Synthesis of porous γ-Fe2O3 from scorodite synthesized using ultrasound irradiation and evaluation of its battery performance

The effect of 200 kHz ultrasound on scorodite synthesis at 70 °C and 3 h reaction conditions was investigated using sulfuric acidic solutions of various pH (3.0, 2.0, 1.5, 1.0, and 0.0). In contrast to the case of only O2 gas flow without ultrasound irradiation, oxidizing radicals generated by ultrasound irradiation promote Fe(II) oxidation in solution and precursor, allowing scorodite to synthesize with high crystallinity (>99%), which relates to low solubility, even in strong acid solution at pH 1.0. During synthesis, particle shape was changed to polyhedral or spindle type depending on the pH of 0.0 to 3.0. The spindle-shaped scorodite was probably formed by the decrease of precursor amount produced in initial stage of the synthesis. Furthermore, porous maghemite obtained by alkali treatment of scorodite showed initial discharge capacities of 146 mAh/g (polyhedron) and 167 mAh/g (spindle), indicating that its potential use as a cathode material for lithium-ion batteries.

Heterogeneous Iron Catalyst Fe/SBA-15 towards sp3 C-O bond activation in the absence of base and additive

A heterogeneous iron-catalyzed (8wt%Fe/SBA-15) mediated direct alkylation of benzyl alcohol with aryl boronic acid in the absence of base and additive via C-O bond activation is demonstrated. This catalyst system led to an efficient Friedel-crafts alkylation reaction. The acidic site in the catalyst system had been confirmed by NH3-TPD, which shows the presence of three different acidic sites viz., weak, moderated, and strong acid sites. The catalyst showed five times recyclable ability.

Electrochemical deposition of electronic rich Pt single atoms and nanocrystals on porous carbon for enhanced electrocatalysis in strong acid

Here, we present an attractive approach to construct electronic rich Pt single atoms and nanocrystals via simple electrochemical cycling. Hollow carbon nanoballoons decorated with cobalt were used as support, which...

Strong Acid-promoted Skeletal Remodeling of the Aphid Pigment: Red Uroleuconaphin to Green Viridaphin

We present herein a strong acid-promoted single-step transformation of red uroleuconaphin A1 into green viridaphin A2. Viridaphin A1 and bis-naphthoquinone were also obtained by performing the reaction in aqueous media....

Screening factors affecting chitosan extraction from mud crab (Scylla sp.) shell using microwave irradiation for the Response Surface Approach

Extracting chitosan from crab shell using conventional method requires processing in strong acid and alkali conditions under high temperature with long reaction time. Microwave-based extraction proposes shorter processing time, and hence energy and cost efficient. This study intended to screen factors affecting the extraction of chitosan from mud crab shell using microwave irradiation. The factors would be used in Response Surface Methodology (RSM) approach to obtain the optimum conditions for chitosan extraction. Microwave irradiation was employed in all of the three steps of chitosan extraction, the demineralization, deproteination, and deacetylation processes. A fractional factorial design was used to screen eight independent factors to determine the most significant ones to be optimized to determine the maximum value of four responses, which were yield, mineral removal, degree of deacetylation and moisture content. The results show that all of the main independent variables were significant in affecting minimal one of the 4 responses (P < 0.05). Mud crab chitosan had the degree of deacetylation of 87.72 – 95.13 %. Results of the screening analysis concluded, the main independent factors that are going to be applied in the optimization study are NaOH concentration, microwave oven power, and reaction time in deacetylation process.

Composite systems for medical purposes, created on the basis of hydrophobic silica

Composite systems with certain cytotoxic (AM1/lectin) and adsorption (AM1/gelatin) activity have been developed on the basis of methyl silica and protein molecules – lectin and gelatin. For both types of composites, mechanisms of water binding to the surface and methods of transferring of hydrophobic materials into the aquatic environment have been investigated. The state of interfacial water in air, organic and acid media was studied. It has been found that the presence of a hydrophobic component in composites stabilizes of surface water in a weakly associated state, when a significant part of water molecules does not form hydrogen bonds. Liquid hydrophobic medium enhances this effect, and the strong acid (trifluoroacetic), added to it, promotes the transition of water to a strongly associated state. It has been shown that the redistribution of water in the interparticle intervals of AM1 with protein molecules immobilized on their surface changes under the influence of mechanical loads. Mechanoactivated samples are characterized by the possibility of water penetration into the spaces between the primary particles of methyl silica. It has been shown that immobilization of lectin on the surface of AM1 is accompanied by an increase in the interfacial energy gS from 4.1 to 5.2 J/g. This is due to an increase in the concentration of strongly bound water. If we analyze the changes in the distributions of radii R of the clusters of adsorbed water, we can state that in the water adsorbed by native lectin molecules, there are two main maxima at R = 1 and 3 nm. In the immobilized state, the maximum at R = 1 nm is present in both types of water (of different order), but the second maximum is observed only for more ordered associates.

Heterogeneous Iron Catalyst Fe/SBA-15 towards sp3 C-O bond activation in the absence of base and additive

A heterogeneous iron-catalyzed (8wt%Fe/SBA-15) mediated direct alkylation of benzyl alcohol with aryl boronic acid in the absence of base and additive via C-O bond activation is demonstrated. This catalyst system led to an efficient Friedel-crafts alkylation reaction. The acidic site in the catalyst system had been confirmed by NH3-TPD, which shows the presence of three different acidic sites viz., weak, moderated, and strong acid sites. The catalyst showed five times recyclable ability.

Enhancing Methane Conversion by Modification of Zn States in Co-Reaction of MTA

Limited by harsh reaction conditions, the activation and utilization of methane were regarded as holy grail reaction. Co-reaction with methanol, successfully realizing mild conversion below 450 °C, provides practical strategies for methane conversion on metal-loaded ZSM-5 zeolites, especially for highly efficient Zn loaded ones. However, Zn species, regarded as active acid sites on the zeolite, have not been sufficiently studied. In this paper, Zn-loaded ZSM-5 zeolite was prepared, and Zn was modified by capacity, loading strategy, and treating atmosphere. Apparent methane conversion achieves 15.3% for 1.0Zn/Z-H2 (16.8% as calculated net conversion) with a significantly reduced loading of 1.0 wt.% against deactivation, which is among the best within related zeolite materials. Besides, compared to the MTA reaction, the addition of methane promotes the high-valued aromatic production from 49.4% to 54.8%, and inhibits the C10+ production from 7.8% to 3.6%. Notably, Zn2+ is found to be another active site different from the reported ZnOH+. Medium strong acid sites are proved to be beneficial for methane activation. This work provides suggestions for the modification of the Zn active site, in order to prepare highly efficient catalysts for methane activation and BTX production in co-reaction with methanol.