing (linear component, p=0.02) the muscle:fat ratio. In proportion to the half carcass, the weight of forequarter tended (p=0.08) to increase, while the weight of hindquarter tended (p=0.08) to decrease with zeolite inclusion. Zeolite inclusion tended (linear component, p=0.08) to increase the weight (as g/kg of EBW) of intestines. As result of a linearly decreases of mesenteric (p<0.01) and omental (p=0.03) fat with zeolite inclusion, visceral fat tended (p=0.07) to decrease as zeolite inclusion was increasing in diet. Changes of protein and energy concentration in diet as result of partial substitution of corn and soybean meal by zeolite did not negatively affect carcass yield nor primary cuts. Levels up to 4.5% of zeolite inclusion to diets favors greater muscle deposition, lower visceral fat and lower fat tissue composition in lambs fed with finishing diets.

Determination of the zeolite optimal diameter for the settlement of nitrifying bacteria in an aerobic bed fluidized reactor to eliminate ammonia nitrogen

In this work, the determination of the diameter of zeolite as a support for a microbial aerobic fluidized bed reactor is performed. The design of the reactor is recommended by Navarro and Palladino [1]. For the present study, the zeolite is crushed and classified granulometrically. Subsequently, the diameters of 0.5, 1 and 2 mm are arbitrarily chosen for the study of microbial adhesion. After the study of adherence of nitrifying bacteria, the obtained adhesion values for each diameter are not significantly different from each other. However, 1 mm is chosen to achieve higher adhesion values. Subsequently the aerobic fluidized bed reactor proposed by Navarro and Palladino [1] is built with the 1 mm-diameter zeolite. This presented an inlet flow of 1.35 mL.min-1 and a capacity of 8 L. The optimized quantity of zeolite for proper fluidization is 500 g, which is an 8% of total volume of the column. During operation, a good efficiency of reduction of the organic material is observed (50%).

MECHANICAL AND THERMAL PROPERTIES OF POLYPROPYLENE REINFORCED BY CALCINED AND UNCALCINED ZEOLITE

This study was carried out to compare mechanical and thermal properties of polypropylene (PP) reinforced with uncalcined and calcined zeolites. The PP samples were reinforced with zeolites at various quantities of 2, 4, and 6 (wt %). The comparison of the two types of zeolite was based on mechanical properties, including tensile strength, elongation at break, and Young’s modulus, and thermal characteristics analyzed using DSC, and DTA/TGA technique. The results obtained clearly revealed that both zeolites were able to significantly increase tensile strength and Young’s modulus of the samples, with calcined zeolite was found to work better. Addition of calcined zeolite was found to result in increased fracture elongation of the samples reinforced with up to 4 wt% zeolite but decreased sharply for the sample reinforced with 6 wt% zeolite, while for the samples reinforced with uncalcined zeolite, no consistent trend was observed. Thermal analyses demonstrated that the samples reinforced with calcined zeolite are more resistant to thermal treatment than those reinforced with uncalcined zeolite, as indicated by their higher decomposition temperature. DSC analysis revealed that there was no significant difference of the melting points of the samples was observed, but the effect of the quantity of zeolite on enthalphy was quite evident, in which the enthalpies of the samples reinforced with calcined zeolites were relatively lower than those of the samples reinforced with uncalcined zeolites.

The Development of Haydite Biological Filter by Natural Zeolite Doped with Fly Ash

Complex natural zeolite, fly ash, coment and adherent were chosen as the initial components for preparing biological filter haydite of 5- 7 mm in diameter used in wastewater. The haydite preparation using orthogonal of experiment measured the bulk density, apparent density, specific surface area, crushing strength and wear rate. According to the principles for making aggregates and the results of the orthogonal design method obtained the optimal ratios of the components and reaction time. The results show that zeolite quantity 60%, coment-to- fly ash 6:4 , adherent quantity 4%, zeolite haydite natural drying time 2.8 h, curing in tap-water 28 d. The microstructures and characters of zeolite aggregates were observed by scanning electronic microscope.

Effect of varied quantities of zeolite on the reduction of polycyclic aromatic hydrocarbons in tobacco smoke

This research was carried out to determine the possibility of total and selective reduction of polycyclic aromatic hydrocarbons (PAHs) content in cigarette smoke by applying different amounts of zeolite directly to the cigarette blend. Zeolite catalysts CuZSM-5 were applied in the form of suspension to the cut tobacco blend in the quantities of 1 and 3%. After the equalization of the blend, the cigarettes were rolled on the cigarette making machine type MOLINS–9. The cigarettes were smoked according to the standard of ISO 3308 procedure. The smoke condensate which was extracted from Cambridge filter with methanol was analyzed by gas chromatography-microscopy (GC-MS). The obtained results indicated that there is a possibility of effective and selective catalytic reduction of PAHs in tobacco cigarette smoke. The determined reduction degree for the PAHs was 35.78 to 40.88%. The decrease of PAHs was proportional to the quantity of the zeolite added. CuZSM-5 showed a certain selectivity, especially towards fluoranthene (reduction ratio was 55.25:77.96%) and acenaphthylene (reduction ratio was 42.39:71.15%). It is possible to apply zeolite in the form of suspension to factory-made cigarettes because it does not affect the operation of machinery, especially the work of a cigarette maker.

Asphalt Production at Reduced Temperatures using Zeolites and the Impact on Asphalt Performance

ABSTRACT The potential benefits of producing and paving asphalt at lower temperatures are beyond discussion. There is already a lot of know-how on various techniques for producing warm mix asphalt, but there is insufficient data available about the impact of these techniques on the final performance characteristics of the asphalt. Nynas and BRRC are working together on a research project, to study the most important and promising warm mix techniques on laboratory and field scale. These techniques are: the use of foamed bitumen, the addition of waxes to the bitumen and the addition of zeolites to the mixture. The present paper focuses on the last technique. The performance of warm asphalt mixtures produced with different types and quantities of zeolites is compared to the performance of a reference hot mix asphalt. Several aspects have been studied: compactability, permanent deformation, water sensitivity and low temperature cracking. Small scale field trials were made to validate the findings of the laboratory research.

Structural Evolution of Fly Ash Based Geopolymers in Alkaline Environments

The effects of immersion in alkaline solutions on the gel structure and pore network of fly ash based geopolymers are investigated. Immersion in carbonate or hydroxide solutions of up to pH 14 results in very little leaching of framework components (Si or Al) from the geopolymer gel, and a largely unchanged mesoporous gel structure. Higher concentrations, up to 8 M NaOH, cause more damage to the gel framework as species are leached into solution and the pore network collapses. Crystallization of small quantities of zeolites from the initially X-ray amorphous gel is also observed. The zeolitic products formed are in general the same products that are observed in geopolymers cured at elevated temperatures for extended periods of time, suggesting that the reactions taking place during alkaline immersion are to some extent a continuation of the initial geopolymerization process.

Interaction between antimicrobial drugs and antacid based on cancrinite-type zeolite

A carbonated–nitrated cancrinite-type zeolite was synthesized using zeolite X as silicon and aluminum source under strongly alkaline conditions (NaOH and Na 2CO 3). Additionally, a hydrotalcite-like compound of 0.20 Al/(Al + Mg) ratio with nitrate and carbonate anions into its interlayer was also synthesized. Both solids were characterized by means of techniques such as XRD, FT-IR and BET surface area. These techniques confirmed the presence of pure cancrinite-type zeolite and hydrotalcite, without the presence of collateral phases. These solids had been previously tested as antacid agents and determined their interaction with acidic solution of aspirin. The results showed that these solids could be used as effective antacid without any possible interaction between both drugs. Following with our studies, we determined a possible interaction among tetracycline molecules and our synthesized antacids. These studies were carried out by UV–visible analysis of the supernatants and FT-IR of the interacted solids with tetracycline solutions. Variable quantities of zeolites and hydrotalcites were weighed and placed in contact with aliquots of tetracycline acid solutions at 37 °C and under agitation for 1 h to simulate stomach conditions. The FT-IR studies did not show interaction between the tetracycline molecule and these solids, however, in the studied supernatants, it was possible to confirm the formation of complexes among the cations from the dissolved solids and the tetracycline molecule. These interactions, determined by UV–visible spectrometry, were higher when pH increased. Also, these interactions were superior in the hydrotalcite than in cancrinite zeolite due to a large number of species in solution (Al 3+ and Mg 2+). In spite of our results, we believe that it is possible to administer cancrinite–zeolites as antacid 1 h before administering drugs based on tetracycline. Additionally, these results could represent an important advance in the formulation of new broad range drugs for medical applications.