JOURNAL OF MOLECULAR LIQUIDS
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2024
·
IF 5.3
Wanting Ma,Shengchao Xu,Qifeng Wei,Xiulian Ren
Hydrophobic deep eutectic solvents (HDESs) were considered as a kind of green media and were widely used for extraction, synthesis and catalytic reactions. Exploring the physicochemical property and intermolecular interaction was of great significance. In this work, we synthesized a series of HDESs using amide as hydrogen bond acceptor (HBA) and lactic acid as hydrogen bond donor (HBD). The density, acidity and intermolecular interactions of HDESs were investigated from experimental and theoretical viewpoints. Firstly, density results indicated that the increase of HBD content as well as the decrease of HBA alkyl chain could increase the density of HDESs. Secondly, acidity was found to be more accurate using milliequivalents calculation than pH measurement. The increase of HBD content as well as the decrease of HBA alkyl chain could also enhance the acidity of HDESs. In addition, the intermolecular hydrogen bond was investigated by multiple theoretical approaches, including electrostatic potential distribution map, the length of molecular bond, independent gradient model based on Hirshfeld partition and topology analysis of atoms. Ultimately, Fourier-transform infrared spectroscopy (FT-IR) was further applied to prove the existence of hydrogen bond. We believe this work would be valuable for understanding the nature of HDESs and providing guides for practical applications of HDESs.
研究领域:
化学
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材料科学
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DOI
高影响因子
MICROCHEMICAL JOURNAL
·
2020
·
IF 3.594
Songyang Feng,Sheng Xiang,Xinchao Bian,Gao Li
In aqueous solutions of concentrated lactic acid (>30 wt%), oligomers of lactic acid can produce via the intermolecular esterification of lactic acid, and thus the amount of titratable acidity is often less than that of total acidity. In this paper, the hydrolysis of oligomers of lactic acid was investigated at different temperatures in detail. The experimental results showed that when the content of total acidity is lower than 30 wt% in aqueous lactic acid solutions, the oligomers of lactic acid can been completely hydrolyzed to give monomeric lactic acid and the monomeric lactic acid is stable at temperatures of 8–33 °C, thus the total acidity is equivalent to the titratable acidity and can be determined quantitatively by a direct potentiometric titration. The results for determining total acidities were in good agreement with those obtained from a back titration by a two tailed t -test. Compared with the back titration, the novel method's procedure is simpler and reducing sugars do not interfere with measurements. The relative standard deviation ( RSD ) was less than 0.7% and 1.1% for the direct potentiometric and back titrations, respectively, which indicated that the direct potentiometric titration has a higher precision.
研究领域:
分析化学
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食品科学
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DOI
高影响因子
PLoS One
·
2018
·Vol. 13
·期 3
·e0193659
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IF 2.766
Yaoyao Huang,Yang Hu,Lvcun Chen,Tao Yang,Hanfang Huang,Runping Shi,Peng Lu,Chenghua Zhong
Low–cost biosorbents (ginkgo leaf, osmanthus leaf, banyan leaf, magnolia leaf, holly leaf, walnut shell, and grapefruit peel) were evaluated in the simultaneous removal of La 3+ , Ce 3+ , Pr 3+ , Nd 3+ , Sm 3+ , Eu 3+ , Gd 3+ , Yb 3+ , Lu 3+ , UO 2 2+ , Th 4+ , Y 3+ , Co 2+ , Zn 2+ , Ni 2+ , and Sr 2+ from aqueous solutions. In single metal systems, all adsorbents exhibited good to excellent adsorption capacities toward lanthanides and actinides. In a simulated multicomponent mixed solution study, higher selectivity and efficiency were observed for Th 4+ over other metal cations, with ginkgo leaves providing the highest adsorptivity (81.2%) among the seven biosorbents. Through optimization studies, the selectivity of Th 4+ biosorption on ginkgo leaf was found to be highly pH–dependent, with optimum Th 4+ removal observed at pH 4. Th 4+ adsorption was found to proceed rapidly with an equilibrium time of 120 min and conform to pseudo–second–order kinetics. The Langmuir isotherm model best described Th 4+ biosorption, with a maximum monolayer adsorption capacity of 103.8 mg g –1 . Thermodynamic calculations indicated that Th 4+ biosorption was spontaneous and endothermic. Furthermore, the physical and chemical properties of the adsorbent were determined by scanning electron microscopy, Brunauer–Emmett–Teller, X-ray powder diffraction, and Fourier transform infrared analysis. The biosorption of Th from a real sample (monazite mineral) was studied and an efficiency of 90.4% was achieved from nitric acid at pH 4 using ginkgo leaves.
研究领域:
环境科学
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放射生物学
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DOI
PubMed
高影响因子
Journal of Environmental Chemical Engineering
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2023
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IF 7.7
Hang Yin,Qiuqiu Xiong,Miao Zhang,Bowen Wang,Fenge Zhang
In this study, magnetic composite microspheres (SCFP) were prepared by cross-linking chitosan (CS), sodium alginate (SA), poly(vinyl alcohol) (PVA), and ferric tetraoxide (Fe 3 O 4 ) in a CaCl 2 solution. CS and Fe 3 O 4 were encapsulated in gel spheres formed by cross-linking SA with Ca(II), while PVA facilitated the dispersion of CS in SA. SCFP was utilized as an adsorbent to remove Cu(II) from water. The effects of the initial pH of the solution, SCFP dosage, and initial Cu(II) concentration on the adsorption efficiency were investigated through batch experiments. The results demonstrated that the adsorption capacity reached 58.260 mg/g (removal rate = 97.1%) after 100 min of adsorption at a pH of 5. The removal rate remained above 90% even after 6 cycles of the cycling experiment. The incorporation of CS with other functional materials allowed SCFP to compensate for its inherent drawbacks such as low mechanical strength, poor acid resistance, and short service life. The pseudo-first-order kinetic model and Freundlich adsorption isotherm provided better descriptions of the adsorption process. A comprehensive analysis was conducted on the structure and adsorption mechanism of SCFP using characterization techniques such as SEM-EDS, FTIR , BET, XRD , etc. In summary, SCFP has the potential to be an excellent environmentally friendly material for the removal of Cu(II).
研究领域:
环境科学
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材料科学
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DOI
高影响因子
JOURNAL OF POLYMER SCIENCE PART A-POLYMER CHEMISTRY
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2017
·Vol. 55
·期 20
·3357-3369
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IF 2.952
Biwei Qiu,Zhoujing Li,Xia Wang,Xiaoyan Li,Jinrui Zhang
Under microwave-assisted synthesis, polyaniline (PANI) products with multiple nanostructures were synthesized by the oxidative polymerization of aniline and ammonium peroxodisulfate in the different concentrations of hydrochloric acid solutions. The structural analysis of PANI using FTIR, UV, and XPS indicated that phenazine-like oligomers were produced in acid-free and low acidic systems. Moreover, long linear PANI chains were obtained in the presence of highly acidic solutions. The morphology of PANI observed by SEM and TEM showed that nanoscale structures, including stacked sheets, nanotubes, branched nanofibers, and uniform nanofibers, occurred respectively in acid-free solution, low acidity, medium and high acidity systems, effectively regulating by acidity. The formation mechanism of PANI nanostructures was explored here. The sheets were formed by the oligomers containing flat phenazine rings that can be stacked together with strong π–π interactions. Furthermore, nanotubes were fabricated by the self-curling of thin sheets consisted of phenazine-like oligomers with numerous linear units in the chains. The nanofibers are supposed to form by the linear PANI chains and the secondary growth during aniline polymerization caused the branch formation on the nanofibers. All results indicate that acidity, rather than microwave assistance, is the critical factor that determines the polymerization mechanism and the final nanostructure. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 3357–3369
研究领域:
材料科学
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化学
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DOI
高影响因子
ENERGY & FUELS
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2021
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IF 3.605
Hailing Sun,Liyuan Cao,Yuhao Zhang,Liang Zhao,Jinsen Gao,Chunming Xu
The effect of acid concentration and reaction temperature on the reaction of 1-hexene cracking to propylene was investigated. The catalysts with different acid concentrations were prepared by the alkali ion and phosphorus modification of ZSM-5 zeolite. It was observed that both decreasing the concentration of strong Brønsted acid sites (SBASs) and increasing reaction temperatures can enhance the selectivity and yield of propylene and hinder the formation of side products including hydrogen, C1∼C5 alkanes, aromatics, and coke. The hydrogen transfer reaction had an important effect on the selectivity of C3∼C5 olefins in the high concentration of SBASs. Besides, high temperatures intensified monomolecular reactions and hindered bimolecular or multimolecular reactions.On the basis of product distributions, possible main and side reaction routes were summarized under the real industrial reaction conditions. The conclusion was significant to optimize the catalyst design of olefin cracking or pyrolysis processes and operation conditions for increasing the yield of propylene.
研究领域:
化学工程
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催化科学
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DOI
高影响因子
ACS Applied Materials & Interfaces
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2024
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IF 8.3
Xu Zhang,Jingjing Yao,Yueer Yan,Yahong Zhang,Yi Tang,Yuliang Yang
Paper-based cultural relics often undergo acidification and deterioration during long-term preservation. Accurate detection of paper acidity is of great significance to assess aging status and extend the preservation lifetime of paper-based cultural relics. Rapid identification of the acidification degree and acid distribution across multiple regions of paper is essential. Inspired by fluorescent sensing technology, pH-sensitive cadmium telluride (CdTe) quantum dots (QDs) and rhodamine B (RB) fluorescent probes are synthesized and incorporated onto the nanofibers of a bacterial cellulose (BC) membrane to enable visual acidity detection of paper. Due to the complementary pH detection range of CdTe QDs and RB probes, the composite BC membrane exhibits a clear pH response across an acidic to neutral range (pH 3.0–7.5). Notably, the contrasting fluorescent colors of the two probes within the BC membrane allow for easy visualization of paper pH and acidity distribution with the naked eyes. A distinct color transition from red to green was observed on the fluorescent BC membrane when it is applied to a model paper with a gradient pH distribution. The feasibility of this method was verified by using the flat-headed pH electrode method. Additionally, common metal ions in most paper fillers, inks, pigments, as well as some sugars and amino acids showed minimal interference with the pH response of the composite BC membrane, highlighting its potential and broad applicability for visual acidity detection in paper-based cultural relics.
研究领域:
文物保护
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材料科学
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分析化学
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DOI
PubMed
高影响因子
APPLIED SURFACE SCIENCE
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2022
·
IF 7.392
Yang Gao,Xiaodong Wu,Rui Ran,Zhichun Si,Ziran Ma,Baodong Wang,Duan Weng
Monometallic (V/TiO 2 and Mo/TiO 2 ) and bimetallic (V-Mo/TiO 2 ) catalysts were prepared for selective catalytic reduction (SCR) of NO x with NH 3 at low temperatures (100–300 °C). The effect of MoO x on the dispersion of vanadia with different V 2 O 5 loadings was investigated on the basis of X-ray diffraction (XRD), inductively coupled plasma optical emission spectrometry (ICP-OES), N 2 adsorption–desorption, Raman spectroscopy, ultraviolet–visible (UV–Vis) spectroscopy, X-ray photoelectron spectroscopy (XPS), H 2 temperature-programmed reduction (H 2 -TPR) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). As the molybdenum precursor, NH 4 Mo 7 O 24 increased the solution acidity and promoted polymerization of VO x in liquid phase. At a low vanadia loading, polymerization of VO x , the adsorption rate of NH 3 and transformation of active intermediate species NH 2 were enhanced by adding MoO x , while at a high vanadia loading, the steric hindrance became dominant leading to the formation of crystalline V 2 O 5 and MoO 3 and caused decline in SCR activity.
研究领域:
化学工程
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环境科学
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催化材料
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DOI
高影响因子
CHEMOSPHERE
·
2019
·
IF 5.108
Pianpian Chang,Zhe Chen,Yunhong Zhang,Yong Liu
Acidity of aerosol particles plays important roles in atmospheric chemistry , in turn, impacting climate system and public health. Current knowledge of acidity in atmosphere aerosols remains fairly scarce largely because of difficulty in direct measurement. On the other hand, indirect methods for estimating aerosol pH are often inconsistent with pH values predicted by thermodynamic models. Recently, a direct Raman spectroscopy method has been reported to determine pH values of acid-conjugate base equilibria systems based on Raman intensity of distinct characteristic peaks of conjugate acid-base pair. Nevertheless, for pure carboxylic acid aerosol particles, such as malonic acid (MA), characteristic peak of its conjugate base cannot be clearly observed in Raman spectra owing to small K a value (weak acid dissociation constant), which leads to little dissociation of weak acid and low concentration of its conjugated base. As a result, pH of carboxylic acid particles cannot be directly determined by calibrating concentrations of acid and its conjugated base using the above-mentioned method. To address such an issue, we demonstrate a new approach for determining pH values of malonic acid (MA) and citric acid (CA) droplets under different relative humidity (RH) based on calibration curves. We measure Raman intensity ratios of acid solutions at different concentrations and their pH values to establish a calibration curve, and then using the intensity ratio of MA and CA droplets under different RH to determine aerosol particle pH based on calibration curves. Results have shown that aerosol pH of MA droplet decreases with a decreasing RH and pH values ranges from 1.03 to −0.12, when RH value is reduced from 90% to 26%, in good agreement with model prediction values. In addition, we also, for the first time, report pH values of CA droplets under different RH conditions and its pH values range from 1.13 to −0.74 when RH is reduced from 91% to 28%.
研究领域:
大气化学
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环境科学
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分析化学
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DOI
PubMed
高影响因子
FOOD CHEMISTRY
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2014
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IF 3.259
Songbai Liu,Yuanqing Fu,Si Nian
Anthocyanins are intriguing natural pigments with beneficial bioactivities and their colour is extremely susceptible to acidity variation. Minimisation of colour fluctuation is essential to maintain quality consistency in food industry. A new strategy employing surfactants to mimic encapsulation was attempted with typical anionic, cationic and nonionic surfactants and proved effective although the traditional copigmentation method was inactive. The exceptional colour fluctuation buffering effect of anionic surfactants especially sodium dodecyl sulphate (SDS) was revealed and then carefully analysed by colorimetric and spectroscopic methods. The outstanding activity of SDS presumably resulted from effective shielding of anthocyanins from external acidity through strong interaction with the positively charged flavylium cations owing to its anionic nature. These results suggest SDS is a valuable additive for buffering colour fluctuation of anthocyanins. The strategy of surfactant will be useful for buffering colour fluctuation of natural colourants.
研究领域:
食品科学
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植物化学
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DOI
PubMed
高影响因子
RSC Advances
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2013
·Vol. 4
·期 1
·1-7
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IF 2.562
Duan-Jian Tao,Jing Wu,Zhen-Zhen Wang,Zhang-Hui Lu,Zhen Yang,Xiang-Shu Chen
Six Brønsted acidic ionic liquids (BAILs) composed of [HSO4] were prepared, characterized, and used as catalysts of low dosage in the synthesis of isoamyl salicylate. The effects of various parameters such as the kind of BAILs, temperature, catalyst loading, and molar ratio of the reactants on the conversion of salicylic acid were also examined in detail. The results suggested that the catalytic performances of BAILs were of close relevance to their Hammett acidities. The SO3H-functionalized BAILs 1-(4-sulfonic acid) butyl-3-methylimidazolium hydrogen sulfate ([BSmim][HSO4]) and N-(4-sulfonic acid) butyl triethylammonium hydrogen sulfate ([BSEt3N][HSO4]) of strong acidities exhibited excellently catalytic activities and selectivities in the esterification of salicylic acid with isoamyl alcohol. The fully optimized geometries of [BSmim][HSO4] and [BSEt3N][HSO4] further manifest that their strong acidities are derived from the strong interactions between the anion with the sulfonic acid group. In addition, it was found that [BSmim][HSO4] could be also recovered easily and used repetitively at least six times without obvious decline in activity and quantity.
研究领域:
化学
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催化材料科学
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高影响因子
CHEMICAL PHYSICS LETTERS
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2021
·
IF 2.328
Xuelian Wu,Xie Liu,Zhengying Wu,Wenjun Zhu,Junchao Qian,Feng Chen,Zhigang Chen
An Al/Cu bifunctional mesoporous silica was successfully synthesized through an acidity-regulated method. AlCl 3 instead of HCl was served as catalyst for the hydrolysis and condensation of siliceous source and forming the mesostructure. Cu and Al species were then feasibly incorporated into the matrix of mesoporous SiO 2 under the mildly acidic conditions. The obtained Al/Cu-SiO 2 bifunctional composite preserves structural ordering of the mesopores. Al is highly dispersed and Cu nanoparticles of ca. 54 nm are decorated on Al/Cu-SiO 2 . The Al/Cu-SiO 2 material presents large adsorption capacity, remarkable catalytic behavior and good cycling performance in the degradation of organic methylene blue from aqueous solutions.
研究领域:
材料科学
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环境科学
·
化学工程
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产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）