THE DEGRADATION OF CARRAGEENIN: I. KINETICS IN AQUEOUS SOLUTION AT pH 7

1955 ◽  
Vol 33 (4) ◽  
pp. 597-603 ◽  
Author(s):  
C. R. Masson
Keyword(s):  
Aqueous Solution ◽  
Kinetic Analysis ◽  
Rapid Degradation ◽  
Complete Hydrolysis ◽  
First Order ◽  
Temperature Range ◽  
Weak Linkage ◽  
Reducing Properties

The degradation of carrageenin in buffered aqueous solution at pH 7.0 has been studied over the temperature range 60° to 101 °C. by following the change in viscosity and reducing properties. Kinetic analysis indicates the occurrence of two reactions: (a) an initial rapid degradation representing only about 0.3% of the complete hydrolysis, followed by (b) a first-order random degradation having k = 2.75 × 1013 e−29,200,/RT hr−1. The latter reaction becomes important at temperatures above 60 °C. The results indicate that carrageenin is more unstable than would be expected of a simple 1–3 galactan, and that two types of weak linkage are involved in the structure of the polysaccharide.

scholarly journals Kinetic Analysis of Genipin Degradation in Aqueous Solution

2010 ◽  
Vol 5 (12) ◽  
pp. 1934578X1000501 ◽  
Author(s):  
Paul Slusarewicz ◽  
Keng Zhu ◽  
Tom Hedman
Keyword(s):  
Aqueous Solution ◽  
Kinetic Analysis ◽  
Crosslinking Agent ◽  
Order Reaction ◽  
First Order Reaction ◽  
Protein Crosslinking ◽  
First Order ◽  
Natural Protein ◽  
Phosphate Ions ◽  
Low Toxicity

Degradation of genipin (GP), a low toxicity natural protein crosslinking agent, in aqueous solution was monitored by HPLC at various pH levels. Degradation of GP was consistent with a mechanism consisting of a first order reaction with a reversible first step. Formation of the intermediate was slowest at more neutral pHs while formation of the irreversible product was correlated to increasing alkalinity. Degradation at all pHs was enhanced by the presence of phosphate ions. Degradation of GP most likely proceeds via the reversible opening of the dihydropyran ring by water followed by irreversible polymerization of the intermediate. Degraded solutions containing no detectable GP or intermediate, however, are still capable of crosslinking proteins.

The decomposition mechanism for TDO in aqueous solution within 25–95 °C temperature range

2019 ◽  
Vol 731 ◽  
pp. 136603
Author(s):  
Jianzhong Shao ◽  
Xiaoyun Liu ◽  
Sergei V. Makarov ◽  
Kemei Pei
Keyword(s):  
Aqueous Solution ◽  
Decomposition Mechanism ◽  
Temperature Range

Area-based speciation kinetic analysis of the multipollutant removal in Constructed Wetlands to enhance its treatment efficiency

2021 ◽  
Author(s):  
Manoj Kumar ◽  
Rajesh Singh
Keyword(s):  
Wastewater Treatment ◽  
Kinetic Analysis ◽  
Constructed Wetlands ◽  
Municipal Wastewater ◽  
Zero Order ◽  
Pollutant Removal ◽  
Municipal Wastewater Treatment ◽  
Treatment Efficiency ◽  
First Order ◽  
Present Study Area

In the present study area-based, pollutant removal kinetic analysis was considered using the Zero-order, first-order decay and efficiency loss (EL) models in the constructed wetlands (CWs) for municipal wastewater treatment....

Consecutive reactions in the thermal decomposition of phenylalkyldiazirines

1977 ◽  
Vol 55 (20) ◽  
pp. 3596-3601 ◽  
Author(s):  
Michael T. H. Liu ◽  
Barry M. Jennings
Keyword(s):  
Thermal Decomposition ◽  
Kinetic Parameters ◽  
Diazo Compounds ◽  
First Order ◽  
Temperature Range ◽  
Decomposition Reactions ◽  
Consecutive Reactions ◽  
Rate Processes ◽  
Subsequent Decomposition

The thermal decomposition of phenyl-n-butyldiazirine and of phenylmethyldiazirine in DMSO and in HOAc have been investigated over the temperature range 80–130 °C. The intermediate diazo compounds, 1-phenyl-1-diazopentane and 1-phenyldiazoethane respectively have been detected and isolated. The decomposition of phenyl-n-butyldiazirine and the subsequent decomposition of its product, 1-phenyl-1-diazopentane, are an illustration of consecutive reactions. The kinetic parameters for the isomerization and decomposition reactions have been determined. The isomerization of phenylmethyldiazirine to 1-phenyldiazoethane is first order and probably unimolecular but the kinetics for the subsequent reactions of 1-phenyldiazoethane are complicated by several competing rate processes.

Electrochemical studies of the Pb2+/Pb(Hg) system in aqueous and aqueous ethylene glycol solutions

1979 ◽  
Vol 57 (14) ◽  
pp. 1801-1803 ◽  
Author(s):  
Tibor Rabockai
Keyword(s):  
Aqueous Solution ◽  
Ethylene Glycol ◽  
Organic Solvent ◽  
Electrochemical Behavior ◽  
Experimental Error ◽  
Electrochemical Studies ◽  
Temperature Range ◽  
All Solutions ◽  
Aqueous Ethylene Glycol ◽  
Current Reversal

The electrochemical behavior of the Pb2+/Pb(Hg) system in aqueous and aqueous ethylene glycol solutions is studied in the temperature range of 20.0 to 50.0 °C by means of current reversal chronopotentiometry. It is shown that the reduction of Pb2+ ion is reversible and that kinetic or catalytic complications are not present. The value of dE1/2/dT is −0.6 mV/deg in the aqueous solution and −0.5 mV/deg in the solution with 56% (w/w) or higher concentrations of the organic solvent. In the above concentration range of ethylene glycol the activation energies of diffusion and viscosity vary from 4.3 × 103 to 7.2 × 103 cal mol−1 and from 3.7 × 103 to 6.7 × 103 cal mol−1, respectively. For all solutions the solvodynamic mean radius of the diffusing species remains constant within the experimental error, suggesting that the diffusing species is always the hydrated Pb2+ ion.

The mechanism of the oxidation of thiocyanate ion by peroxomonosulphate in aqueous solution. II. Kinetics of the reaction

1966 ◽  
Vol 19 (8) ◽  
pp. 1365 ◽  
Author(s):  
RH Smith ◽  
IR Wilson
Keyword(s):  
Aqueous Solution ◽  
Initial Rate ◽  
Stopped Flow ◽  
Thiocyanate Ion ◽  
First Order ◽  
Conductance Method ◽  
Rate Of Reaction ◽  
Kinetics Of

Initial rates of reaction for the above oxidation have been measured by a stopped-flow conductance method. Between pH 2 and 3.6, the initial rate of reaction, R, is given by the expression R{[HSO5-]+[SCN-]} = {kb+kc[H+]}[HSO5-]0[SCN-]20+ka[H+]-1[HSO5]20[SCN-]0 As pH increases, there is a transition to a pH-independent rate, first order in each thiocyanate and peroxomonosulphate concentrations.

Performance of poly-o-phenylenediamine and its carbon dot composite electrode in the removal of Cu2+ from its aqueous solution

2021 ◽  
pp. 2151037
Author(s):  
Yu Meng ◽  
Qing Zhong ◽  
Arzugul Muslim
Keyword(s):  
Aqueous Solution ◽  
Electrochemical Reduction ◽  
Composite Electrode ◽  
Reduction Process ◽  
Order Kinetic ◽  
Carbon Dot ◽  
First Order ◽  
Oxidation Reduction ◽  
Order Kinetic Model ◽  
Optimal Ph

Because −NH2 and −NH− in poly-[Formula: see text]-phenylenediamine (P[Formula: see text]PD) can interact strongly with the empty orbitals of Cu to show unique electrochemical activity, P[Formula: see text]PD is suitable for the removal of Cu[Formula: see text] by electrochemical oxidation–reduction process. In this study, with P[Formula: see text]PD and its carbon dot composite (CDs/P[Formula: see text]PD) as working electrodes, the electrochemical reduction and removal of Cu[Formula: see text] in the aqueous solution were carried out with the potentiostatic method. According to effects of voltage, pH of the solution, initial concentration of Cu[Formula: see text], and electrochemical reduction time on the Cu[Formula: see text] removal, the Cu[Formula: see text] removal ratios of P[Formula: see text]PD and CDs/P[Formula: see text]PD were up to 64.69% and 73.34%, respectively, at −0.2 V and the optimal pH. Additionally, results showed that these processes were in line with the quasi-first order kinetic model. Both P[Formula: see text]PD and CDs/P[Formula: see text]PD showed good reproducibility in six cycles. After five times of repeated usage, the regeneration efficiencies of P[Formula: see text]PD and CDs/P[Formula: see text]PD dropped to 77.04% and 79.36%, respectively.

Thermochromism of Metal Exchange Reaction between Zinc(II) and Mercury(II) Porphyrins

1995 ◽  
Vol 50 (4) ◽  
pp. 545-550 ◽  
Author(s):  
Masaaki Tabata ◽  
Masahiro Ide ◽  
Kentaro Kaneko
Keyword(s):  
Aqueous Solution ◽  
Exchange Reaction ◽  
Thermodynamic Parameters ◽  
Distribution Curve ◽  
Equilibrium Constants ◽  
Metal Exchange ◽  
Free Base ◽  
Temperature Range ◽  
Base Form ◽  
Metal Exchange Reaction

Thermochromism was observed for an aqueous solution containing zinc(II) and mercury( II) cations and N-p-nitrobenzyl-5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin anion (NO2Bz(Htpps)4-) in the temperature range 10 to 70 °C. The equilibrium constants and the thermodynamic parameters of Zn(NO2Bztpps)3- and Hg(NO2Bztpps)3- have been determined spectrophotometrically to elucidate the thermochromism at 10, 15, 20, 25 and 30 °C in 0.1 mol dm-3 NaNO3. The protonation and metalation constants of NO2Bz(Htpps)4- are defined as K2 = [H2P][H+]-1[HP]-1, K3 = [H3P][H+]-1[H2P]-1 and KMP = [M P][H+][M2+]-1[HP]-1, where HP and MP denote the free base form of the prophyrin and the metalloporphyrins of zinc(II) and mercury(II), respectively. Charges of the prophyrin and metalloporphyrins are omitted for simplicity. The following values were found: logK2 = 7.75 ±0.02 (25 °C), ΔH°/kJmol-1 = -21.2±0.5 and ΔS°/Jmol-1K-1 = 77±1, logK3 = 2.55±0.02 (25 °C), ΔH°/kJmol-1 = -25±0.8 and ΔS°/Jmol-1K-1 = -35±3 and log KZnP = 0.63±0.03 (25 °C), ΔH°/kJmol-1 = 31.0±0.8 and ΔS°/Jmol-1K-1 = 116±3, logKHgP = 6.22±0.03 (25 °C), ΔH°/kJmol-1 = 4.5±0.7 and ΔS°/Jmol-1K-1 = 134±2. The distribution curve calculated from the thermodynamic parameters sufficiently agrees with the observed metal exchange reaction between the metalloporphyrins.

scholarly journals EFFECT OF DIATOMEAOUS EARTH TREATMENT USING HYDROGEN CHLORIDE AND SULFURIC ACID ON KINETICS OF CADMIUM(II) ADSORPTION

2010 ◽  
Vol 2 (2) ◽  
pp. 107-112
Author(s):  
Nuryono Nuryono ◽  
Narsito Narsito
Keyword(s):  
Aqueous Solution ◽  
Sulfuric Acid ◽  
Hydrogen Chloride ◽  
Rate Constant ◽  
Diatomaceous Earth ◽  
Adsorption Rate ◽  
Physical Interaction ◽  
First Order ◽  
Adsorption Rate Constant ◽  
Kinetics Of

In this research, treatment of diatomaceous earth, Sangiran, Central Java using hydrogen chloride (HCl) and sulfuric acid (H2SO4) on kinetics of Cd(II) adsorption in aqueous solution has been carried out. The work was conducted by mixing an amount of grounded diatomaceous earth (200 mesh in size) with HCl or H2SO4 solution in various concentrations for two hours at temperature range of 100 - 150oC. The mixture was then filtered and washed with water until the filtrate pH is approximately 7 and then the residue was dried for four hours at a temperature of 70oC. The product was used as an adsorbent to adsorb Cd(II) in aqueous solution with various concentrations. The Cd(II) adsorbed was determined by analyzing the rest of Cd(II) in the solution using atomic absorption spectrophotometry. The effect of treatment was evaluated from kinetic parameter of adsorption rate constant calculated based on the simple kinetic model. Results showed  that before equilibrium condition reached, adsorpstion of Cd(II) occurred through two steps, i.e. a step tends to follow a reaction of irreversible first order  (step I) followed by reaction of reversible first order (step II). Treatment with acids, either hydrogen chloride or sulfuric acid, decreased adsorption rate constant for the step I from 15.2/min to a range of 6.4 - 9.4/min.  However, increasing concentration of acid (in a range of concentration investigated) did not give significant and constant change of adsorption rate constant. For step II process,  adsorption involved physical interaction with the sufficient low adsorption energy (in a range of 311.3 - 1001 J/mol).     Keywords: adsorption, cdmium, diatomaceous earth, kinetics.

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