Zeolite 4A Research Articles

Synergetic effect between zeolite 5 A and maghemite nanoparticles for fast lead uptake from the Peruvian river Cumbaza: Study of surface adsorption mechanism using X-ray photoelectron spectroscopy

A novel magnetic composite of zeolite 5A and maghemite nanoparticles has been synthesized at 300 K and its lead removal properties from the Peruvian river Cumbaza were systematically studied. Its kinetic adsorption properties were investigated, and a fast equilibrium time of 15 min was achieved with 97% of removal and an adsorbent dose of 0.5 g L−1. A 100% Pb removal efficiency was reached by increasing the adsorbent dose to 1.0 g L−1, which concomitantly also removed iron species from the river aliquots. During the kinetic tests, the optimum pH was from 6.5 to 7.5, showing that no chemical reactant alteration was required to achieve a remarkable efficiency for the magnetic composite. The kinetic adsorption behavior matched well with the pseudo-first and second-order models. Post-adsorption analysis confirmed the presence of lead in all the samples. The combined results also demonstrated a synergetic response between lead and both adsorbent phases. The adsorption mechanism was governed by three steps, including inner surface complexation between lead species and maghemite, followed by lead cationic exchange between calcium-bulk and sodium-surface from zeolite 5A. Hence, this novel magnetic adsorbent exhibits a high lead removal efficiency, and it is easy-to-handle separation properties in real effluents.

Selection and optimisation of a zeolite/catalyst mixture for sorption-enhanced CO2 methanation (SEM) process

The sorption-enhanced methanation (SEM) process has emerged as a promising technology to produce high quality synthetic natural gas (SNG) from renewable sources under milder conditions than conventional methanation technologies. During the SEM process developed in this paper, an H2O adsorbent is combined with a Rhodium-based catalyst to remove the H2O generated during the CO2 methanation reaction, shifting the equilibrium towards CH4 formation. In this work, several commercial zeolites (3A, 4A, 5A and 13X) were studied as H2O adsorbents under SEM conditions. Based on the study performed, zeolite 4A demonstrated to be the most suitable zeolite which, combined with the proposed catalyst, allowed maximising the production and purity of the obtained CH4. The influence of gas space velocity, H2/CO2 ratio in the feed gas, zeolite/catalyst proportion and cyclic stability were analysed and optimized to maximise CH4 production. When the process was run under SEM conditions using zeolite 4A as sorbent at 275 °C and a gas space velocity of 230 Nml/h·gcat, the CH4 content increased from 10.6 vol% in conventional methanation up to 85 vol% in the SEM conditions. Thus, the enhanced performance of the SEM process was demonstrated.

Continuous adsorption process of [formula omitted]/[formula omitted]/[formula omitted] from [formula omitted] flow using type A zeolite adsorbents in the presence of ultrasonic waves

In this study, the adsorption capacity of different types of zeolite (3A, 4A, and 5A) for adsorbing CO2 from a mixture of CH4, N2, and water vapor was investigated with and without the use of ultrasonic waves. In this study, functional groups of O–H, Si–O–Al and Si–O–Si bands were identified in Fourier transform infrared (FTIR) spectroscopy of these adsorbents. X-ray diffraction patterns (XRD) for zeolite 3A and 5A showed the structure of chabazite and for zeolite 4A the structure of sodalite. In the Brunauer-Emmett-Teller (BET) test, the specific surface area of zeolites was measured as 16, 11.96 and 437 m2g−1, respectively. Ultrasonic waves increased the adsorption capacity of zeolites to adsorb CO2 at lower temperatures 80.64 to 175.44 mgg−1. Zeolite 5A has a higher affinity for CO2 than CH4 or N2, the selectivity of CO2/ N2 and CO2/ CH4 were 19.55 and 24.17, respectively. Data from adsorption experiments were used to learn an artificial neural network (ANN), and the ANN provided acceptable results for predicting the adsorption process.

Mixed matrix membrane based on DOCDA polyimide with twisted kink structure and zeolite 4A for energy-efficient oxygen purification

Membrane technology has advanced, offering high-quality polymeric membranes with great potential for commercial use. However, producing these advanced membranes is usually costly and involves complex manufacturing. To tackle this issue, a cost-effective alternative has emerged in the form of polyimide (PI) membranes, particularly those derived from DOCDA-ODA, a low-cost organic compound. However, the initial gas permeance of DOCDA-ODA membranes is lower than those of commercial PI membranes such as Matrimid® 5218 and 6FDA-DAM membranes. To address this limitation, this study was aimed at fabricating mixed matrix membranes (MMMs) by incorporating zeolite 4A into the DOCDA-ODA matrix. The MMMs demonstrate promising O2/N2 separation performance, surpassing that of Matrimid® 5218-based membranes. Furthermore, they exhibit an O2/N2 selectivity of 14.8 with an O2 permeability of 2.3 Barrer, surpassing recent benchmarks established by the Robeson upper bounds for polymeric membranes. This exceptional O2/N2 separation performance can be attributed to favorable interfacial interactions between the polymer chains and LTA crystals. Molecular dynamics simulations clarify the role of electronegative atoms, especially oxygen, within the kinked structure of DOCDA-ODA.. Thus, DOCDA-ODA-based MMMs hold potential for O2 purification applications, reducing energy consumption by an impressive 49.3% compared to equivalent commercial membrane processes.

Comparative performance and machine learning-based optimization of TSA configurations for NH3 removal from NH3 cracking gas

To meet the H2 standard used in fuel cells, removing ammonia (NH3) from NH3 cracking gas to less than 0.1 ppm still faces technical challenges. In this study, novel configurations of a three-bed temperature swing adsorption (TSA) process using zeolite 4A and machine learning (ML)-based optimization were developed for effective NH3 removal. Three TSA configurations, consisting of a cooling gas, three-bed TSA, heat exchangers, an expander, and/or a compressor, were designed and evaluated using the TSA model with zeolite 4A pellets after the model validation with a reference. In a techno-economic comparison, the configuration using H2 pressure swing adsorption (PSA) tail gas as the cooling gas and NH3 TSA off-gas from the cooling step as the heating gas for energy recovery (TSA-TGER) performed the best. Dynamic behavior and sensitivity analyses were conducted to elucidate the characteristics of the TSA-TGER configuration. Using five main operating variables selected from the Pearson correlation method, the developed artificial neural network model could precisely predict the results with a reduction in computational cost of 1800 times compared with the process simulation. Finally, at the optimum condition found from the ML-based optimization, the TSA-TGER configuration consumed 2174.8 MJ/tNH3 and 162.33 $/tNH3 to produce an H2 mixture with less than 0.1 ppm NH3, indicating that the NH3 removal cost contributed to only approximately 0.98% of the referred H2 production cost (3580 $/tH2) via the NH3-to-H2 process. These results provide guidelines for designing an effective NH3 removal configuration from NH3 cracking gases. The proposed ML-based optimization approach can also be applied to other purification processes.

Green Synthesis for Carbon Quantum Dots via Opuntia ficus-indica and Agave maximiliana: Surface-Enhanced Raman Scattering Sensing Applications.

In this study, we present an alternative method for synthesizing carbon quantum dots (CQDs) using a green synthesis approach via extracts from Agave maximiliana and Opuntia ficus-indica(Ofi). The extracts from both plants were used as the carbon source for the CQDs. The synthesis method employs mesoporous zeolite 4A as a refractory for the thermal treatment of the samples. Transmission electron microscopy analysis established that the size of the CQDs shows a narrow distribution centered around 2 nm with a maximum size of less than 3 nm for both cases. The CQDs exhibit absorption bands associated with π-π* transitions located around 220 nm. In both cases, photoluminescence (PL) phenomenon was detected by irradiating the samples with a UV wavelength and detecting emissions close to the blue wavelength. Additionally, both kinds of CQDs were tested as surface-enhanced Raman scattering (SERS) substrates against methylene blue (MB), indicating an enhancement associated with ring deformation and stretching modes of the v(C-C) and v(C-N) bonds located around 1400 and 1620 cm-1, respectively. Complementarily, in the framework of density functional theory, H2nC2(2m+1) structures (with n = 3-5 and m = 1-3) were used as a theoretical representation of CQDs in interaction with the MB molecule. It is used for developing the analysis of charge transfer effects between both systems and for specifying elements that generate the SERS effect associated with the chemical enhancement mechanism.

Towards a Correlation Between Iron/Cobalt Content, Support Pore Size and Metal Particle Size in Supported Catalysts

AbstractFe−Co‐based catalysts supported on γ‐Al2O3, Aerosil 200 silica and zeolite 4A were prepared by co‐precipitation of the respective nitrates in the presence of ammonium hydroxide. The objective was to demonstrate the influence of Fe/Co mass ratio and support pore size on metal particle size. Catalysts were characterized by thermogravimetric analysis (TGA), X‐ray diffraction (XRD), N2 physisorption, Fourier‐transformed infrared spectroscopy (FTIR), and scanning (SEM) and transmission (TEM) microscopies. It was demonstrated that the minimal presence of Fe was enough to reduce the average particle diameters by half. Increasing Fe content did not cause proportional decreases in the average particle diameter. The support pore diameter probably played a role in the crystallization step of bimetallic and Fe monometallic catalysts, whose particle diameters were similar to those observed for the pores. This phenomenon was not observed for Co monometallic catalysts.

Tuning crystallization for controlled morphology of Zeolite A by an eco-friendly sonochemical precursor-less method

This study describes the sustainable synthesis of zeolite 4A from industrial solid residues without the addition of chemical precursors, as well as the optimization of its structural and morphological control using a central composite design. High-modulus silicate and aluminate are extracted from fly ash and red mud by low-temperature alkali fusion (350 °C) followed by ultrasonication. The transformation of colloidal aluminosilicate sol into a stable crystal of zeolite 4A by the hydrothermal method was studied to observe morphological changes and hypothesize a crystal growth mechanism. A total of 20 experiments were conducted to optimize high-quality truncated edge cubic zeolite 4A formation. A pure zeolite 4A (85% of crystallinity, 79.825 m2/g of specific surface area, uniform pore size distribution of 3.69 nm) is obtained under the optimized conditions of FA/RM extract = 1.02, crystallization temperature = 90 °C, crystallization time = 10.25hrs. The surface morphology of zeolite 4A appears in three distinct forms: sharp edge cube when FA/RM extract is greater than 1.02 (Run 19), truncated edge cube when FA/RM extract is equal to 1.02 (Run 2), and rounded edge cube when FA/RM extract is less than 1.02 (Run 18). Based on the ANOVA and desirability function results, we can infer that our anticipated model is a fit and the desired goal of maximum crystallinity was achieved with 95% confidence. The optimized zeolite 4A shows a higher hardness removal capacity of Ca2+(184.6 Ca2+mg/g in just 15 min) and Mg2+ (253.94 mg Mg2+/g in 5 h) for moderately hard pond water than commercial one. The kinetic and thermodynamic study reveals a better fit for the pseudo 2nd order kinetic model with a faster exchange rate of Ca2+(1.5 × 10−2 g.mg−1. min−1) than Mg2+ (7.4 × 10−5 g mg−1. min−1) and cation exchange is a spontaneous endothermic process.

The Effect of Natural and Synthesised Zeolites on Cement-Based Materials Hydration and Hardened State Properties.

The synthesis of zeolites from difficult-to-utilise waste materials facilitates the creation of more financially attractive and efficient synthetic zeolites. These can be incorporated into construction materials, resulting in a reduction in cement usage and the production of superior, clean, and sustainable construction materials. The potential to enhance the hydration rate of fresh cement paste by substituting up to 10% of the cement with two synthetic zeolites-one commercially produced and the other synthesised from waste and natural zeolite-was explored. Due to a higher Al/Na ratio, newly sintered waste-based zeolite possesses six times higher electrical conductivity compared to industrially produced 4A zeolite and more than 20 times higher electrical conductivity compared to natural zeolite. As the sequence of this fact, substituting up to 10% of the cement with AX zeolite cement paste accelerates the maximum heat release rate time and increases the total heat by 8.5% after 48 h of hydration. The structure, compressive strength, and water absorption of the hardened cement paste depends on the Al/Na ratio, pH, and electrical conductivity values of the zeolite used. The findings revealed that AX zeolite, due to presence of mineral gibbsite, which speeds up hydration products, such as CSH development, increases the compressive strength up to 28.6% after 28 days of curing and reduces the water absorption by up to 1.5%. Newly synthesised waste-based AX zeolite is cheap because its production is based on waste materials and is mostly promising due to superior properties of created construction materials compared to the other presented zeolites.

Fractal-like kinetics for enhanced boron adsorption on heterogeneous magnetic composite surfaces

Co-precipitated 14 nm γ-Fe2O3 and 35 nm MgO nanoparticles (NPs) decorated on zeolite 5 A (Z5A) templates were systematically studied. 57Fe Mössbauer and transmission electron microscopy data indicated a broad particle size distribution. The spinel structure of γ-Fe2O3 is strongly affected by size effects (particles smaller than 10 nm in size have an octahedral/tetrahedral iron site ratio of 7/3 instead of 5/3 found in bulk). 27Al nuclear magnetic resonance (NMR) showed the formation of octahedral Al species after boric acid reaction with MgO NPs. 11B NMR spectra indicated adsorption of B on the MgO/Z5A surface, whereas B adsorption in the pure Z5A framework is absent. Adsorption isotherms and kinetic studies of the nanohybrids showed that the B-rich species adsorption is described by Freundlich and fractal-like models, respectively. B adsorption occurs dominantly by the MgO fraction. The nanohybrids presented a good B removal efficiency when compared with other materials reported in literature.

Adsorption-Induced Deformation of Zeolites 4A and 13X: Experimental and Molecular Simulation Study.

Gas adsorption in zeolites leads to adsorption-induced deformation, which can significantly affect the adsorption and diffusive properties of the system. In this study, we conducted both experimental investigations and molecular simulations to understand the deformation of zeolites 13X and 4A during carbon dioxide adsorption at 273 K. To measure the sample's adsorption isotherm and strain simultaneously, we used a commercial sorption instrument with a custom-made sample holder equipped with a dilatometer. Our experimental data showed that while the zeolites 13X and 4A exhibited similar adsorption isotherms, their strain isotherms differed significantly. To gain more insight into the adsorption process and adsorption-induced deformation of these zeolites, we employed coupled Monte Carlo and molecular dynamics simulations with atomistically detailed models of the frameworks. Our modeling results were consistent with the experimental data and helped us identify the reasons behind the different deformation behaviors of the considered structures. Our study also revealed the sensitivity of the strain isotherm of zeolites to pore size and other structural and energetic features, suggesting that measuring adsorption-induced deformation could serve as a complementary method for material characterization and provide guidelines for related technical applications.

Theoretical insight into the polymerization of ethylene on the surface of 3A zeolite: A DFT + kMC study

Separation is the core process of ethylene production, in which the reaction gas is usually dried using 3A zeolite. In this work, ethylene polymerization on the surface of 3A zeolite were investigated by the combination of Density Functional Theory (DFT) and kinetic Monte Carlo (kMC). DFT calculations showed that stepwise mechanism is the dominant path of ethylene dimerization on the surface of 3A zeolite. Then the effect of temperature on the polymerization of ethylene was studied by kMC simulation. When the temperature is higher than 473 K, ethylene begins to polymerize to form corresponding species, which cover the surface and reduce the dehydration performance of 3A zeolite. Based on these, the desorption process with low temperature using pure ethylene as desorption gas for 3A zeolite regeneration is proposed, which can avoid the use of N2, and reduce the equipment investment and energy consumption.

Chitosan-based mixed matrix composite membranes for CO2/CH4 mixed gas separation. Experimental characterization and performance validation

Membrane technology is acknowledged as one of the most efficient for biogas upgrading, separating simultaneously CH4 and CO2 in the retentate and permeate streams, respectively. The sustainability would still be improved by using renewable and environmentally friendly materials for membrane fabrication. Specifically, this study is focused on laboratory-scale mixed gas separation tests of composite membranes prepared from chitosan (CS), a hydrophilic, biodegradable and biocompatible polymer from abundant natural resources, with good adhesive and film forming properties and high affinity for CO2 due to the primary amine and hydroxyl groups functionalities in CS. To improve mechanical resistance and CO2/CH4 separation, CS was hybridized by a 5 wt% loading of non-toxic ionic [emim][acetate] liquid (IL), and variable loadings of compatible inorganic fillers, such as 3D zeolite 4A and NaETS-10, and layered AM-4 titanosilicate. The CS-based mixed matrix layer was coated on porous polyether sulfone (PES) support. The CO2 permeance and CO2/CH4 separation were measured at different feed concentrations to evaluate the membranes performance in the treatment of different streams. This separation behavior was explained by the wet thickness, water uptake, morphology and ionic resistance of the composite membrane. As such, the 5 wt% Zeolite 4A and NaETS-10-filled ILCS/PES membranes provided a good dispersion in the ILCS matrix and the mixed matrix layer a good adhesion with the porous PES support, leading to high CO2 permeances and separation factors up to 30, whereas the more hydrophilic lamellar AM-4 titanosilicate-filled ILCS layer showed cluster agglomeration in the matrix and a faster detachment of the coated layer from the PES substrate. With increasing filler loading, an increase of the permeance of both CO2 and CH4 gas components was, although selectivity decreased upon increasing AM-4 filler loading. The CO2/CH4 mixed gas separation performance was validated by a custom-built model for a wide range of feed composition, to cover such processes as natural gas sweetening, biogas upgrading and enhanced oil recovery with acceptable relative error below 10% (absolute value), except for the AM-4 titanosilicate-filled ILCS membranes, showing morphological fabrication defects.

Preparation of Cu-BTC MOF extrudates for CH4 separation from CH4/N2 gas mixture

Metal-Organic Frameworks (MOF) are promising materials for gas separation and storage. The shaping of MOFs is an essential step for their practical industrial application. In this work, Cu-BTC MOF extrudates (B-5, B-10, and B-15) were prepared by using 5, 10, and 15 wt% of carboxymethyl cellulose as a binder and well characterized by powder X-ray diffraction (PXRD), N2 adsorption-desorption at 77 K, FTIR, TGA, and Scanning Electron Microscopy (SEM). The equilibrium adsorption isotherms of CH4 and N2 with Cu-BTC extrudates were measured at 298, 313, and 328 K and up to 10 bar pressure and compared with zeolite 13X and 5A. The isotherm data of both adsorbates were fitted in Dual Site Langmuir equations, and adsorption selectivity of methane over nitrogen was predicted using Ideal Adsorbed Solution Theory (IAST) method for 20:80, 30:70, and 50:50 (mol%/mol%) CH4/N2 feed gas mixtures representing nitrogen bearing coal bed methane. The CH4/N2 selectivity of Cu-BTC extrudates B-5, B-10, and B-15 was higher than commercial zeolite 13X and 5A. For example, for the 20:80 CH4/N2 feed mixture, the CH4/N2 selectivity of Cu-BTC extrudates B-5, B-10, and B-15 was 3.21, 3.24, and 3.25, respectively, which are about 38 & 34% higher than zeolite 13X and 5A which makes them potential adsorbent for further dynamic studies for the said separation application.

An innovative approach based on microwave radiation for synthesis of zeolite 4A and porosity enhancement

Advantages of microwave radiation in terms of reducing reaction time and enhancing product quality were exploited for template-free zeolite 4A synthesis, in which a domestic microwave oven was purposely utilized instead of a scientific microwave reactor. Experimental data proved that the microwave-assisted hydrothermal synthesized product crystallized at the same phase as the zeolite obtained from the conventional hydrothermal method. Moreover, compared to the hydrothermal synthesis, microwave radiation considerably improves zeolite's properties, including forming more uniform and finer zeolite crystals. However, both synthesis methods produced zeolites with relatively limited surface areas. To solve this problem, an attempt to utilize microwave radiation as a post-washing technique gained a significant improvement of the zeolite's exposed surfaces that revealed effectiveness of microwave on removing the obstacles to release the blocked pores in the zeolite's structure. On that basis, the adsorption characteristics of the 4A zeolites prepared from the two synthesis methods were studied in consideration of the influence of post-washing steps. A comparison on adsorption of these materials was carried out in treating a synthetic dye-containing wastewater of which methylene blue (MB) was used as a model compound. Experiments showed an increment of about quadruple MB uptake achieved from the microwave-assisted method in comparison to the conventional route.

Influence of sodium and potassium proportion on the adsorption of methanol and water on LTA zeolites at high temperature

Catalytic hydrogenation of CO2 or CO, obtained from biomass gasification, is the most used technology to produce renewable methanol. The main problem is that the reactions are controlled by equilibrium, achieving low conversions to methanol, leading to high purification costs and reagent recirculation rates. At 250 °C and 50 bar, the equilibrium conversion of CO2 is around 25%, and methanol selectivity is about 64%. The process can be improved by a sorption-enhanced reaction process (SERP), removing the reaction products in situ and overcoming the equilibrium. To carry out the process, adsorbents with high affinity to the products at high temperatures, like LTA zeolites, are required. Experimental data on methanol and water adsorption at reaction temperatures is quite scarce in the literature, and it is usually assumed that methanol is not adsorbed onto 4A and 3A zeolites. This information is required to design a SERP process with this adsorbent. In this work, the influence of sodium and potassium proportion on the adsorption of methanol and water on LTA zeolites is studied by measuring Henry's adsorption equilibrium constants and reciprocal diffusion time constants. Sodium LTA zeolites (4A) strongly adsorb water and methanol. Potassium-rich LTA zeolites (3A) have higher water/methanol selectivity than sodium-rich LTA zeolites.

Adsorptive removal of ultra-low concentration H2S and THT in CH4 with and without CO2 on zeolite 5A and 13X pellets

Desulfurization of ultra-low sulfur species remaining in natural gas (NG) is important because of its critical effects on both chemical and clean energy applications. Environmental regulations and fuel cell guidelines require NG with a sulfur content of ppm or less. In this study, the adsorptive behavior of representative trace-level sulfur compounds in CH4 balance, H2S, and tetrahydrothiophene (THT) at 4 and 50 ppm, was investigated on zeolite 5A and 13X pellets. Breakthrough experiments were conducted in various binary systems (one sulfur compound in CH4), and surface analysis of the used zeolites was performed to elucidate the adsorption mechanism. The influence of the CO2 impurity level in CH4 on sulfur removal was also investigated in ternary systems (one sulfur compound with 1.5 % CO2 in a CH4 balance). The main pathway of H2S adsorption on zeolite 13X was catalytic oxidation, whereas it was presumed to be dissociative adsorption on zeolite 5A. In contrast, physisorption was dominant for THT removal in both zeolites. The lower contribution of chemisorption in THT led to less adsorptive amount than that in H2S removal at ultra-low concentrations. Furthermore, the molecular structure of THT (higher kinetic diameter) resulted in a faster breakthrough for zeolite 5A than for zeolite 13X. Therefore, more amount of H2S was removed than THT in both zeolites, and zeolite 13X demonstrated better performance for both sulfur compounds than zeolite 5A. Notably, the presence of 1.5 % CO2 in the feed promotes the catalytic oxidation of H2S.

Atomic and electronic structures of an Ag-containing 4A zeolite

Atomic structure of an Ag-containing 4A zeolite with the Ag/Al atomic ratio of about 10% was investigated by a pair distribution function (pdf) analysis. Valence- and conduction-band O 2p partial electronic structures of this insulating material were respectively measured by soft X-ray emission and absorption spectroscopies using an O 1s-2p resonance technique. Moreover, a density functional theory (DFT) hybridized by 25% of Hartree–Fock exchange was applied to determine the atomic structures and electronic states. Although the box size of the DFT calculation was small due to the limited computational power, the present DFT results excellently reproduce the pdf data as well as O 2p partial electron density of states (DOS). The electronic charge distributions in this zeolite with an antibacterial function obtained by the present DFT calculation revealed half-filled charges on the Ag atoms, which may act as a formation of deactivating the bacteria.

Enhanced Removal of As(V) and Pb(II) from Drinking and Irrigating Water Effluents Using Hydrothermally Synthesized Zeolite 5A

Zeolites 5A were obtained by ion exchange of a zeolite 4A, previously synthesized by the hydrothermal method from precursor kaolin, with the aim of removal As(V) from drinking water and Pb(II) from irrigation surface water. Zeolite 5A was characterized before and after adsorption by X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, and X-ray photoelectron spectroscopy. To find the adsorption mechanisms of both As and Pb in real waters, experiments on adsorption kinetics, optimum pH, adsorbent dose, and adsorption isotherms were developed. Adsorption kinetics and adsorption isotherm models were evaluated, and the selection criterion for the appropriate model was made using the residual sum of squares (RSS) and Bayesian information criterion (BIC). As a result, removal adsorption of As(V) and Pb(II) was higher than 95% in 9 and 12 h, respectively. The estimated maximum adsorption capacities for As and Pb were 36.35 mg g−1 and 46.67 mg g−1, respectively. Zeolite 5A is a low-cost adsorbent, through which a concentration of less than 0.01 mg L−1 of As and Pb was obtained in drinking and irrigation water, which is below the permissible limit established by the World Health Organization (WHO).

Design and optimization of multilayer composite membrane for biomethane enrichment: Process simulations and economics

The depletion of fossil fuels has led to the development of various biogas upgrading techniques that can be a reliable and sustainable energy source. At present, membrane-based gas separation and enrichment have received more acceptance to contend with the traditional biogas upgrading processes. Remarkably, multilayered composite membranes (MCM) fabricated from selective polymers and fillers have achieved high consideration in the field of CO2separation. In this regard, the present study focuses on fabricating and optimizing the porous layer of MCM using Polyether sulfone (PES) and Torlon polymers and their morphological influences on overall membrane performance. The MCM membranes fabricated from the PES porous substrate exhibited 3–4 fold higher permeation than the Torlon. Besides, the effect of zeolite type and % loading on the selective layer performance in CO2gas permeation was examined. From the gas permeation experiments, a 6 % loaded 3A zeolite sample exhibited maximum permeation flux for CO2, which is 1.7 folds compared to the neat Polyether block amide (PEBAX)/PES membrane and 5.8 fold to the neat PEBAX/Torlon without compromising the selectivity. Furthermore, process simulation using Aspen Hysys reveals the economic feasibility of membrane-based biomethane enrichment. Overall, the study results are compared with Robeson’s plot, which reveal the substantial potential of MCM-based membrane technology as a biogas upgrading process and offers assistance in developing an appropriate porous support for MCM.