Despite
the fact that lithium–sulfur batteries are regarded
as promising next-generation rechargeable battery systems owning to
high theoretical specific capacity (1675 mA h g–1) and energy density (2600 W h kg–1), several issues
such as poor electrical conductivity, sluggish redox kinetics, and
severe “shuttle effect” in electrodes still hinder their
practical application. MXenes, novel two-dimensional materials with
high conductivity, regulable interlayer spacing, and abundant functional
groups, are widely applied in energy storage and conversion fields.
In this work, a Ti3C2/carbon hybrid with expanded
interlayer spacing is synthesized by one-step heat treatment in molten
potassium hydroxide. The subsequent experiments indicate that the
as-prepared Ti3C2/carbon hybrid can effectively
regulate polysulfide redox conversion and has strong chemisorption
interaction to polysulfides. Consequently, the Ti3C2/carbon-based sulfur cathode boosts the performance in working
lithium–sulfur batteries, in terms of an ultrahigh initial
discharge capacity (1668 mA h g–1 at 0.1 C), an
excellent rate performance (520 mA h g–1 at 5 C),
and an outstanding capacity retention of 530 mA h g–1 after 500 cycles at 1 C with a low capacity fade rate of 0.05% per
cycle and stable Coulombic efficiency (nearly 99%). The above results
indicate that this composite with high catalytic activity is a potential
host material for further high-performance lithium–sulfur batteries.
An experimental study on adsorption of phenol and o-cresol using ionic liquid-immobilized silica contained different functional groups was carried out. The effects of various operating parameters such as type of ionic liquid group, different adsorption time and ambient temperatures, different solvents in solid phase extraction (SPE) process and several aqueous ion solutions on adsorption of two phenols had been experimentally investigated. It was found that amino ionic liquid-immobilized silica had the highest adsorption efficiency and stability. The optimized adsorption conditions were 15 min under 35oC. In SPE, the acidity solution such as ethanol-HCl (0.1% vol.) and NaH2PO4 could reduce the adsorption efficiency of sorbents. Finally, the sorbent was applied to determining two phenols in real samples and relative standard deviation (RSD) less than 6.14% showed the high precision.
Introduction
Ephedrine is a typical compound found in lots of plant species that is used in several medicines for the treatment of asthma and bronchitis. However, excess amounts are harmful to humans, so it needs to be removed.
Objective
This study developed a multi‐phase extraction (MPE) method with a molecular imprinted polymer (MIP) coated ionic liquid (IL)‐based silica (SiO2@IL@MIP) to simultaneously extract and separate ephedrine from Pinellia ternata, 10 medicines, and urine samples.
Methods
IL was immobilized on silica. Subsequently, the IL was combined with the functional monomer, followed by the addition of the crosslinker and template. The resulting sorbent was applied to the MPE, and the extraction, washing and elution solvents were evaluated.
Results
Fourier‐transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) confirmed the synthesis of SiO2@IL@MIP. A maximum adsorption amount of 5.76 mg/g was obtained at 30°C at a neutral pH. In MPE, 10.00 mL of methanol could extract all the ephedrine from Pinellia ternata. The interference was removed by washing with 4.00 mL of water, ethanol, and acetonitrile. Finally, 8.00 mL of methanol/acetic acid (99:1, v/v) was applied as the elution solvent. The following were extracted: 5.50 μg/g of ephedrine from Pinellia ternata, 0.00–46.50 μg/g from the 10 herbal medicines, and 68.70–102.80 μg/mL in the urine samples.
Conclusion
The proposed method was applied successfully to the simultaneously extraction and separation of ephedrine from plants and medicines. These results are expected to provide important data for the development of new methods for the separation and purification of bioactive compounds.
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