Rate Law Model Research Articles

Modeling of Biofoam Destabilization by Biodefoamers in Poultry Slaughterhouse Wastewater Treatment Activated Sludge

Biofoam formation in wastewater treatment is a challenge globally. Previously, we successfully proposed the use of biodefoamers instead of synthetic defoamers for environmental protection. In this study, we report on biodefoamation modeling using activated sludge organisms. Overall, the rate law model was determined to adequately describe foam drainage including collapse while applying biodefoamers. The target industry is the poultry processing industry whereby foam formation during wastewater treatment is an ongoing challenge.

A grain-scale modeling on the surface burning and agglomeration of the metalized solid propellants

This study delves into the dynamic behavior of reactive grains within metalized propellants during surface deflagration. Our grain-scale simulations account for both fast and slow deflagration processes involving two distinct metal fuels, namely zirconium and magnesium, with potassium perchlorate (KClO4) as the common oxidizer. Our primary goal is to develop a model and numerical technique capable of replicating the surface reactions observed in experiments. To achieve this, we utilize the compressible Navier–Stokes equations, incorporating the Arrhenius rate law and Johnson-Cook stress model. We pay particular attention to the melt layer, where surface burning occurs in an open atmosphere, and we develop a mechanism to describe the interaction between reactive grains and exhaust gases. We differentiate between two limiting scenarios: convective burning, where unreacted particles experience high-speed compression waves leading to reduced thermal diffusion within the cold reactant, and diffusive burning, characterized by insufficient pressure from particles undergoing both reaction and deformation to erode the burning surface. This results in pronounced agglomeration and the formation of gaseous metal oxides above the melt layer. The results shed light on critical factors influencing surface combustion, including the thermal softening of reactive particles, the time required for particle agglomerations, and tangential forces at multi-element interfaces within the grain-scale simulation domain.

True Order Determination of Sonochemical Degradation Kinetics of Organic Contaminants in Water Using the Half-lives Method

In the literature, the modeling of the sonolytic decomposition kinetics of organic contaminants in water has been carried out using the pseudo-first and pseudo-second order equations. The results obtained with this method are totally biased because it requires the assumption of the order of the degradation reaction, which is a real limitation, and the sonochemical oxidation mechanism is a very complex phenomenon that cannot be described by such simple models. In this paper, for the first time, the true order of the sonochemical degradation kinetics of organic pollutants in aqueous solutions at various initial substrate concentrations was determined using the half-lives method combined with the general rate law model, i.e., the pseudo-nth order equation. Linear and nonlinear regression techniques were used to determine the order of the sonolytic destruction reaction. The half-life technique for the general rate law model can adequately describe the experimental results of the sono-destruction of the investigated pollutants. For rhodamine B and naphthol blue black, the sono-destruction mechanism for both contaminants does not change as the initial contaminant concentration varies over the range examined, while for 4-isopropylphenol and furosemide, the sono-destruction mechanism changes as the initial substrate concentration varies. A fractional order of the sonolytic destruction reaction was determined for all the pollutants tested. These fractional orders of sono-destruction reactions indicate the complex nature and behavior of the reactions, often involving multiple steps or mechanisms. They also reveal a more complex interaction between pollutant concentration and sonolytic destruction rate. In a word, the method developed in this paper should be used to determine the real order of the sono-oxidation reaction of nonvolatile organic pollutants in aqueous phase.

Application of the general rate law model to the sonolytic degradation of nonvolatile organic pollutants in aqueous media

The pseudo-first and pseudo-second order equations have been the most commonly used models to characterize the sonolytic disappearance kinetics of nonvolatile pollutants in aqueous media. In this work, the general rate law model, i.e., pseudo-nth order kinetics equation, was applied for the first time to the sono-decomposition of different nonvolatile organic pollutants, naphthol blue black (NBB), furosemide (FSM), 4-isopropylphenol (4-IPP), and rhodamine B (RhB), in water. It was shown that the general rate law for a chemical reaction would apply to the kinetics of sonochemical decomposition. It is not feasible to set the order of ultrasonic pollutant degradation kinetics to pseudo-first or pseudo-second, as is typically used in numerous studies. The sonochemical oxidation reaction has a fractional order, the order is often non-integer, which frequently indicates a complex sonolytic decomposition reaction mechanism. The degradation mechanism of NBB and RhB does not change with the initial substrate concentration. They are ultrasonically degraded by hydroxyl radicals both in the bulk liquid solution and at the liquid/bubble interfacial layer. The destruction mechanism of FSM and 4-IPP changes as the initial contaminant concentration changes. At low initial substrate concentrations, these pollutants are oxidized mainly by reaction with hydroxyl radicals in the bulk liquid solution and at the interfacial shell of the cavitation bubbles. At high initial substrate concentrations, FSM and 4-IPP are degraded by thermal destruction in the liquid/bubble interfacial layer and by •OH radicals both in the bulk liquid solution and at the liquid/bubble interfacial layer. Additionally, the pseudo-nth order model predicts very well the sonolytic degradation at various sonication frequencies and intensities. The general rate law expression should be used to assess the real kinetics order of the sonolytic destruction process without any predetermined assumptions or constraints.

Thermometry of stored molecular ion beams

The radiative cooling of a stored, initially rotationally hot OH^{-} ion beam is probed by photodetachment using an electrostatic ion beam trap combined with an in-trap velocity map imaging spectrometer, providing direct measurement of the time-dependent rotational population. The rotational temperatures are estimated from photodetached electron spectra as a function of time using a Boltzmann distribution model and further verified by a rate law model using known Einstein coefficients. We demonstrate that during the entire cooling time, the rotational population can be well described by a Boltzmann distribution.

Identifying the cooling heterogeneity and quality decay of Indian mangoes during cold chain export by multiphysics modeling

AbstractPrediction and analysis of temperature‐based quality evolution of those perishables subjected to extreme temperatures in a shipment can guide the stakeholders and decision‐makers regarding the final quality of shipment and export mode. This study aims to forecast the temperature heterogeneity among the perishables packed in a standard ventilated carton for sea‐borne cold chain and airways export, using Computational Fluid Dynamics (CFD) simulation. The biochemical processes affecting the fruit quality are also evaluated, and the overall quality is predicted with the help of the Kinetic rate law model. The case of an Indian mango export to United States is considered for the present study, and a preferable export mode is suggested. The model is experimentally validated with a discrepancy of 1.516 K (RMSE) and 9.504% (MAPE), respectively. The findings indicate more heterogeneous temperature distribution in the case of seaways export (nearly 3 K) compared to airways (1.5 K). The temperature‐dependent quality attributes, following different kinetics, decays by 46% and 89.6% on the 10th day of seaways export. This observation indicates that the mangoes will be spoiled in transit as seaways export to United States takes around 28 days. From these observations, under the given transit conditions, it is recommended to export mangoes via airways to the United States from India, which takes about 3 days.Practical ApplicationsMonitoring the temperature of perishables is an indispensable part of cold chain export for maintaining their quality and extending their shelf life. This study proposes a virtual or simulation‐based approach to analyze the cooling behavior of individual mangoes and hence predict the evolution of its various quality attributes, passing through different stages of the cold chain. The technique used is quite promising in predicting the export potential and export mode of the produce before the actual export process takes place, thus preventing excessive in‐transit loss. The method mentioned above is applied in an illustrative case study of Indian mango export to the United States. Its application can be further extended to the export of other perishables to various importing countries.

Biosynthesis of Ag Nanoparticles Using Caralluma acutangula Extract and Its Catalytic Functionality towards Degradation of Hazardous Dye Pollutants

Nanomaterials, today, are an integral part of our everyday lives, industrial processes and appliances. Biosynthesis, because of its environmental sustainability, is now becoming a hot topic. The biosynthesis of nanomaterials using plant phytochemicals enhances the nanomaterial’s biocompatibility and its compatibility with the environment too. Hence, forthe first time, this study uses Caralluma acutangula (CA) plant extracts to synthesize silver nanoparticles (CA-AgNPs) and characterize them using UV–visible spectroscopy, FTIR, Raman spectroscopy, XRD, TEM, TGA, SEM, EDX, zeta potential, and bandgap analysis. The particle size distributions of CA-AgNPs were observed to fall in the range of 2–6 nm predominantly using TEM images. High crystallinity % was calculated as 86.01 using XRD data. Extracted phytochemicals from CA were characterized and analyzed using GC-MS. The bandgap (Eg) of CA-AgNPs was calculated as 3.01 eV and zeta potential was found to be −16.1 mV. The biosynthesized CA-AgNPs were confirmed for their degradation efficiency of two toxic water pollutant dyes: Congo red, CR (95.24% degradation within 36 min), and methylene blue, MB (96.72% degradation within 32 min), in the presence of NaBH4. Different doses of CA-AgNPs and NaBH4 were checked for their chemical kinetics and rate constant analysis. The chemical kinetics were explored on the basis of integrated rate law model equations and confirmed as pseudo-zero-order reactionsfor CR and MB dyes. The rate constant ‘k’ for CR and MB was calculated as 0.0311 and 0.0431 mol.L−1.min−1, respectively.

Kinetic evaluation of gelatin extraction from chicken skin and the effect of some extraction parameters

AbstractKinetic models have been extensively studied for the prediction of yield and quality for plant‐sourced ingredients although that is very rare for animal‐sourced products. This study is designed to evaluate common kinetic models for the prediction of yield in gelatin extraction from chicken skin. Kinetic models used for comparison were the Peleg's, the first order, and the rate law models while extraction parameters studied were solvent pH, solid:liquid ratio, and sample size. Extraction is evaluated based on the protein and hydroxyproline (Hyp) concentrations of each extract. The success of the models is evaluated based on the root‐mean‐square error (RMSE) and the coefficient of determination (R2) values calculated for fittings of the models to the experimental data. The protein content of the dried and degreased skin was over 50% before gelatin extraction. Neutral pH led to the highest yield for both protein and Hyp, which were close to 2,100 and 200 mg per 10 g of skin, respectively. Similarly, smaller sample size or lower solid:liquid ratio resulted in a higher yield. In general, the first 60 min of the extraction was by rapid washing and later on by slow diffusion. Peleg's model is found to be the best fit to the experimental data with the highest R2 values between 0.97 and 0.99 and the lowest RMSE values compared to that of other kinetic models. This is the first report on the kinetics of gelatin extraction as well as one of the few studies on extraction kinetics of animal‐sourced products.Practical ApplicationsExtraction parameters including the size of the raw material and raw material:solvent ratio showed significant effects on extraction yield. The smaller the size and the ratio, the higher the yield. Kinetics of gelatin extraction is reported for the first time by this manuscript, dealing with the yield during the whole extraction process. Extraction parameters may create substantial variability in quality and yield; thus, the data presented here may be utilized in minimizing those potential variations, by minimizing the time, energy and solvent required. The gelatin industry may use this report in the design of the gelatin extraction process as the data presented concludes that a high‐rate extraction was completed within the first hour of the extraction, leading over 80% of the expected yield. Gelatin manufacturers and researchers in this field may find this manuscript useful as it provides valuable insights on gelatin extraction and its kinetics.

Kinetics of the in−situ hydrogenation of phenol with formic acid as a hydrogen source

Highly active phenolic compounds in biomass pyrolysis oil are an important factor for limiting the utilization of the biofuel. The catalytic hydrogenation of phenolic compounds is considered to be an effective method for reforming bio−oil. Pd/CB (carbon black), which was synthesized by using a facile impregnated method, is found to be an effective catalyst for the in-situ hydrogenation of phenol (a representative model compound of bio−oil) using FA as a hydrogen source to produce cyclohexanone. A 98.99% of the conversion of phenol and 90.20% of the selectivity of cyclohexanone were obtained under the optimized reaction conditions. The catalyst also showed excellent stability after three recycled process. The catalytic kinetics study of the in−situ hydrogenation of phenol was investigated using Power−Rate Law model and Langmuir−Hinshelwood model. The Langmuir−Hinshelwood model fit well to the experimental data and the apparent activation energies (Ea) was 50.96 kJ mol−1.

Coupling regeneration strategy of lithium-ion electrode materials turned with naphthalenedisulfonic acid.

The resource exhaustion and environmental assessment driven by sustainable development make recycle of spent LIBs urgent to be achieved. However, the conventional recycling processes are quite complicated in terms of the tedious steps and secondary contamination. In this paper, hydrosoluble naphthalenedisulfonic acid is firstly proposed to selectively extract valuable metals (Co and Li) for the regeneration of battery materials. Lithium is selectively recovered as lithium enriched solution with a high yield of 99%, while 96.6% cobalt remains in a complex-precipitate benefited from the high acidity and coordination role of naphthalenedisulfonic acid. The leaching of Li fits well with the logarithmic rate law model with an activation energy of 32.42kJ/mol. Additionally, the regenerated lithium-ion battery active materials (Co3O4 anode and LiCoO2 cathode) prepared from the cobalt complex-precipitate and lithium-enriched solution exhibit excellent discharged-charged performances and rate capability. This feasible strategy assisted by multifunctional naphthalenedisulfonic acid may offer an alternative option for the simultaneous recovery of Li and Co and the rational resource utilization of spent lithium-ion batteries.

Theory of delayed response in river morphodynamics: Applicability and limitations

The delayed response of fluvial rivers to external disturbances has been described by many researchers. To simulate such behavior, the rate law model (or the delayed response model) was developed by previous researchers, and has been applied to a series of river morphological problems. However, to date, the applicability of the rate law model has not been fully understood. In the current paper, a physically-based analysis of the rate law model is presented to assess the responses of bed elevation and the grain size of surface sediment, using the response of the Shi-ting River, China, after the 2008 Wenchuan Earthquake as an example. First, a physically-based river morphodynamic model is implemented to reproduce the post-earthquake adjustments of the Shi-ting River. Next, the mathematical properties of the Hirano–Exner equation, which describes the dynamics of both bed elevation and surface texture, are analyzed. It is shown that the dynamics of bed elevation are dominated by a diffusion process and the analytical solution for bed elevation has a similar mathematical formulation to that of the rate law model. Thus, the rate law and morphodynamic models similarly predict the adjustment of bed elevations. In contrast, the dynamics of bed surface texture are controlled by both advection and diffusion processes. The advection and diffusion processes dominate adjustments over the short (annual to decadal scale) and long (century to millenial scale) terms, respectively. These physics produce the multi-scale and non-monotonic character of the adjustment of bed surface texture. As a result, the rate law model is incapable of describing the adjustment of bed surface texture. These findings highlight the applicability and limitations of the rate law model in simulating river morphodynamic processes.

Rheological properties of Indian coffee plum (Flacourtia jangomas) pulp in steady and dynamic shear at different temperatures

ABSTRACT Indian coffee plum (Flacourtia jangomas) is an underutilized fruit with many great nutritional and medicinal value generally available in the northeastern part of India. Although rheological study of different fruit pulps have been studied till now, however no such study has been undertaken on Indian coffee plum. The present study was aimed to evaluate the steady-state shear and viscoelastic rheological properties of Flacourtia jangomas (F. jangomas) pulp as function of temperature in the range 20 to 80°C using dynamic oscillatory viscometry, as well as applicability of Cox-Merz rule. Under steady-state shear tests, the shear stress versus shear rate data were adequately fitted to the Bingham model (R2 = 1) for too low shear rate (0.1to 1.0 s−1) and Power law model (R2 > 0.83) for moderate shear rate (1.0 to 100 s−1). Oscillatory shear data of the fruit pulp showed weak gel behavior where loss modulus exceeded the value of storage modulus. The power modified Cox-Merz rule was tested for all temperature and found applicable for lower temperatures. These results could be beneficial for future studies on food properties and industries.

Prediction of the remaining service lifetime of inflatable rubber dam with deep hole damage

This paper exhibits a method to predict the remaining service lifetime of inflatable rubber dam by considering the appearance of deep hole damage. The material used for the rubber dam is a composite comprising three layers of woven fabric as fiber and EPDM/SBR 64 474 rubber as a matrix. The service lifetime is predicted by calculating the degradation of rubber dam’s material properties. Simple Rate Law model and Time-Temperature Superposition model are employed to calculate the rubber properties degradation. A finite element analysis is then conducted to investigate stress and strain distributions which occur in the rubber dam membrane during operational loading. Furthermore, the effect of deep hole damage in the rubber dam, which is caused by improper maintenance, is modeled as well. The results show that a 7 mm depth of the hole can accelerate rubber degradation, which causes catastrophic failure. This can happen because two layers of the woven fabric in the rubber dam have been broken. Suggestion to hold up the degradation is also discussed.

Reaction rate law model and reaction mechanism covering effect of plasma role on the transesterification of triglyceride and methanol to biodiesel over a continuous flow hybrid catalytic-plasma reactor

This study investigated predictions of reaction mechanisms and reaction rate law model covering effect of plasma role on the heterogeneous catalytic reaction of triglyceride and methanol to produce biodiesel (fatty acid methyl ester - FAME or fatty acid alkyl ester – FAAE) over a continuous flow hybrid catalytic-plasma reactor. This catalytic reaction was carried out in a dielectric-barrier discharge plasma reactor over 5 wt% K2O/CaO–ZnO catalyst under conditions of atmospheric pressure and the reactor temperature of 65 °C. During the hybrid catalytic-plasma reaction system, the voltage, the catalyst diameter, and the Weight Hourly Space Velocity (WHSV) were kept constant at 5 kV, 5 mm, and 1.186/min, respectively. It was found that transesterification reaction with the hybrid roles of catalytic and plasma achieved 77.2% biodiesel yield. Kinetic studies of this transesterification reaction over a continuous flow hybrid catalytic-plasma reactor suggested following Eley-Rideal mechanism model, where the methanol adsorbed on the catalyst surface reacted with triglycerides in bulk phase to produce an adsorbed methyl ester and glycerol in bulk phase. The possible reaction rate law model found is: -rTG = rME = rs = (0.0078∗(0.0061∗CTG∗CM3–3.0302 × 10−6∗CME3∗CG))/(0.1827∗CM+ 0.0145∗CME+1)3 gmol/gcat.min. This reaction rate law model was useful to design reactor of the hybrid catalytic-plasma chemical reaction system for biodiesel production.

A study of the DR23 dye photocatalytic degradation utilizing a magnetic hybrid nanocomposite of MIL-53(Fe)/CoFe2O4: Facile synthesis and kinetic investigations

In this research, cobalt ferrite (CoFe2O4) magnetic nanoparticles as well as MIL-53(Fe) structure were synthesized by the hydrothermal and solvothermal methods, respectively. Moreover, magnetic composites of MIL-53(Fe)/CoFe2O4 nanoparticles with different cobalt ferrite loadings (i.e.; 0.05, 0.1 and 0.2 g) were prepared via the solvothermal method. The main novelty of the present research was to synthesize a magnetic composite of MIL-53(Fe)/CoFe2O4 nanoparticles in order to perform rapid photodegradation of Direct Red 23 (DR23) dye under the LED visible light irradiation. Good magnetic properties of the fabricated composite led to easy separation and rapid retrieval of the catalyst from the reaction mixture. Effects of operational variables such as the initial dye concentration, photocatalyst loading and solution pH upon the performance of synthesized materials were understudied. Characterizations of the prepared photocatalysts were performed through the XRD, SEM, TEM, EDX, FTIR, as well as VSM, DRS, BET-BJH and EIS analyses. Results of the XRD, SEM and FTIR analyses confirmed successful synthesis of CoFe2O4, MIL-53(Fe) and their magnetic composites. Moreover, the desired magnetic value of 28.5 emu/g at 8128 Oe was determined for the MIL-53(Fe)/0.1gCoFe2O4 material. Furthermore, the highest light absorption intensity by this composite was obtained through the UV–Visible DRS analysis. In addition, the value of optical bandgap energy (Eg) for the aforementioned composite was determined to be 2.1 eV. Furthermore, the BET surface areas of the MIL-53(Fe), MIL-53(Fe)/0.1gCoFe2O4 and CoFe2O4 species were evaluated to be 13, 34 and 52 m2/g, respectively. Finally, the photocatalytic degradation of the DR23 over the MIL-53(Fe)/0.1gCoFe2O4 was revealed to be 99.35% after 80 min of duration under the LED irradiations. This was higher than the rest of other understudied materials. In addition, results displayed that, the hydroxyl radicals (OH) as well as photo-generated holes (h+) were the main active species in photocatalytic degradation process undertaken. Ultimately, sufficient yet simple rate law models of the aforementioned dye degradation implementing first- and second-order chemical kinetics upon the prepared catalysts were developed.

Recycling of cathode material from spent lithium ion batteries using an ultrasound-assisted DL-malic acid leaching system

Herein, a novel process involving ultrasound-assisted leaching developed for recovering Ni, Li, Co, and Mn from spent lithium-ion batteries (LIBs) is reported. Carbonate coprecipitation was utilized to regenerate LiNi0.6Co0.2Mn0.2O2 from the leachate. Spent cathode materials were leached in DL-malic acid and hydrogen peroxide (H2O2). The leaching efficiency was investigated by determining the contents of metal elements such as Li, Ni, Co, and Mn in the leachate using atomic absorption spectrometry (AAS). The filter residue and the spent cathode materials were examined using Fourier transform infrared (FTIR) and scanning electronic microscopy. The leaching efficiencies were 97.8% for Ni, 97.6% for Co, 97.3% for Mn, and 98% for Li under the optimized conditions (90 W ultrasound power, 1.0 mol/L DL-malic acid, 5 g/L pulp density, 80 °C, 4 vol% H2O2, and 30 min). The leaching kinetics of the cathode in DL-malic acid are in accordance with the log rate law model. The electrochemical analysis indicates that the LiNi0.6Co0.2Mn0.2O2 regenerated at pH 8.5 has good electrochemical performance. The specific capacity of the first discharge at 0.1 C is 168.32 mA h g−1 at 1 C after 50 cycles with a capacity retention of 85.0%. A novel closed-loop process to recycle spent cathode materials was developed, and it has potential value for practical application and for contributing to resource recycling and environmental protection.

Immobilization of biosorbent in hydrogel as a new environmentally friendly fertilizer for micronutrients delivery

Abstract The aim of this work was to study the use of alginate-carboxymethyl cellulose-eggshell biocomposites as a material with controlled release of Cu2+ ions. The composition of biocomposites was optimized with Response Surface Methodology (5.0 wt% sodium alginate, 1.2 wt% carboxymethyl cellulose, 10.0 wt% eggshells). Physicochemical properties of biocomposites, kinetics and equilibrium of copper(II) ion sorption on structures were investigated. The General Rate Law model best described the kinetics data and the values of kinetic rate constants were 0.259, 0.358 min −1 for wet and dry capsules. The description of the sorption kinetics was also presented with the Weber-Morris diffusion model, which indicated a multi-stage process. The maximum sorption capacities for wet and dry biocomposites were 281 and 49 mg g−1. The composites presented a slow release of ions in the model soil solution (9 wt%/14 days). Studied biocomposites have a good potential as controlled release fertilizers fitting into the concept of sustainable development and precision agriculture. The new fertilizer formulations have the potential to by used as a new type of slow-release fertilizer that delivers micronutrient ions according to the plants uptake pattern with minimization of losses into the environment.

Hydrogel capsules with alfalfa as micronutrients carrier

The aim of this work was to study the properties of biocomposite based on sodium alginate and carboxymethyl cellulose with immobilized alfalfa as a material with controlled release of Cu2+ ions. Physicochemical (swelling, pHZPC) and sorption (kinetics, equilibrium) properties of the produced structures were investigated. Kinetic data were best described using a general rate law model, and the value of kinetic rate constant was 5.34 × 10−6. The sorption kinetics are also described using the Weber–Morris model, and the analysis revealed a three-step sorption. The maximum sorption capacity was determined using the Sips model and amounted to 9 mg g−1. Desorption of Cu2+ ions in soil solution (NaNO3 1 wt%) was carried out, and biocomposites released micronutrients in a slow way. The results showed that biocomposites with immobilized alfalfa are a very good material for potential applications in the agrochemical industry as a controlled released fertilizer.

Effective Removal of CF4 by Combining Nonthermal Plasma with γ-Al2O3

Conversion of CF4 was experimentally evaluated with three systems including catalytic hydrolysis, NTP-alone and plasma catalysis. Firstly, activity of γ-Al2O3 for CF4 conversion was tested via catalytic hydrolysis. Experimental results indicate that the highest CF4 conversion (72%) could be achieved with γ-Al2O3 in the presence of 45% H2O(g) with the operating temperature of 900 °C and the apparent activation energy is calculated as 85 kJ/mol using power rate law model. For plasma-based systems, results indicate that CF4 conversions achieved with plasma catalysis remain 100% with the applied voltage ranging from 12 to 23 kV, while the highest CF4 conversion achieved with NTP-alone is 86%. For the effects of various parameters on plasma-based systems, the results indicate that plasma catalysis also has better resistivity for higher total flow rate, CF4 concentration and O2 contents. Especially, CF4 conversion could maintain at 100% with the operating applied of 23 kV as CF4 concentration is increased to 10,000 ppm. On the other hand, CF4 conversion achieved with NTP-alone is 18% at the same conditions. In addition, negative effect of O2 on plasma catalysis could be reduced by the addition of Ar due to its good discharge properties and high excitation threshold energy (13 eV). The kinetics of plasma catalysis is investigated for CF4 conversion by a simplified model, and the results indicate that overall energy constant achieved with plasma catalysis reaches 0.015 mg J−1. Overall, plasma catalysis is demonstrated with good potential for the reduction of CF4 emission.

Phytoremediation of Copper in Mineral, Distilled and Surface Water using Limnocharis Flava plant

Abstract Phytoremediation provides a low cost and sustainable remediation to eliminate the contaminants in water particularly heavy metals. Some plants have the ability to absorb certain metals while some plants do not. This research investigates the potential of different green plants to absorb copper (Cu) in three types of water; distilled, mineral and surface water. A green plant scientifically named as Limnocharis Flava plant were found to be effective in absorbing the Cu contaminants. The rate of absorption of Cu for different plants and water types were determined and monitored in fume cupboard equipped with tungsten bulb under controlled environment; light intensity, humidity, temperature and concentration of CuSO4. In just 5 days of experiment, the highest rate of absorption of Cu was observed in distilled water where the efficiency was 39.9%. Meanwhile, the absorption efficiency of copper in surface water and mineral water samples were 31.5% and 23.6% respectively. The absorption of Cu in different types of water fitted the 1st order, Rate Law model with >90% coefficient of determination. Other plant named Hydrilla Verticillata were studied using the same metal contaminant and conditions resulted with no observable Cu absorption. The concentration of Cu in the water samples throughout the research were analyzed at 324.8 nm wavelength using Atomic Absorption Spectroscopy (AAS).