COLLOID AND POLYMER SCIENCE
·
2012
·Vol. 291
·期 4
·919-925
·
IF 2.331
Ambreen Jaweria,Yang Jinxian,Ye Xiaodong,Siddiq Mohammad
The temperature-induced phase transition of poly(2-ethyl-2-oxazoline) (PEtOx) aqueous solution under mixing with a series of small carboxylic acids has been studied by turbidity measurements and laser light scattering. It has been found that cloud point temperature ( T
cp ) of the PEtOx was changed to varying degrees depending upon the pH, ionic strength, molar ratio of acids to 2-ethyl-2-oxazoline unit, and carbon chain length of small carboxylic acids. Significant change in T
cp was observed in the case of hexanoic acid. At acidic pH, an increase in the molar ratio of hexanoic acid to the 2-ethyl-2-oxazoline unit gradually decreased the phase transition temperature of the polymer as compared to the T
cp of pure PEtOx. At original pH 6 (pH > p K
a ), T
cp shifts to higher value than that of pure PEtOx for lower molar ratios and decreased later on with increasing the molar ratio. The shift in the T
cp is described based on the differences in the driving force of phase transition, including hydrogen bonding between small carboxylic acids and PEtOx polymer and hydrophobic interaction.
研究领域:
高分子化学
·
物理化学
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产品关联
DOI
高影响因子
WATER SCIENCE AND TECHNOLOGY
·
2014
·Vol. 70
·期 12
·1913-1918
·
IF 1.212
Meng Lifen,Ning Jinyan,Yang Yaling
A sensitive and simple method for flame atomic absorption spectrometry determination of traces of cadmium and chromium(III) species in water samples after preconcentration by cloud point extraction has been developed. A novel complex agent of alizarin complexone with cadmium (Cd) and chromium (Cr(III)) was quantitatively extracted in surface primary alcohol ethoxylate-rich phase at 33 °C. The effects of experimental conditions including pH of sample solution, concentration of chelating agent and salt, equilibration temperature and time, and foreign ions were evaluated in order to enhance sensitivity of the method. Under optimal conditions, the low limit detections were 6.7 and 3.2 μg/L, and the enrichment factors were 24 and 20 for Cd and Cr(III), respectively. The relative standard deviations were 3.8 and 2.5% for Cd and Cr(II), respectively ( n = 11). The high recoveries of the spiked Cd and Cr(III) ions were obtained in the range of 90–116%. The proposed method has been successfully applied for the determination of Cd and Cr(III) in water samples.
研究领域:
分析化学
·
环境监测
·
重金属检测
·
水环境科学
·
痕量元素分析
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DOI
高影响因子
ANALYTICAL AND BIOANALYTICAL CHEMISTRY
·
2017
·Vol. 409
·期 19
·4559-4569
·
IF 3.431
Xu Jia,Li Yunfang,Li Cao,Zhang Rui,Xiao Yuxiu
A hexafluoroisopropanol (HFIP)-mediated cloud point extraction (CPE) system was established. A small amount of HFIP (even 1%, v / v ) can dramatically reduce the cloud point of Triton X-100 (TX-100) aqueous solution (even to 1 °C) and make liquid-liquid two-phase separation (coacervate phase and aqueous phase) occur at room temperature over a wide range of TX-100 concentration (0.5∼10%, g/mL). HFIP-mediated coacervate phase has smaller volume (volume ratio is 1.8∼8.9% relative to the volume of the total solution with 1∼5% TX-100) and larger micelle aggregates (30∼80 nm in diameter) compared to temperature-induced coacervate phase (volume ratio at 2.8∼14.0%, the diameter of micelle aggregates at 5∼30 nm). HFIP-mediated CPE was coupled to high-performance liquid chromatography with ultraviolet detection (HPLC-UV) for the extraction and detection of organic pollutants in water, namely, polycyclic aromatic hydrocarbons (PAHs), fluoroquinolones (FQs), and sulfonamides (SAs) with different polarities, charges, and hydrogen-bonding properties. HFIP-mediated CPE provides much higher extraction rates (ERs) and enrichment factors (EFs) for FQs (91∼106%, 50∼59), PAHs (63∼90%, 33∼49), and SAs (26∼55%, 16∼34) compared with the temperature-induced one (ERs: 4∼8% for FQs, 25∼46% for PAHs, and 4∼37% for SAs; EFs: 1∼3 for FQs, 6∼12 for PAHs, and 8∼13 for SAs). The limit of detection ranges from 0.24 to 0.33 ng/mL for FQs, 0.04 to 0.38 ng/mL for PAHs, and 0.63 to 1.31 ng/mL for SAs. The proposed method was applied in the analysis of real water samples, and the recovery of 79.4∼110.8% and the relative standard deviation of 0.2∼16.3% were achieved for the three types of pollutants.
Schematic illustration of HFIP-mediated cloud point extraction
研究领域:
环境科学
·
分析化学
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产品关联
DOI
PubMed
高影响因子
Analytical Methods
·
2014
·Vol. 7
·期 2
·560-565
·
IF 1.938
Yun-Kai Lv,Wei Zhang,Meng-Meng Guo,Fang-Fang Zhao,Xiao-Xue Du
A home-made centrifugal microextraction tube (CMET) was developed and applied to cloud point extraction coupled with microwave-assisted back extraction and gas chromatographic separation of six phthalate esters (PAEs) from mineral water. All phthalate esters were entrapped in the micelles of the non-ionic surfactant Triton X-114 and removed from the bulk phase by centrifugation. The obtained surfactant-rich phase was treated with water-immiscible solvents, and the target analytes were back extracted by short-term microwave application and determined by GC-FID directly. The whole process was finished in the CMET. The proposed method demonstrated good performance concerning linearity (R2 = 0.9977-0.9998), precision (2.3–5.7%), the limits of detection and quantitation (LOD, 11.5-19.3 μg L−1; LOQ, 37.0-63.3 μg L−1), spiked recoveries (89.1–96.3%) and enrichment factor (71-85). The proposed method was successfully applied for the determination of trace amount of phthalate esters in mineral water. DBP and BBP were found in actual mineral water samples.
研究领域:
分析化学
·
环境毒理学
·
食品安全
·
分子监测
·
样品前处理
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DOI
高影响因子
Analytical Methods
·
2014
·Vol. 6
·期 10
·3241-3246
·
IF 1.938
Zonghao Li,Jiaxi Chen,Mousheng Liu,Yaling Yang
A new method based on ultrasound-assisted cloud point extraction (UA-CPE) using the mixture of non-ionic surfactant alkylphenol ethoxylate NP-7 and alkylphenol ethoxylate NP-9 for the preconcentration of trace amounts of lead (Pb) and cadmium (Cd) in water samples prior to determination by FAAS has been developed. In this method, Pb and Cd react with ammonium pyrrolidinedithiocarbamate (APDC), yielding hydrophobic complexes, which then are extracted into the surfactant-rich phase. Compared with the traditional CPE, faster phase separation and higher recovery were obtained using the ultrasound-assisted process and a series of non-ionic nonyl phenol ethoxylate surfactants in the present UA-CPE. Variable parameters affecting the CPE procedure were evaluated and optimized. Under the optimized conditions, the calibration graph was linear in the range of 10–500 μg L−1 for Pb and Cd. The detection limits were 0.5 μg L−1 and 0.28 μg L−1 with relative standard deviations of 2.6% and 3.4% for Pb and Cd, respectively. The enrichment factors were 57 and 63 for Pb and Cd, respectively, for 10 mL of preconcentrated solution. The method was successfully applied to the determination of Pb and Cd in water samples.
研究领域:
分析化学
·
环境监测
·
痕量元素检测
·
样品前处理
·
水环境科学
✓ 已验证
DOI
高影响因子
RARE METALS
·
2012
·Vol. 31
·期 5
·512-516
·
IF 0.593
Lian Yuanpei,Zhen Wei,Tai Zhigang,Yang Yaling,Song Jun,Li Zonghao
Cloud point extraction (CPE) with Tergitol TMN-6 was applied for the extraction of trace amounts of palladium (Pd(II)), platinum (Pt(IV)), and gold (Au(III)) in the soil of industrial sewage. Ammonium pyrolysine dithiocarbamate (APDC) was adopted as the chelating agent prior to CPE and then was detected by atomic absorption spectrometry (AAS). Different parameters such as the concentration of surfactants, chelating agent and salt, sample pH, equilibration temperature and time, centrifugation time and rates, and the effect of foreign ions were studied. Under optimum conditions, the low limits of detections are 1.4, 2.8 and 1.2 ng·ml −1 and the enrichment factors are 21, 12, and 24 for Pd(II), Pt(IV), and Au(III), respectively. The relative standard deviations vary from 0.6% to 1.0% ( n =11). All correlation coefficients of the calibration curves are >0.9960. The proposed method was successfully applied for the determination of Pd(II), Pt(IV), and Au(III) in the real soil of industrial sewage samples.
研究领域:
分析化学
·
环境化学
·
重金属检测
·
分离科学
·
环境监测
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DOI
高影响因子
Materials Today Communications
·
2022
·
IF 3.662
Chao Zheng,Xiaoyan Yu,Xiaoyi Chen,Mingming Chang
Poly(ethylene oxide)- b -poly(propylene oxide)- b -poly(ethylene oxide) (PEO-PPO-PEO) and acrylamide are both commercially available and widely used water-soluble substances. There are many situations that PEO-PPO-PEO coexist with acrylamide in industry applications, while little is known about the influence of acrylamide on cloud point of PEO-PPO-PEO aqueous solution. In this work, it reveals a universal solubilization of PEO-PPO-PEO by acrylamide. There is always an increase in cloud point with addition of acrylamide no matter what the molecular structure and concentration of PEO-PPO-PEO is. It is found the solubilization is more pronounced when PEO-PPO-PEO is with lower molecular weight or lower weight fraction of PPO segments. On the other hand, the cloud point of systems at lower concentration is more sensitive to addition of acrylamide. On the contrary, polyacrylamide exhibits an opposite impact on cloud point of PEO-PPO-PEO. Acrylamide/PEO-PPO-PEO solution changes from clear to cloudy after polymerization of acrylamide.
研究领域:
化学
·
材料科学
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产品关联
DOI
高影响因子
ANALYTICAL CHEMISTRY
·
2024
·
IF 6.7
Ke Shi,Hong Zhang,Yangzhongfu Yang,Yuelin Huang,Jikun Gao,Jiaqian Zhang,Guangfeng Kan,Yanxiao Jiang,Jie Jiang
Nanoplastics have attracted much attention due to their potential hazards. However, analysis of nanoplastics remains challenging. In this study, ionic liquid-assisted cloud-point extraction (IL-assisted CPE) was developed to enrich nanoplastics in the aqueous environment and further coupled with electromagnetic heating pyrolysis mass spectrometry. The use of trace ILs improves the extraction efficiency of CPE for nanoplastics. The effects of ILs (types, contents), nanoplastic properties (type, size), and environmental factors (aging time, humic acid content) were systematically investigated to evaluate the applicability. The limits of detection of poly(methyl methacrylate) (PMMA) and polystyrene (PS) were determined to be 1.78 and 2.67 μg/L, respectively. Real environmental samples including lake water, rainwater, and influent and effluent from wastewater treatment plant were analyzed with good accuracy (79.58–116.87%) and satisfactory precision (RSD ≤ 11.99%). A possible mechanism for ILs being absorbed into the ordered surfactant micellar and generating larger micelles to synergically enclose hydrophobic nanoplastics was proposed. This work provides a simple and efficient approach to the extraction and analysis of nanoplastics in aqueous environments.
研究领域:
环境科学
·
分析化学
·
材料科学
✓ 已验证
DOI
PubMed
高影响因子
Soft Matter
·
2014
·Vol. 11
·期 3
·545-550
·
IF 4.151
Lei Yu,Wenxin Fu,Zhibo Li
Two series of copolymers were prepared by ring-opening polymerization (ROP) of γ-(2-methoxyethoxy)esteryl-L-glutamate (L-EG2Glu) N-carboxyanhydride (NCA) and L-alanine (L-Ala) using HMDS and PEG-NH2 as initiator, respectively. Poly-(L-EG2Glu-co-L-Ala) displayed lower critical solution temperature (LCST) behavior but had a lower phase transition temperature than poly-L-EG2Glu at similar molecular weight (MW). The clouding point (CP) of random copolypeptides can be tuned by altering the alanine content and overall MW. Circular dichroism (CD) and Fourier transform infrared spectroscopy (FTIR) indicated that the thermal-responsive properties depended on the content of ordered conformations. PEG-b-poly-(L-EG2Glu-co-L-Ala) can spontaneously form hydrogels in water at room temperature. Transmission electron microscopy (TEM) and atomic force microscopy (AFM) revealed that these hydrogels were formed by nanoribbons. The intermolecular hydrogen bonding among copolypeptide blocks accounted for the nanoribbon assemblies and hydrogel network formation.
研究领域:
聚合物化学
·
材料科学
·
生物物理学
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产品关联
DOI
PubMed
高影响因子
Analytical Methods
·
2014
·Vol. 6
·期 20
·8129-8135
·
IF 1.938
Jinjiao Shi,Ligang Chen
A sensitive and simple method for high-performance liquid chromatography (HPLC) determination of Sudan dyes in lipstick samples after preconcentration by cloud point extraction (CPE) has been developed. The nonionic surfactant Triton X-114 was chosen as the extraction medium. Various experimental conditions were investigated to optimize the extraction and preconcentration process. Under optimum conditions, 3% Triton X-114 (v/v), ultrasonication for 20 min, pH 7, the satisfied recoveries of Sudan dyes were obtained. For the preconcentration of Sudan dyes by cloud point extraction, the solution was incubated in a thermostatic water bath at 60 °C for 10 min, and 22.5% sodium chloride (m/v) was added to the solution to facilitate the phase separation and increase the preconcentration factor. The limits of detection for the analytes are 0.11, 0.10, 0.07 and 0.08 μg g−1, respectively. The intra-day and inter-day precisions of four Sudan dyes are in the range of 4.6–6.4% and 4.4–6.7%, respectively. The recoveries of four Sudan dyes are 89.3%, 90.3%, 91.8% and 92.0%, respectively. The results demonstrate that this method is simple, rapid, sensitive and low cost. Moreover, it does not require the large consumption of organic solvents and is a non-toxic and eco-friendly method.
研究领域:
分析化学
·
化妆品科学
·
环境化学
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产品关联
DOI
高影响因子
JOURNAL OF SUPERCRITICAL FLUIDS
·
2016
·
IF 2.579
Dongdong Hu,Yingna Zhang,Mei Su,Lei Bao,Ling Zhao,Tao Liu
The low molecular weight, topological structure and end group removal are expected to enhance the CO 2 -philicity of poly(vinyl acetate) (PVAc), which is of great interest for expanding CO 2 applications as a green solvent. This work aims at investigating the effect of molecular weight ( M n ) of PVAc with different molecular chain structure on the CO 2 -philicity through dissolution behavior measurement and molecular modeling. Well-defined 3-armed and 4-armed R-core PVAc was synthesized by RAFT polymerization, and then the corresponding xanthate groups were removed. The CO 2 -philicity of multi-armed PVAc was found to be inferior to that of linear one at low M n . With increasing the M n from 1000 to 7000 g/mol, the cloud point pressures ( P c ) of multi-armed PVAc first decreased, reached a minimum at a given M n , and then increased, which was different from the variation trend of the P c of linear PVAc versus M n . In addition, removal of the xanthate groups could effectively enhance the CO 2 -philicity of PVAc, especially at low M n . Moreover, the molecular dynamics (MD) simulations on the interactions in polymer/CO 2 systems indicated that the multi-armed structure had different effects on the compatibility with CO 2 at different M n . At low M n , the polymer⿿polymer interaction was the main driving force deciding the CO 2 -philicity due to the significant difference in different molecular chain structures. At high M n , multi-armed structure enhanced the CO 2 -philicity due to the synergistic effect of moderate polymer⿿polymer interaction and large polymer⿿CO 2 interaction. The appropriate molecular chain structure could be selected to enhance the CO 2 -philicity of PVAc at a certain M n .
研究领域:
高分子科学
·
材料科学
·
化学工程
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产品关联
DOI
高影响因子
JOURNAL OF POLYMER SCIENCE
·
2021
·Vol. 59
·期 15
·1701-1710
·
IF 0
Jianlei Lu,Xionglin Zhou,Jialin Sun,Mengdi Xu,Mingming Zhang,Chuanzhuang Zhao
Poly(methylacrylamide) (PMAM) is a thermo-responsive polymer with an upper critical solution temperature (UCST). Its cloud point ( T cp ) is around 60 °C, unsuitable for certain biomedical and industrial applications. This study brought up a copolymerization strategy to tune the T cp of PMAM with hydrophilic comonomers. Surprisingly, with a small portion of hydrophilic monomer doped, the T cp of the PMAM copolymer can be significantly shifted. For instances, with ≤7 mol% of acrylamide or 1 mol% of oligo(ethylene glycol) methacrylate, the T cp can be shifted in a wide range from ~69 to ~0 °C. Microdifferential scanning calorimetry demonstrated that the enthalpic effect during the phase transition of the solutions is indistinctive, while fluorescence measurement with pyrene as a probe revealed that the hydrogen-bonding within polymer chains is enhanced by the hydrophobic aggregation of methyl groups. Therefore, the doped hydrophilic monomer could remarkably alter the ordering of water-molecules and the extent for the aggregation of methyl groups, leading to the pronounced shifting in the T cp of the copolymers. This work would facilitate the application of PMAM as smart polymer materials and guide the inventions of functional materials based on UCST polymers. Graphical
研究领域:
材料科学
·
高分子化学
·
生物医学工程
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产品关联
DOI
危险品化学品经营许可证（带存储）