scholarly journals Ventilation of an Isolated Subsurface Structure Induced by Natural Forces

2019 ◽  
Vol 4 (2) ◽  
pp. 33 ◽  
Author(s):  
Thomas Neil McManus ◽  
Assed Haddad
Keyword(s):  
Gasoline Engine ◽  
Operating Time ◽  
Zero Order ◽  
Statistical Testing ◽  
Order Kinetic ◽  
Confined Space ◽  
Subsurface Structure ◽  
Different Seasons ◽  
Cast Concrete ◽  
Isolated Structures

The subsurface infrastructure comprises many types of isolated structures, a type of confined space. This study reports on the effect of engine operating time, number/area and spacing of openings in the manhole cover, and operation during different seasons on ventilation of a subsurface, isolated, pre-cast concrete chamber through opening(s) in the manhole cover. Carbon monoxide (CO) emitted by a small gasoline engine reached 800 ppm in 30 s at the start of testing. Ventilation occurred continuously. Generally, the concentration of CO reported by instruments located at different heights was the same for the same moment in time, suggestive of a rapidly well-mixed atmosphere. Mathematical modelling suggested that ventilation occurred through a zero-order kinetic process. Statistical testing suggested that optimization of ventilation is possible through design modifications such as change in the number/area/shape/spacing/geometric arrangement of openings in the manhole cover. Optimizing the rate of ventilation induced by natural forces during the interval between entries will reduce the risk of explosion of the confined atmosphere and overexposure of workers when opening the manhole cover to prepare for entry. This improvement will have immense implications to safety worldwide.

scholarly journals Process modeling of municipal solid waste compost ash for reactive red 198 dye adsorption from wastewater using data driven approaches

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mohammad Hadi Dehghani ◽  
Mehdi Salari ◽  
Rama Rao Karri ◽  
Farshad Hamidi ◽  
Roghayeh Bahadori
Keyword(s):  
Organic Matter ◽  
Municipal Solid Waste ◽  
Solid Waste ◽  
Adsorption Process ◽  
Operating Time ◽  
Organic Matter Content ◽  
Order Kinetic ◽  
Box Behnken Design ◽  
Reactive Red 198 ◽  
Msw Compost

AbstractIn the present study, reactive red 198 (RR198) dye removal from aqueous solutions by adsorption using municipal solid waste (MSW) compost ash was investigated in batch mode. SEM, XRF, XRD, and BET/BJH analyses were used to characterize MSW compost ash. CNHS and organic matter content analyses showed a low percentage of carbon and organic matter to be incorporated in MSW compost ash. The design of adsorption experiments was performed by Box–Behnken design (BBD), and process variables were modeled and optimized using Box–Behnken design-response surface methodology (BBD-RSM) and genetic algorithm-artificial neural network (GA-ANN). BBD-RSM approach disclosed that a quadratic polynomial model fitted well to the experimental data (F-value = 94.596 and R2 = 0.9436), and ANN suggested a three-layer model with test-R2 = 0.9832, the structure of 4-8-1, and learning algorithm type of Levenberg–Marquardt backpropagation. The same optimization results were suggested by BBD-RSM and GA-ANN approaches so that the optimum conditions for RR198 absorption was observed at pH = 3, operating time = 80 min, RR198 = 20 mg L−1 and MSW compost ash dosage = 2 g L−1. The adsorption behavior was appropriately described by Freundlich isotherm, pseudo-second-order kinetic model. Further, the data were found to be better described with the nonlinear when compared to the linear form of these equations. Also, the thermodynamic study revealed the spontaneous and exothermic nature of the adsorption process. In relation to the reuse, a 12.1% reduction in the adsorption efficiency was seen after five successive cycles. The present study showed that MSW compost ash as an economical, reusable, and efficient adsorbent would be desirable for application in the adsorption process to dye wastewater treatment, and both BBD-RSM and GA-ANN approaches are highly potential methods in adsorption modeling and optimization study of the adsorption process. The present work also provides preliminary information, which is helpful for developing the adsorption process on an industrial scale.

Nitrogen removal characteristics of nitrification and denitrification filters

1994 ◽  
Vol 29 (10-11) ◽  
pp. 409-416 ◽  
Author(s):  
F. Çeçen ◽  
I. E. Gönenç
Keyword(s):  
Nitrogen Removal ◽  
Rate Constants ◽  
Order Rate Constant ◽  
Zero Order ◽  
Ammonia Removal ◽  
Nitrite Accumulation ◽  
Order Kinetic ◽  
Order Rate ◽  
In Series ◽  
Nitrification And Denitrification

The kinetics of nitrogen removal was studied in upflow submerged nitrification and denitrification filters in series. Nitrification followed first-, half-, and zero-order kinetics. For the half-order range the half-order rate constant was about 0.9gNH4-N1/2m−1/2d−1. The zero-order rate constants for the DO ranges of 2-3 mg/L and 4-5 mg/L were found as 0.47 gNH4-Nm−2d−1 and 1.82 gNH4-Nm−2d−1, respectively. In the zero-order region ammonia removal proceeded as a half-order reaction in oxygen concentration and the half-order rate constants were about 1.4-2.7 gO21/2m−1/2d−1. Nitrite accumulation reached a considerable degree at bulk oxygen to bulk ammonia ratios lower than 5 since the formation of nitrate was inhibited. Similar to nitrification half- and zero-order kinetic regions were also observed in denitrification. The half- and zero-order rate constants for carbon unlimited cases (influent COD/NOx-N>5) were about 0.23 gNOx-N1/2m−1/2d−1 and 1.9 gNOx-Nm−2d−1, respectively. The nitrite produced in the nitrification stage could be reduced in denitrification. The removal kinetics in the presence of nitrite was found to be similar to the kinetics when the influent consisted of nitrate only.

Added-value porous materials for controlled thymol release obtained by supercritical CO2 impregnation process

2019 ◽  
Vol 38 (5-6) ◽  
pp. 153-166 ◽  
Author(s):  
Stoja Milovanovic ◽  
Darka Markovic ◽  
Jasna Ivanovic
Keyword(s):  
Pore Diameter ◽  
Operating Time ◽  
Zero Order ◽  
Average Pore Diameter ◽  
Added Value ◽  
Average Pore ◽  
First Order ◽  
Supercritical Impregnation ◽  
Bioactive Substance ◽  
Environmentally Friendly Process

This study explores utilization of biodegradable and biocompatible polymers for controlled release of natural bioactive substance. For that purpose, poly(ε-caprolactone) (PCL) beads, cellulose acetate (CA) film, and poly lactic- co-glycolic acid (PLGA) flakes were impregnated with thymol by employing environmentally friendly process of supercritical carbon dioxide (scCO2) impregnation. At selected pressure and temperature, prolongation of operating time increased thymol loading. Pure scCO2 did not affect CA film with average pore diameter of approximately 3 µm, while it enabled change of PCL beads and PLGA flakes into foams with average pore diameter approximately 175 µm and 87 µm, respectively. Additionally to scCO2, thymol acted as a plasticizer increasing pore size of polymers up to three times. Kinetic of thymol release from selected samples was tested using phosphate buffer saline at 37°C and successfully described with Korsmeyer–Peppas, zero-order, first-order, and Higuchi models. The suggested method of PCL, CA, and PLGA supercritical impregnation led to development of porous, solvent free, added-value materials that release thymol in a controlled manner from 5 h to several days.

Browning Reaction Kinetics of High Hydrostatic Pressure-Treated Peach Puree during Storage

2011 ◽  
Vol 7 (4) ◽  
Author(s):  
Thamer Abdul Kadir Khalil ◽  
Mazin Ibrahem Al-Zubaidy ◽  
Omer Fawzi Abdulaziz
Keyword(s):  
Hydrostatic Pressure ◽  
High Hydrostatic Pressure ◽  
Temperature Scale ◽  
Zero Order ◽  
Order Kinetic ◽  
Browning Reaction ◽  
Color Development ◽  
Order Kinetic Model ◽  
Pressure Scale ◽  
Kinetics Of

Kinetics of browning color development, described as browning index (BI), of peach puree subjected to high hydrostatic pressure (HHP) treatments (400, 500, and 600 MPa/1 and 3 min) during 6 weeks of storage at 4 and 20°C were investigated. This research was conducted to modify the use of pressure scale instead of temperature scale in calculating the kinetic parameters of BI values in peach puree samples. The increase in BI values followed the zero-order kinetic model. The highest activation energy (Ea) was experienced with HHP treatment (400, 500, and 600 MPa/3 min) of peach puree samples stored at 4°C.

scholarly journals Effect of Packaging Films on the Quality of Canola Oil under Photooxidation Conditions

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Hao Sun ◽  
Li-xin Lu ◽  
Chang-feng Ge ◽  
Ya-li Tang
Keyword(s):  
Peroxide Value ◽  
Canola Oil ◽  
Transmission Rate ◽  
Zero Order ◽  
Order Kinetic ◽  
High Concentration ◽  
Packaging Films ◽  
Oxygen Transmission Rate ◽  
Oxygen Transmission

The objective of this study was to evaluate the influence of packaging films on the quality of canola oil which contains high concentration of fat under photooxidation condition and get the oxidation kinetics based on measuring the oxidation intensities including peroxide value, hexanal, and photosensitizer (chlorophyll). The canola oil was packaged by PET/CPP; KPET/PE was used for experiments. The change of light and oxygen transmission rate (OTR) of PET/CPP which was considered as the typical fatty foods packaging film under different light intensities was also tested. The results show that the peroxide value increased rapidly under light conditions and fitted the zero order kinetics; also the oxygen transmission rate had great impact on it; hexanal fitted the zero order kinetic in oil whose package of low OTR generated a lot; however package in high OTR films changed very slowly that might be dependent on the performance of hexanal through plastic films. The degradation of chlorophyll fitted the first order kinetic and decreased quickly under light but was almost independent of OTR of transparent packaging material. Light reduced the oxygen barrier properties of the films, which should be considered as the photooxidation condition (and the photooxidation condition thus should be considered).

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

2018 ◽  
Vol XXIII ◽  
pp. 76-87 ◽  
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.

scholarly journals Increased Oral Bioavailability of Resveratrol by Its Encapsulation in Casein Nanoparticles

2018 ◽  
Vol 19 (9) ◽  
pp. 2816 ◽  
Author(s):  
Rebeca Peñalva ◽  
Jorge Morales ◽  
Carlos González-Navarro ◽  
Eneko Larrañeta ◽  
Gemma Quincoces ◽  
...  
Keyword(s):  
Oral Bioavailability ◽  
Oral Solution ◽  
Zero Order ◽  
Order Kinetic ◽  
Naturally Occurring ◽  
Mean Size ◽  
Ph Conditions ◽  
The Mean

Resveratrol is a naturally occurring polyphenol that provides several health benefits including cardioprotection and cancer prevention. However, its biological activity is limited by a poor bioavailability when taken orally. The aim of this work was to evaluate the capability of casein nanoparticles as oral carriers for resveratrol. Nanoparticles were prepared by a coacervation process, purified and dried by spray-drying. The mean size of nanoparticles was around 200 nm with a resveratrol payload close to 30 μg/mg nanoparticle. In vitro studies demonstrated that the resveratrol release from casein nanoparticles was not affected by the pH conditions and followed a zero-order kinetic. When nanoparticles were administered orally to rats, they remained within the gut, displaying an important capability to reach the intestinal epithelium. No evidence of nanoparticle “translocation” were observed. The resveratrol plasma levels were high and sustained for at least 8 h with a similar profile to that observed for the presence of the major metabolite in plasma. The oral bioavailability of resveratrol when loaded in casein nanoparticles was calculated to be 26.5%, 10 times higher than when the polyphenol was administered as oral solution. Finally, a good correlation between in vitro and in vivo data was observed.

scholarly journals Insights into the Time Evolution of Slowly Photodegrading Contaminants

Molecules ◽  
2021 ◽  
Vol 26 (17) ◽  
pp. 5223
Author(s):  
Davide Vione
Keyword(s):  
Time Trend ◽  
Main Role ◽  
Order Kinetic ◽  
Photochemical Degradation ◽  
Transformation Kinetics ◽  
Similar Time ◽  
First Order ◽  
First Order Kinetics ◽  
Different Seasons ◽  
Modelling Approach

Photochemical degradation plays an important role in the attenuation of many recalcitrant pollutants in surface freshwaters. Photoinduced transformation kinetics are strongly affected by environmental conditions, where sunlight irradiance plays the main role, followed by water depth and dissolved organic carbon (DOC). Apart from poorly predictable weather-related issues, fair-weather irradiance has a seasonal trend that results in the fastest photodegradation in June and the slowest in December (at least in temperate areas of the northern hemisphere). Pollutants that have first-order photochemical lifetimes longer than a week take more than one month to achieve 95% photodegradation. Consequently, they may experience quite different irradiance conditions as their photodegradation goes on. The relevant time trend can be approximated as a series of first-order kinetic tracts, each lasting for one month. The trend considerably departs from an overall exponential decay, if degradation takes long enough to encompass seasonally varying irradiance conditions. For instance, sunlight irradiance is higher in July than in April, but increasing irradiance after April and decreasing irradiance after July ensure that pollutants emitted in either month undergo degradation with very similar time trends in the first 3–4 months after emission. If photodegradation takes longer, pollutants emitted in July experience a considerable slowdown in photoreaction kinetics as winter is approached. Therefore, if pollutants are photostable enough that their photochemical time trend evolves over different seasons, degradation acquires some peculiar features than cannot be easily predicted from a mere analysis of lifetimes in the framework of simple first-order kinetics. Such features are here highlighted with a modelling approach, taking the case of carbamazepine as the main example. This contaminant is almost totally biorecalcitrant, and it is also quite resistant to photodegradation.

Performance evaluation of anoxic and facultative wastewater stabilization ponds

1996 ◽  
Vol 33 (7) ◽  
pp. 141-145 ◽  
Author(s):  
Muwaffaq M. Saqqar ◽  
M. B. Pescod
Keyword(s):  
Performance Evaluation ◽  
Kinetic Equation ◽  
Simple Model ◽  
Operating Time ◽  
Order Kinetic ◽  
Sediment Depth ◽  
First Order ◽  
Maximum Value ◽  
Wastewater Stabilization Ponds ◽  
Order Kinetic Equation

The performance of anoxic and facultative ponds in Jordan was investigated for 12 months. Calculated values of the first order kinetic equation rate for CBOD removal (KCBOD) has resulted in different KCBOD's for different ponds in the same month, at the same temperature. It is evident that factors other than temperature must influence values of KCBOD. The KCBOD values determined were generally lower than those reported in the literature. The maximum value found was only 0.16 (/day). A pond was emptied after 18 months of operation and sediment was found randomly distributed over the pond area, with a depth ranging from 2 to 6 cm (averaging ≈ 4 cm). A simple model has been established to estimate sediment depth (Hs in cm) in terms of the operating time in months (t).

TRANSPORTABILITY OF IODIDE IN SOME ORGANIC SOIL MATERIALS FROM THE PRECAMBRIAN SHIELD OF ONTARIO

1987 ◽  
Vol 67 (2) ◽  
pp. 353-366 ◽  
Author(s):  
J. T. KOCH ◽  
B. D. KAY
Keyword(s):  
Rate Constant ◽  
Nuclear Power ◽  
Power Plants ◽  
Organic Soil ◽  
Zero Order ◽  
Organic Soils ◽  
Order Kinetic ◽  
Precambrian Shield ◽  
Zero Order Kinetics ◽  
Order Kinetic Model

Knowledge of the transportability of the long-lived and potentially hazardous nuclide 129I in organic soils is important for evaluating the concept of safely disposing of radioactive fuel waste from Canadian nuclear power plants. The current concept for the disposal of nuclear fuel waste in Canada involves its emplacement in a vault mined 500–1000 m deep in a stable plutonic rock formation in the Canadian Shield. Degradation over time of components of the vault could lead to the entry of 129I to organic soils from contaminated groundwater. Twelve samples from nine organic soils, widely different in degree of humification and in parent vegetation, were collected from the Precambrian Shield of Ontario. Batch reaction techniques were used to measure the kinetics of iodide loss from solution in the presence of the organic soil materials. All soil materials exhibited an initial constant rate of iodide loss from solution (zero-order kinetics). The rate constants for iodide loss for the different soil materials ranged from 1.44 to 36.0 mg iodide per kilogram soil per day. The natural I content for the organic soil samples was positively correlated to the measured rate constant. It is concluded that the rate constant for iodide, as measured in the laboratory, is related to the processes that operate in the field to immobilize I under natural conditions, and that a zero-order kinetic model is appropriate for describing the loss of iodide from the solution phase in an organic soil. Key words: Organic soils, iodide-129, groundwater, transport kinetics, immobilization

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