scholarly journals Influence of Biochar Particulate on the Sorption Behaviour of Sansevieria Cylindrica Reinforced Vinyl Ester Composite

2019 ◽  
Vol 9 (1S3) ◽  
pp. 220-224
Keyword(s):  
Vinyl Ester ◽  
Water Medium ◽  
Corn Cob ◽  
Sorption Coefficient ◽  
Sorption Behaviour ◽  
Marine Applications ◽  
Kinetics Of ◽  
Different Sources ◽  
Chemical Resistivity ◽  
Water Resistivity

Purpose of this research is to evaluate the influence of biochar from corn cob and wood waste residues on the water resistivity of the Sansevieria cylindrica reinforced vinyl ester composite (SCVEC) to be utilized in structural and marine applications. Biochar filled SCVEC was allowed to immerse in different sources of waters like seawater, ground water and distilled water to study the water absorption of the material. Kinetics of water molecule transferring into the composite during immersion was studied by determining the diffusion coefficient, permeability coefficient and sorption coefficient. Fabricated composites were analysed for its Fickian behaviour under 720 Hrs of immersion in different water medium. Chemical resistivity for the fabricated composite were also studied to make the composite more accessible to marine environment. Results reveals that increase in biochar loading up to certain wt. % increases the water resistivity of the composite. Reinforcement of Biochar derived from corn cob was found to have potential water resistivity property compared to the biochar derived from wood wastes.

Inactivation kinetics of Bacillus cereus vegetative cells and spores from different sources by antimicrobial photodynamic treatment (aPDT)

LWT ◽  
2021 ◽  
Vol 142 ◽  
pp. 111037
Author(s):  
Leonardo do Prado-Silva ◽  
Verônica O. Alvarenga ◽  
Gilberto Ú.L. Braga ◽  
Anderson S. Sant’Ana
Keyword(s):  
Bacillus Cereus ◽  
Inactivation Kinetics ◽  
Photodynamic Treatment ◽  
Vegetative Cells ◽  
Kinetics Of ◽  
Different Sources

Effects of additives on the cure kinetics of vinyl ester pultrusion resins

2021 ◽  
pp. 002199832110015
Author(s):  
Alexander Vedernikov ◽  
Yaroslav Nasonov ◽  
Roman Korotkov ◽  
Sergey Gusev ◽  
Iskander Akhatov ◽  
...  
Keyword(s):  
Vinyl Ester ◽  
Mean Squared Error ◽  
Cure Kinetics ◽  
Zinc Stearate ◽  
Heating Rates ◽  
Scanning Calorimetry ◽  
Different Temperatures ◽  
Predicted Values ◽  
Kinetics Of ◽  
Final Degree

Pultrusion is a highly efficient composite manufacturing process. To accurately describe pultrusion, an appropriate model of resin cure kinetics is required. In this study, we investigated cure kinetics modeling of a vinyl ester pultrusion resin (Atlac 430) in the presence of aluminum hydroxide (Al(OH)3) and zinc stearate (Zn(C18H35O2)2) as processing additives. Herein, four different resin compositions were studied: neat resin composition, composition with Al(OH)3, composition comprising Zn(C18H35O2)2, and composition containing both Al(OH)3 and Zn(C18H35O2)2. To analyze each composition, we performed differential scanning calorimetry at the heating rates of 5, 7.5, and 10 K/min. To characterize the cure kinetics of Atlac 430, 16 kinetic models were tested, and their performances were compared. The model based on the [Formula: see text]th-order autocatalytic reaction demonstrated the best results, with a 4.5% mean squared error (MSE) between the experimental and predicted data. This study proposes a method to reduce the MSE resulting from the simultaneous melting of Zn(C18H35O2)2. We were able to reduce the MSE by approximately 34%. Numerical simulations conducted at different temperatures and pulling speeds demonstrated a significant influence of resin composition on the pultrusion of a flat laminate profile. Simulation results obtained for the 600 mm long die block at different die temperatures (115, 120, 125, and 130 °C) showed that for a resin with a final degree of cure exceeding 95% at the die exit, the maximum difference between the predicted values of pulling speed for a specified set of compositions may exceed 1.7 times.

scholarly journals Gelatin Beads/Hemp Hurd as pH Sensitive Devices for Delivery of Eugenol as Green Pesticide

2021 ◽  
Author(s):  
Gianluca Viscusi ◽  
Giuliana Gorrasi
Keyword(s):  
Release Kinetics ◽  
Barrier Properties ◽  
Ph Sensitive ◽  
Release Behavior ◽  
Sorption Coefficient ◽  
Highly Sensitive ◽  
Mean Diameter ◽  
Ph Conditions ◽  
Kinetics Of ◽  
Hemp Hurd

AbstractIn this paper gelatin beads reinforced with natural hemp hurd have been produced as pH sensitive devices for the release of eugenol, as green pesticide. The composites beads, with a mean diameter of about 1 mm, were obtained by polymer droplet gelation in sunflower oil. Thermal properties were evaluated showing no noticeable difference after the introduction of hemp hurd. Barrier properties demonstrated an improvement of hydrophobization. The introduction of 5% w/w of hemp hurd led to a reduction of sorption coefficient of about 85% compared to unloaded gelatin beads. Besides, the diffusion coefficient decreased, introducing 5% w/w of hemp hurd, from 8.91 × 10−7 to 0.77 × 10−7 cm2/s. Swelling and dissolution phenomena of gelatin beads were studied as function of pH. The swelling of gelatin beads raised as pH increased up to 2.3 g/g, 9.1 g/g and 27.33 g/g at pH 3, 7 and 12, respectively. The dissolution rate changed from 0.034 at pH 3 to 0.077 h−1 at pH 12. Release kinetics of eugenol at different pH conditions were studied. The released eugenol after 24 h is 98%, 91%, 81 and 63% w/w (pH 3), 87%, 62%, 37 and 32 wt% (pH 7) and 81%, 68%, 60 and 52 wt% (pH 12) for unloaded gelatin beads and gelatin beads with 1%, 3 and 5% of hemp hurd, respectively. The eugenol release behavior was demonstrated to be highly sensitive to the pH release medium, which allows to tune such devices as green pesticide release systems in soils with different level of acidity/basicity.

A KINETICS AND MECHANISTIC STUDY OF THE OXIDATION OF L-ARGININE BY QDC IN DMF-WATER MEDIUM

2021 ◽  
pp. 11-12
Author(s):  
Deepika Jain ◽  
Shilpa Rathor
Keyword(s):  
Perchloric Acid ◽  
Reaction Rate ◽  
Main Product ◽  
Activation Parameters ◽  
Reaction Rates ◽  
Mechanistic Study ◽  
Water Medium ◽  
Volume Percentage ◽  
Kinetics Of Oxidation ◽  
Kinetics Of

The present paper describes the kinetics of oxidation of l-Arginine by QDC in the presence of perchloric acid in 30% DMF-H O(v/v) medium at 2 + 40⁰C spectrophotometrically at λ =354nm. The reaction is rst order with respect to [QDC], [H ], and [substrate]. The reaction rate increased with max increasing volume percentage of DMF in reaction mixture. Michaelis- Menten type kinetic was observed with l-Arginine. The reaction rates were studied at different temperature and the activation parameters has been computed. The main product was identied as Cr (III) and 4-Guanidino buteraldehyde.

Sorption Kinetics of Uranium-238, Neptunium-237, Caesium-134, and Strontium-85 on a Glacial Deposit

1997 ◽  
Vol 506 ◽  
Author(s):  
L.N. Moyes ◽  
D.J. Bunker ◽  
J.T. Smith ◽  
F.R. Livens ◽  
C.R. Hughes ◽  
...  
Keyword(s):  
Waste Disposal ◽  
Kinetic Models ◽  
Sorption Kinetics ◽  
Kinetic Control ◽  
Glacial Deposit ◽  
Sorption Behaviour ◽  
Low Level ◽  
The Individual ◽  
Kinetics Of ◽  
Uptake Mechanisms

ABSTRACTBatch sorption experiments have been used to assess the sorption behaviour of four radionuclides, important in the context of low-level waste disposal, on a glacial substrate. Data for sorption of 238U, 237Np, 134Cs and 85Sr are compared and agree well with independent studies. A series of well-established kinetic models have been used to describe the individual uptake mechanisms and rate parameters reported. Sorption occurs via both equilibrium and kinetically controlled pathways, with neptunium sorption being under kinetic control to the greatest extent.

scholarly journals INTERPOLYELECTROLYTE COMPLEXATION OF SULFONATE-CONTAINING AROMATIC POLY- AND COPOLYAMIDES IN ORGANIC AND AQUEOUS-ORGANIC MEDIA

2018 ◽  
Vol 59 (7) ◽  
pp. 23
Author(s):  
Nataliya N. Smirnova
Keyword(s):  
Complex Formation ◽  
Phase State ◽  
Hydrophobic Interactions ◽  
Conversion Degree ◽  
Organic Media ◽  
Water Medium ◽  
Sodium Sulfonate ◽  
Interpolyelectrolyte Complexes ◽  
Kinetics Of ◽  
Polyanion Chain

Complex formation of sulfonate-containing aromatic poly- and copolyamides with copolymers of acrylonitrile with N,N-dimethyl-N,N-diallylammonium chloride and N,N-diethylaminoethyl methacrylate was studied in organic and aqueous-organic media. The values of conversion degree for interpolymer reactions were determined. At optimal conditions in the presence of poly-4,4'-(2-sodium sulfonate)diphenylaminoisophthalamide and  poly-4,4'-(2-sodium sulfonate)diphenylaminoterephthalamide the degree of conversion was equal to ~0.80 and 0.78, respectively. The reduction of number of sulfonate containing units in the polymer chain to 10% leads to its decrease to ~0.18.   It was shown that the nature and composition of the solvent affects the kinetics of interpolymer reactions due to the different ratio of reaggregation during the interacting of function groups in water medium with considerable force of hydrophobic interactions and in organic solvent where these forces dramatically reduce. The phase state and the composition of formed interpolyelectrolyte complexes depends on charge density along macromolecule chain of copolyamide and on the composition of the solvent used. The reduction of the number of sulfonate containing units in the macromolecule leads to polycation component increase in the complex. The formation of stoichiometric interpoly-electrolyte complexes takes place in the solvent with the same composition as that when the most significant unfolding of the polyanion chain was observed. The phase separation during the complex formation by the interpolymer reaction with copolyamide containing 5% of units with sulfonate groups or copolymer of acrylonitrile with N,N-diethylaminoethyl methacrylate is not observed.

Experimental Investigation of the SO2 Abatement Capacity of South African Calcium-Based Materials

2007 ◽  
Author(s):  
Zachary O. Siagi ◽  
Makame Mbarawa
Keyword(s):  
Particle Size ◽  
Dissolution Rate ◽  
South African ◽  
Efficient Operation ◽  
Shrinking Core ◽  
Caco3 Particle ◽  
Ph Stat ◽  
Kinetics Of ◽  
Different Sources ◽  
So2 Absorption

One of the most important steps in the wet limestone-gypsum flue gas desulphurization (WFGD) process is CaCO3 dissolution, which provides the dissolved alkalinity necessary for SO2 absorption. Accurately evaluating the CaCO3 dissolution rate is important in the design and efficient operation of WFGD plants. In the present work, the dissolution of limestone from different sources in South Africa has been studied in a pH-stat apparatus under conditions similar to those encountered in wet FGD processes. The influence of various parameters such as the reaction temperature (30 ≤ T ≤ 70°C), CaCO3 particle size (25 ≤ dp ≤ 63μm), solution acidity (4 ≤ pH ≤ 6), and chemical composition were studied in order to determine the kinetics of CaCO3 dissolution. The results obtained indicate that the dissolution rate increased with a decrease in particle size and an increase in temperature. The dissolution curves were evaluated in order to test the shrinking core model for fluid–solid systems. The analysis indicated that the dissolution of CaCO3 was controlled by chemical reaction, i.e. 1 − (1 − X)1/3 = kt.

Four- and five-step kinetic models of lactate dehydrogenase

1976 ◽  
Vol 54 (10) ◽  
pp. 915-918 ◽  
Author(s):  
Uwe Borgmann ◽  
Keith J. Laidler ◽  
Thomas W. Moon
Keyword(s):  
Lactate Dehydrogenase ◽  
Forward Direction ◽  
Reverse Direction ◽  
Similar Data ◽  
State Data ◽  
Incomplete Model ◽  
Step Model ◽  
The Relationship ◽  
Kinetics Of ◽  
Different Sources

A five-step model for the reaction catalyzed by beef heart lactate dehydrogenase (EC 1.1.1.27) reconciles differences observed in the four-step model if pre-steady-state data in the forward direction are compared with similar data in the reverse direction. The relationship between the four- and five-step models indicates what problems can develop when an incomplete model is proposed. Nevertheless, there are advantages to using the less complicated four-step model when comparing the molecular kinetics of enzymes catalyzing the same reaction but obtained from different sources.

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