Study of kinetics of degradation of cyclohexane carboxylic acid by acclimated activated sludge

2016 ◽  
Vol 73 (10) ◽  
pp. 2552-2558 ◽  
Author(s):  
Chunhua Wang ◽  
Shuian Shi ◽  
Hongyan Chen
Keyword(s):  
Carboxylic Acid ◽  
Activated Sludge ◽  
Degradation Kinetics ◽  
Experimental Conditions ◽  
First Order Kinetics ◽  
Effects Of Ph ◽  
High Concentrations ◽  
Cyclohexane Carboxylic Acid ◽  
Kinetics Of ◽  
Acclimated Activated Sludge

Activated sludge contains complex microorganisms, which are highly effective biodegrading agents. In this study, the kinetics of biodegradation of cyclohexane carboxylic acid (CHCA) by an acclimated aerobic activated sludge were investigated. The results showed that after 180 days of acclimation, the activated sludge could steadily degrade >90% of the CHCA in 120 h. The degradation of CHCA by the acclimated activated sludge could be modeled using a first-order kinetics equation. The equations for the degradation kinetics for different initial CHCA concentrations were also obtained. The kinetics constant, kd, decreased with an increase in the CHCA concentration, indicating that, at high concentrations, CHCA had an inhibiting effect on the microorganisms in the activated sludge. The effects of pH on the degradation kinetics of CHCA were also investigated. The results showed that a pH of 10 afforded the highest degradation rate, indicating that basic conditions significantly promoted the degradation of CHCA. Moreover, it was found that the degradation efficiency for CHCA increased with an increase in temperature and concentration of dissolved oxygen under the experimental conditions.

scholarly journals PERSISTENCIA DEL ENDOSULFÁN EN MEDIO ACUOSO ESTÁTICO

2001 ◽  
Vol 11 ◽  
Author(s):  
ARGELIA M. L. LENARDÓN ◽  
PATRICIA M. DE LA SIERRA ◽  
FERNANDA MARINO
Keyword(s):  
River Water ◽  
Degradation Kinetics ◽  
Water Type ◽  
Ultrapure Water ◽  
First Order ◽  
First Order Kinetics ◽  
Predominant Factor ◽  
Two Temperatures ◽  
In The Beginning ◽  
Kinetics Of

Estudou-se a cinética de degradação da mistura dos isômeros alfa e beta Endosulfan em diferentes condições de trabalho. Os compostos foram adicionados em água ultrapura, água do rio, água de rio filtrada e água ultrapura com sais (salinidade similar à agua do rio utilizada). As condições de degradação escolhidas foram: escuridão e duas temperaturas (14+1 ºC e 26+1 ºC). As amostragens foram programadas de modo a se obter dados periódicos mais freqüentes no início da experiência e posteriormente mais espaçados até o seu final (230 dias). As amostras foram submetidas à microextração e analisadas por cromatografia em fase gasosa com detector de Ni63 e coluna Megabore DB-5. A degradação foi descrita de acordo com a cinética de primeira ordem, determinando-se os tempos de meia vida (t1/2) e as energias de ativação (Ea). Os dados obtidos evidenciaram que a temperatura é o fator preponderante, sendo possível deduzir que o alfaendosulfan, exceto para água ultrapura (AU), é mais influenciado pela temperatura do que o beta-endosulfan. O segundo efeito mais importante refere-se ao tipo de água utilizada como matriz, devido à influência da salinidade. PERSISTANCE OF ENDOSULFAN IN STATIC AQUEOUS MEDIUM Abstract Degradation kinetics of a mixture of alpha- and beta-Endosulfan isomers was studied under different conditions. The compounds were spiked in ultrapure water, river water, filtered water and ultrapure water with salts (similar salinity condition to that of the river water used). The degradation conditions chosen were: darkness, two temperatures (14+1 ºC e 26+1 ºC). Samplings were programmed in order to obtain more frequent periodical data in the beginning of the experience and after more spaced until its end (230 days). The samples were submitted to microextraction and then analyzed by gas chromatography through a Ni63 detector equipped with a Megabore DB-5 column. Degradation was described using first-order kinetics to determine half-life times (t1/2) and activation energies (Ea). The data obtained evidenced that temperature is the predominant factor, it can possibly be inferred that alfa-endosulfan is much more influenced than beta-endosulfan except for ultrapure water (UW). The second important effect is the water type used as matrix, due to the influence of salinity.

The In Vitro Degradation Kinetics of Polyurethane Prodrug Materials

2011 ◽  
Vol 399-401 ◽  
pp. 1067-1070
Author(s):  
Chun Yan Li ◽  
Cong Cong Hu ◽  
Zhi Guo Wen ◽  
Sheng Xiong Dong
Keyword(s):  
Drug Release ◽  
High Performance ◽  
Degradation Kinetics ◽  
Hplc Method ◽  
In Vitro Degradation ◽  
Erosion Mechanism ◽  
First Order ◽  
First Order Kinetics ◽  
Kinetics Of

The method of high performance liquid chromatography (HPLC) is established to determine the content of antibacterial agent — ciprofloxacin (CF) in the degradation solution of ciprofloxacin-polyurethane (CFPU) and investigate the in vitro degradation kinetics by plotting and fitting the cumulative release curves to inspect the effects of different medium and different concentrations on drug release. The results showed that the HPLC method is accurate, reliable and simple. The drug-release of CFPU was bioresponsive and could be accorded with first order kinetics. It was observed that CF was released from CFPU by a combination of diffusion and erosion mechanism, mainly in the manner of diffusion in the absence of infection while erosion mechanism in the presence of infection.

Evaluation of state variable interface between the Activated Sludge Models and Anaerobic Digestion Model no 1

2008 ◽  
Vol 57 (6) ◽  
pp. 901-907 ◽  
Author(s):  
H. Yasui ◽  
K. Komatsu ◽  
R. Goel ◽  
Y. Y. Li ◽  
T. Noike
Keyword(s):  
Activated Sludge ◽  
State Of The Art ◽  
Degradation Kinetics ◽  
The State ◽  
State Variables ◽  
Anaerobic Conditions ◽  
State Variable ◽  
Kinetics Of ◽  
Aerobic And Anaerobic ◽  
Aerobic And Anaerobic Conditions

For plant wide modelling of wastewater treatment, it is necessary to develop a suitable state variables interface for integrating state of the art models of ASM and ADM1. ADM1 currently describes such an interface, however, its suitability needs to be experimentally evaluated. In this study, we characterised activated sludge under aerobic and anaerobic conditions to obtain representative state variables for both models. ASM state variables of XS, XH and XI (as obtained from aerobic tests) and ADM1 state variables of XC and XI (as obtained from anaerobic tests) were then correlated to assess the suitability of current interface. Based on the seven datasets of this study and seven datasets from literatures, it was found that in general ASM state variables were well correlated to the state variables of ADM1. The ADM1 state variable of XC could be correlated to the sum of state variables of XS and XH, while XI in both the models showed direct correspondence. It was also observed that the degradation kinetics of XC under anaerobic condition could be better described by individual degradation kinetics of XS and XH. Therefore, to establish a one to one correspondence between ASM and ADM1 state variables and better description of degradation kinetics in ADM1, replacing the composite variable of XC by the state variables of XS and XH is recommended.

Effects of pH, Ca, ADH, and theophylline on kinetics of Na entry in frog skin

1978 ◽  
Vol 235 (1) ◽  
pp. C35-C48 ◽  
Author(s):  
L. J. Mandel
Keyword(s):  
Short Circuit ◽  
External Solution ◽  
Short Circuit Current ◽  
Electrochemical Gradient ◽  
Experimental Conditions ◽  
Entry Barrier ◽  
Different Types ◽  
Effects Of Ph ◽  
Kinetics Of ◽  
External Ph

The short circuit current as a function of Na concentration in both solutions was found to obey Michaelis-Menten kinetics under a variety of experimental conditions. Values of maximal transport rate (Im) and half-maximal Na concentrations (Kt) were determined from these experiments. Three type of results were obtained: 1) Im and Kt both decreased by approximately the same fraction when the pH of both solutions was reduced by increasing PCO2, 2) Im decreased and Kt increased when the external pH was decreased, and 3) Im increased with ADH and theophylline, decreased with external Ca, and Kt remained unchanged. Various criteria were utilized to determine that these were properties of the entry barrier for Na into the "transport pool." The results are explained in terms of a model that separates three different types of actions on the entry barrier: 1) competition of Na with other ions in the external solution for entry, 2) modulation of the number of sites available for Na translocation by changing the cytoplasmic pH, and 3) alterations in the rate of Na translocation caused by changes in the Na permeability or the electrochemical gradient across the entry barrier.

Plasmalemma and Tonoplast Influxes of Potassium in Barley Roots, and Interpretation of the Absorption Isotherm at High Concentrations

1975 ◽  
Vol 2 (2) ◽  
pp. 177 ◽  
Author(s):  
JB Robinson ◽  
GG Laties
Keyword(s):  
Steady State ◽  
High Concentration ◽  
Experimental Conditions ◽  
Apparent Increase ◽  
Absorption Isotherm ◽  
Low Salt ◽  
High Concentrations ◽  
High Concentration Range ◽  
Kinetics Of ◽  
Potassium Exchange

Estimates of plasmalemma influx and steady-state vacuolar influx of potassium in low-salt barley roots have been obtained in the concentration range 10-80 mM by the use of controlled loading and washing times. Both fluxes are reduced by preloading the tissue in solutions containing potassium. When the experimental temperature is increased from 20 to 30°C, an apparent increase in the steady-state vacuolar influx occurs; separation of this flux from the apparent plasmalemma influx is not possible. The data support the hypothesis that the kinetics of potassium exchange in barley root tissue may be confounded by both loading time and temperature, and thus interpretation of the influx isotherm in the high concentration range is difficult. Where experiments are carried out at 20-25°C the steady- state vacuolar influx is measured unless closely defined experimental conditions obtain. At higher temperatures the plasmalemma influx may be measured.

scholarly journals Treatment of statins drug (pravastatin and rosuvastatin) in water by electro-Fenton process: Kinetics of degradation/mineralization and optimization of experimental conditions for a biological post-treatment

2019 ◽  
Vol 8 (2) ◽  
pp. 140-157
Author(s):  
Nisrine Beqqal ◽  
Muna Sh yahya ◽  
EL Karbane Miloud ◽  
Hind Chakchak ◽  
El Kacemi Kacem
Keyword(s):  
Degradation Kinetics ◽  
Organic Pollutant ◽  
Oxygen Demand ◽  
Pseudo First Order Reaction ◽  
Experimental Conditions ◽  
A Cell ◽  
Pre Treatment ◽  
Kinetics Of ◽  
Treatment Step ◽  
A Current

The treatment of pravastatin and rosuvastatin contaminated water as much as toxic and persistent organic pollutant was carried out by Electro-Fenton method EF. Several experiments were conducted in a cell compartment equipped with a platinum anode and a carbon felt cathode. The effects of several parameters such as the applied current and the catalyst Fe2+ concentration have been studied. Mineralization aqueous solutions of pravastatin followed by the chemical oxygen demand COD gave a higher degree of reduction of more than 90% for 6 hours of treatment at a current of 100 mA and Fe2+ concentration of 0.2 mM. The study of the degradation kinetics was followed during electrolysis by HPLC giving a pseudo first order reaction using a current of 100 mA and Fe2+ concentration of 0.1mM. A number of intermediate products for pravastatin and rosuvastatin have been identified using HPLC and liquid chromatography-mass spectrometry analyses. Biodegradability of the pre-treated solutions of two statins by EF was evaluated in order to decide the optimal moment to introduce the biological process. It was given by the ratio BOD5/COD which increases from 0 initially to 1.3 after 2 hours for pravastatin and from 0 initially to 1.5 after 3 hours for rosuvastatin as the COD decreases. It implies that EF tends to enhance the biodegradability and could be used as a pre-treatment step for biological treatment.

Thermal Degradation of Green Asparagus Texture

1997 ◽  
Vol 60 (3) ◽  
pp. 315-320 ◽  
Author(s):  
CARMEN RODRIGO ◽  
MIGUEL RODRIGO ◽  
SUSANA FISZMAN ◽  
TERESA SÁNCHEZ
Keyword(s):  
Single Point ◽  
Experimental Conditions ◽  
Cutting Resistance ◽  
First Order ◽  
First Order Kinetics ◽  
Press Method ◽  
The Wire ◽  
Shear Press ◽  
Kinetics Of ◽  
Green Asparagus

A cutting cell was developed to evaluate the texture of green asparagus by measuring its resistance to being cut with a wire. The cell was used in conjunction with a universal texturometer and improved on the single-point method of the Wilder fibrometer. Experimental conditions were determined for using the cell to measure the cutting resistance of asparagus subjected to different extents of heat treatment. Better discrimination between samples was obtained than with a Kramer cell. The fresh asparagus spears. were heated at temperatures between 70 and 100°C for different lengths of time and the kinetics of the degradation of texture was studied. A biphasic (two-component) behavior was observed with each component displaying first-order kinetics, The kinetic parameters calculated by measuring the texture with the wire cell (cutting at a position 5 em from the tip of the asparagus) were Eaa = 9.56 and Eab = 20.43 kcal/mol (activation energy for components A and B), and ka85 = 1.047 and kb85 = 0.057 min−1 (rate constants for A and B of asparagus heated at 85°C). When the texture was determined by measuring the shear force with a Kramer cell, the parameters estimated were Eaa = 23.41 and Eab = 18.32 kcal/mol, and ka85 = 0.25 and kb85 = 0.025 min−1 Both the wire cell cutting method and the Kramer shear-press method are suitable for evaluating the degree of thermal softening of green asparagus heated to temperatures between 70 and 100°C.

scholarly journals Photocatalytic degradation of reactive black 5 on the surface of tin oxide microrods

2018 ◽  
Vol 16 (5) ◽  
pp. 773-781 ◽  
Author(s):  
Shanza Rauf Khan ◽  
Muhammad Umar Khalid ◽  
Saba Jamil ◽  
Songnan Li ◽  
Aiman Mujahid ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Tin Oxide ◽  
Degradation Kinetics ◽  
Xrd Analysis ◽  
Sem Analysis ◽  
Reactive Black 5 ◽  
Unit Cells ◽  
High Concentrations ◽  
Co Precipitation ◽  
Kinetics Of

Abstract A simple co-precipitation technique is proposed for synthesis of tin oxide (SnO2) microrods. Stannous chloride and urea were used during synthesis. X-ray powder diffraction (XRD) analysis revealed that the annealed product consists of SnO2 microrods having tetragonal unit cells, while scanning electron microscopy (SEM) analysis revealed the rod-like morphology of a synthesized product. These synthesized microrods are used as photocatalyst for the degradation of reactive black 5 (RB5). Degradation kinetics of RB5 are monitored under daylight in different concentrations of hydrogen peroxide (H2O2) and catalyst. The percentage of RB5 conversion is also calculated at various concentrations of hydrogen peroxide and catalyst which demonstrate that RB5 shows high catalytic degradation at high concentrations of hydrogen peroxide and catalyst.

scholarly journals Photocatalytic Performance of Electrospun Silk Fibroin/ZnO Mats to Remove Pesticide Residues from Water under Natural Sunlight

Catalysts ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 110 ◽  
Author(s):  
Isabel Garrido ◽  
Salvador Aznar-Cervantes ◽  
Marina Aliste ◽  
María J. Yáñez-Gascón ◽  
Nuria Vela ◽  
...  
Keyword(s):  
Silk Fibroin ◽  
Pesticide Residues ◽  
Degradation Kinetics ◽  
Catalyst Loading ◽  
Similar Amount ◽  
Experimental Conditions ◽  
Electrospinning Technique ◽  
Degradation Rates ◽  
Kinetics Of ◽  
Environmentally Friendly Approach

We have evaluated the efficiency of silk fibroin (SF) coated with ZnO nanoparticles in the photocatalytic disappearance of one acaricide (etoxazole) and three fungicides (difenoconazole, myclobutanil and penconazole) in water exposed to sunlight irradiation. Electrospun SF/ZnO mats were successfully synthesized by electrospinning technique and characterized by XRD, FE-SEM, XPS, XDS, FTIR, and BET. The influence of catalyst loading on the degradation kinetics of the different pesticides was examined in order to gain knowledge of maximum degradation efficiency. A significant increment in degradation rates was observed with the addition of ZnO. SF mats with 25 mg of ZnO were finally selected since no significant differences (p < 0.05) were detected when the loading was enlarged from 25 to 50 mg for the majority of the compounds. In the experimental conditions, the half-lives ranged from 33 min to 93 min for etoxazole and myclobutanil, respectively. The comparison of SF materials coated with similar amount of TiO2 and ZnO showed that the later was slightly more efficient to remove pesticide residues. Hence, the use of electrospun SF/ZnO nanostructures would provide an environmentally friendly approach with photocatalytic activity to be applied in the reclamation of water polluted by pesticides.

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