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Chrysanthemum is a commonly used traditional Chinese medicine. Facing the high moisture content, easy decay and spoilage, and intolerance to storage of fresh chrysanthemums; Addressing the demand for chrysanthemum processing technology and the current issues of low automation and high energy consumption in chrysanthemum drying; A solar powered molecular sieve drying device was developed using the dehumidification characteristics of molecular sieves to solve the drying problem of chrysanthemum processing. At the same time, the device has an auxiliary electric heating function to meet the requirements of different drying methods for chrysanthemum processing under different weather conditions. Practical verification has shown that the molecular sieve drying device based on solar energy can well meet the process requirements of different drying methods for chrysanthemums, and has the characteristics of green environmental protection, low power consumption, high production efficiency, and good drying quality.

With the advancement of industrial production and urban modernization, pollution from heavy metal ions and the accumulation of solid waste have become critical global environmental challenges. Establishing an effective recycling system for solid waste and removing heavy metals from wastewater is essential. Coal gangue was used in this study as the primary material for the synthesis of a fully coal gangue-based phosphorus-silicon-aluminum (SAPO-5) molecular sieve through a hydrothermal process. The SAPO-5 molecular sieve was characterized through several methods, including X-ray diffraction (XRD), scanning electron microscopy (SEM), BET surface analysis, Fourier-transform infrared (FT-IR) spectroscopy, and X-ray photoelectron spectroscopy (XPS), to examine its mineral phases, microstructure, pore characteristics, and material structure. Adsorption performance towards wastewater with Cd2+ and Pb2+ ions was investigated. It was found that the adsorption processes of these ions are well described by both the pseudo-second-order model and the Langmuir isotherm. According to the Langmuir model, the coal gangue-based SAPO-5 molecular sieve exhibited maximum adsorption capacities of 93.63 mg·g−1 for Cd2+ and 157.73 mg·g−1 for Pb2+. After five cycles, the SAPO-5 molecular sieve retained strong stability in adsorbing Cd2+ and Pb2+, with residual adsorption capacities of 77.03 mg·g−1 for Cd2+ and 138.21 mg·g−1 for Pb2+. The excellent adsorption performance of the fully solid waste coal gangue-based SAPO-5 molecular sieve is mainly attributed to its mesoporous channel effects, the complexation of -OH functional groups, and electrostatic attraction.

TS-1 with different Ti/Si molar ratios (0.02 for TS-1a, 0.025 for TS-1b, 0.03 for TS-1c), and Ti–K (TiO2-SiO2) catalysts were prepared through a hydrothermal procedure and characterized by the XRD, BET, SEM/TEM, XPS/ICP, Raman, UV–Vis, FT-IR/Py–IR, and NH3–TPD for gas-glycerol value-added conversion. The acidic [(Ti, Si)O4] sites were considered to be the reactive centers for acetaldehyde production with the selectivity closely related to the concentration of [(Ti, Si)O4] and Smicro/SBET values but not the PyB/PyL value or surface acid density. The [(Ti, Si)O4] in MFI micro-structure promoted acetaldehyde production by 1–2 dehydration and subsequent cracking of gas-glycerol, better than the [(Ti, Si)O4] without MFI micro-structure. Over the TS-1c, gas-glycerol conversion reached 91.5%, with the selectivity towards acetaldehyde and acrolein reaching 34.4% and 29.5%, respectively. Significantly, the catalytic stability of the TS-1c can be obviously improved by using liquid feed of a glycerol-methanol solution.TS-1c (3.3%) showed glycerol catalytic conversion reached 91.5 % with the selectivity of acetaldehyde and acrolein reaching about 34.4 %, and 29.5 %, respectively. The acidic [(Ti, Si)O4] was confirmed to be the reactive centers for acetaldehyde production, especially for the [(Ti, Si)O4] in MFI micro-structure (with b-axis 300 nm, micro-pores 5.8 Å) promoted acetaldehyde production from 1 to 2 and 1–3 dehydration of glycerol. It was new found the catalytic stability of TS-1c can be obviously improved as using liquid feed of glycerol-methanol solution.

Methylene blue is one of the most common compounds in mutagenic, teratogenic and carcinogenic dye wastewater. Adsorption is a simple and effective method for efficient treatment of organic wastewater. In this study, amine functionalized Al-SBA-15 mesoporous molecular sieves were prepared for adsorption of methylene blue solution. Solid waste fly ash was utilized as a cheap source of silica, which was combined with templating agent P123 to form Al-SBA-15 molecular sieves. Then silane coupling agent (APTES) was used to graft amine groups on the surface of Al-SBA-15 to improve the adsorption performance. The adsorption experiments showed that NH 2 -Al-SBA-15 had the best adsorption performance, with 324 mg g −1 against 200 mg L −1 methylene blue solution in 500 min. But the adsorption of Al-SBA-15 was 311 mg g −1 . It proved that the functionalization increased the adsorption of methylene blue by the molecular sieve. Then the kinetic study was carried out, which showed that it conformed to the proposed secondary kinetics as well as Langmuir isothermal adsorption model. Then the effects of pH, adsorption temperature and methylene blue concentration on the adsorption performance were investigated. The optimal adsorption performance was obtained, and it resulted in the optimal adsorption pH value of 10, adsorption temperature of 25 °C, methylene blue concentration of 200 mg L −1 , and mass of adsorbent of 30 mg.

In this study, a ZSM−5/CLCA molecular sieve was prepared by the hydrothermal method using coal gangue as the raw material and cellulose aerogel (CLCA) as the green templating agent, which not only reduces the cost of traditional molecular preparation but also improves the comprehensive resource utilization rate of coal gangue. Through a series of characterization methods (XRD, SEM, FT-IR, TEM, TG, and BET), the crystal form, morphology, and specific surface area of the prepared sample were tested and analyzed. The performance of the adsorption process of malachite green (MG) solution was analyzed by adsorption kinetics and adsorption isotherm. The results show that the synthesized zeolite molecular sieve and the commercial zeolite molecular sieve are highly consistent. At a crystallization time of 16 h, a crystallization temperature of 180 °C, and an additive amount of cellulose aerogel of 0.6 g, the adsorption capacity of ZSM−5/CLCA for MG was up to 136.5 mg/g, much higher than that of commercially available ZSM−5. This provides an idea for the green preparation of gangue-based zeolite molecular sieves to remove organic pollutants from water. Moreover, the process of adsorbing MG on the multistage porous molecular sieve, which is spontaneous, conforms to the pseudo-second-order kinetic equation and Langmuir isothermal adsorption model.

Poly-2,6-dimethylphenylene oxide (PPO) film samples with varying degrees of crystallinity (from 0 to 69%) were obtained by means of different techniques. The films were studied by various physicochemical methods (Fourier-transform infrared spectroscopy, positron annihilation lifetime spectroscopy, X-ray diffraction, and 1H nuclear magnetic resonance relaxation). Solubility coefficients of gases in the PPO samples were measured via sorption isotherms of gases by volumetric technique with chromatographic detection. The apparent activation energy of permeation and the activation energy of diffusion of all gases were estimated based on temperature dependences of gas permeability and diffusivity for amorphous and semi-crystalline PPO in the range of 20–50 °C. The peculiarities of free volume, density, and thermal properties of gas transport confirm the nanoporosity of the gas-permeable crystalline phase of PPO. So, the PPO can be included in the group of organic molecular sieves.

A series of 9-aryl-hexahydroacridine-1,8-diones are synthetized with good to excellent yields (50–99%) via a one-pot four-component reaction of dimedone, aromatic aldehydes and ammonium acetate in the presence of 4 Å molecular sieves modified with iron(III) as an efficient heterogeneous catalyst, in ethanol. The process offers the advantages of high yields, mild reaction conditions and easy work-up procedure. The catalyst can be reused without significant loss of activity. Graphic Abstract

A mesoporous molecular sieve was prepared by the hydrothermal synthesis method with symmetric Gemini surfactant 1,3-bis(hexadecyldimethylammonio)-propane dibromide, symmetric Gemini ionic liquid surfactant 1,3-bis(3-hexadecylimidazolium-1-yl) propane dibromide and self-designed asymmetric Gemini ionic liquid surfactant 1-(3-(hexadecyldimethylammonio)prop-1-yl)-3-hexadecylimidazolium dibromide as the template agent. The structure characterization results for mesoporous molecular sieves show that the material possesses a hexagonal pore structure with uniform channels. The mesoporous silica that was synthesized with self-designed asymmetric Gemini ionic liquid surfactant as the template agent possesses the largest surface area and its pore size and specific surface area are, respectively, 3.28 nm and 879.37 m2/g. The adsorption properties of the prepared MCM-41 for crystal violet were investigated, and the adsorption thermodynamics and kinetics were investigated. The results show that adsorption equilibrium can be reached under pH = 9 and 35 °C for 50 min, and the quantity of adsorption can reach up to 464.21 mg/g. The adsorption process belongs to Langmuir isothermal adsorption, conforming to second-order adsorption kinetics, and the adsorption process is an endothermic process.

The present report describes the structural and physical–chemical variations of the potassium manganese oxide mineral, α–MnO2, which is a specific manganese octahedral molecular sieve (OMS) named cryptomelane (K–OMS–2), with different transition metal cations. We will describe some frequently used synthesis methods to obtain isomorphic substituted materials [M]–K–OMS–2 by replacing the original manganese cationic species in a controlled way. It is important to note that one of the main effects of doping is related to electronic environmental changes, as well as to an increase of oxygen species mobility, which is ultimately related to the creation of new vacancies. Given the interest and the importance of these materials, here, we collect the most recent advances in [M]–K–OMS–2 oxides (M = Ag, Ce, Mo, V, Nb, W, In, Zr and Ru) that have appeared in the literature during the last ten years, leaving aside other metal–doped [M]–K–OMS–2 oxides that have already been treated in previous reviews. Besides showing the most important structural and physic-chemical features of these oxides, we will highlight their applications in the field of degradation of pollutants, fine chemistry and electrocatalysis, and will suggest potential alternative applications.

Carbon molecular sieve (CMS) membranes have been developed to replace or support energy-intensive cryogenic distillation for olefin/paraffin separation. Olefin and paraffin have similar molecular properties, but can be separated effectively by a CMS membrane with a rigid, slit-like pore structure. A variety of polymer precursors can give rise to different outcomes in terms of the structure and performance of CMS membranes. Herein, for olefin/paraffin separation, the CMS membranes derived from a number of polymer precursors (such as polyimides, phenolic resin, and polymers of intrinsic microporosity, PIM) are introduced, and olefin/paraffin separation properties of those membranes are summarized. The effects from incorporation of inorganic materials into polymer precursors and from a pyrolysis process on the properties of CMS membranes are also reviewed. Finally, the prospects and future directions of CMS membranes for olefin/paraffin separation and aging issues are discussed.