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The nucleation and crystal growth of a nanoscale cesium pollucite aluminosilicate zeolite (ANA topology) from an organotemplate-free precursor suspension are reported. By using a new and reactive synthesis recipe (5.5SiO2 : 1Al2O3 : 6Cs2O : 140H2O), zeolite nanocrystals with higher Al content (Si/Al ratio = 2.12) are obtained within 120 min under mild conditions (180 °C), which is much faster and safer as compared to those previously reported. The solid initially experiences amorphous phase re-organization before nucleation, crystallization and crystal growth take place. The resulting Cs-pollucite nanocrystals (average size 55 nm) display a trapezohedron morphology. The nanocrystals are colloidally stabilized in water and they are very active in the base-catalyzed cyanoethylation of dipropylamine reaction, giving 89.6% conversion at 180 °C within 50 min. In addition, a high solid yield of nanocrystals (ca. 70%) is also achieved, thus offering a green pathway for synthesizing zeolite nanocrystals with high basicity on a large scale. [ABSTRACT FROM AUTHOR]

Abstract Green synthesis of nanosized AlPO- n and SAPO- n (n = 5 and 18) crystals with AFI- and AEI-type structures from non-reacted precursor suspensions with an essential chemical compensation is presented. The crystallization of both materials was accomplished within few minutes (5–18 min) instead of several days by replacing the conventional with microwave heating. The nanosized AlPO- n and SAPO- n (n = 5 and 18) crystals were stabilized in coating suspensions and deposited in layers on silicon wafers. It was shown that the AFI-type crystals (one-dimensional pores with a diameter of 0.73 nm) were primarily oriented with (001) direction perpendicular to the substrate, while the AEI-type crystals (three-dimensional pores with a diameter of 0.38 nm) were randomly oriented. The relationship between the crystal orientation and the adsorption behavior of the AFI and AEI layers toward water was studied by GI-XRD and operando IR spectroscopy. Graphical abstract Image 1 Highlights • Green synthesis of nanosized AlPO- n and SAPO- n (n = 5 and 18). • Nanosized AlPO- n and SAPO- n crystals with high yield. • Orientation of AlPO- n and SAPO- n nanocrystals in layers. • Water sorption capacity of AlPO- n and SAPO- n layers. [ABSTRACT FROM AUTHOR]

We reported for the first time the use of bamboo leaf biomass (BLA) as a silica source for the synthesis of aluminosilicate zeolite A (structure code LTA). The BLA with very high silica purity (ca. 99%) was obtained from combustion of acid-treated bamboo leaves, a cheap and abundant agriculture waste. The formation of zeolite A from the BLA precursor was studied by varying the synthesis conditions, i.e. crystallization time, heating temperature and initial gel molar composition. The study revealed that the synthesis parameters had profound effects on crystalline phase, morphology and crystal size of the zeolite A produced. Moreover, this study also demonstrated that the BLA-synthesized zeolite A showed excellent catalytic performance in solvent-free cyanoethylation reaction of methanol under moisture-tolerant and autogenic pressure conditions, with ca. 82% reactant conversion and 100% product selectivity even reused up to ten reaction cycles. [ABSTRACT FROM AUTHOR]

The formation of colloidal AlPO-5 nanocrystals were studied under hydrothermal and microwave conditions in the presence of a new templating agent, 1-ethyl-2,3-dimethylimidazolium hydroxide ([edmim]OH). The syntheses were performed by varying the synthesis conditions, i.e. crystallization time, heating temperature, molar composition and synthesis method. The study revealed that the synthesis parameters had profound effects on crystal growth and physico-chemical properties of AlPO-5 nanocrystals. The resulting AlPO-5 nanocrystals were colloidally stable and the crystallite size with defined shapes can be controlled in the range of 50–900 nm. Moreover, this study demonstrated a facile and fast microwave synthesis method whereby AlPO-5 nanocrystals could be obtained within several minutes instead of hours. The microwave-synthesized AlPO-5 nanocrystals had higher water sorption capacity, higher energy density and fast water desorption than the hydrothermal-synthesized counterpart making it a promising material for water sorption applications. [ABSTRACT FROM AUTHOR]

Most of the conventional catalysts exhibited limitations in catalyzing etherification reactions. In this study, functionalized multi-walled carbon nanotube (F-CNT) catalyst containing Lewis acid sites were preparedviafunctionalization with sulfuric acid and the catalytic performances in the etherification oftert-butyl alcohol (TBA) with ethanol were investigated. Characterization of F-CNTs with thermogravimetric analysis, Raman spectroscopy, Fourier transform-infrared spectroscopy, pyridine adsorption, temperature-programmed desorption of ammonia and nitrogen adsorption were performed to correlate the characteristics with the catalytic performances. The catalyst showed a high catalytic performance and high selectivity in the etherification reaction. The best reaction conditions obtained consist of 4 h of reaction time at 140°C, an ethanol:TBA molar ratio of 2:1 and a catalyst loading of 3 wt%. The best conversion of TBA and TBA selectivity toward ethyltert-butyl ether (ETBE) were 64% and 68%, respectively. No significant degradation of the catalytic performance was observed after four consecutive reactions and the catalyst was easily regained after regeneration. A mechanism for the etherification reaction was also proposed. [ABSTRACT FROM AUTHOR]

The ionothermal crystallization of FeAPO-5 molecular sieves in the presence of phosphorous acid (H3PO3) has been investigated. The use of H3PO3 enabled the formation of a metastable intermediate phase (FeNKX-2) that transforms into a more open-framework crystalline phase (FeAPO-5). The initial raw materials dissolved rapidly in the presence of the [bdmim]Cl polar ionic liquid, and the addition of the Fe3+ salt resulted in the crystallization of the FeNKX-2 intermediate. At this stage, the [bdmim]+ cation did not play the role of a pore filler for the FeNKX-2 crystalline structure. Consecutive phase transformation from the FeNKX-2 to the FeAPO-5 phase occurred under prolonged ionothermal treatment, and during this stage, the tetrahedral Fe3+ species was found to not only participate in the construction of the FeAPO-5 framework but also act as an intermediary electron-transfer medium. The fast crystallization of FeAPO-5 was explained by the presence of Fe3+ as an intermediate electron-transfer medium promoting the fast release of phosphorus nutrients (P5+) from the phosphite (P3+) reservoir that were further required for the crystallization of the FeAPO-5 molecular sieves. The use of ionic liquids as dual solvents and templates in combination with H3PO3 as an alternative phosphorus source thus opens the possibility to synthesize other microporous materials via a phase transformation approach. [ABSTRACT FROM AUTHOR]

Synthesis of EMT zeolite nanocrystals from rice husk ash biomass (RHA) under continuous ultrasonic irradiation is reported. The aging, nucleation and crystallization stages of EMT zeolite in the system were monitored at ambient temperature, and compared with the conventional hydrothermal method. It was found that ultrasonic wave induced rapid crystal growth of the nanosized EMT zeolite. Complete crystallization of EMT nanocrystals was achieved within 24 h which was much faster than conventional hydrothermal synthesis (36 h). Furthermore, XRD and TEM analyses revealed that more nuclei were formed during the nucleation stage, allowing the preparation of smaller zeolite nanocrystals with high crystallinity. The results also showed that sonocrystallization produced EMT zeolite with high yield (ca. 80%). The ultrasound-prepared EMT nanocrystals were also found to have high porosity and high hydrophilicity, making the material promising for water sorption applications including vapor sensing, heat pump and adsorption technologies. [ABSTRACT FROM AUTHOR]

Highlights: [•] ZnCl2 nanoparticles (∼10nm) are strongly attached on the CMS support. [•] The catalysts possess strong Lewis acidity and high surface area (∼700m2/g). [•] The catalysts show synergistic effect in hydroamination of cyclohexene. [•] The catalysts has better performance than common homo- and heterogeneous catalysts. [•] The catalyst can be easily separated after reaction and is recyclable. [Copyright &y& Elsevier]

A detailed investigation on the crystallization of offretite (OFF) zeolite templated by non-toxic cetyltrimethylammonium bromide (CTABr) is reported. Various hydrothermal synthesis conditions are prepared by systematically adjusting the synthesis variables, namely crystallization time, heating temperature and amount of reactants (SiO 2 , Al 2 O 3 , K 2 O, M 2 O (M = Na+, Cs+), CTABr and H 2 O) to investigate their effects on the crystal growth of OFF zeolite. It is shown that each variable has its profound influences on the crystallization process, which further affect the properties of final zeolite products (e.g. phase purity, morphology, crystal size). Unlike classical synthesis pathway using tetramethylammonium (TMA+) as organic template, the CTABr-templating approach successfully produces large OFF single crystals (framework Si/Al ratio = 4.11) with hexagonal prism shape (ca. 9.4 × 1.8 μm2) and smooth surface. Besides that, the OFF zeolite (81.9% conversion) also shows comparable or even higher catalytic performance than other zeolites reported in this work and other works in microwave assisted-Knoevenagel reaction of benzaldehyde and ethyl cyanoacetate, offering a sustainable and facile pathway for preparing zeolitic materials for advanced applications. [Display omitted] • Offretite (OFF) zeolite is synthesized using CTABr amphiphile-templating method. • Various synthesis conditions are studied. • Large OFF single crystals with hexagonal prism shape are successfully synthesized. • CTABr serves as both structure-directing agent and mesoporogen. • The OFF zeolite shows high activity in microwave assisted-Knoevenagel reaction. [ABSTRACT FROM AUTHOR]

Covalently linked sulfonic acid (—SO3H) modified MCM-41 mesoporous catalysts was prepared, characterized and its catalytic activity under microwave irradiation was evaluated. The NH2-MCM-41 was first prepared by anchoring (3-aminopropyl)triethoxysilane (APTES) on Si-MCM-41 and further reacted with 1,4-butane-sultone to yield the desired acid catalyst. The mesophase and porosity of samples were determined by XRD, TEM and N2 sorption isotherm analyses. The presence of sulfonic acid moiety was confirmed by FT-IR, TG/DTA, sulfur elemental analysis and in situ IR study of pyridine and ammonia adsorptions. The catalyst showed high catalytic activity and high selectivity in tert-butylation of hydroquinone under microwave irradiation. No leaching problem was observed after several runs, while the catalyst can be recovered and reused without loss of reactivity under the described reaction conditions. [Copyright &y& Elsevier]

The process of formation of ultrasmall EMT-type zeolitefrom organic-template-freehomogeneous suspensions is presented. The formation of transparentuniform suspension utilizing sodium aluminate, sodium silicate, andsodium hydroxide under controlled mixing is found to be of primaryimportance to control the nucleation and growth process of EMT-typecrystals. The investigation of zeolite intermediates reveals the formationof uniformly sized gel particles (5–10 nm in size). The meanhydrodynamic diameter of the crystalline EMT-type zeolite correspondsto the size of the amorphous particles formed after preparation ofthe clear precursor suspension. Controlled formation of uniform precursorparticles predetermines, to great extent, the following nucleationand growth steps and, thus, the characteristicsof the ultimate product. The amorphous particles are transformed tosingle EMT-type crystals 6–15 nm in size at 303 K within 36h. Small changes in the initial composition or the preparation procedurelead to the formation of other sodalite-cage-containing zeolites.Thus, it is of critical importance to control the nucleation kineticsin order to obtain the EMT-type material as pure phase. Besides theEMT zeolite, the crystallization fields of other zeolites upon low-temperaturesynthesis conditions are studied. The careful control of gel chemistry,combined with slow nucleation kinetics at low temperature, can provideaccess to important nanoscale zeolites while avoiding the use of expensiveorganic templates. [ABSTRACT FROM AUTHOR]

An investigation of aluminosilicate zeolite L (structure code LTL) nanocrystals converted from rice husk ash in template-free system is reported. Crystallization evolution of the zeolite L was monitored and followed by X-ray diffraction, high-resolution transmission electron microscopy, scanning electron microscopy, atomic absorption spectroscopy, and infrared spectroscopy techniques. It was found that fully crystalline zeolite L ( Si/Al = 3.0) with square tablet morphology was nucleated at 4 h, and the crystals with a mean particle size of 210 nm was completely transformed from amorphous silica after 24 h of hydrothermal treatment. [ABSTRACT FROM AUTHOR]

Lubricants play a significant part in current environmental considerations since they are an integral and indispensable component of modern technology. The production, application and disposal of the lubricants have to follow increasingly strict requirements for protecting the environment and living organisms. In this respect, molecular sieve (LTL type zeolite) is investigated as a potential environmentally friendly alternative to traditional antioxidant additives for lubricant oils. Accelerated oxidation experiments using pure base oil and additivated base oil in the presence of the LTL molecular sieve are carried out in parallel, and the oxidation processes are monitored by FT-IR spectroscopy, spectrophotometry, chromatography, total acid number (TAN) and Karl-Fischer titrations. The LTL molecular sieve shows the potential of slowing down the oxidation rate of the oils and also resulted in a lower rate of production of solid polymeric residues. In addition, it is demonstrated that the mode of action of the LTL molecular sieve is different in nature in comparison to the organic counterparts (original antioxidants). The LTL type molecular sieve controls the water generation, while the amount of carboxylic acids is only affected in a modest amount. Apparently during the continuous oxidation of the lubricants, the zeolite adsorbs not only carboxylic acids but also other acid products such as alcohols, ketones and aldehydes. And more importantly, the LTL type molecular sieve has a greater influence in halting the steps which lead to the polymerization of the oils. [ABSTRACT FROM AUTHOR]

Lubricants play a significant part in current environmental considerations since they are an integral and indispensable component of modern technology. The production, application and disposal of the lubricants have to follow increasingly strict requirements for protecting the environment and living organisms. In this respect, molecular sieve (LTL type zeolite) is investigated as a potential environmentally friendly alternative to traditional antioxidant additives for lubricant oils. Accelerated oxidation experiments using pure base oil and additivated base oil in the presence of the LTL molecular sieve are carried out in parallel, and the oxidation processes are monitored by FT-IR spectroscopy, spectrophotometry, chromatography, total acid number (TAN) and Karl-Fischer titrations. The LTL molecular sieve shows the potential of slowing down the oxidation rate of the oils and also resulted in a lower rate of production of solid polymeric residues. In addition, it is demonstrated that the mode of action of the LTL molecular sieve is different in nature in comparison to the organic counterparts (original antioxidants). The LTL type molecular sieve controls the water generation, while the amount of carboxylic acids is only affected in a modest amount. Apparently during the continuous oxidation of the lubricants, the zeolite adsorbs not only carboxylic acids but also other acid products such as alcohols, ketones and aldehydes. And more importantly, the LTL type molecular sieve has a greater influence in halting the steps which lead to the polymerization of the oils. [ABSTRACT FROM AUTHOR]

Abstract: Quantitative measurements of moisture in mineral and synthetic polyol ester based lubricating oils using FTIR spectroscopy combined with solvent extraction approach are described. The samples are prepared by mixing dry dimethyl sulfoxide (DMSO) and lubricating oils, and after phase separation, the extracted bottom DMSO layers are analyzed with FTIR. The results from the solvent extraction show that the DMSO is an excellent aprotic solvent for water removal from lubricating oils. The spectroscopic data reveal that near IR region (5400–4800cm−1, molecular water) gives the best results for water determination in both mineral and synthetic lubricants, followed by mid-IR region (3800–3200cm−1, O―H stretching). However, the water content estimated from the IR region (1800–1550cm−1, O―H bending) has the lowest accuracy due to the interference from aminic, phenolic additives and other oxidation products present in the lubricants. The accuracy of the FTIR spectroscopy combined with solvent extraction approach is exemplified by monitoring the water content in mineral oil during oxidation process at 150°C for 30days. The quantitative determination of the moisture in the fresh and oxidized oils by the developed approach is shown to be an alternative technique to Karl Fischer titration. [Copyright &y& Elsevier]

Abstract: The main types of nanoporous adsorbents for water are identified and described with emphasis on the mechanism of adsorption, modification, improvement of the water sorption capacity, possible regeneration, and stabilization. Among the three main groups of water sorbents, i.e. inorganic materials (zeolites, clays, silica), carbon based materials and organic polymers, the first one is described in details. The significance of their porosity, chemical and structural features relative to the water adsorptive properties of each inorganic type materials is reviewed. Important features for silicates, zeolites, aluminophosphates, mesoporous materials and clays are described, which define the interactions between the water and the porous structures. The significant improvements of the water sorption capacity of nanoporous materials under modification of their surface, particle size, morphology, and chemical specificity are explored for each type of inorganic porous compounds. The hydrophilic nanoporous materials are of significant importance for construction of regularly operating sorption equipments, reversible physi- or chemisorption reactors for generation of heat and cold, purification of lubricants, and sensing of water with different concentrations. [Copyright &y& Elsevier]

Abstract: AlMCM-41 mesoporous molecular sieve modified by impregnation with sulphuric acid in toluene possesses only Brönsted acid sites. The catalyst exhibits a high catalytic activity for tert-butylation of phenol with high selectivity to 2,4-di-tert-butylphenol in liquid phase. 27Al MAS NMR study indicates that the modification of AlMCM-41 with sulphuric acid in toluene leaves only octahedrally coordinated Al species. The tetrahedrally coordinated Al species which exist before modification with sulphuric acid in toluene being dealuminated to form extraframework octahedrally coordinated Al species. The mesoporous structure of AlMCM-41 is retained after modification, but pore size decreases by ca. 3Å by the modification. The active sites are postulated on the basis of XRD, FTIR, 27Al MAS NMR, TGA, BET analysis and FTIR-pyridine adsorption studies that –OSO3H bonded to octahedrally coordinated Al species. [Copyright &y& Elsevier]

Offretite zeolite synthesis in the presence of cetyltrimethylammonium bromide (CTABr) is reported. The offretite crystals were synthesized with a high crystallinity and hexagonal prismatic shape after only 72 h of hydrothermal treatment at 180 °C. The CTABr has dual-functions during the crystallization of offretite, viz. as structure-directing agent and as mesoporogen. The resulting offretite crystals, with a Si/Al ratio of 4.1, possess more acid sites than the conventional offretite due to their high crystallinity and hierarchical structure. The synthesized offretite is also more reactive than its conventional counterpart in the acylation of 2-methylfuran for biofuel production under non-microwave instant heating condition, giving 83.5% conversion with 100% selectivity to the desired product 2-acetyl-5-methylfuran. Hence, this amphiphile synthesis approach offers another cost-effective and alternative route for crystallizing zeolite materials that require expensive organic templates. [ABSTRACT FROM AUTHOR]

The effects of various alkali metal hydroxide mineralizers (LiOH, NaOH, KOH and CsOH) on the formation of AlMCM-41 mesoporous materials were investigated. The ordering of mesostructure was reduced when stronger base was used which led to the reduction of the porosity and surface area of the solids. The pore size was significantly affected upon changing the mineralizers and a significant morphological transformation of worm-like particles into hollow nanospheres with ultra-thin wall was observed. Furthermore, the basicity of the mesoporous solids was also changed when stronger basic mineralizers were employed. Lastly, the catalytic behavior of these AlMCM-41 molecular sieves in base-catalyzed aldol condensation of heptanal with benzaldehyde under non-microwave instant heating was also tested and discussed. Image 1 • Effects of mineralizers on the formation of AlMCM-41 are reported. • LiOH, NaOH, KOH and CsOH are used as mineralizers. • The changes in morphological and porosity properties of AlMCM-41 are observed. • The surface basicity is altered upon using different mineralizers. • Cs-AlMCM-41 nanospheres show good catalytic performance in aldol condensation. [ABSTRACT FROM AUTHOR]

In this study, ultra-small MCM-41 mesoporous solids (<30 nm) were synthesized using colloidal silica and cesium hydroxide as cheap silica source and mineralizer, respectively. Four samples with a SiO 2 /Al 2 O 3 ratio of 5, 20, 30 and ∞ (designated as CsM-5, CsM-20, CsM-30 and CsM-∞, respectively) have been prepared. The effects of SiO 2 /Al 2 O 3 ratio on the formation, physico-chemical and catalytic properties of CsMCM-41 nanoparticles were studied. The results show that incorporation of high content of Al atoms into the framework reduces the ordering of the mesostructure, and hence the porosity of the solids decreases. By using CsOH as mineralizer, the morphology and the size of CsMCM-41 were also tuned from 3-D nanospheres (CsM-5: 29 nm and CsM-20: 27 nm) to hollow nanospheres with very thin walls (CsM-30: 25 nm, CsM-∞: 20 nm) when Al content was decreased. The basicity of CsMCM-41 nanoparticles was also affected by the Al and Cs contents. Hence, their catalytic behavior in the base-catalyzed reactions such as aldol condensation of heptanal with benzaldehyde, and Perkin condensation of benzaldehyde with acetic anhydride was evaluated under microwave heating conditions. CsM-20 displays the best catalytic activities among the samples studied, achieving 87.2% conversion and 78.4% selectivity to jasminaldehyde under optimum reaction conditions, while it also shows comparable catalytic performance as NaOH homogeneous catalyst in the Perkin condensation reaction under non-microwave instant heating conditions. Image 1 • One-pot synthesis of ultra-small AlMCM-41 nanoparticles (<30 nm) is reported. • Colloidal silica and cesium hydroxide are used as cheap silica source and mineralizer. • The effects of Al incorporation on MCM-41 nanoparticles are studied. • The changes in morphological and porosity properties of nanosolids are observed. • The nanoparticles exhibit good catalytic performance in aldol condensation reaction. [ABSTRACT FROM AUTHOR]

Time-dependent crystallization evolution for synthesizing SAPO34 and SAPO-20 zeolites from a very active hydrogel is followed and reported where the XRD, FTIR, TGA/DTG, SEM/EDX, N2 adsorption–desorption and TPD-NH3 techniques are used. During the crystallization process, the hydrophobic trimethylbenzylammonium cation (BTMA+) has shown its ability as an effective structure-directing and pore filling agent. The resulting pure SAPO-34 and SAPO-20 show high crystallinity, where SAPO-34 exhibits higher porosity (393 m2 g−1, 0.24 cm3 g−1) and acidity (1.20 mmol g−1) than SAPO-20 (29 m2 g−1, 0.16 cm3 g−1, 0.02 mmol g−1), and these features are highly beneficial in the microwave-assisted ethanolysis of furfuryl alcohol. SAPO-34 shows outstanding catalytic activity (100% conversion, 72.5 ± 0.3% yield of ethyl levulinate) and its performance is much superior to that of SAPO-20 and other classical catalysts thanks to its medium pore size that induces molecular sieving effect. The spent SAPO-34 catalyst has high recyclability with stable activity, making it a superior and cost-effective catalyst for various selective petrochemical reactions. [ABSTRACT FROM AUTHOR]

Highlights • The optimum ratio of GGBS and PFA was 4:1 at 50% cement replacement level by total binder's weight. • The optimum dosage of PCE superplasticizer was 1.0% by total binder's weight in GGBS-PFA ternary blended cement system. • The water demand of fresh concrete mixes reduced with the inclusion of GGBS-PFA incorporating PCE superplasticizer. • The inclusion of GGBS-PFA with PCE superplasticizer in concrete mixes showed a positive strength development. Abstract This experimental investigation was conducted to study the development of ternary blended concrete that containing high cement replacement level of ground granulated blast furnace slag (GGBS) and pulverised fly ash (PFA) with the polycarboxylate-based superplasticizer (PCE). In order to make this GGBS-PFA ternary blended cement system at high cement replacement level suitable for practical production, measures need to be developed to enable acceptable early strength development for concrete produced using the materials to be achieved. An optimum combination ratio of GGBS and PFA in ternary blended cement system was prior determined in this study for consistent production control. Besides, an optimum dosage of M-PEG type PCE was determined by using marsh funnel test as well for the compatible use in this GGBS-PFA ternary blended cement system. Experimental results indicated that the optimum ratio for GGBS and PFA was 4:1 at 50% cement replacement level by total binder's weight while the optimum dosage of PCE was 1.0% by total binder's weight in this ternary blended cement system. Mechanical properties such as flexural and compressive strengths and UPV were then examined on hardened concretes at 7, 28, 56 and 90 days. In addition, Scanning Electron Microscopy (SEM) techniques combined with Energy Dispersive X-ray (EDX) had been performed for better understanding the phase changes and microstructures development of maturing GGBS-PFA ternary blended cement system. In this study, the GGBS-PFA ternary blended concrete with 60% cement replacement achieved the optimum performance with the inclusion of 1.0% of PCE superplasticizer by total binder's weight. [ABSTRACT FROM AUTHOR]

Abstract Alkali metal-containing NKX-2 (M-NKX-2) aluminophosphite crystals were hydrothermally synthesized in the Al 2 O 3 –P 2 O 5 –M 2 O–H 2 O system for the first time using various alkali metal hydroxides (MOH: M = Li, Na, K, Cs). The results showed that NKX-2 crystalline phase could be obtained within several hours without using harmful organic amine structure-directing agent. In addition, the alkali metal hydroxides played an important role in controlling the crystallization rate and the morphology of M-NKX-2 particles in aqueous medium. The resulting M-NKX-2 solids possessed basicity which was catalytically active in base-catalyzed cyanoethylation reaction of methanol. Graphical abstract Image Highlights • Alkali metal containing NKX-2 is synthesized in Al 2 O 3 –P 2 O 5 –Na 2 O–H 2 O system. • The use of different metal hydroxides significantly alters the crystallization time. • The morphological and crystallographic properties are also changed. • The solids exhibit basic character and are active in cyanoethylation of methanol. [ABSTRACT FROM AUTHOR]

Zeolitic imidazolate framework-8 (ZIF-8) is a microporous and crystalline material with strong prospect for many engineering applications. In particular, nanosized ZIF-8 particles with well-defined structure and aperture are highly desirable. In this study, nanosized ZIF-8 particles with narrow and monomodal particle size distribution were successfully synthesized by carrying out the ZIF-8 synthesis in ice bath condition using high concentrations of zinc (Zn 2+ , 0.20 M) and 2-methylimidazolate (2-mIm − , 1.60 M) ions. Under low temperature (5 °C), ZIF-8 nucleation was enhanced while the subsequent ZIF-8 nuclei growth was suppressed to produce monomodal particle size with mean particle size of ca. 60 nm. The ZIF-8 nanoparticles were also shown to be fully crystalline and possessed proper chemical structure with well-developed pore network as well as good thermal stability up to 200 °C. [ABSTRACT FROM AUTHOR]

Acetylation of glycerol to yield monoacetin (MAT), diacetin (DAT), and triacetin (TAT) over NiO-supported CeO2 (xNiO/CeO2) catalysts is reported. The catalysts were synthesized utilizing a sol-gel technique, whereby different quantities of NiO (x = 9, 27, and 45 wt%) were supported onto the CeO2 substrate, and hexadecyltrimethylammonium bromide (CTABr) served as a porogen. The utilization of EDX elemental mapping analysis confirmed the existence of evenly distributed Ni2+ ion and octahedral NiO nanoparticles on the CeO2 surface through the DRS UV-Vis spectroscopy. The most active catalyst is 27NiO/CeO2 based on TAT selectivity in the glycerol acetylation with ethanoic acid, attaining 97.6% glycerol conversion with 70.5% selectivity to TAT at 170 °C with a 1:10 glycerol/ethanoic acid molar ratio for 30 min using a non-microwave instant heating reactor. The 27NiO/CeO2 is reusable without significant decline in catalytic performance after ten consecutive reaction cycles, indicating high structure stability with accessible active acidity. [ABSTRACT FROM AUTHOR]

A detailed investigation of the hydrothermal crystallization of SAPO-34 in the presence of the novel 1-propylpyridinium hydroxide ([PrPy]OH) organic structural directing agent is presented. The synthesis conditions are systematically tuned to investigate the effects of various parameters (viz. concentrations of each reactant, crystallization time, and temperature) on the nucleation and crystallization of SAPO-34. The results show that a careful variation in each of the synthesis parameters results in the formation of competing phases such as SAPO-5, SAPO-35, and SAPO-36. Pure and fully crystalline SAPO-34 can be crystallized using a precursor hydrogel of a molar ratio of 2.0 Al: 4.7 P: 0.9 Si: 6.7 [PrPy]OH: 148 H2O at 200 °C for only 19 h, which is a shorter time than that found in previous studies. The prepared SAPO-34 is also very active in the esterification of levulinic acid and 1-propanol. By using microwave heating, 91.5% conversion with 100% selectivity toward propyl levulinate is achieved within 20 min at 190 °C. Hence, the present study may open a new insight into the optimum synthesis study of other zeolites using novel pyridinium organic moieties and the opportunity of replacing conventional harmful and non-recyclable homogeneous catalysts in levulinate biofuel synthesis. [ABSTRACT FROM AUTHOR]

A study using a novel pyridinium ionic liquid, namely 1-propylpyridinium bromide ([PPy]Br), to crystallize SAPO-11 under ionothermal conditions is reported. By carefully following the crystallization process, SAPO-11 can readily be crystallized in the presence of [PPy]Br, which serves as a synthesis solvent and structure-directing agent, at 150 °C after 133 h of heating. The study also focuses on manipulating other synthesis parameters (e.g., crystallization temperature, phosphorous content, silicon amount and [PPy]Br concentration) and investigating their respective effects on the formation of SAPO-11. The crystallized SAPO-11 has an acidic nature and a high surface area. Under conductive instant heating conditions, the SAPO-11 catalyst is very active in the conversion of levulinic acid into ethyl levulinate; 93.4% conversion and 100% selectivity of ethyl levulinate are recorded at 180 °C after 30 min of reaction. This result is comparable to or even better than those of conventional homogeneous catalysts. [ABSTRACT FROM AUTHOR]

Hydrazine borane (HB) is a chemical hydrogen storage material with high gravimetric hydrogen density of 15.4 wt%, containing both protic and hydridic hydrogen. However, its limitation is the formation of unfavorable gaseous by-products, such as hydrazine (N2H4) and ammonia (NH3), which are poisons to fuel cell catalyst, upon pyrolysis. Previous studies proved that confinement of ammonia borane (AB) greatly improved the dehydrogenation kinetics and thermodynamics. They function by reducing the particle size of AB and establishing bonds between silica functional groups and AB molecules. In current study, we employed the same strategy using MCM-41 and silica aerogel to investigate the effect of nanosizing towards the hydrogen storage properties of HB. Different loading of HB to the porous supports were investigated and optimized. The optimized loading of HB in MCM-41 and silica aerogel was 1:1 and 0.25:1, respectively. Both confined samples demonstrated great suppression of melting induced sample foaming. However, by-products formation was enhanced over dehydrogenation in an open system decomposition owing to the presence of extensive Si-O···BH3(HB) coordination that further promote the B-N bond cleavage to release N2H4. The Si-OH···N(N2H4) hydrogen bonding may further promote N-N bond cleavage in the resulting N2H4, facilitating the formation of NH3. As temperature increases, the remaining N-N-B oligomeric chains in the porous silica, which are lacking the long-range structure may further undergo intramolecular B-N or N-N cleavage to release substantial amount of N2H4 or NH3. Besides open system decomposition, we also reported a closed system decomposition where complete utilization of the N-H from the released N2H4 and NH3 in the secondary reaction can be achieved, releasing mainly hydrogen upon being heated up to high temperatures. Nanosizing of HB particles via PMMA encapsulation was also attempted. Despite the ester functional group that may favor multiple coordination with HB molecules, these interactions did not impart significant change towards the decomposition of HB selectively towards dehydrogenation. [ABSTRACT FROM AUTHOR]

In this study, the electrospinning process modifies the commercial polyester filter media to increase filtration efficiency. The polyethylene terephthalate (PET) solution produces electrospun fiber on commercial polyester filter media at various rotation speeds and durations. The PET concentration and electrospinning applied voltage were adjusted accordingly to obtain bead-free electrospun fibers. As a result, the modified filter media's filtration efficiency is approximately two times higher than the commercial polyester filter media at 300 rpm and 5 hours of electrospinning duration. Furthermore, the efficiency of the single unit modified filter media is 53.76% with an airflow resistance of 39.2 Pa and quality factor of 0.01968 Pa−1 which are comparable to the combination of two units' air filters. Thus, replacing two units' air filters having a primary and secondary filter with a single unit modified filter media is justifiable. [ABSTRACT FROM AUTHOR]

In this study, we report on the application of high surface area activated carbon (AC) derived from rice husks as a supercapacitor electrode. The prepared AC was free from Brønsted or Lewis acid sites, thus making the electrical double layer capacitance as the main charge storage mechanism. Three samples of AC with different surface areas were prepared at different activation temperatures and studied electrochemically using cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy. All AC samples exhibited good electrochemical performance as supercapacitor electrode. The maximum specific capacitance (147 F g −1 ) was obtained by the AC sample (surface area of 2696 m 2 g −1 ) which was prepared at an activation temperature of 850 °C. Detailed impedance studies revealed the low resistivity (0.23 Ω) of AC sample and the fast frequency response (0.11 s) of the supercapacitor electrode. [ABSTRACT FROM AUTHOR]

Highly active hierarchical mordenite zeolite with micro/mesoporosity (TM- n) for selective synthesis of cyclic acetals via acetylation reaction is reported. The hierarchical zeolite is synthesized using soft-templating approach with variations in octadecyltrimethoxysilane (OTMS/Al 2 O 3 ratio, n = 0.2, 0.3 and 0.4) in precursor hydrogels. The results reveal that OTMS not only creates secondary mesoporosity in zeolite framework (larger mesopore volume, external surface area, average pore diameter), but also influences the crystallization process, altering the crystal morphology, crystallinity and Si/Al ratios. Among TM- n zeolites prepared, TM-0.3 hierarchical mordenite has the optimum OTMS amount incorporated while further increasing the OTMS amount leads to the formation of ANA/GIS intergrowth. Thanks to the accessible hierarchical porosity, reduced acidity and morphological effects, the TM-0.3 hierarchical mordenite exhibits excellent catalytic performance (84.1% conversion, TOF = 0.087 s−1, 61.5% dioxolane selectivity) in acetylation of glycerol and benzaldehyde (160 °C, 20 min) better than pristine mordenite. The catalyst is reusable for five runs with minimal loss of activity (TOF = 0.087 → 0.084 s−1), making it a promising catalyst for chemical productions involving bulky molecules. In addition, comparative catalytic tests with classical homogeneous and heterogeneous catalysts, including H 2 SO 4 , HCl, CH 3 COOH, H–Y, H-LTL, Na-X, Na-A, were performed. [Display omitted] • Hierarchical mordenite is crystallized using new organosilane via soft templating method. • Octadecyltrimethoxysilane (OTMS) serves as a mesoporogen. • OTMS governs crystallization process, affecting morphology, crystallinity and Si/Al ratio. • Hierarchical modernite catalyst is very active in acetalization of benzaldehyde and glycerol. • 84.1% conversion with 61.5% selective to dioxolane is recorded at 160 °C for 20 min. [ABSTRACT FROM AUTHOR]

Properties of nanoparticles (NPs) are responsible for their interaction with various biomolecules such as proteins in biological environments. Amount and composition of the proteins associated with NPs, i.e. protein corona, are strongly dependent on physicochemical characteristics of the particles, as well as incubation parameters including temperature and protein concentration. More importantly, the protein corona can define the biological fate of the NPs. Here, we demonstrate that variations in the concentration of plasma protein led to significant changes in the composition of the hard corona adsorbed on the surface of different NPs including hydrophilic amorphous silica (SiO), hydrophilic crystalline zeolite (EMT), and hydrophobic sulfonated-modified polystyrene. Alteration in the corona composition of the NPs is a result of the plasma concentration, i.e. it affects the release of inflammatory cytokines in a plasma concentration-dependent manner. The amorphous silica nanoparticles with hydrophilic surfaces induced the release of the inflammatory cytokines interleukin-8 (IL-8) and tumor necrosis factor (TNFα) in 10 % plasma concentration, but not at higher concentrations. A reverse trend was observed for the hydrophobic, sulfonated-modified polystyrene NPs. Remarkably the hydrophilic highly porous EMT NPs exhibited no cellular toxicity regardless to the plasma concentration. The results obtained in this study can be used to define optimal pathways for nanoparticles administration in vivo. These findings can assist researchers to better understand how NPs with different surface properties may interact with various proteins in vivo, and elucidate safety considerations for their biomedical applications. [ABSTRACT FROM AUTHOR]

Highlights: [•] MCM-41-Imi/Br showed synergistic action for the ring opening of epoxides. [•] The mechanism of the ring opening process by MCM-41-Imi/Br was investigated. [•] No solvent was necessary for liquid substrates. [ABSTRACT FROM AUTHOR]

Abstract: Iron modified zeolite L nanocrystals (Fe/KL) were synthesized hydrothermally by the incorporation of Fe3+ in zeolite L lattice. XRD results showed an increase in the inter-planar spacing and lattice parameters. Transition characteristic of the tetrahedral Fe3+ species were observed in the UV–Vis spectrum. The oxidation of phenol in the presence of acetic acid over Fe/KL gave 93.40% conversion in 30min with selective formation of 77.47% catechol and 22.53% hydroquinone. The catalytic activity was significantly enhanced by the addition of acetic acid. It was found that the acetic acid was oxidized by hydrogen peroxide to form peracetic acid, which served as a better oxidizing agent. [Copyright &y& Elsevier]

Abstract: Zeolite Linde Type L (LTL) crystals with different length, diameter and particle size (nanosized LTL, rod LTL, cylinder LTL and needle LTL) were synthesized, characterized and were used as sorbent in the micro-solid phase extraction of ochratoxin A (OTA) before the high performance liquid chromatography detection. Under the optimized conditions, the detection limits of OTA for coffee and cereal were 0.09ngg−1 and 0.03ngg−1, respectively, while the quantification limits were 0.28ngg−1 and 0.08ngg−1, respectively. The recoveries of OTA of coffee and cereal spiked at 0.5, 10 and 25ngg−1 ranged from 91.7 to 101.0%. The proposed method was applied to forty-five samples of coffee and cereal. The presence of OTA was found in twenty-five samples, ranging from 0.28 to 9.33ngg−1. [Copyright &y& Elsevier]

Biofertilizers encompass microorganisms that can be applied to plants, subsequently establishing themselves within the plant's rhizosphere or internal structures. This colonization stimulates plant development by enhancing nutrient absorption from the host. While there is growing literature documenting the applications of microalgae-based and bacterial-based biofertilizers, the research focusing on the effectiveness of consortia formed by these microorganisms as short-term plant biofertilizers is notably insufficient. This study seeks to assess the effectiveness of microalgae-bacterial biofertilizers in promoting plant growth and their potential contribution to the circular economy. The review sheds light on the impact of microalgae-bacterial biofertilizers on plant growth parameters, delving into factors influencing their efficiency, microalgae-bacteria interactions, and effects on soil health. The insights from this review are poised to offer valuable guidance to stakeholders in agriculture, including farmers, environmental technologists, and businesses. These insights will aid in the development and investment in more efficient and sustainable methods for enhancing crop yields, aligning with the Sustainable Development Goals and principles of the circular economy. [Display omitted] • Microalgae and bacteria's combinations are looking promising in development of biofertilizer. • A substitution for conventional chemical fertilizer as it is more environmental friendly and sustainable. • Efficiency of microalgae and bacterial' biofertilizers highly dependent on compositions and targeted crops. • It adds on high value onto circular economy. [ABSTRACT FROM AUTHOR]

This study employed the microwave-assisted acid hydrolysis pretreatment using wet torrefaction on two indigenous microalgae, Chlorella vulgaris ESP-31 and Chlorella sp. GD with different biomass composition to investigate the yields of solid biochar and total reducing sugar in the liquid hydrolysate. Operating conditions at low temperatures (160, 170 °C) with short holding time (5, 10 min) under several concentrations of diluted acid medium (0, 0.1 and 0.2 M) were carried out to investigate the torrefaction severity effects towards the properties of the solid and liquid products. The highest biochar yields of 54.5% and 74.6% are obtained from C. vulgaris ESP-31 and Chlorella sp. GD, respectively under the wet torrefaction conditions with an improvement in the properties for fuel and value-added environmental application. The highest total reducing sugar concentration of 98.11 g/L and 12.08 g/L are obtained in C. vulgaris ESP-31 and Chlorella sp. GD liquid hydrolysates, respectively after acid hydrolysis pretreatment. With the co-production of high total reducing sugar in the liquid hydrolysate that can be utilized for bioethanol production and solid biochar as another value-added product, the acid hydrolysis pretreatment using wet torrefaction can be one of the conversion technologies towards the application of renewable energy production. Image 1 • The co-production of biochar and reducing sugar by wet torrefaction is studied. • Results of two microalgae species with different biomass composition are compared. • Characterization of microalgal biochar for environmental application is performed. • The highest reducing sugar concentration of 98.11 g/L and 12.08 g/L are obtained. • Bioethanol production utilizing reducing sugar hydrolysate is outlined. [ABSTRACT FROM AUTHOR]

• PCE effectively reduces water demand of GGBS-PFA ternary blended cement concretes. • PCE polymer with higher main chain density creates agglomeration in fresh state. • GGBS-PFA cement concrete with PCE (1:8) provides optimal mechanical performance. • PCE polymers with optimal chain densities promote hydration product formation. Ground Granulated Blast Furnace Slag-Pulverized Fly Ash (GGBS-PFA) ternary blended cement concretes are commonly applied in construction to reduce carbon footprint of concrete materials. Nevertheless, the interaction of polycarboxylate (PCE) polymer, the third generation super-plasticizer used in concrete manufacturing, with this concrete remains scarcely explored. For effective and optimum performance of the PCE in ternary blended concrete production, the main and side chain molecular structure is a predominant consideration. Thus, this study was aimed to derive the influence of PCE polymers with various main and side chain densities on the engineering properties and microstructural development of GGBS-PFA ternary blended cement concretes. The laboratory tests conducted in the study includes flow table test, flexural strength, compressive strength and ultrasonic pulse velocity (UPV). Besides, thermogravimetric analysis (TGA) and microstructure assessment were determined for thermal decompositions analysis and hydration kinetics assessment. It was observed that the water-binder ratio of GGBS-PFA ternary blended cement concretes can be reduced effectively with PCE (1:1), PCE (1:2), PCE (1:4) and PCE (1:8), respectively. Besides, GGBS-PFA ternary blended cement concrete with PCE (1:8) provides optimal mechanical strength performance. [ABSTRACT FROM AUTHOR]

Ionic liquid functionalized MCM-41 has been synthesized using post-grafting technique. The catalyst denoted as MCM-41-Imi-All/Br was used for the solvent free cycloaddition of several epoxides with carbon dioxide. The low angle powder XRD analysis indicated the presence of several peaks correlating to the (100), (110) and (200) planes typical for MCM-41. The TEM images showed the honeycomb structure of the MCM-41 whereas the average pore width indicates the presence of mesopores predominantly. In addition, the presence of free Br− anions and quaternary nitrogen (N+) species were proven via XPS analysis indicating the successful functionalization of the ionic liquid onto the MCM-41 support. The catalyst exhibited good conversion depending on the functional groups on the epoxides and showed very high selectivity (>95%) for the respective cyclic carbonates. Unlabelled Image • Imidazolium-allyl bromide ionic liquid functionalized on MCM41 was synthesized. • TEM images showed that MCM41 structure was retained after functionalization. • Presence of free Br− and quaternary nitrogen (N+) species were proven from XPS. • The catalyst showed high selectivity in the production of several cyclic carbonates. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A series of alkaline metal titanates were successfully synthesized. • XPS analysis showed oxygen vacancies and Ti3+ ions. • Lithium titanate showed highest photocatalytic activity under sunlight. • The lithium titanate sample was stable upon successive reuse up to four cycles. Abstract Alkaline titanate nanomaterials with mixed anatase and titanate phases had been produced via hydrothermal synthesis. The XRD patterns of the samples indicated the presence of the anatase peak at 2 θ = ∼25° except for Na-TiO 2 200°C/12 h. The Dr-UV/Vis analysis indicated that the band gap energy for Li-TiO 2 200°C/12 h, Na-TiO 2 200°C/12 h, K-TiO 2 200°C/12 and Cs-TiO 2 200°C/12 h to be 3.12, 3.05, 3.07 and 3.17 eV respectively. The alkaline titanate samples were shown to possess lower recombination rate of the photogenerated charge carriers (e−/h+) in comparison to that of pure anatase TiO 2 , except for K-TiO 2 200°C/12 h. The surface area of the samples was calculated to be 32.0, 120.0, 155.0 and 24.3 m2 g-1 for Li-TiO 2 200°C/12 h, Na-TiO 2 200°C/12 h, K-TiO 2 200°C/12 h and CsTiO 2 200°C/12 h respectively. Li-TiO 2 200°C/12 h exhibited enhanced photocatalytic efficiency in the photodegradation of MB compared to Degussa P25 and anatase TiO 2. In addition, NaTiO 2 200°C/12 h, K-TiO 2 200°C/12 h and Cs-TiO 2 200°C/12 h also showed excellent adsorptive properties. [ABSTRACT FROM AUTHOR]

Abstract Cesium-aluminosilicate zeolite nanocrystals with ABW framework structure are synthesized free of organic template using hydrothermal approach. The crystallization process of Cs-ABW zeolite nanocrystals by varying the initial gel molar composition, heating temperature and crystallization time was studied. More detailed investigations of the formation of Cs-ABW nanozeolite using a reactive clear precursor hydrogel (4SiO 2 :1Al 2 O 3 :16Cs 2 O:160H 2 O) were then carried out. Fully crystalline Cs-ABW nanozeolites were obtained within 120 min at 180 °C and 22 bar, which is considerably faster and safer in comparison to the currently available method involving treatment at 695 °C, 1000 bar and 46 h. The Cs-ABW nanocrystals have grain shape morphology with a mean size of 32 nm and they do not agglomerate for long durations. The nanosized Cs-ABW zeolite has high alumina content (Si/Al ratio = 1.04). These nanocrystals can be prepared in high solid yield (ca. 82%) thus offering a promising route for large-scale production of highly basic zeolite nanoparticles. Graphical abstract Image 1 Highlights • Cs-ABW zeolite is prepared under low temperature (180 °C) and pressure (22 bar). • The nucleation and crystallization of nanozeolites in template-free hydrogel are studied. • Fully crystalline Cs-ABW nanocrystals are formed after 120 min. • The crystals (ca. 32 nm, Si/Al = 1.0) have grain shape morphology. • High solid yield offering large-scale production of highly basic zeolite nanoparticles. [ABSTRACT FROM AUTHOR]

Continuous exploitation of natural resources especially in fossil fuels to fulfil the market demand has jeopardized the natural resources in the Earth. Bioethanol produced by microalgae is one of the promising biofuel for energy security and ecological sustainability. Yet, to date only a modest review has been reported on the bioethanol production technology from microalgae by using various pretreatment methods, fermentative microorganisms, fermentation processes, commercialization techniques and its environmental perspectives. This review paper aims to provide a comprehensive information by comparing the recent pretreatment technologies by using different types of ethanologenic microorganisms in various fermentation processes to maximize the bioethanol production. Studies of the economic viability and environmental perspectives of bioethanol from microalgae have been carried out to investigate its potentialities to eliminate environmental issues and towards commercialization. Therefore, this review is essential in providing ideas for the future researches in renewable energy resources technology to develop a more efficient way to scale-up the bioethanol production from microalgae for commercial and industrial application. [ABSTRACT FROM AUTHOR]

A series of modified hexagonal mesoporous silica (HMS) supported by various Ni loading (5 wt% Ni, 10 wt% Ni, 40 wt% Ni and 100 wt% Ni) have been synthesized and systematically characterized. The resultant Ni catalysts improved the performance of the deoxygenation (DO) of triolein at a reaction temperature of 380 °C in a simple glass batch reactor under a solvent-free condition and are hydrogen-free. The incorporation of Ni loading into the HMS framework casued the catalytic activity to increase when compared to that of HMS. Surprisingly, 10 wt% Ni/HMS catalyst exhibited the highest conversion. It was observed that 10 wt% Ni loading was highly dispersed on the HMS which is capable of achieving 92.5% and 95.2% of conversion and selectivity, respectively. This is due to the synergistic effect of Si-O-Ni bonding and high dispersion of NiO on HMS. In this respect, the nature of catalyst support such as pore size and the high surface areas of HMS play an important role in enhancing the catalytic performance of DO reaction. This study has revealed that Ni/HMS catalyst is a promising catalyst that can be applied to the development of sustainable biofuel from non-edible oil. [ABSTRACT FROM AUTHOR]

Algal biomass is known as a promising sustainable feedstock for the production of biofuels and other valuable products. However, since last decade, massive amount of interests have turned to converting algal biomass into biochar. Due to their high nutrient content and ion-exchange capacity, algal biochars can be used as soil amendment for agriculture purposes or adsorbents in wastewater treatment for the removal of organic or inorganic pollutants. This review describes the conventional (e.g., slow and microwave-assisted pyrolysis) and newly developed (e.g., hydrothermal carbonization and torrefaction) methods used for the synthesis of algae-based biochars. The characterization of algal biochar and a comparison between algal biochar with biochar produced from other feedstocks are also presented. This review aims to provide updated information on the development of algal biochar in terms of the production methods and the characterization of its physical and chemical properties to justify and to expand their potential applications. [ABSTRACT FROM AUTHOR]

K-F zeolite nanocrystals (structure code EDI) are synthesized from a template-free Al 2 O 3 –SiO 2 –K 2 O–H 2 O precursor system. The use of a very reactive organic-template-free gel system (4SiO 2 : 1Al 2 O 3 : 16K 2 O: 160H 2 O) enables the crystallization of EDI-type nanosized zeolite to accomplish within 3 h at 100 °C. The K-F zeolite crystals have flattened cuboid shape morphology (ca. 27 nm) and they tend to agglomerate and form secondary spherical particles (ca. 310 nm). The K-F zeolite nanocrystals have high alumina content (Si/Al ratio = 1.10) and high crystalline solid yield (79%) offering a promising route for large-scale production of hydrophilic zeolite nanoparticles. [ABSTRACT FROM AUTHOR]

An investigation of nanosized potassium aluminosilicate F-type zeolite (K-F, structure code EDI) converted from rice husk ash (RHA) is reported. The crystallization process was studied in an organic template-free system under microwave radiation at 100 °C and the evolution was followed by spectroscopy and microscopy techniques. The study indicated that the crystallization rate of K-F zeolite was significantly enhanced using microwave radiation. The zeolite started to nucleate at 0.5 min and flattened cuboid shaped K-F zeolite crystals (ca. 39 nm, Si/Al = 1.26) were formed after 2 min onwards. The nanocrystalline K-F zeolite exhibited good catalytic performance in solvent-free Aldol condensation reaction between benzaldehyde and heptanal, with ca. 75% reactant conversion and ca. 67% jasminaldehyde selectivity even after fifth cycle of reaction. [ABSTRACT FROM AUTHOR]

The low-temperature synthesis of zeolite ZSM-5 below 100 °C is gaining new attention. This is due to the fact that such synthesis may simultaneously implement the introduction of mesopores into crystalline microporous zeolite structure. Herein, we report the use of natural silica precursors from rice husks in the mesoporogen-free synthesis of hierarchical ZSM-5 below 100 °C and their structural properties which govern the course of crystallization. Rice husks are agricultural wastes with high silica content, which should be exploited to give a positive impact, i.e. highly value-added materials. In this study, the amorphous silica from rice husks was extracted using sequential base-acid treatment. The extracted silica was similarly reactive as Ludox HS-40, even with the reduced amounts of the organic structure-directing agent (OSDA). The product was highly crystalline ZSM-5 with spherical morphology composed of small crystallites, enabling the presence of intercrystallite mesopores. The subjection of extracted silica into the calcination at 550 °C for 6 h, prior to the low-temperature synthesis, altered the silica structure via hydroxyl condensation. The distinct structural properties affected the occurring crystallization in which the resulted products were ZSM-5–disordered-mesoporous silica composites. The possible mechanisms of these two different results may involve the dual roles of tetrapropylammonium ion (TPA + ) as zeolite OSDA and non-templating structure directing agent. These insights were based on the spectroscopic (FTIR, Raman, 29 Si and 27 Al MAS NMR spectroscopy), microscopic (TEM and HRTEM) and physicochemical characterizations (XRD and N 2 adsorption-desorption isotherm). [ABSTRACT FROM AUTHOR]

The partitioning behavior of immunoglobulin G (IgG) in the aqueous two-phase system (ATPS) composed of poly(ethylene glycol) (PEG) and phosphate was studied. The parameters of ATPS exhibiting the pronounced effects on the partitioning behavior of IgG include phase composition, PEG molecular weight, and the addition of sodium chloride (NaCl). The accumulation of IgG at the interface of the ATPS increased drastically as the tie-line length (TLL) was increased. This trend was correlated with a linear relationship relating the natural logarithm of interfacial partition coefficient (ln G ) to the difference of PEG concentration between the top phase and the bottom phase (Δ[ PEG ]), and a good fit was obtained. An attempt was made to correlate the natural logarithm of partition coefficient (ln K ) to the presence of NaCl with the proposed linear relationship, ln K = α ″ ln [ Cl − ] + β ″. The proposed relationship, which serves as a better description of the underlying mechanics of the protein partitioning behavior in the polymer-salt ATPS, provides a good fit ( r 2 > 0.95) for the data of IgG partitioning. An optimum recovery of 99.97% was achieved in an ATPS (pH 7.5) composed of 14.0% (w/w) PEG 1450, 12.5% (w/w) phosphate and 5.0% (w/w) NaCl. [ABSTRACT FROM AUTHOR]

The absence of organic structure directing agent (OSDA) in the synthesis of zeolite has shown progress recently, nevertheless the formation mechanism is still not clearly understood and the technique cannot be fully generalized for the synthesis of various types of zeolite frameworks. In this research, the drastic reduction of OSDA in the synthesis of ZSM-5 employing the steam-assisted crystallization (SAC) was studied. The used tetrapropylammonium bromide as OSDA in the synthesis of ZSM-5 was one-fifth and one-twentieth of typical amount reported in literature. Upon OSDA reduction, the crystallization leads to the formation of ZSM-5 with hierarchical pore structure revealed by SEM and TEM images in which it is different compared to the parent spherical-like crystal morphology of ZSM-5 synthesized without reducing the OSDA amounts. A quantitative analysis of the X-ray diffractograms suggests that 100% crystallinity could not be achieved in the sample synthesized under the OSDA reduction confirming that the orientation of crystal growth is not similar to the conventional coffin-type ZSM-5 crystal. The deviancy in crystal growth is further associated with the formation of mesopores originated from severe defect planes of ZSM-5. On the verge of gradual disappearance, a broadened distribution of mesoporosity could return the crystallinity to 100% in which faulty elongated crystal shape, close to typical coffin-type growth orientation appeared as the product after commencing the Oswald ripening of longer period of synthesis time. The conventional hydrothermal synthesis may not be used for crystallizing ZSM-5 when the OSDA was one-twentieth of typical starting amount making the SAC to be an appropriate technique for synthesizing ZSM-5 under drastically reduced OSDA, in particular to simultaneously perform the hierarchically porous zeolite. [ABSTRACT FROM AUTHOR]