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Equilibrium and kinetic studies of Cr (VI) removal from synthetic wastewater by Acroptilon repense flower powder

In this study the removal of Cr (VI) from synthetic wastewater was investigated using Acroptilon repens (Russian Knapweed) flower powder under various conditions (pH, contact time and initial concentration of Cr). The capacity of chromium adsorption at equilibrium conditions by this biosorbent was increased by adsorbate concentration. The results also showed that the removal efficiency of Cr (VI) was increased by increasing the contact time. By increasing the initial concentration of Cr (VI) solution, chromium removal was reduced. The suitability of adsorbents and their constants was tested or evaluated with the Langmuir, Freundlich and Temkin isotherms models. The results indicated that the Freundlich and Langmuir models (R2 > 0.99) gave a better concordance to the adsorption data in comparison with the Temkin equation (R2 = 0.97). The adsorption of Cr (VI) followed the pseudo-second-order kinetics (R2 = 0.991). The study showed that Acroptilon repens flower powder can be used as an effective lignocellulosic biomaterial and biosorbent for the removal of Cr (VI) from wastewater.

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Kinetics and thermodynamics of gossypol extraction from defatted cottonseed meal by ethanol

Kinetics and thermodynamics of gossypol extraction from defatted cottonseed meal by ethanol

Gossypol is polyphenolic aldehyde, a toxic substance naturally present in cotton plant to protect it from insects, pests and diseases. Maximum gossypol is concentrated in the seed. After extraction of oil from the cottonseed, the defatted cottonseed meal which contains both the gossypol and proteinous matter is left behind. A number of attempts have been made using different solvents to extract gossypol from the seeds. However, all these efforts have remained in the realm of academic activity only as none of them could be commercialized. If a pilot plant or commercial scale plant is to be developed then the data on the kinetics and thermodynamics of the extraction process is required. In this study ethanol has been used as the solvent at temperature below 323K for removal of gossypol from the defatted seed. This study finds the effects of parameters viz. temperature, solvent to solid ratio (SR) and extraction time on the gossypol extraction efficiency. The data obtained are used to establish the kinetics and thermodynamics of the extraction process.

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Application of catalysts in the treatment of selected waste chloroorganic compounds

Application of catalysts in the treatment of selected waste chloroorganic compounds

Tetrachloromethane (TCM) and 1,1,2,2-tetrachloroethane (TChE) were oxidized in the temperature range from 300 to 600°C and at contact time of 0.36 s. The following catalysts were applied during the process: the granular one - platinum (0.12%) at the TiO2-SiO2 carrier, platinum ZChO-80 (0.15%) at γ-Al2O3 carrier, palladium (1%) at γ-Al2O3 carrier and monolithic platinum-rhodium catalyst (Pt - 0.09% and Rh - 0.04%) at the cordierite carrier.

The substrates were oxidized in the presence of the above mentioned catalysts with various efficiencies depending on the molecular structure and the type of the catalyst. Palladium contact appeared to be the most active among the others. In the presence of this catalyst, total oxidation of TCM and TChE proceeded at the temperature of 425 and 500°C, respectively. The content of PCDD/Fs in gaseous products obtained during the oxidation of both substrates, was significantly lower than the admissible value of the toxicity equivalent (0.1 ng TEQ/m3).

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The effect of important parameters on the natural gas vehicles driving range

Abstract

One of the most important issues regarding Natural Gas Vehicles (NGVs) is the Driving Range, which is defined as capability of a NGV to travel a certain distance after each refueling. The Driving Range is a serious obstacle in the development and growth of NGVs. Thus the necessity of studying the effects of various parameters on the Driving Range could be realized. It is found that the on-board storage capacity and the natural gas heating value have the greatest effect on the Driving Range. The charged mass of NGV cylinders is varied due to the natural gas composition and the final in-cylinder values (temperature and pressure). Underfilling of NGV cylinders, during charging operations, is a result of the elevated temperature which occurs in the NGV storage cylinder, due to compression and other processes could be overcome by applying extensive over-pressurization of the cylinder during the fuelling operation. Here, the effects of the most important parameters on the Driving Range have been investigated. The parameters are natural gas composition, engine efficiency and final NGV on-board in-cylinder temperature and pressure. It is found that, the composition has big effects on the Driving Range. The results also show that as final in-cylinder pressure decreases (or temperature increases), the Driving Range will be increased.

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Ultrasound-assisted emulsification–microextraction and spectrophotometric determination of cobalt, nickel and copper after optimization based on Box-Behnken design and chemometrics methods

Abstract

A fast, simple, and economical method for extraction, preconcentration and determination of cobalt, nickel and copper as their 1-(2-pyridilazo) 2-naphthol (PAN) complexes based on ultrasound-assisted emulsification–microextraction (USAEME) and multivariate calibration of spectrophotometric data is presented. Various parameters affecting the extraction efficiency were optimized both with univariate and Box–Behnken design. The resolution of ternary mixtures of these metallic ions was accomplished by using partial least-squares regression (PLS), orthogonal signal correction-partial least-squares regression (OSC-PLS), and orthogonal signal correction-genetic algorithmspartial least-squares regression (OSC-GA-PLS). Under the optimum conditions, the calibration graphs were linear in the range of 2.0–150.0, 2.0–120.0 and 2.0–150.0 ng mL−1 for Co2+, Ni2+, and Cu2+, respectively, with a limit of detection of 0.14 (Co2+), 0.13 (Ni2+) and 0.14 ng mL−1 (Cu2+) and the relative standard deviation was <2.5%. The method was successfully applied to the simultaneous determination of these cations in different samples.

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Extraction of rubidium and cesium from brine solutions using a room temperature ionic liquid system containing 18-crown-6

Abstract

Application of 1-butyl-3-metyhlimidazaolium hexafluorophosphate ([C4mim][PF6]), in the extraction of rubidium and cesium from brine solutions using 1,4,7,10,13,16-hexaoxacyclooctadecane (18C6) as extractant was investigated. Parameters that affect the extraction including pH of aqueous phase, equilibration time, dosage of the ionic liquid, phase ratio, concentration of 18C6 were studied. Under the optimal conditions, the single extraction efficiency of rubidium ions and cesium ions were up 84.11% and 94.99%, respectively. The stripping of alkali metal ions from the loaded organic phase with different stripping agents and concentrations were also investigated. The initial value of the K/Cs and K/Rb ratios were 93.0 and 104.3, respectively, which have dropped 91.21% and 88.01%, respectively, after the extraction and stripping experiments. It was taken a big step in the separation and enrichment of cesium (rubidium) ion and potassium ion. The extraction mechanism was revealed most likely to be a cation exchange mode in this system.

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Batch removal of Pb (ΙΙ) ions from aqueous medium using gamma-Al2O3 nanoparticles/ethyl cellulose adsorbent fabricated via electrospinning method: An equilibrium isotherm and characterization study

Abstract

The aim of the present work is to study the efficiency of a biocompatible polymer-based adsorbent for the removal of Pb (II) ions whose devastating effects on people’s health is a matter of great concern from aqueous solution. In this study, ethyl cellulose and gamma-Al2O3 nanoparticles/ethyl cellulose electrospun adsorbents were prepared for the batch removal of Pb (II) ions from aqueous solution. Both samples were characterized using contact angle analysis, N2 adsorption/desorption technique, FT-IR and SEM. The Freundlich model (R-square = 0.935 and RMSD (%) = 6.659) and the Dubinin-Radushkevich model (R-square = 0.944 and RMSD (%) = 6.145) were found to be more reliable in predicting the experimental data from the adsorption of Pb (II) ions onto the electrospun gamma-Al2O3 nanoparticles/ethyl cellulose than the Langmuir model (R-square = 0.685 and RMSD (%) = 14.61) and also the Temkin model (R-square = 0.695 and RMSD (%) = 14.38).

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COD reduction studies of paper mill effluent using a batch recirculation electrochemical method

COD reduction studies of paper mill effluent using a batch recirculation electrochemical method

The conventional method of treating pulp and paper mill effluent involves the biological oxidation by bacterial action of aerobic and anaerobic conditions and aerobic lagooning method, which are less efficiency of removing COD. To overcome the drawbacks of the existing treatment process, in the present work an attempt has been made to study the electro oxidative destruction of the pulp and paper mill effluent using an electrochemical method and the effect of various parameters such as concentration of supporting electrolytes, current densities, flow rates of electrolyte and reservoir volumes of the effluent were conducted. From the experimental results it is observed that the rate of reduction of COD of the effluent increased with an increase in the supporting electrolyte (sodium chloride) concentration, current density where as it decreased with increase in the reservoir volume and the flow rate of electrolyte. The residence time distributions studies have also been conducted to study the behavior of the electrochemical reactor.

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Vegetable oils derivatives as the modifiers of the lubricating properties of water

Vegetable oils derivatives as the modifiers of the lubricating properties of water

Water has been used as a lubricating medium in a number of applications in tribology. Its insufficient lubricating properties are modified by appropriate additives. The aim of the tribological studies presented in this paper is an application of a mixture containing triglyceride ethoxylates and partial glycerides as well as esters and a block copolymer as additives. All the components are commercially available and relatively cheap. In order to examine the aqueous solutions, two kinds of tests were carried out on a four-ball apparatus: at the fixed load - measurements of the friction coefficient and wear as a function of time and seizure tests which made it possible to determine the scuffing load (Pt), the seizure load (Poz) and the limiting pressure of seizure (poz). Changes in the quantities measured were analyzed as a function of concentrations ranging from 0.001% to 100%. In the fixed load tests the coefficient of friction decreased almost eight-fold, reaching the lowest value of 0.06 at above 0.1% concentration of the additive. Wear decreased over 3.5-fold. In the seizure tests a relatively high efficiency of the additive package was observed at the concentration of the order of the thousandth part of one percent. The compositions reached the maximum anti-seizure capacity at the concentrations of 4 and 10%. It is particularly interesting to note that the stability of the lubricating film being formed was characterized by the scuffing load. The maximum value of Pt was about 4kN high. Summing up, on the basis of the results obtained it may be concluded that the choice of package additives was correct and it effectively modified the lubricating properties of water.

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Development of approach to modelling and optimization of non-stationary catalytic processes in oil refining and petrochemistry

). Modeling and optimal control of catalytic reforming reactor units: PhD. Dis. 6. Buzko, V.Y., Suhno, I.V., Panyushkin, V.T. & Ramazanova, D.N. (2005). Theoretical study of 1,4-dioxane complexes in the chair conformation with water by MNDO/PM3 semi-empirical method/ Journal of Structural Chemistry , (46), 618-624. DOI: 10.1007/s10947-006-0176-0. 7. Ivashkina, E.N. (2007). Improving of higher hydrocarbons C9-C14 dehydrogenation process efficiency: Ph.D. Dis. 8. Chenier P. (2002). Survey of Industrial Chemistry . Kluwer

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