scholarly journals Features of the kinetics of degradation of dark gray podzolized soil of Lviv Roztochia

2017 ◽  
pp. 43-52
Author(s):  
Oksana Bonishko
Keyword(s):  
Degradation Kinetics ◽  
Soil Aggregates ◽  
Mechanical Degradation ◽  
Water Degradation ◽  
First Order ◽  
Complex Process ◽  
Lower Ability ◽  
Kinetics Of Degradation ◽  
Kinetics Of ◽  
Diffusive Layer

The kinetics of mechanical, water degradation and deflation of dark gray podzolized soils of Lviv Roztochia has been investigated. By the equation of the velocity of these processes, their constant of the reaction and order has been determined: for deflation (V=4.0645·C0.8625), water degradation (V=0.2829·C0.7559), mechanical degradation (V=0.7363·C1.5173). The processes of disaggregation of soil particles due to water and wind degradation of dark gray podzolized soil had been occurred as unilateral first-order reactions. Mechanical degradation in the soil is a more complex process of heterogeneity (n = 1.5), in which the formation of nuclei (particles <0.25 mm in size) on the surface of the soil aggregate occurs in several stages. Has been established that in the mechanical degradation of dark gray podzolized soil the equilibrium state reaches through 2–3 minutes, after deflation – after 10 minutes of wind action at a speed of 2.2 m/s, for water degradation – after 12 minutes, when the micro aggregate particles are 25 %, 16 % and 2 % respectively. Hence, dark gray podzolized soils exhibit a lower ability to aqueous deformation than to deflation, which is confirmed by a light-grit granulometric composition, brylove. First of all, this has been due to the slowest response among these processes. Secondly, the dissolution of soil aggregates has been due to the thickness, the area of the diffusive layer and the diffusion coefficient. Low anti-erosion resistance of dark gray podzolized soil due to mechanical degradation is associated with two-stage, cloakiness and low bending of brylove. Key words: degradation, kinetics, macro and micro aggregates, equilibrium constant.

scholarly journals Comparative Study of Chemical Stability of Two H1Antihistaminic Drugs, Terfenadine and ItsIn VivoMetabolite Fexofenadine, Using LC-UV Methods

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Anna Gumieniczek ◽  
Anna Berecka-Rycerz ◽  
Rafał Pietraś ◽  
Izabela Kozak ◽  
Karolina Lejwoda ◽  
...  
Keyword(s):  
Comparative Study ◽  
Chemical Stability ◽  
First Order ◽  
First Order Kinetics ◽  
Kinetics Of Degradation ◽  
Effects Of Temperature ◽  
High Doses ◽  
Antihistaminic Drugs ◽  
Kinetics Of

A comparative study of chemical stability of terfenadine (TER) and itsin vivometabolite fexofenadine (FEX) was performed. Both TER and FEX were subjected to high temperature at different pH and UV/VIS light at different pH and then quantitatively analyzed using new validated LC-UV methods. These methods were used to monitor the degradation processes and to determine the kinetics of degradation for both the compounds. As far as the effects of temperature and pH were concerned, FEX occurred more sensitive to degradation than TER. As far as the effects of UV/VIS light and pH were concerned, the both drugs were similarly sensitive to high doses of light. Using all stress conditions, the processes of degradation of TER and FEX followed the first-order kinetics. The results obtained for these two antihistaminic drugs could be helpful in developing their new derivatives with higher activity and stability at the same time.

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.

Degradation of azo dye with dirhodium(II) caprolactamate as heterogeneous catalyst

2012 ◽  
Vol 65 (12) ◽  
pp. 2175-2182
Author(s):  
Abeer S. Elsherbiny ◽  
Sahar H. El-Khalafy ◽  
Michael P. Doyle
Keyword(s):  
Hydroxyl Radicals ◽  
Azo Dye ◽  
Degradation Kinetics ◽  
Oxidative Degradation ◽  
Total Carbon ◽  
Order Kinetic ◽  
First Order ◽  
Pseudo First Order ◽  
Kinetics Of ◽  
Degradation Of Azo Dye

The kinetics of the oxidative degradation of an azo dye Metanil Yellow (MY) was investigated in aqueous solution using dirhodium(II) caprolactamate, Rh2(cap)4, as a catalyst in the presence of H2O2 as oxidizing agent. The reaction process was followed by UV/Vis spectrophotometer. The decolorization and degradation kinetics were investigated and both followed a pseudo-first-order kinetic with respect to the [MY]. The effects of various parameters such as H2O2 and dye concentrations, the amount of catalyst and temperature have been studied. The studies show that Rh2(cap)4 is a very effective catalyst for the formation of hydroxyl radicals HO• which oxidized and degraded about 92% of MY into CO2 and H2O after 24 h as measured by total carbon analyzer.

Kinetic studies on the degradation of crystal violet by the Fenton oxidation process

2010 ◽  
Vol 62 (1) ◽  
pp. 1-7 ◽  
Author(s):  
H. Wu ◽  
M. M. Fan ◽  
C. F. Li ◽  
M. Peng ◽  
L. J. Sheng ◽  
...  
Keyword(s):  
Crystal Violet ◽  
Oxidation Process ◽  
Degradation Kinetics ◽  
Kinetic Studies ◽  
Fenton Oxidation ◽  
Dyeing Wastewater ◽  
First Order ◽  
Fenton Oxidation Process ◽  
System Variables ◽  
Kinetics Of

The degradation of dye crystal violet (CV) by Fenton oxidation process was investigated. The UV–Vis spectrogram has shown that CV can be degraded effectively by Fenton oxidation process. Different system variables namely initial H2O2 concentration, initial Fe2 +  concentration and reaction temperature, which have effect on the degradation of CV by Fenton oxidation process, have been studied systematically. The degradation kinetics of CV was also elucidated based on the experimental data. The degradation of CV obeys the first-order reaction kinetics. The kinetic model can be described as k = 1.5 exp(−(7.5)/(RT))[H2O2]00.8718[Fe2+]00.5062. According to the IR spectrogram, it is concluded that the benzene ring of crystal violet has been destroyed by Fenton oxidation. The result will be useful in treating dyeing wastewater containing CV by Fenton oxidation process.

Tertiary treatment of slaughterhouse effluent: degradation kinetics applying UV radiation or H2O2/UV

2009 ◽  
Vol 60 (7) ◽  
pp. 1869-1874 ◽  
Author(s):  
D. B. Luiz ◽  
A. K. Genena ◽  
H. J. José ◽  
R. F. P. M. Moreira ◽  
H. Fr. Schröder
Keyword(s):  
Uv Radiation ◽  
Aromatic Compounds ◽  
Water Reuse ◽  
Degradation Kinetics ◽  
Water Source ◽  
Tertiary Treatment ◽  
First Order ◽  
Pseudo First Order ◽  
Over Exploitation ◽  
Kinetics Of

In some Brazilian regions, surface water has become scarce, e.g. semi arid climate areas and densely populated and industrial areas, where water over-exploitation and/or fluvial pollution has been more common. Advanced oxidative processes (AOP) provide treated water as a source of reuse water even with the characteristics of drinking water enabling water reuse practices also in food industries. The secondary wastewater of a slaughterhouse was the water source for a tertiary treatment study evaluating the kinetics of the photo-induced degradation of color and UV254 under UV radiation with and without the addition of H2O2. The proximity of the k′ values of color and UV254 degradation by UV indicates that the compounds responsible for color may be the same content measured by UV254. The H2O2/UV treatment was 5.2 times faster than simple UV in removing aromatic compounds. The degradation kinetics of aromatic compounds in both treatments followed a pseudo-first order law. The pseudo-first order constant for H2O2/UV and UV treatments were kUV254′=0.0306 min−1 and kUV254′=0.0056 min−1, respectively.

scholarly journals Enhanced removal of refractory pollutant from aniline aerofloat wastewater using combined vacuum ultraviolet and ozone (VUV/O3) process

2019 ◽  
Vol 80 (12) ◽  
pp. 2250-2259
Author(s):  
Xiaoyu Deng ◽  
Dachao Zhang ◽  
Meng Wu ◽  
Philip Antwi ◽  
Hao Su ◽  
...  
Keyword(s):  
Reaction Time ◽  
Degradation Rate ◽  
Vacuum Ultraviolet ◽  
Degradation Kinetics ◽  
Environmental Risks ◽  
Pollutant Degradation ◽  
Elimination Kinetics ◽  
First Order ◽  
Kinetics Of ◽  
Coexisting Ions

Abstract Aerofloats, such as aniline aerofloat ((C6H5NH)2PSSH), are extensively employed for collection activities in wastewater particularly in cases where minerals are in flotation. Although this aniline aerofloat has efficient collection properties, they are ordinarily biologically persistent chemicals in which case their residual, as well as their byproducts, pose great environmental risks to water and soils. In this study, the removal efficiency of aniline aerofloat (AAF) by a combined vacuum ultraviolet (VUV) and ozone (O3) process (VUV/O3) was evaluated. Furthermore, the impacts of pH, O3, the concentration of AAF and coexisting ions (SiO32−, CO32−, Cl− (Na+), SO42−, Ca2+) were systematically studied. The experiments revealed that, with an initial AAF of 15 mg/L, AAF removal &gt;88% was feasible with a reaction time of 60 min, pH of 8 and O3 of 6 g/h. The order of influence of the selected coexisting ions on the degradation of AAF by VUV/O3 was Ca2+ &gt; CO32− &gt; SiO32− &gt; Cl− (Na+) &gt;SO42−. Compared with VUV and O3 in terms of pollutant degradation rate, VUV/O3 showed a remarkable performance, followed by O3 and VUV. Additionally, the degradation kinetics of AAF by the VUV/O3 process agreed well with first-order elimination kinetics.

Parameters controlling the advanced oxidation degradation kinetics of nitroglycerin and pentaerythritol tetranitrate

2018 ◽  
Vol 7 (1) ◽  
pp. 61-67
Author(s):  
Do Ngoc Khue ◽  
Tran Dai Lam ◽  
Dao Duy Hung ◽  
Vu Quang Bach ◽  
Nguyen Van Anh ◽  
...  
Keyword(s):  
Advanced Oxidation Processes ◽  
Degradation Kinetics ◽  
Advanced Oxidation ◽  
Reaction Rates ◽  
Pentaerythritol Tetranitrate ◽  
Order Model ◽  
Oxidation Processes ◽  
First Order ◽  
Oxidation Degradation ◽  
Kinetics Of

AbstractSeveral advanced oxidation processes have been performed for the decomposition of ester nitrates (ENs), such as nitroglycerine (NG) and pentaerythritol tetranitrate (PETN). The reaction kinetics for removing NG and PETN by some of the advanced oxidation processes (e.g. UV-H2O2, Fenton, UV-Fenton) followed the pseudo-first-order model. The reaction rates in different systems followed the sequence ENs/UV<ENs/H2O2<ENs/UV-H2O2<ENs/Fenton<ENs/UV-Fenton. The effect of various parameters, such as pH, concentration of hydrogen peroxide, and temperature, on the degradation of NG and PETN were studied.

Removal of Acid Yellow 17 Dye by Fenton Oxidation Process

2018 ◽  
Vol 0 (0) ◽  
Author(s):  
Jehangeer Khan ◽  
Murtaza Sayed ◽  
Fayaz Ali ◽  
Hasan Mahmood Khan
Keyword(s):  
Ph Value ◽  
Degradation Kinetics ◽  
Research Work ◽  
Degradation Process ◽  
Optimum Conditions ◽  
Pseudo First Order Reaction ◽  
First Order ◽  
Degradation Reaction ◽  
Fenton Oxidation Process ◽  
Kinetics Of

Abstract In the present research work the degradation of acid yellow 17 (AY 17) by H2O2/Fe2+ was investigated. The effect of various conditions such as pH value, temperature, conc. of H2O2, Fe2+, conc. of AY 17 were studied. Additionally the scavenging effects of various anions such as Cl−, SO42−, CO32− and HCO3−, on percent degradation of AY 17 were examined. It was found that these anions decrease percent degradation as well as rate of degradation reaction. The optimum conditions were determined as [AY 17]=[Fe2+]=0.06 mM [H2O2]=0.9 mM, and pH 3.0 for 60 min of reaction time. It was found that at optimum conditions 89% degradation of AY17 was achieved. The degradation kinetics of AY17 followed pseudo-first-order reaction kinetics. Thermodynamic studies under natural conditions showed positive value of ∆H (enthalpy) which indicates the degradation process is endothermic.

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