Mixture Of Zeolite Research Articles

Ni phosphide catalysts on Al2O3‐zeolite prepared by phosphidation for methyl palmitate hydroconversion

AbstractBACKGROUNDOne‐stage hydroconversion of fatty‐acid based feedstocks is a promising way to obtain high‐quality fuels. This process is based on hydrodeoxygenation, isomerization and hydrocracking reactions. In this work, Ni2P/Al2O3‐zeolite catalysts were synthesized and tested in hydroconversion of a model compound – methyl palmitate.RESULTSNi2P catalysts were prepared by in situ phosphidation of metallic Ni/Al2O3‐zeolite precursors by PPh3. Mixtures of zeolite (30 wt%) and boehmite were peptized and extruded to obtain the support granules. SAPO‐11, ZSM‐5, ZSM‐22, ZSM‐23 and ZSM‐12 were used as a zeolite component. The catalysts and supports were characterized by a range of physicochemical methods: chemical analysis (ICP‐AES), low‐temperature N2 adsorption, H2‐temperature programmed reduction, NH3‐temperature programmed desorption, Fourier transform infrared spectroscopy of adsorbed CO, X‐ray diffraction, transmission electron microscopy, X‐ray photoelectron spectroscopy, and 27Al and 31P magic angle spinning nuclear magnetic resonance. The catalysts were studied in methyl palmitate hydroconversion (one‐stage hydrodeoxygenation‐isomerization‐hydrocracking) in a continuous‐flow fixed bed reactor at 290–340 °C, 2 MPa, H2/feed = 600 Ncm3/cm3 and LHSV = 5.3 h−1. SAPO‐11 containing sample showed high selectivity to C15 and C16 iso‐alkanes (63%, at 340 °C), and all ZSM‐containing samples showed high selectivity to cracked C5–C9 products (55–100%, at 340 °C) with varying amounts of iso‐alkanes (31–57%, at 340 °C).CONCLUSIONThe results show that by choosing the zeolite component of the catalyst it is possible to finely tune product quality in the range from low‐temperature diesel fuel to jet fuel or gasoline. © 2024 Society of Chemical Industry (SCI).

Alkali-activated materials containing mine tailings and zeolite for seepage water treatment in a closed nickel mine

AbstractIn the present study, alkali-activated materials were assessed as adsorbents for mine water treatment. The composition of alkali-activated materials, involving mixtures of metakaolin, blast-furnace slag, mine tailings, and zeolite, was optimized based on their leaching behavior and adsorption performance. The most effective adsorbent contained solely blast furnace slag as an aluminosilicate precursor and was selected for a pilot-scale study at a closed nickel mine in Finland. In the pilot, seepage water from a gangue area with an influent flow rate of 0.5 m3/d was treated using a permeable reactive barrier set-up containing 10 kg of slag-based adsorbent prepared by a granulation-alkali activation process. During a one-week experiment, the adsorbent granules were capable of effectively uptaking Ni, Fe, and Mn from the seepage water; the removal percentages of Ni, Fe, and Mn were 82.4%, 81.6%, and 82.5%, respectively. The results indicated the feasibility of blast furnace slag-based adsorbents for toxic element removal in a potentially sustainable approach.

New Discovery of Natural Zeolite-Rich Tuff on the Northern Margin of the Los Frailes Caldera: A Study to Determine Its Performance as a Supplementary Cementitious Material.

The release of Neogene volcanism in the southeastern part of the Iberian Peninsula produced a series of volcanic structures in the form of stratovolcanoes and calderas; however, other materials also accumulated such as large amounts of pyroclastic materials such as cinerites, ashes, and lapilli, which were later altered to form deposits of zeolites and bentonites. This work has focused on an area located on the northern flank of the San José-Los Escullos zeolite deposit, the only one of its kind with industrial capacity in Spain. The main objective of this research is to characterize the zeolite (SZ) of this new area from the mineral, chemical, and technical points of view and establish its possible use as a natural pozzolan. In the first stage, a study of the mineralogical and chemical composition of the selected samples was carried out using X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray fluorescence (XRF), and thermogravimetric analysis (TGA); in the second stage, chemical-qualitative and pozzolanicity technical tests were carried out at 8 and 15 days. In addition, a chemical analysis was performed using XRF on the specimens of mortars made with a standardized mixture of Portland cement (PC: 75%) and natural zeolite (SZ: 25%) at the ages of 7, 28, and 90 days. The results of the mineralogical analyses indicated that the samples are made up mainly of mordenite and subordinately by smectite, plagioclase, quartz, halloysite, illite, and muscovite. Qualitative chemical assays indicated a high percentage of reactive silica and reactive CaO and also negligible contents of insoluble residues. The results of the pozzolanicity test indicate that all the samples analyzed behave like natural pozzolans of good quality, increasing their pozzolanic reactivity from 8 to 15 days of testing. Chemical analyses of PC/SZ composite mortar specimens showed how a significant part of SiO2 and Al2O3 are released by zeolite while it absorbs a large part of the SO3 contained in the cement. The results presented in this research could be of great practical and scientific importance as they indicate the continuation of zeolitic mineralization beyond the limits of the San José-Los Escullos deposit, which would result in an increase in geological reserves and the extension of the useful life of the deposit, which is of vital importance to the local mining industry.

Microwave catalytic pyrolysis of solid digestate for high quality bio-oil and biochar

Microwave-assisted catalytic pyrolysis (MACP) of solid digestate (SD) into value-added products presents a promising solution for waste SD. Both types of catalysts and reactor temperature critically influence the properties of MACP products. This study systematically investigated pyrolysis of SD mixed with different catalysts (K3PO4, natural zeolite, and mixture of K3PO4 and natural zeolite) at various pyrolysis temperatures (300, 400, and 500 ℃) for bio-oil and biochar production. The results showed that higher temperatures led to reduced bio-oil and biochar yields, favoring gas production. The bio-oil derived from SD with 20 wt% K3PO4 and 20 wt% natural zeolite at 500 ℃ exhibited the largest fraction of aromatic hydrocarbons, reaching 92.43 % and 91.56 %, respectively. Catalytic pyroysis resulted in reduction in bio-oil acidity. Biochar specific surface area is influenced by both heating rate and temperature, with the highest surface area (207 m2/g), pore volume (0.2244 cm³/g), and a more regular pore structure being obtained at 500 ℃ and 66.1 °C/min with 20 wt% K3PO4. This work demonstrated the feasibility of upgrading waste SD into value-added chemicals, materials, and energy-rich fuels by MACP. Notably, SD with 20 wt% K3PO4 at 500 ℃ represents the optimal operating condition for both bio-oil and biochar production.

Enhanced ammonia adsorption-desorption properties of synthesized zeolite-carbon composite with the effect of Si/Al ratio

Effective ammonia (NH3) adsorbent is crucial for removing undecomposed NH3 residue after splitting into N2 and H2 fuel. In this study, a zeolite-activated carbon (AC) hybrid was successfully synthesized with a trace AC amount and different Si/Al ratios via hydrothermal method. The NH3 adsorption–desorption properties and mechanisms were investigated through two major activity tests, employing high pressure adsorption isotherm analyzer and breakthrough set up. Incorporating AC at 1 wt%, effectively shortened the regeneration period of the pure zeolite by ∼50 % due to the AC’s pore-widening effect on zeolite network, reducing the trapping of adsorbed NH3 in the zeolite pores. Interestingly, an optimum Si/Al ratio of 1.6 led to the highest specific surface area of 977.57 m2/g by the formation of zeolite mixture with coexisting NaX (faujasite zeolite with high Al atoms per cell) and NaY (higher crystalline faujasite zeolite with low Al atoms per cell). These improved structural characteristics consequently exhibited the highest NH3 (99.9995 %) storage capacity of 15.6 mmol/g at a partial pressure of 300 kPa in isotherm analysis at 25 °C. Besides, the initial breakthrough adsorption capacity for dilute NH3 (5%/N2 balance) under atmospheric conditions reached 8.9 mmol/g, accurately equivalent to isotherm analysis result at 5 kPa. This reproducibility of consistent adsorption uptake within low pressure region in both tests was credited to the compositional presence of both acidic and alkaline surface functionalities in the optimum zeolite-AC hybrid as stable NH3 adsorption sites. These active sites also provided a uniform dynamic adsorption capacity of ∼4 mmol/g throughout 15 cycles. Conclusively, this work highlighted the importance of zeolite composition and AC-incorporated proportion for the H2 purification aspect.

Control of phosphorus release from sediment by the combined use of Elodea nuttallii, hydrous ferric oxide, zeolite and calcite: Efficiency, mechanism and response of bacterial communities

The effectiveness of Elodea nuttallii combined with a mixture of hydrous ferric oxide, zeolite and calcite (HZC) to reduce the internal loading of phosphorus (P) from sediment and its mechanism were studied, and the effect of Elodea nuttallii combined with HZC on the composition and function of the microbial communities in the surface sediment was also investigated. The results showed that the combination utilization of Elodea nuttallii and HZC can decrease the risk of phosphorus liberation from sediment to the overlying water, and the controlling efficiency of Elodea nuttallii combined with HZC was higher than that of Elodea nuttallii or HZC alone. The passivation of labile P measured by diffusive gradient in thin film device and mobile P played a crucial role in the control of internal P loading from sediment by the combined Elodea nuttallii + HZC treatment. HZC capping had a promoting effect on the growth of Elodea nuttallii. This was beneficial to the absorption of phosphorus from sediment by Elodea nuttallii. The combined application of Elodea nuttallii and HZC not only had a certain negative effect on the diversity of bacteria in the surface sediment, but also changed the microbial compositions of the surface sediment at the levels of phylum and genus. However, the microbial communities in the surface sediment still can perform good ecological function. The above results suggest that the combined application of Elodea nuttallii and HZC has a high potential in the management of internal P loading from sediment.

Jet fuel production via palm oil hydrodeoxygenation over bifunctional zeolite mixture supported Ni catalyst: Effect of Si/Al ratio

The influence of the Si/Al ratio of ZSM-5 on 10 wt% Ni/ZSM-5.SAPO-11 catalysts were investigated through the palm oil hydrodeoxygenation (HDO) process, based on the product selectivity of alternative jet fuel. This study utilizes a 1 L batch reactor at 60 bar and 350 °C for palm oil hydrodeoxygenation over 10 wt% Ni/ZSM-5.SAPO-11 catalysts. Si/Al ratio of 50 produces a 10 wt% Ni/ZSM-5.SAPO-11 catalyst with the optimum physicochemical properties for palm oil hydrodeoxygenation. TGA/DTG analysis of the spent catalyst shows that the catalyst has good thermal and catalyst stability with minor carbon deposition. GC/MS analysis also demonstrated a 100 % palm oil conversion to alternative jet fuel. The highest jet fuel yield of 51 % was attained with a Si/Al ratio of 50. The physicochemical properties of alternative jet fuel samples were measured to ensure that the conventional fuel standard limits were appropriately followed. These results indicated that such types of bifunctional Ni-based catalysts have the potential to be used in the conversion of triglycerides to alternative jet fuel.

Adsorption of 3‐monochloropropane‐1,2‐diol ester and glycidyl ester from refined bleached deodorized palm oil using zeolite‐based adsorbents

AbstractPalm oil processing can result in different food products like cooking oil and margarine. Nevertheless, these food products might contain harmful contaminants, namely 3‐monochloropropane‐1,2‐diol ester (3‐MCPDE) and glycidyl ester (GE), which can negatively affect animal organs and potentially cause human cancer. Therefore, the objective of this study was to lower the concentration of 3‐MCPDE and GE in refined, bleached, and deodorized palm oil (RBDPO) using zeolite as an adsorbent. Adsorption experiments were conducted in a batch reactor, varying the percentage of adsorbents, temperature, type of zeolite, and the use of a mixture of zeolite and activated carbon (AC). The sample was analyzed before and after adsorption using gas chromatography–mass spectroscopy (GC–MS) to confirm the concentration alteration of 3‐MCPDE and GE. The study showed that the most effective temperature for adsorption was 35°C and used a zeolite percentage of 2%. Beta zeolites resulted in the highest removal of 3‐MCPDE (86%) among the evaluated zeolites attributed to their elevated pore volume, Si/Al ratio, and overall acidity strength. Through a synergistic combination of beta zeolite and AC, the removal percentage of 3‐MCPDE was enhanced to 94%, with a corresponding 75% reduction in GE. This study paves the way for addressing 3‐MCPDE and GE concerns in RBDPO by combining zeolite and AC.

Understanding the effect of spatially separated Cu and acid sites in zeolite catalysts on oxidation of methane

Unraveling the effect of spatially separated bifunctional sites on catalytic reactions is significant yet challenging. In this report, we investigate the role of spatial separation on the oxidation of methane in a series of Cu-exchanged aluminosilicate zeolites. Regulation of the bifunctional sites is done either through studying a physical mixture of Cu-exchanged zeolites and acidic zeolites or by systematically varying the Cu and acid density within a family of zeolite materials. We show that separated Cu and acid sites are beneficial for the formation of hydrocarbons while high-density Cu sites, which are closer together, facilitate the production of CO2. By contrast, a balance of the spatial separation of Cu and acid sites shows more favorable formation of methanol. This work will further guide approaches to methane oxidation to methanol and open an avenue for promoting hydrocarbon synthesis using methanol as an intermediate.

Determining the Usage Properties of Some Natural Substrate Materials in submerged macrophyte Vallisneria sp. culture

In this research, which targets removing nutrients resulting from the metabolic wastes of fish and unconsumed feed from the environment in aquarium systems where fish, plants, and ground material are used in the same environment and use them as plant nutrients, it was aimed to determine the usage properties of zeolite, leonardite and diatomite materials on the growth parameters of the Vallisneria sp. plant. 
 The study was conducted in three stages for 8 months. The first step of the study was planned as the plant adaptation phase, and no fish were added to the environment. In the second step, fish was introduced. The third step was designed to determine the adsorbent mixture's plant nutrient storage capacity (effective usage period). In the experimental aquariums, no plant nutrient or fertiliser other than fish food was used at all stages. The effects and using duration on the growth of the Vallisneria sp plant of adsorbed nutrients from unconsumed feed by leonardite and zeolite mixture were investigated in three stages in aquarium condition. Trial groups were formed by adding the adsorbent mixture of the feed having a 40% protein value to the first group (G1), the adsorbent mixture of the feed having a 33% protein value to the second group (G2), and the adsorbent mixture without feed to the third group (G3).
 When the SGR values at the end of the experiment were compared, there was no statistical difference between the G1 and G2 groups, which contained 40% and 33% protein (P>0.05). On the other hand, both groups (G1, G2) showed significantly higher (P

Strategy to remove ammonium compounds released from fish feed in aquaculture using natural filtration materials.

The effects of addition of adsorbent mixture at two different stages in aquaculture system were investigated for the first time in this study. In the first stage, in order to determine the effects of natural adsorbents in an environment without feed, a trial consisting of four treatment groups with three replications was conducted. In this trial, individual and combined effects of two natural adsorbents on water parameters in absence of feed were assessed for five days.In the second stage for 9 experimental days, a total of 18 aquaria consisting of three treatment groups with three replications for two different fish feeds were used. Of these aquaria, the first six received only two types of feeds containing 33 and 40% protein, designated as two control groups (C1 and C2). Other two groups (T1 and T2) were prepared by adding a leonardite: zeolite mixture (at 2:1 ratio) to next six replicates simultaneously. The last six replicates received a leonardite: zeolite mixture (at 2:1 ratio) after the 8th day of the study, and formed the last two treatment groups (T3 and T4).In this study, mean pH values varied between 7.01 and 7.82 and ammonia values were found to be maximum of 94.96% and minimum of 38.73% lower compared to the control group when 3g adsorbent mixture (2L: 1Z) was used to balance pH and ammonium (NH4+) values in an aquatic environment containing 0.5l freshwater and 0.5g fish feed with 33-40% protein contents. It was demonstrated that the combined use of zeolite and leonardite had positive effects on ammonium removal and providing optimum pH levels for aquaculture. The combined use of these two adsorbents helped balance the pH-reducing effect of leonardite with zeolite, and the pH-reducing effect of leonardite contributed to the NH4+ adsorption efficiency of zeolite.

Facile Synthesis Method of Zeolite NaY and Zeolite NaY-Supported Ni Catalyst with High Catalytic Activity for the Conversion of CO2 to CH4

In this work, the facile reflux method was used as a crystallization procedure for zeolite NaY synthesis. The zeolite mixture was aged for 7 days and then refluxed for crystallization at 100 °C for 12 h. The synthesized zeolite NaY was impregnated with 10, 20 and 30 wt%Ni solution to use as a catalyst for CO2 methanation. The 30 wt% of Ni on the zeolite NaY catalyst showed the highest CO2 methanation catalytic activity, with almost 100% CH4 selectivity. This can be explained by an appropriate H2 and CO2 adsorption amount on a catalyst surface being able to facilitate the surface reaction between them and further react to form products. The oxidation state of Ni and the stability of the catalyst were monitored by time-resolved X-ray absorption spectroscopy. The oxidation state of Ni2+ was reduced during the catalyst reduction prior to the CO2 methanation and it was completely reduced to Ni° at 600 °C. During CO2 methanation, Ni° remained unchanged. In addition, the stability test of the catalyst was conducted by exposing the catalyst to a fluctuating condition (CO2 + H2 and only CO2). The oxidation state of Ni° remained unchanged under the fluctuating condition. This indicated that the Ni/zeolite catalyst has high stability, which can be attributed to an appropriate binding strength between Ni and the zeolite support.

Enhanced ammonia removal in tidal flow constructed wetland by incorporating steel slag: Performance, microbial community, and heavy metal release

Utilizing alkaline solid wastes, such as steel slag, as substrates in tidal flow constructed wetlands (TFCWs) can effectively neutralize the acidity generated by nitrification. However, the impacts of steel slag on microbial communities and the potential risk of heavy metal release remain poorly understood. To address these knowledge gaps, this study compared the performance and microbial community structure of TFCWs filled with a mixture of steel slag and zeolite (TFCW-S) to those filled with zeolite alone (TFCW-Z). TFCW-S exhibited a much higher NH4+-N removal efficiency (98.35 %) than TFCW-Z (55.26 %). Additionally, TFCW-S also achieved better TN and TP removal. The steel slag addition helped maintain the TFCW-S effluent pH at around 7.5, while the TFCW-Z effluent pH varied from 3.74 to 6.25. The nitrification and denitrification intensities in TFCW-S substrates were significantly higher than those in TFCW-Z, consistent with the observed removal performance. Moreover, steel slag did not cause excessive heavy metal release, as the effluent concentrations were below the standard limits. Microbial community analysis revealed that ammonia-oxidizing bacteria, ammonia-oxidizing archaea, and complete ammonia-oxidizing bacteria coexisted in both TFCWs, albeit with different compositions. Furthermore, the enrichment of heterotrophic nitrification-aerobic denitrification bacteria in TFCW-S likely contributed to the high NH4+-N removal. In summary, these findings demonstrate that the combined use of steel slag and zeolite in TFCWs creates favorable pH conditions for ammonia-oxidizing microorganisms, leading to efficient ammonia removal in an environmentally friendly manner.

VALUATION OF THE INFLUENCE OF ENCAPSULATED MINERAL FERTILIZERS ON PLANT GROWTH KINETICS

The work investigated the effect of encapsulated mineral fertilizers on the growth and development of plants for 45 days. As a mineral fertilizer, nitroammophoska was used, which was encapsulated by a shell of different compositions: sample KD1 – a mixture of polystyrene, lignin, and carbon; sample KD2 – a mixture of polystyrene, lignin, and zeolite. The bioindication method was used to determine the effect of encapsulated mineral fertilizers on plant growth kinetics. Based on the study's results, the average rate of germination of ryegrass in the experimental samples and the average rates of the main plant parameters (stem height, root length, plant weight) were determined. It was established that the highest rate of germination was in the sample with encapsulated mineral fertilizer KD1 — 100%, and the lowest in the sample GD — 85%. The highest average indicators of measurement of the main parameters of ryegrass were in samples KD1 and KD2. The highest average indicators of measurement of the main parameters of ryegrass were in samples KD1 and KD2, and the lowest in the control sample (soil). It was established that on the 45th day, the mineral fertilizer in the KD1 sample was fully absorbed by the plants.

Development of a cap liner composite film incorporating zinc oxide, celite, and zeolite for kimchi-storing bottles to absorb volatile sulfur compounds

Bottle cap liner films (“ZnO[celite]–zeolite film”) that absorb volatile sulfur compounds from kimchi were developed for kimchi-packaging plastic bottles using zinc oxide (ZnO) in celite (ZnO[celite]), zeolite, and low-density polyethylene (LDPE). The ZnO[celite] concentration-dependent deodorizing effect of the films and their physicochemical properties were evaluated. When the ZnO[celite] and zeolite mixture concentration in the film was 18% (w/w), the concentration of allyl methyl disulfide absorbed in the film increased by 98% compared with when this mixture was not used. Addition of ZnO[celite] and zeolite into the LDPE films altered their surface and cross-sectional morphologies and yellowness, but did not change their thermal stability, thermal properties, oxygen barrier, or tensile properties. These results suggest that the bottle cap liner prepared using the ZnO[celite]–zeolite film can effectively absorb volatile sulfur compounds and may be used as a liner for kimchi-containing bottles, replacing the conventional LDPE liner.

Transformation of Single‐Use Plastics into Lighter Hydrocarbons via an Economical Coal Fly Ash based Zeolite Catalyst

AbstractA mixture of zeolite X and A, derived from coal fly ash (CFA), was protonated and utilized as an acid catalyst to decompose single‐use plastics (SUP) waste into lighter hydrocarbons. Low‐density polyethylene (LDPE) was selected as the source of SUP, and this study aimed to investigate the catalytic effects of the protonated CFA‐derived zeolite (H‐XA) as an economical option on the LDPE pyrolysis temperature and output. CFA converted into H‐XA through the conventional alkali fusion, followed by sonication and simplified hydrothermal and protonation processes. The impact of the alkali agent ratio on the resulting product was investigated, and outcomes were evaluated. The product with optimum properties was then selected for investigation in the LDPE pyrolysis studies. Finally, the results were compared with commercial Protonated Zeolite Socony Mobil‐5 (H‐ZSM5) and thermal decomposition without catalysts. Regarding LDPE degradation temperature, H‐XA could lower that by 97 °C compared to thermal degradation, which was almost the same as commercial H‐ZSM5 with 110 °C. The pyrograms obtained through the Pyrolysis‐gas chromatography‐mass spectrometry (Py‐GCMS) analysis indicated the elimination of heavier hydrocarbons in the presence of H‐XA and the product spectra laid in the range of C3 to C9, which was entirely different from the LDPE with hydrocarbons of varying lengths. Moreover, kinetic studies on the LDPE decomposition reactions in this work have revealed that LDPE conversion occurs at a lower activation energy level in the presence of H‐XA, which is comparable to the energy level observed when H‐ZSM5 is used as the catalyst. The synthesis of H‐XA with desirable catalytic activity, such as the ability to lower the LDPE degradation temperature and make lighter hydrocarbons as the pyrolysis output, suggests the great potential of the CFA‐based acid catalyst for use in SUP recycling. This represent a game of waste versus waste within the framework of the circular economy, where the environment is the ultimate winner.

A Commercial Clay-Based Material as a Carrier for Targeted Lysozyme Delivery in Animal Feed.

The controlled supply of bioactive molecules is a subject of debate in animal nutrition. The release of bioactive molecules in the target organ, in this case the intestine, results in improved feed, as well as having a lower environmental impact. However, the degradation of bioactive molecules' in transit in the gastrointestinal passage is still an unresolved issue. This paper discusses the feasibility of a simple and cost-effective procedure to bypass the degradation problem. A solid/liquid adsorption procedure was applied, and the operating parameters (pH, reaction time, and LY initial concentration) were studied. Lysozyme is used in this work as a representative bioactive molecule, while Adsorbo®, a commercial mixture of clay minerals and zeolites which meets current feed regulations, is used as the carrier. A maximum LY loading of 32 mgLY/gAD (LY(32)-AD) was obtained, with fixing pH in the range 7.5-8, initial LY content at 37.5 mgLY/gAD, and reaction time at 30 min. A full characterisation of the hybrid organoclay highlighted that LY molecules were homogeneously spread on the carrier's surface, where the LY-carrier interaction was mainly due to charge interaction. Preliminary release tests performed on the LY(32)-AD synthesised sample showed a higher releasing capacity, raising the pH from 3 to 7. In addition, a preliminary Trolox equivalent antioxidant capacity (TEAC) assay showed an antioxidant capacity for the LY of 1.47 ± 0.18 µmol TroloxEq/g with an inhibition percentage of 33.20 ± 3.94%.

Molecular Simulation of Adsorption Separation of CO2 from Combustion Exhaust Mixture of Commercial Zeolites

The adsorption thermodynamics and kinetics of CO2 and six combustion products (H2O, SO2, N2, O2, NO and NO2) of two most commonly used commercial zeolites (13X and 5A) were studied based on validated molecular simulations. Adsorption isotherms at wide range of temperatures (253–333 K) were fitted by a Langmuir model, obtaining equilibrium parameters including the adsorption capacity, strength, heterogeneity and CO2 selectivity from the mixture. The diffusion coefficients, isosteric adsorption heats and distributions of potential energy were simulated for further explanation. The comprehensive evaluation results suggest that, in actual combustion product mixtures, the presence of H2O in combustion products has a significant impact on CO2 capture efficiency. Under the influence of water, the adsorption capacity of CO2 was reduced by over 80%.

Complex Effect of Portland Cement Modified with Natural Zeolite and Ground Glass Mixture on Durability Properties of Concrete

This article analyses the combined effect of a mixture of natural zeolite and ground soda lime silicate glass on the durability properties of concrete. The specimens were prepared by replacing 25% of the cement with a mixture of zeolite and glass at different proportions with zeolite particles of two different sizes and cured for 28 and 90 days. Chloride migration, the depth of water penetration under pressure, and freeze–thaw cycle tests were performed, and compressive strength was determined. The combined effect of the mixture on the composition and microstructure of the cement matrix was studied by analysing the results of XRD, TGA, SEM-BSE, and porosity tests. The test results showed that irrespective of the cement “dilution” effect, the mixture of additives had a beneficial combined effect: increased durability of concrete, a denser structure of the cement matrix, the formation of calcium aluminate hydrates, faster rate, and higher degree of hydration.

Effect of Zeolite Mixture Percentage on the Free Compressive Strength Test Value of Clay Soil in Pulo Padang Village in Mandailing Natal Regency

High plasticity clay soils which are often encountered in field construction work have low bearing strength and large volume changes (shrinkage expansion). Soil will expand when the pores are filled with water and will shrink in dry conditions. This makes the soil unstable, and it is unable to support a building construction. Therefore, soil improvement efforts are needed to increase this soft clay soil. Soil stabilization is a soil improvement effort to strengthen soil that has low bearing capacity. In this research, the soil stabilization method is carried out using mixed materials to reduce or eliminate the unfavorable properties of the soil to be used. To improve the quality of the soil, zeolite is used. In its utilization, zeolite is able to withstand high heat and can increase the bearing capacity of clay soil. This research was conducted to determine the effect of zeolite addition on the compressive strength value of clay soil. In this study, the percentage of zeolite mixture used was 0%, 2%, 4%, 6%, 8%, and 10%. Based on the research results, the addition of zeolite mixture percentage in clay soil can increase the compressive strength value of the soil where the compressive strength value of the soil increases. However, the increase in soil compressive strength value occurred only until the addition of zeolite by 8% with a compressive strength value of 12.208 kg/cm2. At the time, at the addition of zeolite at 10%, the compressive strength value of the soil decreased to 9.928kg/cm2. Thus, the addition of zeolite can increase the compressive strength value of soil at the maximum addition limit of 8%. So, zeolite can be used as an alternative material for soil stabilization for subgrade layers. Keywords: Clay, Stabilization, Zeolite, Soil compressive strength