An Examination of Assumptions Underlying the First-Order Kinetic Model for Release of Water-Soluble Drugs from Dicalcium Phosphate Dihydrate Matrices

Gallic acid (GA) is a naturally occurring plant polyphenol compound. Experiments were conducted to study the kinetics and effects of pH, temperature, irradiation, and initial hexavalent chromium (Cr(VI)) concentration on Cr(VI) reduction by GA. Results indicated that Cr(VI) could be reduced to chromium oxide (Cr(III)) with GA in a wide range of pH values from 2.0 to 8.5. The reaction followed a pseudo-first-order kinetic model with respect to Cr(VI) and GA in acid conditions (pH 2.0–5.0). However, the reaction did not follow the pseudo-first-order kinetic model at pH 6.5 and 8.5. Removal efficiencies and reaction rate constants of Cr(VI) significantly increased with decreasing pH value and increasing temperature. The effect of irradiation on Cr(VI) reduction increased with increasing pH, and irradiation improved the removal efficiency of Cr(VI) by 11.29% at pH 6.5. At pH 2.0, nearly all molar ratios of GA required for the reduction of Cr(VI) were 1:2 (±0.1) under different initial Cr(VI) concentrations; however, the molar ratios of GA required for the reduction of Cr(VI) were 1:1.29, 1:1.43, and 1:1.69, respectively, when the initial Cr(VI) concentrations were 10, 25, and 50 mg/L at pH 5.5.

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Kinetic Analysis for Agglomeration-Flotation of Finely Ground Chalcopyrite: Comparison of First Order Kinetic Model and Experimental Results

MATERIALS TRANSACTIONS ◽

10.2320/matertrans.m-m2020843 ◽

2020 ◽

Vol 61 (10) ◽

pp. 1940-1948

Author(s):

Vothy Hornn ◽

Mayumi Ito ◽

Ryosuke Yamazawa ◽

Hiromasa Shimada ◽

Carlito Baltazar Tabelin ◽

...

Keyword(s):

Kinetic Model ◽

Kinetic Analysis ◽

Experimental Results ◽

Order Kinetic ◽

First Order ◽

Order Kinetic Model

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CHARACTERISTICS OF ASCORBIC ACID RELEASE FROM TPP-CROSSLINKED CHITOSAN/ALGINATE POLYELECTROLYTE COMPLEX MEMBRANES

Progress on Chemistry and application of Chitin and its Derivatives ◽

10.15259/pcacd.23.007 ◽

2018 ◽

Vol XXIII ◽

pp. 76-87 ◽

Cited By ~ 1

Author(s):

Magdalena Gierszewska ◽

Jadwiga Ostrowska-Czubenko ◽

Ewelina Chrzanowska

Keyword(s):

Ascorbic Acid ◽

Kinetic Model ◽

Polyelectrolyte Complex ◽

Zero Order ◽

Order Kinetic ◽

Initial Burst ◽

First Order ◽

Order Kinetic Model ◽

Acid Release ◽

Release Data

Chitosan/alginate polyelectrolyte complex membranes (Ch/Alg) additionally cross-linked with tripolyphosphate (TPP) and containing ascorbic acid (AA) were prepared. The dynamic swelling behaviour of Ch/Alg/TPP and ascorbic acid release from the membrane were characterised in different buffer solutions. It has been found that the pH of the buffer solution affects the swelling and release behaviour of AA. Ascorbic acid release, observed over a period of 360 min, exhibited a biphasic pattern, characterised by a fast initial burst release, followed by a slow, sustained release. Different mathematical models were used to study the kinetics and transport mechanism of AA from Ch/Alg/TPP hydrogels. Drug release data were fitted to the zero order kinetic model and first order kinetic model. To characterise the drug mechanism, the release data were fitted to the Higuchi and Korsmeyer-Peppas equations. The initial burst AA release followed zero order kinetics and was quasi-Fickian in nature. The second step of AA release followed first order kinetics.

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Pesticide production wastewater treatment by Electro-Fenton using Taguchi experimental design

Water Science & Technology ◽

10.2166/wst.2021.372 ◽

2021 ◽

Author(s):

Thanh Luu Pham ◽

Faten Boujelbane ◽

Hiep Nghia Bui ◽

Hieu Trung Nguyen ◽

Xuan-Thanh Bui ◽

...

Keyword(s):

Kinetic Model ◽

Density Functional ◽

Reaction Kinetic ◽

Polynomial Regression ◽

Treated Wastewater ◽

Order Kinetic ◽

Functional Theory ◽

First Order ◽

Toc Removal ◽

Order Kinetic Model

Abstract In this study, the electro – Fenton (EF) method was applied to remove total organic carbon (TOC) from the pesticide production wastewater containing tricyclazole (TC). Statistical Taguchi method was used to optimize the treatment performance. Analysis of variance (ANOVA) indicated that the polynomial regression model fitted experimental data with R2 of 0.969. The optimal conditions for eliminating 75.4% TOC and 93.7% TC, were 0.2 mM of Fe2+, 990 mg/L of Na2SO4, 180 min of reaction time at pH 3 with 2.22 mA/cm2 of current density. The removal of TC present in the wastewater followed the first-order reaction kinetic model (R2 = 0.993); while that was the second-order kinetic model in the case of the TOC removal (R2 = 0.903). In addition, the experimental results and theory approaches (density functional theory and natural bond orbital calculations) also showed that the C-N bond breaking and nitrate ions cleavage ammonia. Acute toxicity of the pesticide wastewater after treatment (PWAT) on microcrustacean showed that the treated wastewater still exhibited high toxicity against D. magna, with LC50 values of 3.84%, 2.68%, 2.05%, and 1.78% at 24 h, 48 h, 72 h, and 96 h, respectively.

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SOME EFFECTS OF MOISTURE AND TEMPERATURE ON TRANSFORMATION OF MONOCALCIUM PHOSPHATE IN SOIL

Canadian Journal of Soil Science ◽

10.4141/cjss62-031 ◽

1962 ◽

Vol 42 (2) ◽

pp. 229-239 ◽

Cited By ~ 9

Author(s):

W. C. Hinman ◽

J. D. Beaton ◽

D. W. L. Read

Keyword(s):

Water Soluble ◽

Dicalcium Phosphate ◽

Dicalcium Phosphate Dihydrate ◽

Inorganic P ◽

Monocalcium Phosphate ◽

Liesegang Rings ◽

Phosphate Dihydrate ◽

The Mean ◽

Surrounding Soil

Pre-weighed monocalcium phosphate pellets, containing about 15 milligrams of P, were placed in 200 grams of soil and stored for 2 weeks at four moisture tensions and three temperatures. Pellet residues were then removed and the amount of phosphorus remaining was determined. Small cores containing pellet residues and the surrounding soil contacted by fertilizer solution were removed for determination of water-soluble and total inorganic P. Phosphate phases present at the granule sites and the surrounding soil were identified by their optical properties.The mean amount of phosphorus remaining at the granule sites was 20.2 per cent. Although both moisture tension and temperature significantly affected the quantity of phosphorus retained, no consistent trend was apparent. Residues remaining at the site of application were found to be mixtures of anhydrous and dihydrated dicalcium phosphate, with the latter predominating. Moisture tension and temperature did not greatly alter the proportion of the two phases.Periodic precipitates or Liesegang rings of dicalcium phosphate were formed in the soil surrounding monocalcium phosphate pellets. Dicalcium phosphate dihydrate was the predominant phase. The proportion of dihydrated to anhydrous dicalcium phosphate increased as the temperature decreased and as the moisture tension increased.Water-soluble P increased significantly with increased moisture tension and was significantly greater at 5 °C. than at either 16 or 27 °C. The mean of all treatments was 5.6 per cent. Increased amounts of dicalcium phosphate dihydrate in the surrounding soil seemed to be responsible for the increase in water solubility.Between 89.5 and 99.2 per cent of the added phosphorus was recovered in the water and acid extracts of soil cores containing about 1.4 cm.3 of soil.

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