Home-Made Membraneless Vaporization Gas-Liquid Separator for Colorimetric Determination of Ethanol in Alcoholic Beverages.

This work utilized the simplicity of a so-called membraneless vaporization (MBL-VP) unit as a gas separator for the colorimetric determination of ethanol in alcoholic beverages. A beverage sample with a volume of 1 mL was directly injected into a small container which was hung from a lid inside a closed 40 mL reused glass bottle without pretreatment such as distillation. An acidified potassium dichromate (Cr2O7 2-) acceptor solution, preadded to the glass bottle, was reduced to Chromium (III) ion by the diffusion of vaporized ethanol from the sample. After 5 min, the absorbing solution was collected for colorimetric detection at 590 nm. The unit manually quantifies ethanol in the range 1.0-90% (v/v) with satisfactory interday precision but without matrix effect (recovery 89-109%). The method was validated with the conventional distillation/pycnometer method which showed no significant difference of ethanol contents between those two methods and the declared values of 12 alcoholic beverages, indicating sufficient accuracy. Analyses of alcoholic beverages using this method were successful with benefits of simplicity, cheapness, and less energy consumption.

Magnetic Adsorbents for Wastewater Treatment: Advancements in Their Synthesis Methods.

The remediation of water streams, polluted by various substances, is important for realizing a sustainable future. Magnetic adsorbents are promising materials for wastewater treatment. Although numerous techniques have been developed for the preparation of magnetic adsorbents, with effective adsorption performance, reviews that focus on the synthesis methods of magnetic adsorbents for wastewater treatment and their material structures have not been reported. In this review, advancements in the synthesis methods of magnetic adsorbents for the removal of substances from water streams has been comprehensively summarized and discussed. Generally, the synthesis methods are categorized into five groups, as follows: direct use of magnetic particles as adsorbents, attachment of pre-prepared adsorbents and pre-prepared magnetic particles, synthesis of magnetic particles on pre-prepared adsorbents, synthesis of adsorbents on preprepared magnetic particles, and co-synthesis of adsorbents and magnetic particles. The main improvements in the advanced methods involved making the conventional synthesis a less energy intensive, more efficient, and simpler process, while maintaining or increasing the adsorption performance. The key challenges, such as the enhancement of the adsorption performance of materials and the design of sophisticated material structures, are discussed as well.

Colorimetric determination of trace orthophosphate in water by using C18-functionalized silica coated magnetite.

In this study, we customized magnetic sorbents by functionalizing silica coated magnetite with octadecyl(C18)silane (Fe3O4@SiO2@C18). This sorbent was intended for the determination of trace orthophosphate (o-PO43-) in unpolluted freshwater samples. The o-PO43- was transformed to phosphomolybdenum blue (PMB), a known polyoxometalate ion. Then the PMB were coupled with cetyl trimethyl ammonium bromide (CTAB), cationic surfactant, in order to hydrophobically bound with the Fe3O4@SiO2@C18 particles through dispersive magnetic solid-phase extraction (d-MSPE) as part of sample preconcentration. The PMB-CTAB-magnetic particles are simply separated from the aqueous solution by the external magnet. The acidified ethanol 0.5 mL was used as PMB-CTAB eluent to produce an intense blue solution, which the absorbance was measured using a UV-Vis spectrophotometer at 800 nm. The proposed method (employing 2 mg of Fe3O4@SiO2@C18) yielded an enhancement factor of 32 with a linear range of 1.0-30.0 µg P L-1. Precision at 6.0 µg P L-1 and 25.0 µg P L-1 were 3.70 and 2.49% (RSD, n = 6) respectively. The lower detection limit of 0.3 µg P L-1 and quantification limit of 1.0 µg P L-1 allowed trace levels analysis of o-PO43- in samples. The reliability and accuracy of the proposed method were confirmed by using a certified reference material. Our method offers highly sensitive detection of o-PO43- with simple procedures that can be operated at room temperature and short analysis time.

Synthesis of MOR Zeolite/Magnetite Composite via Seed Assisted Method.

MOR zeolite is an effective adsorbent for separating organic molecules from various solutions owing to its large windows of 0)65 × 0)70 nm and its relatively high silica-alumina ratio which provides higher hydrophobicity. Fine powdery MOR zeolite is desirable for adsorption of organic molecules considering its larger surface area; however, fine particles are difficult to remove from solutions after treatment. Intensification of magnetic susceptibility through combination with magnetic particles ensure quick and easy removal of fine adsorbents by magnetic force. Meanwhile, seed assisted method is a powerful technique to direct and accelerate zeolite synthesis by adding seed crystals into the precursor sol prior to hydrothermal synthesis. In this work, we selected magnetite as the magnetic particle and propose the hydrothermal synthesis of MOR zeolite/magnetite composite via seed assisted method for the first time. MOR zeolite/magnetite composite with high MOR zeolite crystallinity was obtained by synthesizing for only 6 hours at 463 K when adding seed crystals, while no sign of crystallization was observed even after 24 hours in their absence. In addition, pre-milling of seed crystals together with magnetite was found to be effective to incorporate magnetite into MOR zeolite during crystallization and to decrease the primary crystal size of the crystallized MOR zeolite.