Silica Zeolite Research Articles

Development of Biomass Based-Activated Carbon for Adsorption Dehumidification

The demand for dehumidification in tropical regions contributes to a significant portion of the building energy consumption. Desiccant dehumidification can mitigate energy consumption by recovering the exergy potential from the waste heat and renewable energy sources. Material development is the bottleneck in realizing the full potential of desiccant dehumidification systems beyond conventional adsorbents such as silica gel and zeolite. Therefore, it is necessary to develop novel materials that can be regenerated using the heat source under 70°C. In this study, we developed activated carbons (ACs) as the desiccant materials derived from waste biomass. The ability of activated carbon (AC) to remove the moisture was controlled by carefully preparing the material using several conditions to achieve the right operation window for optimum moisture sorption processes. The porous and surface characteristics of the newly-prepared AC were analyzed and compared with those of silica gel. The adsorption isotherm measurements were conducted, and the data were fitted with Henry-Sips and Do-Do isotherm models. The current AC exhibited an excellent water adsorption capacity (up to 0.41 g/g). The efficacy of the ACs for dehumidification applications was assessed using the weather data from several regions of Indonesia, from North Sumatera to Papua. The results revealed that under the studied conditions, the new desiccant material showed a better dehumidification capacity than silica gel. Moreover, the reported AC can be regenerated using temperatures as low as 40°C, which is readily available from waste heat, including the heat rejection from the condenser of any air-conditioning unit.

Neuroprotective Effect of Terpenoids Recovered from Olive Oil By-Products.

The neuroprotective potential of 32 natural extracts obtained from olive oil by-products was investigated. The online coupling of supercritical fluid extraction (SFE) and dynamic adsorption/desorption allowed the selective enrichment of olive leaves extracts in different terpenoids’ families. Seven commercial adsorbents based on silica gel, zeolite, aluminum oxide, and sea sand were used with SFE at three different extraction times to evaluate their selectivity towards different terpene families. Collected fractions were analyzed by gas chromatography coupled to quadrupole-time-of-flight mass spectrometry (GC-QTOF-MS) to quantify the recoveries of monoterpenes (C10), sesquiterpenes (C15), diterpenes (C20), and triterpenes (C30). A systematic analysis of the neuroprotective activity of the natural extracts was then carried out. Thus, a set of in vitro bioactivity assays including enzymatic (acetylcholinesterase (AChE), butyrylcholinesterase (BChE)), and anti-inflammatory (lipoxidase (LOX)), as well as antioxidant (ABTS), and reactive oxygen and nitrogen species (ROS and RNS, respectively) activity tests were applied to screen for the neuroprotective potential of these extracts. Statistical analysis showed that olive leaves adsorbates from SS exhibited the highest biological activity potential in terms of neuroprotective effect. Blood–brain barrier permeation and cytotoxicity in HK-2 cells and human THP-1 monocytes were studied for the selected olive leaves fraction corroborating its potential.

Extraction and Mass Spectrometric Characterization of Terpenes Recovered from Olive Leaves Using a New Adsorbent-Assisted Supercritical CO2 Process.

This work reports the use of GC-QTOF-MS to obtain a deep characterization of terpenoid compounds recovered from olive leaves, which is one of the largest by-products generated by the olive oil industry. This work includes an innovative supercritical CO2 fractionation process based on the online coupling of supercritical fluid extraction (SFE) and dynamic adsorption/desorption for the selective enrichment of terpenoids in the different olive leaves extracts. The selectivity of different commercial adsorbents such as silica gel, zeolite, and aluminum oxide was evaluated toward the different terpene families present in olive leaves. Operating at 30 MPa and 60 °C, an adsorbent-assisted fractionation was carried out every 20 min for a total time of 120 min. For the first time, GC-QTOF-MS allowed the identification of 40 terpenoids in olive leaves. The GC-QTOF-MS results indicate that silica gel is a suitable adsorbent to partially retain polyunsaturated C10 and C15 terpenes. In addition, aluminum oxide increases C20 recoveries, whereas crystalline zeolites favor C30 terpenes recoveries. The different healthy properties that have been described for terpenoids makes the current SFE-GC-QTOF-MS process especially interesting and suitable for their revalorization.

Investigation of Water Vapour Harvesting Unit Using Solar Energy

water-harvesting unit is built and the effects of design parameters are studied experimentally and theoretically under Baghdad conditions (33. 3°N, 44.33° E). The unit consists of desiccant materials contained in many trays that enclosed in a metal container covered by a glass cover. The desiccant materials aim to adsorb the water vapor that associated with the air, an axial fan is used to blow the ambient air over the desiccant. The unit container is built from aluminum of 0.6 mm thickness; the dimensions of the container are 27 cm wide, 93cm length and 10 cm height. Two gets are installed in the unit for the inlet and outlet of air. The front face of the container is covered by a glass cover of 4 mm thickness. Different types of desiccant materials are used to adsorb the water vapour from the air, namely; silica gel powder, silica gel pellets, zeolite 13X, zeolite 3A and MCM-41 Nano powder. The effect of the mass flow rate of air over the desiccant materials and the types of desiccant material on the amount of freshwater production is studied in this work. Tóth model is used to build a mathematical of the adsorption/desorption process. The mathematical model aims to cover the performance of the water-harvesting unit around the year. The results show that the maximum daily production of the water-harvesting unit using MCM-41 is 0.5 kgw/kgads when the mass flow rate of air is 14 kg/hr, as the mass flow rate of air increases more than 14 kg/hr the daily water production reduces. The use of other desiccant materials like Zeolites and silica gels shows encourage results in the daily production of water of less than 0.1 kgw/kgads. The mathematical modelling of the water-harvesting unit shows the maximum water production about 0.55 kgw/kgads in December. The error between the experimental and mathematical models for daily water production is in the range of 12.5 to 17.8% for the desiccant materials used in this work.

Preparation and evaluation of chiral open-tubular columns supported with zeolite silica nanoparticles and single/dual chiral selectors using capillary electrochromatography with amperometric detection

In this work, novel stationary phase coatings by zeolite SiO2NPs coupled with β-cyclodextrin (β-CD) or β-CD/L-phenylalanine were developed for chiral open-tubular capillary electrochromatography (OT-CEC). The OT columns were prepared taking advantage of the strong adhesion of polydopamine in one-step method. Scanning electron micrography and electroosmotic flow were used to characterize the prepared single/dual-selector OT columns. Chiral separation of four chiral analytes (catechin/epicatechin, ephedrine/pseudoephedrine, ritodrine and salbutamol) was carried out in order to evaluate the performance of the prepared columns in OT-CEC with amperometric detection system. In terms of migration time, peak area, resolution, and selectivity factor of catechin/epicatechin and salbutamol, the run-to-run, day-to-day, and column-to-column repeatability were within 8.9%. Under the optimum conditions, the developed methods were applied for the analyses of Chinese herbal medicine Catechu herbs and salbutamol aerosol samples.

Modelling and simulation of water vapor adsorption in silica gel bidisperse beds

Desiccant cooling systems are widely recognized as an alternative technology to vapor compression cooling. Desiccant systems are attractive for air conditioning applications due to the possible use of low-grade heat and green refrigerants in their operation. In such systems, air dehumidification is achieved using bed compacted with desiccant materials such as silica gel, activated alumina, and zeolite. Desiccant systems, on the other hand, present a low coefficient of performance due to the poor heat and mass transfer in the adsorbent bed. A way to enhance the heat and mass transfer in desiccant systems can be accomplished by optimizing the adsorbent packing in the bed. This paper presents a numerical investigation of the dynamics of water vapor adsorption in silica gel bidisperse bed. The adsorbent bed is compacted with particles of two different sizes to reduce the voids between the adsorbent particles and hence increase the amount of desiccant and the adsorbed water mass in the bed. The effect of bidisperse packing in the air dehumidification capacity and adsorbed water mass is studied. The influence of the pressure drop applied on the adsorbent column and the inlet air conditions in the dehumidification process is also investigated. The numerical results showed that bidisperse packing increases the dehumidification capacity (improvement of 22.9%) and the amount of water adsorbed (improvement of 25%) in the bed compared to the case where monodisperse packing is applied to the system, contributing to the improvement in the performance of desiccant beds in air conditioning applications.

Pembuatan Penyaring Air Untuk Peternak Ayam Petelur Di Dusun I Kubu Cubadak Simpang Petai

In order to supply the water for laying hens farm in Kubu Cubadak Simpang Petai, the service team from University of Riau has designed a water purification system using the filtration technique. Before designing the filtration, sample of water from the well around the farm is taken and analyzed in the laboratory. Based on this result, the filtration is characterized to get the water satisfying the needs of the farm. There are two tubs in the filtration system containing silica sand, zeolite, and active carbon. Water from the well is pumped to the tank with three-meter height. From there, water is pumped back again to the tube to get the optimal water flow. The quality of water from the filtration have enhancement in terms of color, turbidity, and pH. The color and turbidity of water are improved from 41 NTU to 0 NTU and from 22,5 NTU to 5,59 NTU, respectively. Furthermore, there is an increasing in pH of water, from 5,44 to 6,32. These results have fulfilled the standard for laying hens farm.

Palladium confined in pure-silica TON zeolite for furfuryl alcohol hydrogenation into tetrahydrofurfuryl alcohol

Fabrication of robust noble metal nanoparticles (NPs) usually suffers from instability due to the large surface energy of small particles. Herein, highly dispersive Pd nanoparticles (average size: ~3 nm) with controllable content were directly encapsulated within pure silica zeolite matrix with TON topology via a dry gel conversion pathway, in which 1-butyl-3-methylimidazolium bromide and (3-mercaptopropyl) trimethoxysilane were utilized as the structure-directing agent and metal stabilizer, respectively. High crystallinity and large surface area were reached over this Pd containing zeolites. The champion catalyst Pd–Si-ZSM-22 effectively catalyzed the transformation of furfuryl alcohol into tetrahydrofurfuryl alcohol via hydrogenation by using H2. High conversion (>99%) and selectivity (>99%) were reached with large turnover numbers and the stable activity was observable during the recycling test. The comparison with the post-impregnated counterpart indicates that the straightforward synthesis is favorable for the construction of stable and robust Pd species within the confined microchannels of TON zeolites.

Removal of Copper and Magnesium Cations from Aqueous Solutions by Clinoptilolite Zeolite Adsorption

The aim of this study is to determine the potentials of clinoptilolite zeolite in removing selected heavy metals, that are copper and magnesium in aqueous solutions. The removal of both metal cations has been studied by using the batch techniques. Three experimental variables were carried out under predetermined conditions of contact time (20 – 100 minutes), effect of dosage (0.20 – 1.00 gram), and effect of pH solution (pH 2 to 10). Adsorption capacity of zeolite towards heavy metal removal was then determined at various initial concentrations of metal ions between 20 to 100 ppm. Results obtained shows that adsorption of Cu 2+ and Mg 2+ on zeolite has been shown to depend significantly on the pH, adsorbent amount and contact time. The significant value of pH was reached at pH 6, followed by 1 hour of contact time for 1 gram of adsorbent; for both metal ions studied. Studies on the rate of uptake of heavy metal ions by the zeolite indicated that the process was quite rapid and maximum adsorption occurred within the first hour of contact. The results show that high silica zeolite such as clinoptilolite is a promising adsorbent as they combine high adsorption capacities and molecular sieve properties.

A Transferable Force Field for Predicting Adsorption and Diffusion of Hydrocarbons and Small Molecules in Silica Zeolites with Coupled-Cluster Accuracy

We present a transferable force field for hydrocarbons (linear and branched olefins and paraffins) and small adsorbates (CO2, O2, N2, and H2O) in pure silica zeolites. The fitting procedure is base...

Hydrothermal interconversion of FAU-type zeolite in the presence of sodium and tetramethylammonium ions

Abstract Hydrothermal interzeolite transformation is one of the well-known methods for synthesizing zeolites with novel structures and/or compositions. Since various crystallization factors can influence the interzeolite conversion process like in general hydrothermal synthesis, it is important to examine them. In this study, we explored the interconversion process of the FAU-type zeolite in the simplest interzeolite transformation system, containing tetramethylammonium (TMA+) and Na+ ions as structure-directing agents. The effects of various synthetic parameters, such as the concentration of OH−, Na+, and TMA+ ions, the Si/Al ratio, crystallization time and temperature, and types of inorganic and organic cations were investigated during the interzeolite crystallization. In the optimal synthetic condition, the initial structure of parent high silica zeolite Y was transformed in the order of X-ray amorphous → low silica FAU → MAZ → SOD. The solid products obtained under the various crystallization conditions were characterized by powder XRD, SEM, framework IR, 29Si MAS NMR, elemental and thermal analyses, etc. to investigate the prevailing factor in each transformation step. The proper concentration of OH− in the synthetic mother liquor was determined to be the governing factor necessary to initiate the interzeolite transformation, and to expect a certain zeolitic phase by the structure-directing of inorganic and/or organic cations.

Kinetic, Isotherm, and Thermodynamic Studies of Methylene Blue Adsorption over Metal-doped Zeolite Nano-adsorbent

In this work, the adsorption of cationic dye by the modified high silica zeolite nano-adsorbent was investigated. The support was prepared hydrothermally and doped by the iron. The morphology, structure, and textural properties of the nano-adsorbents were characterized using XRD, FT-IR, N2 adsorption-desorption, and FE-SEM. The results showed that the nano-adsorbent had a high specific surface area, crystallinity, and pore volume. The maximum adsorption (6.09 mg g-1) was at the pH level of 9.0, 10 mg L-1 of dye concentration, T=25 °C, and 1.0 gL-1 of nano-adsorbent dosage. The kinetic of Methylene blue (MB) adsorption was pseudo-second-order with the high correlation factor (R2=0.99). The MB adsorption was in line with the Langmuir model, as an exothermic and spontaneous process. The results confirmed that the metal-doped high silica ZSM-5 zeolite was an efficient nano-adsorbent for the cationic dye adsorption through wastewater treatment.

Ion-exchanged ETS-10 adsorbents for CO2/CH4 separation: IAST assisted comparison of performance with other zeolites

ETS-10, the well-known member of titanosilicates, was synthesized, characterized, and then employed to study CO2 and CH4 adsorption on its cation exchanged forms. Equilibrium isotherms of as-synthesized, K-, Mg-, and Sr-ETS-10 were analyzed at 298 K and pressures up to 100 kPa. High selectivities of CO2/CH4 were observed for all the adsorbents. By a closer look at equilibrium isotherms, adsorption selectivity was found to be in the order of K- > as-synthesized- > Sr- > Mg-ETS-10. Analyses of the data revealed that ETS-10 adsorbents containing monovalent cations have more rectangular isotherms and higher CO2/CH4 selectivity. On the other hand, ETS-10 adsorbents exchanged by divalent cations showed lower selectivity but more curvature isotherms which makes the regeneration easier in the pressure swing adsorption process (PSA). High-pressure adsorption experiments at different temperatures up to 348 K were also studied for the most selective adsorbent, i.e., K-ETS-10. Finally, the ETS-10 adsorbents performance in different binary mixtures of CO2/CH4 was investigated by Ideal Adsorption Solution Theory (IAST), and the results were evaluated and compared with the performance of other aluminosilicates and high silica zeolites in CO2/CH4 separation. The comparison led to a new trade-off plot, i.e., adsorption capacity versus CO2/CH4 selectivity, which can be helpful for adsorbent selection.

Locating Structure Directing Agent and Al in CHA: Combined Study of Structure Determination of X‐Ray Powder Diffraction and Classical Lattice Energy Calculation

Locating the structure directing agent and Al in zeolite CHA has been performed using structure determination of X‐ray powder diffraction combined with General Utility Lattice Program (GULP) calculation. Trimethyladamantylammonium ion (TMAdaOH+) and benzyltrimethyl ammonium ion (BTMAOH+), respectively, have been found to fit in the pore, resulting in the formation of high silica zeolite CHA, which shows the superior catalytic performance in abatement of NOx using NH3 in the exhaust gas stream of mobile car. The intimate interaction between the corresponding structure directing agent (SDA) and the counter ion due to the Al substitution in the framework has been characterized using the lattice energy calculation. The difference in the lattice energy of the zeolite CHA prepared with TMAdaOH was large compared to that of the zeolite CHA prepared with BTMAOH, which can be attributed probably to the molecule's size. Thereby, the SDA in the zeolite pore has been located readily and the resulting information can be useful for increasing the understanding in the zeolite formation mechanism and designing novel zeolite.

Ex situ nucleation and growth study of the pure silica HPM-1 zeolite

In this manuscript, we reveal some insights into the nucleation and growth mechanism of pure silica zeolite HPM-1. This chiral material has attracted interest from academic and industrial researchers due to its potential for application in asymmetric catalysis and the separation of racemic products. We investigate four samples synthesized with different crystallization times and characterize them by X-ray diffraction, infrared spectroscopy, electron microscopy and small-angle X-ray scattering (SAXS). We propose a four-step synthesis mechanism based on the different populations of nanoparticles and the porous surface intermediate that is observed. We demonstrate that this synthesis follows a nonclassical mechanism of zeolitic nucleation and growth.

Heat Transfer in Adsorption Chillers with Fluidized Beds of Silica Gel, Zeolite, and Carbon Nanotubes

One of the main disadvantages of conventional fixed-bed adsorption chillers is the low coefficient of performance due to the high voidage of the sorbent beds. The common method, which can help to handle this problem, is modifying the beds’ design, including the application of fluidization. An innovative idea, shown in the article, constitutes in the use of the fluidized bed of sorbent, instead of the conventional, fixed-bed, commonly used nowadays in the adsorption chillers. Bed-to-wall heat transfer coefficients for fixed and fluidized beds of adsorbent are determined in the study. Effects of Sorbent particles diameters and velocities of fluidizing gas are discussed in the study. The calculations confirmed that the bed-to-wall heat transfer coefficient in the fluidized bed of adsorbent is much higher than that in a conventional bed. The proposed idea allows significantly reducing the size of a chiller and overcome the main reason for the limited dissemination of the adsorption cooling technology.

Progress in Direct Synthesis of High Silica Zeolite Y

Progress in Direct Synthesis of High Silica Zeolite Y

Analysis of multimedia filter effectiveness to improve the quality of rainwater runoff in fulfilling urban raw water supply

Rainwater is recommended as a clean water supply through several water treatment methods. Based on preliminary data test results, several parameters exceed the sanitary hygiene water standard. This research aimed to improve the quality of rainwater runoff using the multimedia filter, which combined filtering and physical adsorption process. The combination of silica sand, activated carbon, and zeolite media was simulated into a pilot-scale of 1:2 reactor. Based on the first experimental results, the use of proposed media has a significant effect (p-value≅0) on several parameters. The best improvement in effluent quality reaches 100% in nitrites removal, 29% in nitrates removal, and 94.4% in total coliform removal. However, the media thickness variation factor has an insignificant effect (p-value 0.616) to effluent quality. Based on the second experiment results, hydraulic loading rate (HLR) variation shown a significant effect (p-value 0.01) on several parameters. Effluent quality improvement reaches 71.4% in nitrites removal, 100% in nitrates removal, and 91.9% in total coliform removal. However, variation in HLR gave an insignificant effect (p-value 0.769) on improving effluent quality.

Reducing the dosage of the organic structure-directing agent in the crystallization of pure silica zeolite MFI (silicalite-1) for volatile organic compounds (VOCs) adsorption

Zeolite silicalite-1 (MFI) was synthesized with a lower amount of TPA+ but an appropriate amount of seed.

River Water Purifier as an Alternative for Clean Water Supply in Sei Siarti Village, Panai Tengah District, Labuhanbatu Regency

Sei Siarti Village, Panai Tengah District, Labuhanbatu Regency have problems in the form of limited clean water sources that are suitable for use. There are several potentials including peat water, drilled well water, and Barumun river water that crosses the village. The condition of peat water that does not comply with quality standards for water that is fit for consumption has a brownish color, high acidity, and the organic matter contained in peat water is high enough to cause an odor. The well water has a salty taste (high salt content) so that what has the potential is Barumun river water even though it has a cloudy color. The method used to purify cloudy river water is through the processes of coagulation (deposition), filtration (filtering), absorption (absorption), and adsorption (ion exchange). This water purifier is made using 2 tubes filled with silica sand, MGS, activated carbon, and zeolite sand so that the water produced is clear and fit for consumption and can be utilized by the surrounding community. The results obtained from this water purification are water that does not have a smell, taste, and is clear in color so that it is suitable for use by the surrounding community