Magnetic deep eutectic solvents: formation and properties.

Deep eutectic solvents (DESs) are well-known as novel solvents due to their unique properties, which are indispensable for the development of green chemistry in the future. CoCl2·6H2O and NiCl2·6H2O-based DESs, which could be called magnetic DESs (MDESs) for short in view of their responsive behavior to an external magnetic field, have been widely used in many industrial applications, such as biomass treatment, electrolytes, and material preparation. For better application and full-scale development of these MDESs in various fields, eleven MDESs were prepared in this work by using CoCl2·6H2O and NiCl2·6H2O as hydrogen bond acceptors (HBAs) with alcohols, carboxylic acids and amides as hydrogen bond donors (HBDs), respectively. The intermolecular interactions between the components of MDESs were characterized via FTIR, 1H NMR and DSC analysis. In addition, physicochemical properties including density, viscosity, conductivity, ionicity, pH values, surface tension, thermostability and solvatochromic parameters were investigated. All MDESs exhibit acid characteristics and have good conductivity comparable with ionic liquids (ILs) and other DESs used for electrolytes. The results show that stronger H-bonding networks in Ni-based MDESs make them have higher density, viscosity, polarity and surface tension values than Co-based MDESs. Moreover, all prepared MDESs possess a good conductivity behavior which could be comparable to that of common organic solvents and ILs. According to this work, we could better comprehend the behavior of Co/Ni-based MDESs and choose the appropriate one for particular applications.

A Weak Acidic and Strong Coordinated Deep Eutectic Solvent for Recycling of Cathode from Spent Lithium-Ion Batteries.

The leaching and recycling of valuable metals via environmentally benign solvents is important because of the ever-increasing waste lithium-ion batteries, but it remains a challenge. Herein, a multi-functional deep eutectic solvent (DES) based on lactic acid (LA) and guanidine hydrochloride (GHC) was used to extract cobalt and lithium ions from LiCoO2 . Due to the strong acidity (protons) and abundant chlorine coordinating ions of LA/GHC, the solubility of LiCoO2 in LA/GHC could reach as high as 19.9 mg g-1 (stirred at 80 °C for 24 h), and a little LiCoO2 powder even could be dissolved at room temperature without stirring. Oxalic acid was used to strip and separate the oxalates of cobalt and lithium. Furthermore, LA/GHC could be recycled with a similar dissolving performance. This work avoided using corrosive acids and could be realized at low temperature (80 °C), making it energy-saving and cost-effective. It shows DESs have great potential in extracting strategically important metals from LiCoO2 cathodes and provides an efficient and green alternative for sustainable recycling of spent lithium-ion batteries.

Acidity scales of deep eutectic solvents based on IR and NMR.

Acidic deep eutectic solvents (ADESs) have been utilized in various applications. Clearly, it is crucial to obtain acidity information that could reveal the relationship with performance. However, appropriate methods for measuring acidity are limited. Herein, we developed two promising approaches (without additional solvents) to identify and characterize both Lewis and Brønsted acidities by applying acetonitrile as an infrared probe and trimethylphosphine oxide (TMPO) as a nuclear magnetic resonance (NMR) probe. The acetonitrile IR approach is suitable for measuring the acidity of Lewis ADESs by monitoring the peak of ν(CN) around 2300 cm-1, and the 31P-TMPO NMR approach could identify and scale both Lewis and Brønsted acidities precisely. Moreover, a perfect linear relationship between the IR shift of ν(CN) and the effective charge density of metal cations was established, which provides a better understanding of Lewis acidity. In short, this study not only offers two efficient acidity measurement methods but also provides a molecular basis for optimizing the performance of ADESs in applications.

An emerging deep eutectic solvent based on halogen-bonds.

A new deep eutectic solvent (DES) driven by halogen bonding (XB) was exploited. A family of eutectic mixtures in the liquid state was obtained by the combination of quaternary ammonium salts and dihalogens. The formation mechanism was discussed based on experiments and DFT calculations. It not only broadens the potential DES systems but unlocks the possibility of XB complexes as solvents.

Deep eutectic solvent-assisted synthesis of porous Ni2CO3(OH)2/SiO2 nanosheets for ultra-efficient removal of anionic dyes from water.

Wastewater treatment is a severe environment issue, especially the discharge of excessive synthetic dyestuffs in the aquatic environment. In this study, a facile binary deep eutectic solvothermal process plus silica surface modification was successfully applied for preparation of porous nanosheet Ni2CO3(OH)2/SiO2 composites. The composites show powerful anionic dyes removal ability due to the high specific surface areas, hydrogen bond connection, coordination effect and strong electrostatic interactions with anionic dyes. A maximum adsorption capacity of 2637 mg g-1 at neutral pH (ca.7) and 303 K was achieved for Ni2CO3(OH)2/SiO2 composite to adsorb Congo red, a representative anionic dye. Moreover, the composite has an excellent specificity for anionic dyes and could maintain above 95% removal efficiency after 5 cycles. Therefore, the as-prepared nanocomposites could be qualified as candidates for industrial environmental remedy. Furthermore, the proposed material preparation strategy could be extended to fabricate various advanced energy and environmental materials.

The prevalence and specific characteristics of hospitalised pressure ulcer patients: A multicentre cross-sectional study.

OBJECTIVE: To ascertain the pressure ulcer prevalence in secondary and tertiary general hospitals in different areas of Guangdong Province in China and explore the possible risk factors that are related to pressure ulcers. BACKGROUND: Few multicentre studies have been conducted on pressure ulcer prevalence in Chinese hospitals. DESIGN: A cross-sectional study design was used. METHODS: Data from a total of 25,264 patients were included in the analysis at 25 hospitals in China. The investigators were divided into two groups. The investigators in group 1 examined the patients' skin. When a pressure ulcer was found, a pressure ulcer assessment form was completed. The investigators in group 2 provided guidance to the nurses, who assessed all patients and completed another questionnaire. A multivariate logistic regression analysis was used to analyse the relationship between the possible risk factors and pressure ulcer. RESULTS: The overall prevalence rate of pressure ulcers in the 25 hospitals ranged from 0%-3.49%, with a mean of 1.26%. The most common stage of the pressure ulcers was stage II (41.4%); most common anatomical locations were sacrum (39.5%) and the feet (16.4%). Braden score (p < .001), expected length of stay (p < .001), incontinence (p < .001), care group (p = .011), hospital location (p < .001), type of hospitals (p = .004), ages of patients (p < .001) were associations of pressure ulcers from the multivariate logistic regression analysis. CONCLUSIONS: The overall prevalence rate of pressure ulcers in Chinese hospitals was lower than that reported in previous investigations. Specific characteristics of pressure ulcer patients were as follows: low Braden score, longer expected length of stay, double incontinence, an ICU and a medical ward, hospital location in the Pearl River Delta, a university hospital and an older patient. RELEVANCE TO CLINICAL PRACTICE: The survey could make managers know their prevalence level of pressure ulcers and provide priorities for clinical nurses.

[Selection of matrix modifier for GF-AAS determination of trace lead in soil watered with waste water and its application].

The rapid and direct method of selection of the matrix modifier for the determination of trace lead in soil watered with waste water by graphite furnace atomic absorption spectrometry under the best matrix modifier selected has been developed. The effect of the matrix modifiers including NH4 Hz2PO4, (NH4)3PO4, NH4CI, Pd-Mg, NH4H2PO4+MgNO3+NH4NO3 etc. was determined by using graphite furnace atomic absorption spectroscopy. The results showed that NH4H2PO4 is the best matrix modifier for the determination of lead in soil watered with waste water, and the content of lead was determined by using 4.0 mg x L(-1) NH4H2PO4 as a matrix modifier, ashing and atomization temperature of 850 degrees C and 1600 degrees C, respectively, and rectifying background. The relative standard deviation of the method was 2.6%, and the recovery was in the range of 92.4%-104%.