Dual mechanisms based on synergistic effects of evaporation potential and streaming potential for natural water evaporation

Electricity generation by natural water evaporation generators (NWEGs) using porous materials shows great potential for energy harvesting, but mechanistic investigations of NWEGs have mostly been limited to streaming potential studies. In this study, we propose the coexistence of an evaporation potential and streaming potential in a NWEG using ZSM-5 as the generation material. The iron probe method, salt concentration regulation, solution regulation, and side evaporation area regulation were used to analyze the NWEG mechanism. Our findings revealed that a streaming potential formed as water flowed inside the ZSM-5 nanochannels, driven by electrodynamic effects that increased from the bottom to the top of the generator. In addition, an evaporation potential existed at the surface interface between ZSM-5 and water, which decreased from the bottom to the top as the evaporation height of the generator increased. The resulting open-circuit voltage (Voc) depended on the balance between the evaporation and streaming potentials, both of which were influenced by the evaporation enthalpy (Ee) or vapor pressure. Generally, a higher Ee or lower vapor pressure led to a lower evaporation potential and subsequently a lower Voc. A dual mechanism involving synergistic evaporation potential and streaming potential is proposed to explain the mechanism of NWEGs.

Effective adsorption of Pb(II) ion from aqueous solution onto ZSM-5 zeolite synthesized from Vietnamese bentonite clay

ZSM-5 zeolite was successfully synthesized from bentonite clay sourced from Lam Dong Province, Vietnam, using the hydrothermal method at 170 °C for 18 h. The synthesized ZSM-5 (SiO2/Al2O3 ratio ~ 34) exhibited a single phase with high crystallinity (91.8%), and a clear and uniform shape. In a detailed examination of the synthesized material's Pb(II) adsorptive capacity, various factors were taken into account, including pH, interaction time, ionic strength, and the amount of adsorbent. Isotherms and kinetics were examined to elucidate the uptake behavior. Study results suggested that Pb(II) ion uptake by ZSM-5 was most appropriately described by the Sips isotherm and intraparticle diffusion kinetic models. The calculated maximum monolayer adsorption capacity according to the Langmuir isotherm model was 48.36 mg/g. Furthermore, the adsorption mechanisms of Pb(II) on ZSM-5 involving electrostatic interactions, ion exchange, and diffusion into pores were demonstrated using the analytical techniques before and after Pb(II) adsorption. These findings demonstrate that ZSM-5 synthesized from bentonite clay exhibits an excellent adsorption capacity for Pb(II), resulting in promising applications for treating drinking water or aqueous industrial waste containing Pb(II) ions.

Enhancing H2O2 utilization efficiency for catalytic wet peroxide oxidation through the doping of La in the Fe-ZSM-5 Catalyst

Iron-loaded zeolite (Fe-zeolite) has shown great potential as an efficient catalyst for degrading organic pollutants with high concentrations in the catalytic wet peroxide oxidation (CWPO) process under mild conditions. Here, 0.4 wt% Lanthanum (La) was added in the 1.0 wt% Fe-ZSM-5 by two-step impregnation method for an enhanced H2O2 utilization efficiency. For a systematical comparison, the CWPO process at 55 °C, where m-cresol with a high concentration of 1000 mg/L as a substrate, was studied over Fe-ZSM-5 and Fe-La-ZSM-5 catalysts. Compared with Fe-ZSM-5, Fe-La-ZSM-5 showed 15% higher H2O2 utilization efficiency with comparable total organic carbon (TOC) removal at around 40%, meanwhile with a 15% reduced metal leaching. Transmission electron microscopy (TEM) with elemental mapping (EDS), surface acidity analysis by Fourier transform infrared (FT-IR) and NH3-temperature programmed desorption (NH3-TPD), redox property analysis by Raman spectroscopy and H2-temperature-programmed reduction (H2-TPR) of both catalysts revealed, that the La doped Fe-ZSM-5 can provide an altered surface acidity, a more uniform and evenly dispersed surface Fe species with a promoted reducibility, which effectively promoted the accurate decomposition of H2O2 into the reactive •OH radicals, enhanced the H2O2 utilization efficiency, and increased the catalyst stability. Also, more than 90% conversion was maintained during the continuous experiment for more than 10 consecutive test days under 55 °C without pH adjustment, showing a promising possibility of the Fe-La-ZSM-5 for a practical wastewater treatment process.

Production of combustible fuels and carbon nanotubes from plastic wastes using an in-situ catalytic microwave pyrolysis process

This study performed in-situ microwave pyrolysis of plastic waste into hydrogen, liquid fuel and carbon nanotubes in the presence of Zeolite Socony Mobil ZSM-5 catalyst. In the presented microwave pyrolysis of plastics, activated carbon was used as a heat susceptor. The microwave power of 1 kW was employed to decompose high-density polyethylene (HDPE) and polypropylene (PP) wastes at moderate temperatures of 400-450 °C. The effect of plastic composition, catalyst loading and plastic type on liquid, gas and solid carbon products was quantified. This in-situ CMP reaction resulted in heavy hydrocarbons, hydrogen gas and carbon nanotubes as a solid residue. A relatively better hydrogen yield of 129.6 mmol/g as a green fuel was possible in this process. FTIR and gas chromatography analysis revealed that liquid product consisted of C₁₃₊ fraction hydrocarbons, such as alkanes, alkanes, and aromatics. TEM micrographs showed tubular-like structural morphology of the solid residue, which was identified as carbon nanotubes (CNTs) during X-ray diffraction analysis. The outer diameter of CNTs ranged from 30 to 93 nm from HDPE, 25-93 nm from PP and 30-54 nm for HDPE-PP mixure. The presented CMP process took just 2-4 min to completely pyrolyze the plastic feedstock into valuable products, leaving no polymeric residue.

Synthesis and characterization of gentamicin loaded ZSM-5 scaffold: Cytocompatibility and antibacterial activity

Porous structure, biocompatibility and biodegradability, large surface area, and drug-loading ability are some remarkable properties of zeolite structure, making it a great possible option for bone tissue engineering. Herein, we evaluated the potential application of the ZSM-5 scaffold encapsulated GEN with high porosity structure and significant antibacterial properties. The space holder process has been employed as a new fabrication method with interconnected pores and suitable mechanical properties. In this study, for the first time, ZSM-5 scaffolds with GEN drug-loading were fabricated with the space holder method. The results showed excellent open porosity in the range of 70-78% for different GEN concentrations and appropriate mechanical properties. Apatite formation on the scaffold surface was determined with Simulation body fluid (SBF), and a new bone-like apatite layer shaping on all samples confirmed the in vitro bioactivity of ZSM-5-GEN scaffolds. Also, antibacterial properties were investigated against both gram-positive and gram-negative bacteria. The incorporation of various amounts of GEN increased the inhibition zone from 24 to 28 (for E. coli) and 26 to 37 (for S. aureus). In the culture with MG63 cells, great cell viability and high cell proliferation after 7 days of culture were determined.

Efficient Removal of Organic Dye from Aqueous Solution Using Hierarchical Zeolite-Based Biomembrane: Isotherm, Kinetics, Thermodynamics and Recycling Studies

Bio adsorbents have received tremendous attention due to their eco-friendly, cheap and non-toxic nature. Recently, bio-adsorbent-based membranes have been frequently employed for water treatment. The work reports the preparation of a novel adsorbent membrane from hierarchical zeolite, polyvinyl alcohol, carboxymethyl cellulose and agar. The fabricated membrane was characterized spectroscopically and microscopically with several techniques such as XRD, UTM, TGA, optical microscopy and FT-IR, as well as contact-angle studies. The result showed that the hierarchical-zeolite-loaded membrane is superior in terms of thermal stability, mechanical properties and surface roughness. The fabricated membrane was investigated for its efficiency in the removal of Congo red dye in aqueous conditions. The influence of pH, temperature, contact period and the initial concentration of dye and zeolite loading on the adsorption process are also explored. The adsorption results highlighted the maximum sorption property of Congo red on agar/zeolite/carboxymethyl cellulose/polymer biomembrane was found to be higher (15.30 mg/g) than that of zeolite powder (6.4 mg/g). The adsorption isotherms and kinetic parameters were investigated via Langmuir, Freundlich and pseudo-first order, pseudo-second order and the intraparticle diffusion model, respectively. The adsorption isotherms fitted well for both considered isotherms, whereas pseudo-second order fitted well for kinetics. The thermodynamic parameter, ΔG at 303 K, 313 K and 323 K was −9.12, −3.16 and −0.49 KJ/mol, respectively. The work further explores the antibacterial efficacy of the prepared membrane and its reusability.

An efficient green protocol for the synthesis of 1,2,4,5-tetrasubstituted imidazoles in the presence of ZSM-11 zeolite as a reusable catalyst

In this study, we have synthesized a series of ZSM-11 zeolite catalysts using tetrapropyl ammonium hydroxide as a structure-directing agent through a highly efficient hydrothermal method. The series of catalysts were studied by different techniques such as FT-IR spectroscopy, XRD, FE-SEM, HR-TEM, EDS, pyridine-FT-IR spectroscopy, and BET analysis. We focused on varying reaction time intervals from 18 to 48 hours to investigate the effect on catalytic activities of the synthesized series of catalysts. The percentages of aluminum increased in the framework of zeolites with increasing crystallinity, surface area, external surface area, and acidity in the series of ZSM-11 zeolites by increasing the time from 18 to 48 h. Then, we studied the catalytic activity of a series of ZSM-11 zeolites and found that the ZSM-11 zeolite (48 h) possesses higher catalytic activity towards the synthesis of 1,2,4,5-tetrasubstituted imidazoles under solvent-free conditions. The present protocol scored well with excellent yield, short reaction time, clean reaction profiles, low catalyst loading, and no tedious workup. The catalyst (ZSM-11 zeolite 48 h) was recycled and reused in five runs without any considerable loss of activity and product yield.

In situ DRIFT studies on N2O formation over Cu-functionalized zeolites during ammonia-SCR

The influence of the zeolite framework structure on the formation of N2O during ammonia-SCR of NOx was studied for three different copper-functionalized zeolite samples, namely Cu-SSZ-13 (CHA), Cu-ZSM-5 (MFI), and Cu-BEA (BEA).

Effect of H-ZSM-5 zeolite content on the intrinsic kinetics of methanol dehydration to dimethyl ether over H-ZSM-5/Al2O3 molded catalyst

The catalyst composition affects the activation energy and methanol absorption heat, whereas the mechanism of methanol absorption (associative or dissociative) and pre-exponential factor exhibit no sensitivity to catalyst composition.

Synthesis and Characterization of Sn, Ge, and Zr Isomorphous Substituted MFI Nanosheets for Glucose Isomerization to Fructose

Various metals including Sn, Ge, and Zr have been successfully incorporated into the MFI nanosheets via a one-pot synthesis. The as-synthesized zeolites exhibit high external surface area and mesopore volume without large metal oxides aggregated on zeolite surfaces. Interestingly, the successful introduction of heteroatoms in MFI nanosheets can be confirmed by shifted XRD peaks corresponding to the unit cell expansion due to the replacement of metals into the framework. In addition, the UV-Vis absorbance spectra reveal that at the suitable metal loading the incorporated tetrahedral coordination of metal species in the zeolite framework has been obtained. To illustrate the benefits of the prepared catalysts, the glucose isomerization to fructose was carried out in a water/dioxane system. Obviously, the SnMFI-NS samples, containing the high dispersion of metal isomorphous species demonstrate the outstanding catalytic behavior in term of fructose selectivity (>85 %).

Comprehensive Understanding of the Eco-Friendly Synthesis of Zeolites: Needs of 21st Century Sustainable Chemical Industries

Zeolites have taken a leading position in petrochemical, fine, and bulk chemical industries due to their porous architecture, pore sizes, tunable acidity, and thermal stability. Various strategies of zeolites preparation, including template-free, solvent-free, and toxic mineral-free strategies are summarized. Moreover, the zeolite synthesis using naturally occurring minerals and sustainable natural templates is also discussed, which involves the synthesis of nanocrystalline zeolites of different framework structures using plant-based natural templates and biomass-derived renewable chemicals. Overall this personal account provides the fundamentals of various sustainable synthetic strategies reported in the literature for the synthesis of zeolites with suitable examples that will be useful for the students and will motivate experienced researchers to develop various novel sustainable methods for the synthesis of zeolites and other inorganic materials of industrial relevance.

Zeolites for theranostic applications

Theranostic platforms bring about a revolution in disease management. During recent years, theranostic nanoparticles have been utilized for imaging and therapy simultaneously. Zeolites, because of their porous structure and tunable properties, which can be modified with various materials, can be used as a delivery agent. The porous structure of a zeolite enables it to be loaded and unloaded with various molecules such as therapeutic agents, photosensitizers, biological macromolecules, MRI contrast agents, radiopharmaceuticals, near-infrared (NIR) fluorophores, and microbubbles. Furthermore, theranostic zeolite nanocarriers can be further modified with targeting ligands, which is highly interesting for targeted cancer therapies.

Structural variations and generation of binding sites in Fe-loaded ZSM-5 and silica under the effect of UV-irradiation and their role in enhanced BTEX abatement from gas streams

Here, we have investigated the effect of UV-pretreatment on the physicochemical properties of an adsorbent. The UV-irradiated Fe-incorporated ZSM-5 (UV-FZ5) showed structural and chemical changes arising due to UV-cleaving of framework bonds resulting in a decreased crystallinity and change in the local environment of Fe species. More visible modifications were observed for UV-irradiated iron-containing silica (UV-Fe/AS) where silica network reconfiguration, increased hydroxyl density, and change in the Fe coordination were estimated. A 0.5-81.2% increase in BTEX adsorption was recorded for UV-irradiated adsorbents. These hiked performances were attributed to the increased pore size, increased hydroxyl density, and formation of newer isolated Fe³⁺ framework species. For FZ5, adsorption occurred via size-selective diffusion followed by hydrogen bonding and cation-pi interaction, whereas, for Fe/AS, diffusion was followed by cation-pi interactions. Moreover, adsorbents retained their adsorption capacity for multiple cycles and were found economically suitable for treating VOCs-contaminated air.

CO2 and water vapor adsorption properties of framework hybrid W-ZSM-5/silicalite-1 prepared from RHA

Framework hybrid W-ZSM-5 and W-silicalite-1 zeolites were synthesized by hydrothermal methods using rice husk ash (RHA) as a silicon raw material. RHA is a low-cost precursor material, and its use can also alleviate the environmental and human health related problems that may occur when it is stacked in open fields. A series of comparative samples were characterized by XRD, FTIR, ICP-OES, SEM, N₂ adsorption–desorption and pore size analysis in order to examine their crystal structure, hybrid state, morphology and textural properties. The maximum CO₂ adsorption capacities of W-ZSM-5 and W-silicalite-1 are 81.69 and 69.96 cm³ g⁻¹, respectively, measured at 15 bar. The isotherms of CO₂, N₂ and O₂ are perfectly fitted by the Toth model, and it is noted that the presence of Al atoms increases the heterogeneity. It can be seen that the greater the heterogeneity of the adsorbent, the larger the CO₂ adsorption capacity achieved. The incorporation of tungsten into the framework does not affect the crystallization of the zeolite, but it prevents the formation of silanol and O–H groups at the adsorption sites. Therefore, the CO₂/H₂O selectivity of W-ZSM-5 is slightly higher than that of ZSM-5, and that of W-silicalite-1 is three times that of silicalite-1. W-ZSM-5/silicalite-1 are promising adsorbents for separating CO₂ under humid industrial conditions.

Framework hybrid W-ZSM-5 and W-silicalite-1 zeolites were synthesized by hydrothermal methods using rice husk ash (RHA) as a silicon raw material.

Induction of apoptotic effects of anti-proliferative zeolite X from coal fly ash on cervical cancer (HeLa) cell lines

The synthesised zeolite X from coal fly ash showed significant cytotoxic activity in contradiction of HeLa cells (cervical cancer) in a concentration-dependent way at concentrations ranges from 200 µg to 0.781 µg/ml as shown by MTT assay and failed to cause cytotoxic effect in normal cells (Gh239). Cell cycle analysis exposed that zeolite X (10 and 15 µg/ml) endorses cell growth inhibition by inducing G2/M phase arrest in HeLa cells as observed using flow cytometry. The confocal microscopic results depicted increased early apoptotic related changes in HeLa cell lines induced by zeolite X at a dosage of 10, 15 and 20 µg/ml. Zeolite X at a dosage of 10, 15 and 20 µg/ml in HeLa cells showed fragmentation of DNA by ladder pattern thereby indicates that cell death is related with apoptosis. By the increase of Bax/Bcl-2 ratio, zeolite X leads to the caspase-3 and caspase-9 activation and allow the cells to enter apoptosis. These collective results evidently showed that the influence of mitochondria-mediated signalling pathway in zeolite X induced apoptosis and intensely delivered investigational suggestion for the use of zeolite X as a significant curative agent in the preclusion and therapy of human cervical carcinoma.