scholarly journals Purification of Polybutylene Terephthalate by Oligomer Removal Using a Compressed CO2 Antisolvent

Polymers ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1230 ◽  
Author(s):  
Wen Yu ◽  
Jian-Hao Huang ◽  
Chung-Sung Tan
Keyword(s):  
Molecular Weight ◽  
Response Surface Methodology ◽  
Experimental Design ◽  
Operating Time ◽  
Operating Conditions ◽  
Low Molecular Weight ◽  
Polybutylene Terephthalate ◽  
Operating Variables ◽  
Cyclic Oligomers ◽  
Short Operating Time

In this study, the cyclic oligomers in the highly chemically resistant polyester polybutylene terephthalate (PBT) were effectively removed using a compressed CO2 antisolvent technique in which 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) was used as the solvent. In addition to the oligomers, tetrahydrofuran was completely removed because of its low molecular weight and liquid state. The effects of the operating variables, including temperature, pressure, and the PBT concentration in HFIP, on the degree of removal of the oligomers were systematically studied using experimental design and the response surface methodology. The most appropriate operating conditions for the purification of PBT were 8.3 MPa and 23.4 °C when using 4.5 wt % PBT in HFIP. Under these conditions, the cyclic trimers and dimers could be removed by up to 81.4% and 95.7%, respectively, in a very short operating time.

scholarly journals Modeling and Sensitivity Analysis of the Forward Osmosis Process to Predict Membrane Flux Using a Novel Combination of Neural Network and Response Surface Methodology Techniques

Membranes ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 70
Author(s):  
Jasir Jawad ◽  
Alaa H. Hawari ◽  
Syed Javaid Zaidi
Keyword(s):  
Response Surface Methodology ◽  
Experimental Design ◽  
Response Surface ◽  
Forward Osmosis ◽  
Feed Solution ◽  
Operating Conditions ◽  
Ann Model ◽  
Membrane Flux ◽  
Input Variables ◽  
Rsm Model

The forward osmosis (FO) process is an emerging technology that has been considered as an alternative to desalination due to its low energy consumption and less severe reversible fouling. Artificial neural networks (ANNs) and response surface methodology (RSM) have become popular for the modeling and optimization of membrane processes. RSM requires the data on a specific experimental design whereas ANN does not. In this work, a combined ANN-RSM approach is presented to predict and optimize the membrane flux for the FO process. The ANN model, developed based on an experimental study, is used to predict the membrane flux for the experimental design in order to create the RSM model for optimization. A Box–Behnken design (BBD) is used to develop a response surface design where the ANN model evaluates the responses. The input variables were osmotic pressure difference, feed solution (FS) velocity, draw solution (DS) velocity, FS temperature, and DS temperature. The R2 obtained for the developed ANN and RSM model are 0.98036 and 0.9408, respectively. The weights of the ANN model and the response surface plots were used to optimize and study the influence of the operating conditions on the membrane flux.

Using Taguchi Experimental Design to Investigate Operating Variables That Significantly Affect Wear in Mud Pumps

1995 ◽  
Vol 209 (1) ◽  
pp. 29-40
Author(s):  
S H Mok ◽  
D G Gorman
Keyword(s):  
Experimental Design ◽  
Normal Load ◽  
Drilling Fluid ◽  
Operating Conditions ◽  
Taguchi Experimental Design ◽  
Drilling Mud ◽  
Test Rig ◽  
Offshore Drilling ◽  
Wear Rates ◽  
Operating Variables

Maintenance of offshore drilling mud pumps is normally based on running hours. It is generally accepted, however, that time does not provide an accurate means of scheduling maintenance, given the varying operating conditions of the reciprocating mud pumps. The energy expended at the interaction of sliding surfaces is hypothesized to be a better alternative. The effects of operating variables on wear rates are investigated. A Taguchi experimental design was used to identify those factors that significantly affect wear. Within the confines of an experimental test rig, the normal load and abrasive sand content was found to have a significant effect on the specific wear rate of nitrile rubber sliding on steel in drilling fluid.

scholarly journals Assessment of By-Product from Botryosphaeria rhodina MAMB-05 as an Effective Biosorbent of Pb(II)

Molecules ◽  
2019 ◽  
Vol 24 (18) ◽  
pp. 3306 ◽  
Author(s):  
Antonio J. Muñoz ◽  
Francisco Espínola ◽  
Encarnación Ruiz ◽  
Aneli M. Barbosa-Dekker ◽  
Robert F. H. Dekker ◽  
...  
Keyword(s):  
Response Surface Methodology ◽  
Fourier Transform ◽  
Infrared Spectroscopy ◽  
Experimental Design ◽  
Langmuir Model ◽  
Operating Conditions ◽  
Biosorption Capacity ◽  
A Value ◽  
Botryosphaeria Rhodina ◽  
M3 Subtype

In this work, two types of biomass preparations (VMSM and M3) from the filamentous fungus Botryosphaeria rhodina MAMB-05, which were previously used in a process of production of β-glucan, were assessed as biosorbents of lead. The operating conditions, optimized through response surface methodology and experimental design, were shown to be pH 5.29 and a biosorbent dose of 0.23 g/L for the VMSM biomass type; and pH 5.06 and a dose of biosorbent of 0.60 g/L for the M3 biomass type, at a constant temperature of 27 °C. Fourier transform-infrared spectroscopy analyzed the presence of functional groups on the biomass surface. In addition to give an extra value to the by-product biomass, the VMSM-type from B. rhodina MAMB-05 showed an excellent lead biosorption capacity (qm) with a value of 403.4 mg/g for the Langmuir model, comparing favorably with literature results, while the M3 subtype biomass showed a value of 96.05 mg/g.

scholarly journals A Multivariate Statistical Analyses of Membrane Performance in the Clarification of Citrus Press Liquor

2019 ◽  
Vol 3 (1) ◽  
pp. 10
Author(s):  
René Ruby-Figueroa ◽  
Monica Nardi ◽  
Giovanni Sindona ◽  
Carmela Conidi ◽  
Alfredo Cassano
Keyword(s):  
Molecular Weight ◽  
Pore Size ◽  
Bioactive Compounds ◽  
Colloidal Particles ◽  
Operating Time ◽  
Partial Least Square ◽  
Operating Conditions ◽  
Membrane Thickness ◽  
Permeate Flux ◽  
Membrane Performance

The orange press liquor is a by-product of the orange juice production containing bioactive compounds recognized for their beneficial implications in human health. The recovery of these compounds offers new opportunities for the formulation of products of interest in food, pharmaceutical and cosmetic industry. The clarification of orange press liquor by microfiltration (MF) and/or ultrafiltration (UF) processes is a valid approach to remove macromolecules, colloidal particles, and suspended solids from sugars and bioactive compounds. In this work the clarification of orange press liquor was studied by using three flat-sheet polymeric membranes: a MF membrane with a pore size of 0.2 μm and two UF membranes with nominal molecular weight cut-off (MWCO) of 150 and 200 kDa, respectively. The membrane performance, in terms of permeate flux and membrane rejection towards hesperidin and sugars, was studied according to a multivariate analyses approach. In particular, characteristics influencing the performance of the investigated membranes, such as molecular weight cut-off (MWCO), contact angle, membrane thickness, pore size distribution, as well as operating conditions, including temperature, and operating time, were analysed through the partial least square regression (PLSR). The multivariate method revealed crucial information on variables which are relevant to maximize the permeate flux and to minimize the rejection of hesperidin and sugars in the clarification of orange press liquor.

Effect of the operating conditions on a nanofiltration process to separate low-molecular-weight phenolic compounds from the sugars present in olive mill wastewaters

2021 ◽  
Vol 148 ◽  
pp. 428-436
Author(s):  
Carmen M. Sánchez-Arévalo ◽  
Álvaro Jimeno-Jiménez ◽  
Carlos Carbonell-Alcaina ◽  
María Cinta Vincent-Vela ◽  
Silvia Álvarez-Blanco
Keyword(s):  
Molecular Weight ◽  
Phenolic Compounds ◽  
Operating Conditions ◽  
Low Molecular Weight ◽  
Olive Mill Wastewaters ◽  
Olive Mill

A high-performance oil-free backing pump for electron microscopes

1978 ◽  
Vol 36 (1) ◽  
pp. 110-111
Author(s):  
G.K.W. Balkau ◽  
E. Bez ◽  
J.L. Farrant
Keyword(s):  
Molecular Weight ◽  
Electron Microscope ◽  
Hot Spots ◽  
High Performance ◽  
Carbonaceous Material ◽  
Contamination Rate ◽  
Low Molecular Weight ◽  
Principal Source ◽  
Rotary Pumps ◽  
Electron Microscopes

The earliest account of the contamination of electron microscope specimens by the deposition of carbonaceous material during electron irradiation was published in 1947 by Watson who was then working in Canada. It was soon established that this carbonaceous material is formed from organic vapours, and it is now recognized that the principal source is the oil-sealed rotary pumps which provide the backing vacuum. It has been shown that the organic vapours consist of low molecular weight fragments of oil molecules which have been degraded at hot spots produced by friction between the vanes and the surfaces on which they slide. As satisfactory oil-free pumps are unavailable, it is standard electron microscope practice to reduce the partial pressure of organic vapours in the microscope in the vicinity of the specimen by using liquid-nitrogen cooled anti-contamination devices. Traps of this type are sufficient to reduce the contamination rate to about 0.1 Å per min, which is tolerable for many investigations.

Low-molecular-weight heparin in the prevention and treatment of thromboembolic disorders

1998 ◽  
Vol 1 (5) ◽  
pp. 166-174 ◽  
Author(s):  
Evelyn R Hermes De Santis ◽  
Betsy S Laumeister ◽  
Vidhu Bansal ◽  
Vandana Kataria ◽  
Preeti Loomba ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Low Molecular Weight Heparin ◽  
Low Molecular Weight ◽  
Prevention And Treatment
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