JOURNAL OF INDUSTRIAL AND ENGINEERING CHEMISTRY
·
2024
·
IF 5.9
Ruixiang Zhou,Weilong Li,Jiayi Li,Jiwen Hu,Xuefeng Gui,Yonglu Dong,Hongcai Yang,Xiaohua Huang,Shudong Lin
Polyurethane materials are widely used, yet their thermal hazards remain underexplored. This study investigates the solvent-free polyaddition of hexamethylene diisocyanate (HDI) and hydroxyethyl acrylate (HEA) under trace moisture conditions. Titration results showed that moisture significantly reduces the reaction rate, while Karl Fischer titration confirmed effective moisture removal using molecular sieves. NMR and FTIR revealed that dehydration enhances isocyanate electrophilicity and hydroxyl nucleophilicity, accelerating the reaction. DSC indicated that moisture induces additional exothermic peaks due to side reactions, and ARC testing showed elevated initial temperatures and reduced adiabatic temperature rise. A kinetic model revealed a consistent reaction order of 0.8, regardless of moisture. T D8 and T D24 were predicted, and a risk matrix assessed the thermal hazards. This study provides essential guidance for the safe and efficient development of novel eco-friendly polyurethane formulations and offers valuable insights for large-scale industrial safety.
研究领域:
材料科学
·
化学工程
·
安全工程
✓ 已验证
产品关联
DOI
高影响因子
FIBERS AND POLYMERS
·
2020
·Vol. 21
·期 6
·1251-1258
·
IF 1.797
Liang Huazhe,Cao Meng,Yang Desheng,Sun Tingting,Chu Xiaomeng,Liu Shaojie
A series of polyamidoamine (PAMAM) immobilized TEMPO macromolecular catalysts were prepared by condensation reduction reactions between carbonyl groups in 4-O-TEMPO and primary amines in PAMAM. The macromolecular catalyst and NaBr/NaClO were used as catalytic system for selective oxidation of cellulose in aqueous medium. Effects of various factors, such as TEMPO loading ratios and PAMAM generations, were studied on the catalytic performances. Compared with free TEMPO, the macromolecular catalyst with less than 50 % TEMPO loading ratio had a higher reaction rate in the initial stage of the reaction. Especially, the reaction rate of G1.0 PAMAM with 30 % TEMPO loading ratio was comparable to free TEMPO in the whole reaction process. Its cellulose oxidation degree (or catalytic activity) was also equivalent to the level of free TEMPO. Interestingly, the cellulose depolymerization degree of macromolecular catalyst was not affected by the cellulose oxidation degree and was lower than that of free TEMPO. The macromolecular catalyst could be recycled efficiently by the combination of supernatant circulation and salting-out extraction, and the recycling performance was excellent.
研究领域:
化学工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF CHEMICAL EDUCATION
·
2014
·
IF 1.001
John J. Dolhun
Concerns have surfaced regarding the safety of several online demonstrations on the decomposition of H2O2. In the demonstrations, a H2O2 decomposition reaction happens rapidly followed by a plume of condensed water vapor shooting out of the flask. A modified protocol with improved safety considerations is described for the decomposition of H2O2 demonstration. In these demonstrations, 44 μm and 10 μm size particles of MnO2 are compared in catalyzing the decomposition of 30% H2O2 in a 1 L plastic bottle. The use of 44 μm particle size MnO2 slowed the reaction significantly relative to 10 μm particle size MnO2. The experimental procedure developed using 44 μm particle size MnO2 is reliable and has been tested dozens of times over the past ten years. Critical parameters were identified to ensure the success of the demonstration without compromising the safety of the demonstrator and the audience. This demonstration can easily be conducted in a large well-ventilated classroom and affords an excellent presentation for teaching students about rates of chemical reactions and several topics related to catalysis.
研究领域:
化学教育
·
催化科学
✓ 已验证
DOI
高影响因子
CHEMOSPHERE
·
2017
·
IF 4.208
Jie Ma,Haiyan Li,Liping Chi,Hongkun Chen,Changzhao Chen
Persulfate (peroxydisulfate, S 2 O 8 2− ) is the newest oxidant used for the in situ chemical oxidation (ISCO) remediation of soil and groundwater. The present study investigated impacts of solution pH, temperature, and persulfate concentration on the reaction rate constant ( k 1 ), activation energy ( E a ), and reaction order of the heat-activated persulfate process. Phenol was chosen as the model organic contaminant . As temperature increased from 30 °C to 70 °C, k 1 exhibited a significant increase from 0.003 h −1 ∼0.962 h −1 (pH 1.3–13.9) to 1.184 h −1 ∼9.91 h −1 (pH 1.3–13.9), which corroborated with the activation of persulfate using heat. As pH increased from 1.3 to 13.9, k 1 exhibited a 4.3-fold increase at 70 °C and a 320-fold increase at 30 °C, thereby suggesting that: 1) the phenol oxidation rate increased under alkaline conditions, and 2) the enhancement of reaction rate due to alkaline activation was more pronounced at a lower temperature. Increasing pH significantly reduced E a from 139.7 ± 1.3 kJ/mol at pH 1.3 to 52.0 ± 3.3 kJ/mol at pH 13.9. In contrast to changing pH, increasing persulfate concentration from 20 to 320 mM significantly increased k 1 but did not affect E a . Changes in E a suggest that persulfate oxidation of phenol experienced different reaction pathways or elementary reaction sequences as the pH changed from 1.3 to 13.9. In addition, the k 1 and E a data also suggest that a minimal pH threshold of ∼11 was required for the effective alkaline activation of persulfate.
研究领域:
环境科学
·
化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
RSC Advances
·
2022
·Vol. 12
·期 15
·9077-9086
·
IF 4.036
Quan Hongping,Zhen Xuele,Lu Qiangying,Wang Linyuan,Jiang Silong
Acidizing retarders are used to reduce the reaction rate between hydrochloric acid (HCl) and carbonates to increase the efficiency of acidification of oil and gas wells and increase oil and gas recovery. We synthesized two polymeric acidizing retarders (AR-1 and AR-2) to explore ways to improve the efficiency of this process. Retarder AR-1 is based on acrylamide (AM) and allyl polyethylene glycol (APEG-1000), and retarder AR-2 is composed of AM, APEG-1000, and octadecyl dimethyl allyl ammonium chloride (C-18). The molecular structures of AR-1 and AR-2 were characterized by Fourier transform infrared (FT-IR) and 1H nuclear magnetic resonance (1H-NMR). The retarding performance and acid–rock reaction rates of AR-1 and AR-2 were evaluated, and the experimental results indicated that AR-2 had a better retarding performance than AR-1, and the acid–rock reaction rate of AR-1 was higher than AR-2. This could be because AR-2 with its hydrophobic chains forms a thicker adsorbed film. This was confirmed by X-ray photoelectron spectroscopy (XPS) and adsorption behavior studies. The scanning electron microscope (SEM) images, contact angle, and XPS results showed that both retarders form adsorption films on the surface of rocks, indicating that the introduction of AM and APEG-1000 makes the retarder adsorb on rock surfaces. The introduction of hydrophobic chains for AR-2 enhanced the thickness of adsorbed film, indicating that adding hydrophobic chains to the acidizing retarder significantly improves its retarding performance.
研究领域:
石油工程
·
化学工程
✓ 已验证
DOI
PubMed
高影响因子
SCIENCE OF THE TOTAL ENVIRONMENT
·
2023
·
IF 9.8
Roujia Du,Qianxin Zhang,Frank Leresche,Mengmeng Zhong,Ping Chen,Jun Huang,Shubo Deng,Fernando L. Rosario-Ortiz,Gang Yu
To determine and predict the reaction rate between 3 DOM* and PPCPs in various water bodies, this study defines a reaction rate coefficient ( α 3 DOM ∗ ) to describe the reaction between 3 DOM* and PPCPs. As the values also included the inhibition effect of DOM's antioxidant moieties, the calculation of α 3 DOM ∗ is inconsistent with that of a bimolecular rate constant via the steady-state kinetic method. The α 3 DOM ∗ values of 12 selected PPCPs were determined in two DOM solutions and ten DOM-containing water samples collected from typical surface water bodies in Beijing. The Pearson coefficients between nine predictors including the absorbance ratio (E2/E3), specific absorption coefficient at 254 nm (SUVA 254 ), fluorescence index (FI), biological index (BIX), humification index (HIX), pH, total organic carbon (TOC), total fluorescence intensity (TFI) and TOC normalized TFI (TFI/TOC) and α 3 DOM ∗ were examined. Correlation patterns for sulfonamides, β-blockers and diclofenac supported the electron transfer pathway, and was distinctly different from those appeared for FQs where quenching effect played a main part. TFI and TFI/TOC were recognized as the most useful surrogates in empirically predicting α 3 DOM ∗ . For PPCPs that went through the electron transfer pathway, α 3 DOM ∗ could be well fit to the Rehm-Weller model assuming a proportional relationship between TFI and △G et . For FQs, α 3 DOM ∗ was found to linearly correlated with TFI/TOC. The α 3 DOM ∗ values determined in this study enrich the database of PPCPs photolysis parameters, and the correlation analysis provides reference for forecasting PPCPs fate in the aquatic environment.
研究领域:
环境科学
·
水处理工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Journal of the American Chemical Society
·
2013
·
IF 10.677
Yu Zou,Xiong Su,Jiang Jiang
Cu2ZnSnS4 (CZTS) nanocrystals with different morphologies and phases have been synthesized in hot organic solvents such as dodecanethiol and oleylamine. The crystallographic phases could be controlled by the sulfur precursor and the ligand species of the metal salts used for the synthesis. When a highly reactive sulfur precursor and metal acetates were used, wurtzite CZTS nanocrystals were obtained. On the other hand, using a low-reactivity sulfur precursor or metal chlorides produced CZTS nanocrystals in a kesterite phase. The experimental results from systematic investigations indicated that the reaction rate between Zn and S precursors played a determining role for the growth of CZTS nanocrystals with different crystalline phases. A relatively faster reaction between Zn and S precursors in comparison to the Sn–S reaction favored the formation of a metastable wurtzite phase, which could be accelerated by increasing the reactivity of the S precursor. This work provided a safe and economical way to synthesize high-quality phase-controlled Cu2ZnSnS4 nanocrystals, especially wurtzite nanorods, for potential photovoltaic applications. Moreover, preliminary results show that the proposed mechanism also applies to the phase-controlled synthesis of other quaternary Cu2MSnS4 (M = Cd2+, Mn2+) nanocrystals.
研究领域:
材料科学
·
化学工程
·
纳米技术
✓ 已验证
DOI
PubMed
高影响因子
FARADAY DISCUSSIONS
·
2016
·Vol. 190
·487-508
·
IF 3.544
Binjie Hu,Yiyang Kong,Rongmeihui Zheng,Jie Dong,Kwang-Leong Choy,Huanhuan Zhao
C8mimPF6, as a type of room temperature ionic liquid (RTIL) with non-volatility and a low melting point, may replace conventional coalescing agents in latex coatings, thus preventing volatile organic compound (VOC) emissions caused by coalescing agents. In this study, systematic investigations on the effect of various factors including initiator type, initiator concentration, temperature and C8mimPF6 concentration on the conversion of latex and droplet/particle size of a miniemulsion during polymerization have been conducted. The presence of C8mimPF6 has shown to have a marked effect on the reaction rate. Such an effect strongly depends on the type of initiator being used. For polymerization initiated by 2,2-azobis (isobutyronitrile) (AIBN), C8mimPF6 had a promoting effect on the reaction rate at low concentrations, but this effect might be reversed upon certain C8mimPF6 concentrations, e.g. 10 wt%. While initiated by H2O2/Vc, this promoting effect faded even at low C8mimPF6 concentrations. The different limiting factors, which determine the reaction rate with different types of initiator, may contribute to the results. For reactions initiated by hydrophobic AIBN, the reaction was dominated by kinetics. The presence of C8mimPF6 may cause an enhanced chain propagation rate and reduced chain termination rate, which may further contribute to the increase in reaction rate at lower concentrations of C8mimPF6. With hydrophilic H2O2/Vc, the resistance for the transfer of radicals into a droplet/particle might be increased significantly with increasing C8mimPF6 concentration due to a tighter interfacial structure at lower concentrations of C8mimPF6. Thus, such transfer of radicals may become a limiting step whilst the presence of C8mimPF6 increases the transfer resistance on radicals resulting in a decrease in reaction rate. The reaction temperature, which is related to the decomposition temperature of the initiator being used, was another factor affecting the conversion of latex and the size of latex particles. A higher temperature e.g. 50 °C promotes the coalescence of droplets/particles, and hence produces larger latex particles. In the presence of C8mimPF6, the reaction temperature could be significantly reduced to as low as 40 °C, which prevents phase separation. The final particle size depends on the nucleation mechanism as well as the coalescence of droplets/particles during polymerization.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ENVIRONMENTAL RESEARCH
·
2023
·
IF 8.3
Banghao Du,Gongduan Fan,Shangwu Yang,Jing Luo,Jiaxin Wu,Kai-Qin Xu
In this study, humic acid (HA) enhanced 17β-estradiol (17β-E2) degradation by Er 3+ -CdS/MoS 2 (ECMS) was investigated under ultrasonic and light conditions. The degradation reaction rate of 17β-E2 was increased from (14.414 ± 0.315) × 10 −3 min −1 to (122.677 ± 1.729) × 10 −3 min −1 within 90 min sonophotocatalytic (SPC) reaction with the addition of HA. The results of quenching coupled with chemical probe experiments indicated that more reactive intermediates (RIs) including reactive oxygen species (ROSs) and triplet-excited states were generated in the HA-enhanced sonophotocatalytic system. The triplet-excited states of humic acid (3 HA*), hydroxyl radical (•OH), and superoxide radical (•O 2 − ) were the dominant RIs for 17β-E2 elimination. In addition, the energy- and electron-transfer process via coexisting HA also account for 12.86% and 29.24% contributions, respectively. The quantum yields of RIs in the SPC-ECMS-HA system followed the order of 3 HA* > H 2 O 2 > 1 O 2 > •O 2 − > •OH. Moreover, the spectral and fluorescence characteristics of HA were further analyzed during the sonophotocatalytic reaction process. The study expanded new insights into the comprehension of the effects of omnipresent coexisting HA and RIs formation for the removal of 17β-E2 during the sonophotocatalytic process.
研究领域:
环境科学
·
化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2023
·
IF 4.2
Yubin Wang,Yang Jin,Lianyu Jia,Chenxi Xiong,Jun Li,Ming Chen
The combination of a photocatalytic reaction and microfluidic technology is an increasingly popular method utilized to continuously degrade wastewater. In this work, a novel photocatalytic microreactor with TiO2 loaded on the channel center insert was designed and the photocatalytic degradation process of oxytetracycline (OTC) was investigated. Parameters such as TiO2 loading, OTC initial concentration, light intensity, and ion (NO3– and SO42–) concentrations were systematically investigated. The results show that the degradation efficiency of OTC was 56% under the optimal experimental conditions. Compared with the conventional miniaturized photocatalytic reactors, the reaction rate constant and space–time degradation efficiency of the plug-in three-dimensional photocatalytic microreactor proposed in this work were 1–2 orders of magnitude higher. In addition, dimensionless correlation was obtained to predict the degradation efficiency. This work provides a promising microfluidic technology for the process intensification of photocatalytic reaction and wastewater treatment.
研究领域:
环境科学
·
化学工程
·
生物技术
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF CHEMICAL EDUCATION
·
2021
·
IF 2.979
Paweł Bernard,Paweł Stelmachowski,Paweł Broś,Wacław Makowski,Andrzej Kotarba
Heterogeneous catalysis plays an important role in many chemical reactions, especially those applied in industrial processes, and therefore, its theoretical foundations are introduced not only to students majoring in chemical engineering or catalysis but also as part of general chemistry courses. The consideration of catalytic activity of various solids and mechanisms of catalytic reactions requires the introduction of the concept of an active site, which together with the catalyst specific surface area are discussed as key parameters controlling the reaction rate. There are many known demonstrations of heterogeneous catalysis phenomena that can be performed live in a lecture hall, but all of them focus only on the general idea of catalytic processes and are not suitable for quantitative analysis. Therefore, herein we present a simple demonstration of the influence of the specific surface area of a catalyst on the rate of a catalytic reaction. This demonstration is based on a model reaction of hydrogen peroxide decomposition catalyzed by cobalt spinel (Co3O4) calcined at various temperatures. The differences in reaction rates can be monitored visually, and the obtained data can be used directly for a simple kinetic analysis, including comparison of numerical values of the reaction rate constants.
研究领域:
化学工程
·
催化科学
✓ 已验证
DOI
PubMed
高影响因子
ACS Earth and Space Chemistry
·
2024
·
IF 2.9
Cici Fan,Weigang Wang,Bo Shi,Zheng Sun,Maofa Ge
The relative rate method was used to determine the rate constant of Cl atoms and 3-buten-1-ol at ambient temperature and pressure. The main products of the reaction were identified as HCOOH with a yield of (50.07 ± 2.65)%, HCHO with a yield of (18.24 ± 0.65)%, HOCH2CHO with a yield of (18.69 ± 0.68)%, ClCH2CHO with a yield of (7.64 ± 0.25)%, respectively. The rate constant was (3.04 ± 0.36) × 10–10 cm3 molecules–1 s–1. The calculated theoretical rate constant was 2.91 × 10–10 cm3 molecules–1 s–1, which was in agreement with the experimental results. Moreover, the theoretical calculation showed that the two Cl-addition pathways were the main reaction pathway, but the proportion of H-abstraction pathways reached 29%, and its importance cannot be ignored. Based on this, the possible reaction mechanisms were deduced. The atmospheric implications of the obtained title reaction were briefly discussed.
研究领域:
大气化学
·
物理化学
✓ 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）