Influence of Magnetic Field on Evaporation Rate and Surface Tension of Water

Wettability of Ionic Liquids in High Magnetic Fields

Here, we demonstrate that high magnetic fields alter the wettability of water and ionic solutions on the single-crystal α-Al2O3. We investigated the relationship between the substrate crystal orientation, material magnetism, liquid conductivity, and the surface contact angle. Applying high magnetic fields decreased the water contact angles on all of the surface orientations studied, and the reduction was larger for more magnetic substrates. For ionic solutions, high magnetic fields increased the contact angle on the (0001) α-Al2O3 surface but decreased the contact angles on the (112̅0), (101̅0), and (011̅2) surfaces. We attribute these orientation-dependent ionic solution responses to competition between the field-induced sample magnetization energy and the Lorentz force acting on the ionic solution. Overall, this work provides new magnetic-field-based strategies for changing the wettability and provides guidelines for fabricating novel microfluidic systems or biointerfaces with in situ magnetic control.

Ionic Liquid-Based Magnetic Needle Headspace Single-Drop Microextraction Combined with HPLC/UV for the Determination of Chlorophenols in Wastewater

A magnetic needle headspace single-drop microextraction (MN-HS-SDME) method coupled to HPLC/UV has been developed. Trihexyl(tetradecyl)phosphonium chloride was employed as an ionic liquid (IL) solvent for the headspace extraction of some chlorophenol (CP) compounds from wastewater samples. Despite of the nonmagnetic character of the IL, a significant improvement in the extraction efficiency was obtained by the magnetization of the single-drop microextraction needle using a pair of permanent disk magnets. A simplex method for the fast optimization of the experimental conditions (e.g., stirring speed, ionic strength, pH, extraction time and temperature) was used. The coefficients of determination (R2) varied between 0.9932 and 0.9989, the limits of detection were from 0.004 to 0.007 μg mL-1 and the relative recoveries were in the range of 88-120% for the studied analytes. The developed MN-HS-SDME HPLC/UV method was successfully applied to the determination of CPs in industrial wastewater.

Evaporation of water and urea solution in a magnetic field; the role of nuclear isomers

HYPOTHESIS

Ortho and para water are the two nuclear isomers where the hydrogen protons align to give a total nuclear spin of 1 or 0. The equilibrium ratio of 3:1 is established slowly in freshly evaporated water vapour while the isomers behave distinct gasses, with their own partial pressures. Magnetic-field-induced ortho ⟷ para transformations are expected to alter the evaporation rate.

EXPERIMENT

Evaporation from beakers of deionized water and a 6 M solution of urea is monitored simultaneously for periods from 1 to 60 h with and without a 500 mT magnetic field, while logging the ambient temperature and humidity. Balances with the two beakers are shielded in the same Perspex container. Many runs have been conducted over a two-year period.

FINDINGS

The evaporation rate of water is found to increase by 12 ± 7% of in the field but that of water with dissolved urea decreases by 28 ± 6%. Two effects are at play. One is dephasing of the Larmor precession of adjacent protons on a water molecule in a field gradient, which tends to equalize the isomer populations. The other is Lorentz stress on the moving charge dipole, which can increase the proportion of the ortho isomer. From analysis of the time and field dependence of the evaporation, we infer that the ortho fraction is 39 ± 1% in fresh vapour from water and 60 ± 5% in fresh vapour from urea.

High-pressure treatment enhanced aromatic compound concentrations of melon juice and its mechanism

Introduction

The flavor deterioration blocks the development of melon juice.

Methods

The effects of ultra-high temperature (UHT) and high pressure (HP) treatments on the aromatic compound concentrations of melon juice and their mechanisms were explored with fresh juice as the control.

Results

A total of 57 volatile compounds were identified by gas chromatography-tandem mass spectrometry analysis. β-ionone was shown to be the major aromatic component of melon juice for the first time. The HP at 200 MPa for 20 min increased the total volatile concentration of melon juice by 1.54 and 3.77 times the control and UHT, respectively. Moreover, the sum concentration of a major aromatic component in the HP treatment was 1.49 and 5.94 times higher than that of the control and UHT, respectively.

Discussion

The HP treatment raised the concentration of volatile and aromatic components of melon juice by reducing their surface tension.

Investigation of scale inhibition effect and mechanism of S-HGMF in the clean recirculating cooling water system

The formation of scales in a recirculating water system is a common problem in industrial water treatment; it seriously affects the production in various industries and pollutes the environment. Although conventional scale inhibition methods are effective, they are expensive and harm the environment. Herein, an advanced method is proposed to solve the scaling issue in recirculating cooling water systems using the superconducting high-gradient magnetic field (S-HGMF) treatment. The scale inhibition performance could be improved by changing the magnetic flux density, operation time, and flow rate. The results showed that S-HGMF could increase the number of hydrogen bonds in the recirculating cooling water, enhance molecular interaction, increase the thickness of the ion hydration shell, reduce the nucleation rate, stabilize the water quality, improve the solubility of scale-forming ions, and inhibit scale formation. The scale inhibition performance reached 8.10%. Interestingly, S-HGMF had a memory effect in that it could maintain the scale inhibition effect for some period after treatment completion. Moreover, S-HGMF changed the crystal structure of the scale and promoted the transformation of the scale to a metastable phase. Ultimately, calcite was transformed to aragonite to reduce the precipitation of hard scale (calcite), achieving the purpose of scale inhibition. As a physical method, the application of S-HGMF to inhibit scaling has great potential for industrial applications.

Influence of Magnetic Fields Assisted for Preparation of Ferromagnetic Mono- and Bi-Metallic Co and Co–V SHS Catalysts on Their Activity in Deep Oxidation and Hydrogenation of CO2

Co–Al and Co–V–Al intermetallics produced by centrifugal self-propagating high-temperature synthesis (SHS) were used as precursors for preparation of catalysts for deep oxidation and hydrogenation of CO2. Leaching in NaOH solution and stabilization with H2O2 solution of precursors were carried out in permanent magnetic field (MF) (0.24 Т) and alternating magnetic field (0.13 Т, 50 Hz). Prepared Co и Co–V (95Co–5V, 90Co–10V) granular catalysts with size of 100–300 µm were characterized by XRD, SEM, EDS, and BET method and revealed to have a scaly surface structure. It was shown that the type of MF affects phase composition and surface morphology, as well as specific surface and activity in deep oxidation of CO and hydrocarbons as an important part of the neutralization of gas emissions, and hydrogenation of CO2, the processing of which would reduce atmospheric pollution with this greenhouse gas. Catalysts obtained in alternating MF was found to possess higher activity in the process of deep oxidation.

Electron generation in water induced by magnetic effect and its impact on dissolved oxygen concentration

pH, oxidation-reduction potential (ORP) and dissolved oxygen (DO) concentration are important parameters in water quality surveillance and treatment. The changes of these parameters are associated with electron density in water. Several techniques including electrolysis and catalysis which require redox reactions and electron exchange are employed to improve these parameters. In recent years, studies reported that magnetic effects can impart considerable changes on the pH, ORP and DO concentration of water. However, the correlation between electron density and magnetic effects on these parameters has yet to be disclosed despite the fact that increased electron density in water could improve water’s reductive properties, heat capacity and hydrogen bonding characteristics. In this study, the magnetic effects on pH, ORP and DO concentration were investigated using different magnets arrangements and water flow rates based on reversed electric motor principle. Results showed that the improvement of pH, ORP and DO concentration from 5.40–5.42 to 5.58–5.62 (+ 3.5%), 392 to 365 mV (− 6.9%), and 7.30 to 7.71 mg L^− 1 (+ 5.6%), respectively were achieved using combined variables of non-reversed polarity magnet arrangement (1000–1500 G magnetic strength) and water flow rate of 0.1–0.5 mL s^− 1. Such decrement in ORP value also corresponded to 8.0 × 10¹³ number of electron generation in water. Furthermore, Raman analysis revealed that magnetic effect could strengthen the intermolecular hydrogen bonding of water molecules and favor formation of smaller water clusters. The findings of this study could contribute to potential applications in aquaculture, water quality control and treatment of cancer attributed to free radical induced-oxidative stress.

Boric acid in magnetized water: clean and powerful media for synthesis of 3,4-dihydropyrimidin-2(1H)-ones

Water was magnetized via an external magnetic field and employed, for the first time, as a solvent in green preparation of 3,4-dihydropyrimidin-2(1H)-ones by the one-pot three-component condensation reaction using boric acid as a catalyst. Shorter reaction times, higher yields, and cleaner reaction profiles were some advantages of using magnetic water.

Water was magnetized via an external magnetic field and employed, for the first time, as a solvent in green preparation of 3,4-dihydropyrimidin-2(1H)-ones by the one-pot three-component condensation reaction using boric acid as a catalyst.