scholarly journals Determination of Sorption Properties of Heavy Metals in Various Biosorbents

2018 ◽  
Vol 25 (2) ◽  
pp. 201-216 ◽  
Author(s):  
Andrzej Kłos
Keyword(s):  
Data Interpretation ◽  
Copper Cation ◽  
Reaction Model ◽  
Static System ◽  
Heavy Metal Sorption ◽  
Pseudo Second Order ◽  
High Degree ◽  
Kinetics Of

Abstract Various techniques of determination of properties of physicochemical processes of heavy metal sorption in biosorbents were analysed. The methods of preparing and storing samples, conditions of experiment performance, as well as the methods of data interpretation were discussed. Two procedures of study were analysed: (1) in the static system of biosorbent-solution contact and (2) in the system of dynamic flow of solution. Copper cation sorption was studied. The effect of consecutive stages of the study on the quality of final results was shown. A high degree of uncertainty of the sorption capacity assessment was reported, which was dependent on the manner of conducting the study. The application of the pseudo-second order reaction model was substantiated to describe kinetics of cation-exchange sorption and the model of Langmuir isotherm to describe equilibria. The study conducted reveals that in order to perform comparative analyses, it is necessary to establish a joint concept of conducting studies and the interpretation of results.

scholarly journals Single-sided NMR for the measurement of the degree of cross-linking and curing

2018 ◽  
Vol 7 (1) ◽  
pp. 21-30 ◽  
Author(s):  
Norbert Halmen ◽  
Christoph Kugler ◽  
Eduard Kraus ◽  
Benjamin Baudrit ◽  
Thomas Hochrein ◽  
...  
Keyword(s):  
Relaxation Times ◽  
Curing Kinetics ◽  
Cross Linking ◽  
Scanning Calorimetry ◽  
First Results ◽  
Non Destructive ◽  
Kinetics Of ◽  
Good Agreement

Abstract. The degree of cross-linking and curing is one of the most important values concerning the quality of cross-linked polyethylene (PE-X) and the functionality of adhesives and resin-based components. Up to now, the measurement of this property has mostly been time-consuming and usually destructive. Within the shown work the feasibility of single-sided nuclear magnetic resonance (NMR) for the non-destructive determination of the degree of cross-linking and curing as process monitoring was investigated. First results indicate the possibility of distinguishing between PE-X samples with different degrees of cross-linking. The homogeneity of the samples and the curing kinetics of adhesives can also be monitored. The measurements show good agreement with reference tests (wet chemical analysis, differential scanning calorimetry, dielectric analysis). Furthermore, the influence of sample temperature on the characteristic relaxation times can be observed.

scholarly journals Translocation of Cations During Sorption of Copper in the System Solution - Algae (Spirogyra sp.)/Translokacja Kationów Podczas Procesu Sorpcji Miedzi W Układzie Roztwór - Glony (Spirogyra Sp.)

2014 ◽  
Vol 21 (3) ◽  
pp. 425-433
Author(s):  
Małgorzata Rajfur ◽  
Andrzej Kłos ◽  
Jan Kříž
Keyword(s):  
Order Reaction ◽  
Static System ◽  
Second Order Reaction ◽  
System Solution ◽  
Fixed Proportion ◽  
Pseudo Second Order ◽  
The Difference ◽  
Kinetics Of ◽  
Copper Cations ◽  
Solution Volume

Abstract Kinetics of the sorption of copper cations in Spirogyra sp. algae was analysed, together with the accompanying processes of hydrogen cations sorption and releasing to the solution the cations bonded in the algae: Na+, Mg2+, K+ and Ca2+. It was established that, in a static system, at the fixed proportion of algae mass to the solution volume, these processes occur simultaneously, however presumably the quantity of the released salts influences the parameters of heterophase equilibrium of ion exchange. In the experiment conditions, the quantity of the released cations was nearly 10 times larger than the quantity of the sorbed cations. The equilibrium parameters, determined from the model of pseudo second order reaction, were compared with the parameters obtained after 30 min of the process duration, ie at relatively stable indications of measuring equipment. On the example of the sorbed copper, the difference is approximately 8%. It was confirmed that the solution conductivity is a good parameter for the estimation of the state close to equilibrium.

scholarly journals Amorphous alloys and differential scanning calorimetry (DSC)

2021 ◽  
Author(s):  
Dora Janovszky ◽  
Maria Sveda ◽  
Anna Sycheva ◽  
Ferenc Kristaly ◽  
Ferenc Zámborszky ◽  
...  
Keyword(s):  
Metallic Glasses ◽  
Amorphous Alloys ◽  
Volume Fraction ◽  
Data Interpretation ◽  
Glass Temperature ◽  
Scanning Calorimetry ◽  
Scientific Papers ◽  
Kinetics Of ◽  
Temperature Crystallization

AbstractA remarkable number of scientific papers are available in the literature about the bulk amorphous alloys and metallic glasses. Today, DSC is an essential tool for amorphous alloys research and development, and of course for quality assurance. In many cases, users seek to examine the determination of only one or two properties, although much more information can be obtained from the measurements. The research involved structural relaxation, Curie temperature, glass temperature, crystallization, phase separation, nanocrystalline volume fraction, melting point and liquidus temperature determination subjects and kinetics of microstructural transformations induced by thermal treatment. We collected and present the information that can be obtained with this technique and draws the reader’s attention to some potential problems related to data interpretation.

DEVELOPING OF MATLAB APPLICATION FOR DETERMINING THE REACTION KINETICS OF RUBBER VULCANIZATION PROCESS

2021 ◽  
Author(s):  
Dario Balaban ◽  
◽  
Jelena Lubura ◽  
Predrag Kojić ◽  
Jelena Pavličević ◽  
...  
Keyword(s):  
Kinetic Model ◽  
Reaction Kinetics ◽  
Kinetic Parameters ◽  
Degradation Process ◽  
Complex Process ◽  
Quality Of Fit ◽  
Kinetics Of ◽  
Vulcanization Process

Rubber vulcanization is kinetically a complex process, since it consists of two simultaneous reactions: curing and degradation. To determine reaction kinetics, it is necessary to determine a kinetic model which describes the process adequately. Proposed kinetic model has six adjustable parameters. In order to determine kinetic parameters of the proposed kinetic model, commercially available rubber gum was used. Oscillating disc rheometer was used to investigate experimental dependence of torque on time, at six temperatures in the range from 130 to 180 °C, with a step of 10 °C. Matlab application, built via App Designer feature, was developed in order to fit the experimental data to the proposed kinetic model. Developed Matlab application, consisting of two tabs, enables user to upload raw rheometer data, perform manual fitting or automatic fitting (manual or automatic estimation of initial values of adjustable parameters), test the effect of constant values of some kinetic parameters on the overall quality of fit, visualize the dependence of kinetic parameters on temperature and to determine the values of Arrhenius expression for curing and degradation process. Both fitting methods were proven to be efficient; overall determination coefficient and MAPE value for automatic and manual fitting methods were >0.99 and <1%, and >0.999 and <1%, respectively. Arrhenius parameters were also determined with high accuracy (R2>0.98). Developed application enables simple and efficient determination of kinetic parameters by means of different fitting methods, simultaneous fitting of data on all temperatures, and testing the effect of constant kinetic parameters values on fitting results

QUALITY INCREASING OF TECHNICAL AND POTABLE WATER DUE TO COMPLEXATION BETWEEN AMINO ACIDS AND Ca AND Mg SALTS

2018 ◽  
Vol 61 (6) ◽  
pp. 109
Author(s):  
Vitaly V. Ovchinnikov ◽  
Alexey A. Kulakov
Keyword(s):  
Amino Acids ◽  
Potable Water ◽  
Experimental Results ◽  
Heating Systems ◽  
Home Heating ◽  
Quality Of Waters ◽  
Calcium And Magnesium ◽  
High Degree

The home heating systems as well as the food industry require a high degree of water purification. In the aims of the increasing of the quality of technical and potable water the experiments on the determination of the rigidity of water have been carried out in the fourth districts of Kazan after the addition to the water samples of β-alanine and l-asparagine as the agents for the complex formation with calcium and magnesium salts. The obtained results showed that the chosen amino acids able to reduce the rigidity and increase the quality of waters in 1.10-1.22 time. The calculated heats of combustion and formation of complexes of calcium and magnesium with alanine and asparagine confirm the conducted experimental results on their stability. Such experimental results prompted us to calculate the heat of combustion (DсH°) and formation (DfH°) of complexes of calcium and magnesium with the mentioned above amino acids [Met(amino acid)2, DсH°, DfH° (kJ mol-1± 0.5 % , respectively), number of valence electrons (N-g)] in according to the scheme of thermochemical research. It has been suggested to introduce the above mentioned amino acids or synthesized on their base little peptides into sorption-filters at the water preparation process.Forcitation:Ovchinnikov V.V., Kulakov A.A. Quality increasing of technical and potable water due to complexation between amino acids and ca and mg salts. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 6. P. 109-112

Determination of Pressure in the Mold Cavity of Injected Semi-Crystalline Thermoplastics

2012 ◽  
Author(s):  
Xavier Tardif ◽  
Vincent Sobotka ◽  
Nicolas Boyard ◽  
Philippe Le Bot ◽  
Didier Delaunay
Keyword(s):  
Heat Transfer ◽  
Atmospheric Pressure ◽  
Mold Cavity ◽  
Numerical Comparison ◽  
Ejection Time ◽  
Strongly Coupled ◽  
Kinetics Of ◽  
Pressure Analysis

Injection molding is the most used process for thermoplastic part manufacturing. This process is commonly divided into four steps: injection, packing, cooling and ejection. During the packing step, an amount of material gets into the mold cavity to compensate for shrinkage of the polymer mainly due to the crystallization. Once the gate is frozen, polymer is subjected to isochoric cooling while the pressure of the polymer is higher than atmospheric pressure. Improving the quality of the injected part requires prediction of the shrinkage, warpage and residual stress and pressure impacts deeply on the morphology and consequently on the shape of the final part. The pressure decrease during the isochoric phase also determines the ejection time. However, description of the behavior of the polymer during packing and isochoric steps needs an accurate model that considers coupling between heat transfer and crystallization and also a good knowledge of the behavior (specific volume and crystallization kinetics) of the polymer under high pressure. Some studies have already underlined the influence of shear rate on the kinetics of crystallization. Here, based on a pressure analysis and an experimental-numerical comparison, we confirm crystallization is strongly coupled to flow history.

scholarly journals Application of Kinetic Models to the Sorption of Copper(II) on to Peat

2002 ◽  
Vol 20 (8) ◽  
pp. 797-815 ◽  
Author(s):  
Y.S. Ho ◽  
G. McKay
Keyword(s):  
Sorption Capacity ◽  
Fractional Power ◽  
Sorption Process ◽  
Order Equation ◽  
Second Order ◽  
Process Models ◽  
Elovich Equation ◽  
Pseudo Second Order ◽  
High Degree ◽  
Kinetics Of

A comparison of the kinetics of the sorption of copper(II) on to peat from aqueous solution at various initial copper(II) concentrations and peat doses was made. The Elovich model and the pseudo-second order model both provided a high degree of correlation with the experimental data for most of the sorption process. There was a small discrepancy at the initial stages of sorption which suggested that film diffusion or wetting of the peat may be involved in the early part of the sorption process. Models evaluated included the fractional power equation, the Elovich equation, the pseudo-first order equation and the pseudo-second order equation. The kinetics of sorption were followed based on the sorption capacity of copper(II) on peat at various time intervals. Results show that chemical sorption processes may be rate-limiting in the sorption of copper(II) on to peat during agitated batch contact time experiments. The rate constant, the equilibrium sorption capacity and the initial sorption rate were calculated. From these parameters, an empirical model for predicting the concentrations of metal ions sorbed was derived.

scholarly journals Comprehensive Assessment of Flow and Other Analytical Methods Dedicated to the Determination of Zinc in Water

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 3914
Author(s):  
Paweł Kościelniak ◽  
Paweł Mateusz Nowak ◽  
Joanna Kozak ◽  
Marcin Wieczorek
Keyword(s):  
Analytical Chemistry ◽  
Green Chemistry ◽  
Analytical Method ◽  
Analytical Methods ◽  
Green Analytical Chemistry ◽  
General Quality ◽  
Analytical Strategies ◽  
High Degree

An original strategy to evaluate analytical procedures is proposed and applied to verify if the flow-based methods, generally favorable in terms of green chemistry, are competitive when their evaluation also relies on other criteria. To this end, eight methods for the determination of zinc in waters, including four flow-based ones, were compared and the Red–Green–Blue (RGB) model was exploited. This model takes into account several features related to the general quality of an analytical method, namely, its analytical efficiency, compliance with the green analytical chemistry, as well as practical and economic usefulness. Amongst the investigated methods, the best was the flow-based spectrofluorimetric one, and a negative example was that one involving a flow module, ICP ionization and MS detection, which was very good in analytical terms, but worse in relation to other aspects, which significantly limits its overall potential. Good assessments were also noted for non-flow electrochemical methods, which attract attention with a high degree of balance of features and, therefore, high versatility. The original attempt to confront several worldwide accepted analytical strategies, although to some extent subjective and with limitations, provides interesting information and indications, establishing a novel direction towards the development and evaluation of analytical methods.

scholarly journals Chlorophyll fluorescence: How the quality of information about PAM instrument parameters may affect our research

2021 ◽  
Author(s):  
Tim Nies ◽  
Yuxi Niu ◽  
Oliver Ebenhöh ◽  
Shizue Matsubara ◽  
Anna Matuszyńska
Keyword(s):  
Data Science ◽  
Measurement Techniques ◽  
Mathematical Formulation ◽  
Pulse Amplitude ◽  
Data Interpretation ◽  
Photochemical Quenching ◽  
Non Photochemical Quenching ◽  
Underlying Processes ◽  
Kinetics Of

Chlorophyll a fluorescence is a powerful indicator of photosynthetic energy conversion in plants and photosynthetic microorganisms. One of the most widely used measurement techniques is Pulse Amplitude Modulation (PAM) fluorometry. Unfortunately, parameter settings of PAM instruments are often not completely described in scientific articles although their variations, however small these may seem, can influence measurements. We show the effects of parameter settings on PAM measurements. We first simulated fluorescence signals using a previously published computational model of photosynthesis. Then, we validated our findings experimentally. Our analysis demonstrates how the kinetics of non-photochemical quenching (NPQ) induction and relaxation are affected by different settings of PAM instrument parameters. Neglecting these parameters may mislead data interpretation and derived hypotheses, hamper independent validation of the results, and cause problems for mathematical formulation of underlying processes. Given the uncertainties inflicted by this neglect, we urge PAM users to provide detailed documentation of measurement protocols. Moreover, to ensure accessibility to the required information, we advocate minimum information standards that can serve both experimental and computational biologists in our efforts to advance system-wide understanding of biological processes. Such specification will enable launching a standardized database for plant and data science communities.

Activated bauxite waste as an adsorbent for removal of Acid Blue 92 from aqueous solutions

2010 ◽  
Vol 62 (11) ◽  
pp. 2491-2500 ◽  
Author(s):  
Sh. Norouzi ◽  
Kh. Badii ◽  
F. Doulati Ardejani
Keyword(s):  
Adsorption Kinetics ◽  
Red Mud ◽  
Adsorption Process ◽  
Reaction Model ◽  
Aluminum Production ◽  
Activation Process ◽  
Pseudo Second Order ◽  
Kinetics Of ◽  
Acid Blue ◽  
Better Than

Bauxite waste, known as red mud, is produced in some industrial processes, such as aluminum production process. In this process, the waste material is produced from leached bauxite as a by product. In this research, the removal of Acid Blue 92 (AB92) dye was investigated from aqueous solution onto the activated bauxite waste (red mud) in a batch equilibration system. Besides, the influences of pH, adsorbent dosage, contact time, initial concentration of dye and temperature have been considered. It was found that the OH group is an effective functional group for the adsorption process. The intensity of the peaks correspond to OH group has been significantly climbed after the activation process. The adsorption kinetics of AB92 can be well described by the pseudo-second-order reaction model. Based on the isotherm data obtained from the fittings of the adsorption kinetics, the Langmuir model appears to fit the adsorption process better than the Freundlich and Brunauer-Emmett-Teller (BET) models.

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