Processes

579 KiB

Open AccessCommunication

Ionic Liquid-Based Aqueous Biphasic Systems—A Facile Approach for Ionic Liquid Regeneration from Crude Plant Extracts

by Rozalina Keremedchieva, Ivan Svinyarov and Milen G. Bogdanov

Processes 2015, 3(4), 769-778; https://doi.org/10.3390/pr3040769 - 26 Nov 2015

Cited by 9 | Viewed by 5480

The possibility for simultaneous controlled partition of the biologically active alkaloid S-(+)-glaucine, presented in a crude ionic liquid-aqueous plant extract, and separation of the ionic liquid (IL) employed by means of ionic liquid-based aqueous biphasic systems (IL-ABS) was investigated in this study. The ABS were formed by the addition of inorganic salts with distinct water-structuring properties such as Na₂CO₃, MgSO₄, (NH₄)₂SO₄, and NaH₂PO₄ to an enriched of glaucine extract of Glaucium flavum Cr. (Papaveraceae). The influence of the salt type and concentration on the phase-forming ability, as well as the pH value on the partition of glaucine between the two phases formed, was comprehensively studied. It was found that the target alkaloid is predominantly transferred into the IL-rich phase, regardless the influential factors. The results obtained were further used as a platform for the development of an improved extractive procedure, ensuring simultaneous glaucine recovery, IL recycling and water removal in a single technological step. Thus, based on the formation of a three-phase system consisting of butyl acetate, IL-rich phase, and salt-rich phase, nearly quantitative recovery of glaucine (>99%), IL recycling (ca. 90%), and water removal (ca. 85%) were achieved by salt-induced separation of the crude plant extract. Full article

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271 KiB

Open AccessArticle

Optimal Design for Reactivity Ratio Estimation: A Comparison of Techniques for AMPS/Acrylamide and AMPS/Acrylic Acid Copolymerizations

by Alison J. Scott, Marzieh Riahinezhad and Alexander Penlidis

Processes 2015, 3(4), 749-768; https://doi.org/10.3390/pr3040749 - 10 Nov 2015

Cited by 21 | Viewed by 7589

Abstract

Water-soluble polymers of acrylamide (AAm) and acrylic acid (AAc) have significant potential in enhanced oil recovery, as well as in other specialty applications. To improve the shear strength of the polymer, a third comonomer, 2-acrylamido-2-methylpropane sulfonic acid (AMPS), can be added to the pre-polymerization mixture. Copolymerization kinetics of AAm/AAc are well studied, but little is known about the other comonomer pairs (AMPS/AAm and AMPS/AAc). Hence, reactivity ratios for AMPS/AAm and AMPS/AAc copolymerization must be established first. A key aspect in the estimation of reliable reactivity ratios is design of experiments, which minimizes the number of experiments and provides increased information content (resulting in more precise parameter estimates). However, design of experiments is hardly ever used during copolymerization parameter estimation schemes. In the current work, copolymerization experiments for both AMPS/AAm and AMPS/AAc are designed using two optimal techniques (Tidwell-Mortimer and the error-in-variables-model (EVM)). From these optimally designed experiments, accurate reactivity ratio estimates are determined for AMPS/AAm (r_AMPS = 0.18, r_AAm = 0.85) and AMPS/AAc (r_AMPS = 0.19, r_AAc = 0.86). Full article

(This article belongs to the Special Issue Polymer Modeling, Control and Monitoring)

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1976 KiB

Open AccessArticle

Model-Based Reactor Design in Free-Radical Polymerization with Simultaneous Long-Chain Branching and Scission

by Hidetaka Tobita

Processes 2015, 3(4), 731-748; https://doi.org/10.3390/pr3040731 - 3 Nov 2015

Cited by 8 | Viewed by 8362

Abstract

Polymers are the products of processes and their microstructure can be changed significantly by the reactor systems employed, especially for nonlinear polymers. The Monte Carlo simulation technique, based on the random sampling technique, is used to explore the effect of reactor types on the branched polymer structure, formed through free-radical polymerization with simultaneous long-chain branching and scission, as in the case of low-density polyethylene synthesis. As a simplified model for a tower-type multi-zone reactor, a series of continuous stirred-tank reactors, consisting of one big tank and the same N-1 small tanks is considered theoretically. By simply changing the tank arrangement, various types of branched polymers, from star-like globular structure to a more randomly branched structure, can be obtained, while keeping the following properties of the final products, the monomer conversion to polymer, the average branching and scission densities, and the relationship between the mean-square radius of gyration and molecular weight. Full article

(This article belongs to the Special Issue Polymer Modeling, Control and Monitoring)

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0 pages, 311 KiB

Open AccessRetraction

RETRACTED: Di Capaci, R.B.; Scali, C. Review on Valve Stiction. Part I: From Modeling to Smart Diagnosis. Processes 2015, 3, 422–451

by Michael Henson and Processes Editorial Office

Processes 2015, 3(4), 730; https://doi.org/10.3390/pr3040730 - 25 Sep 2015

Viewed by 4659

Abstract

We have become aware that a review paper [1] recently published in Processes contained a considerable amount of identical text and a similar structure to a previously published review paper [2], although some novel content was presented, including new citations and a section [...] Read more.

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Processes, Volume 3, Issue 4 (December 2015) – 4 articles , Pages 730-778

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