CHROMATOGRAPHIA
·
2016
·Vol. 79
·期 19
·1263-1269
·
IF 1.332
Wang Liang,Wu Minghuo,Wang Qixue,Zhan Jingjing,Chen Hongbo
Polyethylenimine (PEI) and 2,4,6,8-tetramethyl-2,4,6,8-tetrakis(propyl glycidyl ether)cyclotetrasiloxane (POSS–epoxy) were used as precursors for the preparation of organic-silica hybrid monolithic columns (PEI–POSS monolith) via epoxy–amine ring-opening polymerization (ROP). The high density of amine groups in PEI provides rich chromatographic interaction sites for the polar or acidic analytes in hydrophilic interaction (HILIC) and weak anion exchange (WAX) mechanisms. The column preparation conditions, such as the porogens, solvent and reaction temperature, were systematically investigated according to the morphology, permeability and column efficiency. The separation mechanisms of HILIC and WAX were evaluated with neutral polar compounds and halogen benzoic acids. Owing to the existence of reactive amine groups on the matrix surface, the PEI–POSS monolith is also an ideal starting material for the preparation of HILIC or strong anionic exchange (SAX) stationary phases by modification. The modification of PEI–POSS monoliths with iodomethane or bromoacetic acid via the nucleophilic substitution reaction could achieve the retention mechanisms of SAX or zwitterionic HILIC, respectively.
研究领域:
分析化学
·
材料科学
✓ 已验证
DOI
高影响因子
MICROCHEMICAL JOURNAL
·
2025
·
IF 5.1
Jing Zhou,Hongyu Ning,Haixing Wang,Sen Zhao,Yu Xu,Yilei Fan,Zhongping Huang,Jianhong Gao
Cannabis is the most frequently abused drug worldwide, and the number of cannabis users is still growing. The high lipophilicity of cannabinoids results in extremely low concentrations in wastewater, which poses difficulties and challenges for monitoring cannabinoids. In this study, a hyperbranched mixed-mode anion exchange magnetic adsorbent Fe 3 O 4 @poly(GMA/DVB-WAX) was designed based on the structural characteristics of cannabinoids, which was prepared through copolymerization of glycidyl methacrylate (GMA) and divinylbenzene (DVB) on the surface of oleic acid coated Fe 3 O 4 microspheres followed by hyperbranched modification with ethylenediamine (EDA) and 1,4-butanediol glycidyl ether (BDDGE). This magnetic solid-phase extraction (MSPE) adsorbent can selectively extract four cannabinoids, Δ 9 -tetrahydrocannabinol (THC), cannabidiol (CBD), cannabinol (CBN), 11-nor-9-carboxy-Δ 9 -tetrahydrocannabinol (THC-COOH), from wastewater through the synergistic effects of hydrophobic interactions, electrostatic interactions, π-π stacking interactions, and hydrogen bonding interactions. The entire extraction time of the adsorbent only takes five minutes and the extraction recovery rates were in the range of 69.4 %-94.0 % for four cannabinoids after the MSPE procedure optimization. An MSPE-UHPLC-MS/MS quantitative method for determination of four cannabinoids in wastewater was established and validated. The results showed that this method had a good linearity within the range of 0.5–100 ng/L (r 2 > 0.9962). The limits of detection and the limits of quantification were 0.17–0.33 ng/L and 0.50–1.00 ng/L, respectively. The proposed MSPE-UHPLC-MS/MS method based on Fe 3 O 4 @poly(GMA/DVB-WAX) is a convenient, sensitive and reliable strategy and has great application prospects in the analysis of trace cannabinoids in wastewater.
研究领域:
分析化学
·
环境科学
·
毒理学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Materials Chemistry B
·
2022
·Vol. 10
·期 35
·6742-6751
·
IF 7.571
Long Jiang,Tao Jing,Xiantao Shen
The development of an elution-free solid-phase extraction (SPE) process is of special interest in sample pretreatment. Due to the phase-change merits at relatively low temperatures and easy dissolution in n-hexane, wax spheres show great potential in this field. However, the conventional wax spheres possess a low affinity towards the target analytes when they are used as SPE adsorbents. In this study, using octadecanoic acid as the functional monomer and wax as the matrix, molecularly imprinted wax (MIW) spheres were successfully prepared. The obtained MIW spheres displayed remarkable molecular recognition ability and high selectivity towards the template. Interestingly, the as-synthesized molecularly imprinted wax (MIW) could be dissolved in n-hexane or melted by heating for subsequent fluorescence and mass spectrum analysis without the target elution process. Moreover, the melted MIW exhibited high repeatability, sensitivity and specificity for solid-state fluorescence detection. We believe that the imprinting method presented in this study will open a new window in analytical chemistry.
研究领域:
分析化学
·
材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Petroleum Science
·
2023
·
IF 5.6
Bo Yao,Hao-Ran Zhu,Bao-Dong Yan,Chuan-Xian Li,Fei Yang,Guang-Yu Sun,Hong-Bo Zeng
This paper investigated the effects of pre-heating treatment temperatures ( T pre ) on the flowability and wax deposition characteristics of a typical waxy crude oil after adding wax inhibitors. It is found that there is little difference in wax precipitation exothermic characteristics of crude oils at different T pre , as well as the wax crystal solubility coefficient in the temperature range of 25–30 °C. For the undoped crude oil, the flowability after wax precipitation gets much improved and the wax deposition is alleviated as T pre increasing. At T pre = 50 °C, the viscosity and wax deposition rate of crude oil adding wax inhibitors are higher than those of the undoped crude oil. When the T pre increases to 60, 70, and 80 °C, the flowability of the doped crude oil are largely improved and the wax deposition is suppressed with the T pre increase, but the wax content of wax deposit increases gradually. It is speculated that, on the one hand, the T pre increase helps the dispersion of asphaltenes into smaller sizes, which facilitates the co-crystallization with paraffin waxes and generates more aggregated wax crystal flocs. This weakens the low-temperature gel structure and increases the solid concentration required for the crosslink to form the wax deposit. On the other hand, the decrease in viscosity increases the diffusion rate of wax molecules and accelerates the aging of wax deposits. The experimental results have important guiding significance for the pipeline transportation of doped crude oils.
研究领域:
石油工程
·
化学工程
✓ 已验证
DOI
高影响因子
ENERGY & FUELS
·
2020
·
IF 3.421
Yanxiao Chen,Huifen Zhang,Weifeng Dai,Cheng Xiang,Shiyun Jiao,Baocai Li,Mi Zhang
Montan resin removal and oxidation bleaching are two key procedures for preparing refined montan wax (RMW) from lignite and significantly affect the wax’s color appearance. However, due to the large content differences of crude montan wax (CMW) in lignite and montan resin (MR) in CMW, the influence of residual MR in CMW on the character and performance of RMW is unknown. In this study, CMWs with different amounts of residual MR were prepared as raw materials and oxidized into RMWs under the same bleaching conditions. The main physicochemical properties of these RMWs showed that as the residual MR content in CMW increased, the RMW color deepened and the friability and saponification values increased, but the melting point, acid value, and hardness decreased. Meanwhile, the chemicals present in different RMWs were analyzed by gas chromatography–mass spectrometry (GC-MS), and cluster detection showed the content and composition of chemicals in RMWs produced from CMWs with different residual MR contents were significantly different. PCA analysis showed that residual MR in CMW was positively correlated with the friability and saponification value but was negatively correlated with the final melting point, microhardness, and acid value. This work indicates that the residual MR in CMWs has a strong but different influence on the appearance and performance of RMW and provides some basis for further optimization and improvement of refinement techniques for various RMWs used in different areas.
研究领域:
材料科学
·
化学工程
✓ 已验证
DOI
高影响因子
JOURNAL OF MOLECULAR LIQUIDS
·
2023
·
IF 6
Haopeng Zhang,Yanjun Qiu
In recent years, the wax inhibitors (WIs) are used to inhibit premature crystallization of alkane molecules in asphalt at low temperatures has yielded certain benefits. However, the method for effective and sustainable use of WIs in asphalt to avoid inefficient and expensive “trial and error” procedures has not yet been determined. In this paper, the model asphalts were established through non-waxy base asphalt doped with n -alkanes (Eicosane, triacontane and tetradecane) and isoalkane (Squalene), and the wax inhibition efficiencies and cracking resistance of model asphalt with addition of three typical WIs (poly (methyl methacrylate) (PMMA), nano-SiO 2 hybrid PMMA and ionic liquid (IL) modified with graphene oxide (GO)) were directly characterized by wax precipitation temperature (WPT) and extended bending beam rheometer (Ex-BBR), double edge notched tension (DENT) and thermal fatigue tests, respectively. On this basis, the microscopic mechanism of wax inhibition was investigated by molecular dynamic simulation . The results show that the wax inhibition efficiencies are higher for the short-chain n -alkanes and ordered isoalkanes to improve the low-temperature cracking, ductile and thermal fatigue resistances more significantly, but the disordered isoalkanes and high content of long-chain n -alkanes will decrease the wax inhibition efficiencies of WIs. The WIs can increase diffusion coefficient and bond stretching, angle bending and dihedral angle torsion energies but decrease the Coulomb and van der waals (VDW) energies of wax molecules to inhibit the formation of wax crystals network. It is recommended to add WIs with higher content or efficiency for asphalts with heavy n -paraffins and low concentration of branched paraffins to inhibit wax precipitation. As for asphalts containing light n -alkanes and high concentration of branched alkanes, it is suggested to add smaller amount of WIs to save resources.
研究领域:
材料科学
·
化学工程
✓ 已验证
DOI
高影响因子
JOURNAL OF DISPERSION SCIENCE AND TECHNOLOGY
·
2018
·
IF 1.454
Zhengnan Sun,Guolin Jing,Ziyi Tu
The nano-hybrid pour-point depressant (PPD) was prepared with organically modified nano-silica covering in EVA. The effects of modified nano-silica/EVA on the flow behavior and wax crystallization of model oils with different wax contents were evaluated. Compared with pure EVA and nano-silica/EVA, modified nano-silica/EVA exhibited a better effect, when doped with 500 ppm, the pour point of the model oil containing 20 wt% wax was reduced from 33°C to 0°C. However, it is noteworthy that pour point cannot accurately reflect the effect of YSiO2/EVA as cold flow improver for a high wax content. The crystal morphology and crystallization behavior of the model oils at low temperature were also observed using polarizing optical microscopy (POM). The results indicated that modified nano-silica/EVA can reduce the size of the wax crystals and disperse the wax crystals by heterogeneous nucleation.
研究领域:
石油工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
FOOD CHEMISTRY
·
2023
·
IF 8.8
Hua Huang,Jinqiang Yan,Huaxue Yan,Biao Jiang
Surface wax crystals play important roles in protecting plants from pest and disease invasions, and UV irradiation. The wax crystals are less probed individually from the fruit surfaces. Herein the morphologies, chemicals and an efficient method to sample the wax blooms of white wax gourd were addressed. Various crystalloids such as rodlets, platelets, fragments, and granules were observed, which stacked as fine wax film covering on wax gourd fruit surface. The wax blooms were effectively removed by cryo-adhesive after consecutive manipulating set by a high-end device with cylinders. Wax crystals were dominated by triterpenols and triterpenol acetates over 61 % of total crystals, followed by vey-long-chain aliphatics. Accordingly, the high-end device with cryo-adhesive provides an efficient approach to selectively probe the wax crystals from those fruits covering wax blooms. The elucidation of morphologies and chemical compositions of wax crystals may help to better understand their regulations on fruit quality traits.
研究领域:
植物学
·
农业科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
LANGMUIR
·
2018
·
IF 3.789
Zuoxu Xiao,Hongyan Cao,Xubao Jiang,Xiang Zheng Kong
Stable dispersions of paraffin wax droplets and their nano- and microspheres have broad applications. Despite intensive efforts, the production of uniform wax spheres remains a challenge. For their preparation, abundant surfactants and other additives are commonly used to stabilize the dispersions. These additives are hardly removable and entrain often adverse consequence in many applications, particularly in biological and medical applications, where microspheres with absolutely clean surface are preferred. We report here a novel process to prepare stable dispersion of wax droplets in a water–ethanol mixture with a narrow size distribution by simply shaking without any surfactants. The process is featured by using primary polymer particles (PPs) of poly(dodecene-trihydroxymethylpropane triacrylate) as a Pickering stabilizer. PPs were prepared by precipitation polymerization without any surfactant and stabilizer. By rapidly cooling the wax emulsion, solid wax spheres with good uniformity were obtained. Their size, between 50 and 480 μm, was easily adjustable by changing the shaking rate, number of PPs, and particularly the size of PPs. The morphology of the wax spheres was examined by SEM, which showed that they were covered by a layer of PPs. The formation mechanism of the microspheres was also discussed on the basis of the adsorption energy of PPs on wax spheres, estimated from the corresponding contact angle of the solvent toward the PPs and the wax. This paper presents a novel pathway for the preparation of wax microspheres with only polymer particles without the need for any other additives.
研究领域:
胶体与界面科学
·
高分子科学
·
材料化学
·
乳液技术
·
纳米材料
✓ 已验证
DOI
高影响因子
ENERGY & FUELS
·
2020
·
IF 3.421
Haoran Zhu,Chuanxian Li,Zongming Xiu,Zhiqiang Zhao,Kai Mu,Hui Dai,Feng Wang,Fei Yang,Bo Yao
In this paper, a novel ethylene-vinyl acetate copolymer (EVA)/amino-functionalized polymethylsilsesquioxane (PAMSQ) composite wax inhibitor (WI) was prepared through melt blending, and the rheological and wax depositing properties of the doped crude oil were studied. The EVA/PAMSQ composite can strongly crystallize with wax molecules and trigger the formation of compact wax flocs, which greatly improve the rheological properties of crude: compared to the pure EVA at the same dosage, the composite can further decrease the gel point and apparent viscosity (25 °C) by 14.6 °C and 92.0%, respectively. The wax deposition can also be inhibited by adding the composite: adding EVA inhibits the mass of the wax deposit at 24 h by 62.3%, and this number is suppressed by 77.9% after adding the EVA/PAMSQ composite, but the wax molecule diffusion is accelerated and the wax content in the wax deposit rises because of the improved crude oil rheological characteristics. Here, we develop the gel structure theory to consider the wax deposition process affected by the WI. Adding the WI contributes little to the wax precipitation temperature but decreases the gel structural strength of the oil a lot, and thus, the oil near the pipe wall can only form the wax deposit with a higher wax content to resist the pipe wall shearing. Therefore, the crude oil added EVA/PAMSQ composite possesses not only the lowest wax deposit rate and the highest aging rate but also the highest wax content in the wax deposit.
研究领域:
材料科学
·
石油工程
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
FOOD CHEMISTRY
·
2020
·
IF 6.306
Yue Wang,Huijuan Mao,Yunhao Lv,Guogang Chen,Ying Jiang
The cuticular wax of Korla pear stored under different relative humidity (0 ± 1 ℃, 50–55%, 70–75% and 90–95%) was examined in terms of total wax content, chemical composition and crystal morphology. The cuticular wax was composed of alkanes, olefins, fatty acids, alcohols, aldehydes, esters and terpenoids. High humidity maintained the content of total wax, alkanes and aldehydes at sufficient levels, especially C 29 alkane and C 18 aldehyde, which could positively regulate the quality of the pear fruits. Cuticular wax contributes to the capacity of preserving water, maintaining cell wall and delaying senescence. Scanning electron microscopy showed that wax crystals appeared as numerous platelets with irregular ovate crystals, high humidity delayed the transformation of wax structure. Taken together, high humidity delayed the ripening and aging by effectively maintaining wax, which was essential for postharvest storage and provide a reference for the production of synthetic wax for Korla pear fruits.
研究领域:
植物学
·
食品科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
SCIENTIA HORTICULTURAE
·
2022
·
IF 4.342
Sun Yingjie,Zhang Xinyue,Jiang Yaping,Wang Jihan,Li Bingru,Zhang Xinhua,Li Xiaoan,Li Fujun
Ethylene response factors 2 (ERF2) belongs to the AP2/ERF transcription factor family and plays key roles in ethylene signal transduction . The roles of MdERF2 in apple ( Malus × domestica ) cuticular wax synthesis regulated by ethylene were studied in this work. Result shows that MdERF2 overexpression (ERF2-OE) up-regulated the expression levels of wax-related synthetic genes long-chain acyl-CoA synthetase 2 ( MdLACS2), Wax synthase1 ( MdWSD1), Eceriferum 4 ( MdCER4) and Eceriferum 6 ( MdCER6) , while has no effect on the transcription of Eceriferum 1 ( MdCER1) , and shows different regulation effects on the expression levels of mid-chain alkane hydroxylase 1 ( MdMAH1) between calli and fruit. Furthermore, different MdERF2 expression levels changed the apparent structure of the apple cuticular wax and positively regulated the total wax accumulation. ERF2-OE also increased alkane and alcohol production but decreased acid and ester contents. Thus, ethylene regulated the synthesis of apple cuticular wax at the transcriptional level through MdERF2, thereby altering the wax structure and composition.
研究领域:
植物学
·
分子生物学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）