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2021 ◽  
Author(s):  
Anamaria Vartolomei ◽  
Ioan Calinescu ◽  
Mircea Vinatoru ◽  
Adina Ionuta Gavrila

Abstract This work is focused on the study of esterification parameters for the ultrasound assisted synthesis of isoamyl acetate catalyzed by lipase Lipozyme 435 in a continuous loop reactor. Investigating the influence of different parameters shows that a higher concentration of ester (462 mg/gmixture) can be obtained at temperature 50 °C, flow rate 0.16 mL/min. The best ultrasonication conditions are: continuously applied sonication for a short time (20 minutes), ultrasound power 32 mW, and amplitude 20 %. The enzyme can be successfully reused tree times without loss of enzyme activity. Reaction kinetics for isoamyl acetate ultrasound assisted production showed that satisfactory reaction concentration (close to the equilibrium concentrations) could be reached in short reaction times (2 h). Ultrasound assisted enzymatic esterification is consequently a cleaner and a faster process.


TAPPI Journal ◽  
2021 ◽  
Vol 20 (9) ◽  
pp. 567-578
Author(s):  
HAITANG LIU ◽  
XIN JIN ◽  
LIN CHEN ◽  
XIAOCHEN CHANG ◽  
JIE LI ◽  
...  

By combining the structural properties and characteristics of phosphogypsum whiskers, a preliminary study on the modification of phosphogypsum whiskers and their application in papermaking was carried out. The effects of reaction temperature, reaction time, and reaction concentration on the solubility and retention of modified phosphogypsum whiskers and the effects of phosphogypsum whiskers on the physical properties of paper under different modified conditions were explored. The research results show that, after the phosphogypsum whiskers are modified with calcium stearate, a coating layer will be formed on the surface of the whiskers, which effectively reduces the solubility of the phosphogypsum whiskers. The best modification conditions are: the amount of calcium stearate relative to the absolute dry mass of the phosphogypsum whisker is 2.00%; the modification time is 30 min, and the modification temperature is 60°C. The use of modified phosphogypsum whiskers for paper filling will slightly reduce the whiteness, folding resistance, burst resistance, and tensile strength of the paper, but the tearing degree and retention of the filler will be increased to some extent.


2019 ◽  
Vol 6 (9) ◽  
pp. 095026 ◽  
Author(s):  
Di Zhu ◽  
Xinli Li ◽  
Yongchao Chen ◽  
Yafeng Deng ◽  
Dao Chen ◽  
...  

2019 ◽  
Vol 953 ◽  
pp. 101-112
Author(s):  
Zhi Zhang ◽  
Yi Wang Chen ◽  
Xu Liang Lv ◽  
Pin Zhang ◽  
Guang Zhen Cui ◽  
...  

In this paper, a direct co-precipitation method was used to prepare antimony-doped calcium fluoride nanopowders (NPs). The effects of reaction concentration, reaction medium and lanthanum doping on the properties of calcium fluoride NPs were investigatedviaa control variable method and the best preparation conditions was identified. The structural analysis of the powder materials prepared in this work were carried out by XRD, SEM, ICP and other test methods. By analyzing the experimental data, we found that the best performance of Eu-doped CaF2NPs can be acquired under the reaction concentration of 1 mol/L in aqueous solution. In the same time, the NPs possess a high degree of dispersion with an average diameter of 22 nm, which is beneficial to the preparation of transparent Eu3+: CaF2ceramics with excellent up-conversion luminescence. The results show that the grain size, the crystallinity of the NPs and the amount of Eu infiltration have a decreasing tendency with the increasing reaction concentration, while the degree of agglomeration of the NPs can be enhanced by increasing the reaction concentration.


Author(s):  
Mohd Arfian Ismail ◽  
Vitaliy Mezhuyev ◽  
Kohbalan Moorthy ◽  
Shahreen Kasim ◽  
Ashraf Osman Ibrahim

<p>This paper present a hybrid method of Newton method, Differential Evolution Algorithm (DE) and Cooperative Coevolution Algorithm (CCA). The proposed method is used to solve the optimisation problem in optimise the production of biochemical systems. The problems are maximising the biochemical systems production and simultaneously minimising the total amount of chemical reaction concentration involves. Besides that, the size of biochemical systems also contributed to the problem in optimising the biochemical systems production. In the proposed method, the Newton method is used in dealing biochemical system, DE for optimisation process while CCA is used to increase the performance of DE. In order to evaluate the performance of the proposed method, the proposed method is tested on two benchmark biochemical systems. Then, the result that obtained by the proposed method is compare with other works and the finding shows that the proposed method performs well compare to the other works.</p>


2017 ◽  
Vol 13 ◽  
pp. 1871-1878 ◽  
Author(s):  
Marco Mottinelli ◽  
Mathew P Leese ◽  
Barry V L Potter

Background: 1,2,3,4-Tetrahydroisoquinolines (THIQs) are common motifs in alkaloids and in medicinal chemistry. Synthetic access to THIQs via the Pomeranz–Fritsch–Bobbit (PFB) methodology using mineral acids for deactivated, electron-poor aromatic systems, is scarcely represented in the literature. Here, the factors controlling the regiochemical outcome of cyclization are evaluated. Results: A double reductive alkylation was telescoped into a one-pot reaction delivering good to excellent yields of desired aminoacetals for cyclization. Cyclization of activated systems proceeded smoothly under standard PFB conditions, but for non-activated systems the use of HClO4 alone was effective. When cyclization was possible in both para- and ortho-positions to the substituent, 7-substituted derivatives were formed with significant amounts of 5-substituted byproduct. The formation of the 4-hydroxy-THIQs vs the 4-methoxy-THIQ products could be controlled through modification of the reaction concentration. In addition, while a highly-activated system exclusively cyclized to the indole, this seems generally highly disfavored. When competition between 6- and 7-ring formation was investigated in non-activated systems, 5,7,8,13-tetrahydro-6,13-methanodibenzo[c,f]azonine was exclusively obtained. Furthermore, selective ring closure in the para-position could be achieved under standard PFB conditions, while a double ring closure could be obtained utilizing HClO4. Conclusion: Reactivity differences in aminoacetal precursors can be employed to control cyclization using the PFB methodology. It is now possible to select confidently the right conditions for the synthesis of N-aryl-4-hydroxy-1,2,3,4-tetrahydroisoquinolines.


2014 ◽  
Vol 1044-1045 ◽  
pp. 43-46
Author(s):  
Chiu Wen Chen ◽  
Je Wei Li ◽  
Chang Mao Hung ◽  
Jiann Yuh Lou ◽  
Cheng Di Dong

This study investigated the feasibility of the electrochemical degradation of benzene (C6H6) in a NaCl electrolyte solution between 0.05 and 0.5 M under the temperature of 298 K and reaction concentration between 1.28×10-5 and 1.28×10-3 M with an applied potential of 3 V was conducted in this study to investigate the destruction of the C6H6 in the batch reactors using a Pt/XC-72 composite as a catalyst. Experimental results indicated that the optimal conditions in the reaction were developed as a NaCl solution with 0.1 M at pH of 1.0 under C6H6 concentration of 6.41×10-4 M. The results reveal that electrochemical degradation of C6H6 in acidic medium is highly effective, while a maximum about 41% reduction at 120 min was achieved with Pt/XC-72 composite during the electrochemical degradation. In comparsion, the removal efficiency reached only 29% with the Pt electrode, showing the suitability of the Pt/XC-72 composites for electro-oxidation of C6H6. As a result, XC-72 carbon black materials played an important role in the decomposition of C6H6. Furthermore, the Pt/XC-72 composite used in this research has been developed as a potential catalyst for the application of C6H6 electro-oxidation.


2014 ◽  
Vol 60 (No. 2) ◽  
pp. 75-83 ◽  
Author(s):  
I. Kuneš ◽  
M. Baláš ◽  
V. Balcar

The article assesses the effects of amphibolite applied to the planting holes of spruces on the soil chemistry. The sampling was conducted fourteen growth seasons after the establishment of the experimental spruce plantation. In both treatments (control and amphibolite) the soil samples were taken from the interior of the planting holes as well as from the intact area around the planting holes. Fourteen growth seasons after application the effects of the pulverised amphibolite were not marked despite being detectable. In comparison with the control the soil in the planting holes of the amphibolite treatment showed significantly higher soil reaction, concentration of available phosphorus and partially also concentration of exchangeable Ca. All the significant effects of amphibolite were confined to the soil inside the planting holes. As for the evaluated chemical properties no significant undesirable effects of the amphibolite on soil chemistry were recorded. &nbsp;


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