scholarly journals Enhanced sorption capacity of the metal-dye system from water effluents by using polish activated industrial waste

2020 ◽  
Author(s):  
Eleonora Sočo ◽  
Jan Kalembkiewicz
Keyword(s):  
Coal Fly Ash ◽  
Sorption Process ◽  
Sorption Kinetics ◽  
Coefficient Of Determination ◽  
Isotherm Models ◽  
Particle Model ◽  
Particle Diffusion ◽  
Hexadecyltrimethylammonium Bromide ◽  
Chi Square ◽  
Chi Square Test

Abstract The activated coal fly ash (FA) treated with NaOH and hexadecyltrimethylammonium bromide (HDTMABr) was used as adsorbent for removal of cadmium(II) ions and rhodamine B (RB) form an aqueous solution. Characterization of FA and FA-HDTMABr were done by using Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The sorption equilibrium in the system were analysed by isotherm models, such as Freundlich, Langmuir, generalized Langmiur-Freundlich, Redlich-Peterson, Jovanović, extended Jovanović, Tóth, Fumkin-Fowler-Guggenheim, Fowler-Guggenheim-Jovanović-Freundlich, Temkin, Dubinin-Radushkevich, Halsey, Brunauer Emmett and Teller. The evaluation of fitting of the isotherms studied experimentally points was carried out by means of the reduced chi-square test and the coefficient of determination. The maximum monolayer adsorption capacity of the FA-HDTMABr was found to be 744 mg·g−1 and 666 mg·g−1 for Cd(II) and RB, respectively. The PFO, PSO, Elovich mass transfer, liquid film diffusion and intra-particle diffusion models were analysed. Sorption kinetics data were well fitted by PSO model. The Elovich and intra-particle model also revealed that there are two separate stages in the sorption process, namely, the external diffusion and the inter-particle diffusion.

scholarly journals Nitrate sorption on activated carbon modified with CaCl2: Equilibrium, isotherms and kinetics

2015 ◽  
Vol 21 (1-1) ◽  
pp. 23-33 ◽  
Author(s):  
Odivan Zanella ◽  
Isabel Tessaro ◽  
Liliana Féris
Keyword(s):  
Activated Carbon ◽  
Aqueous Solutions ◽  
Nitrate Removal ◽  
Sorption Process ◽  
Isotherm Model ◽  
Coefficient Of Determination ◽  
Isotherm Models ◽  
Order Kinetic ◽  
Test Statistic ◽  
Chi Square

In this study, nitrate (NO3-) removal from aqueous solutions was investigated using granular activated carbon (GAC) modified with CaCl2. Batch sorption studies were performed as a function of sorbent dose, initial nitrate concentration and pH. Sorption was maximized between pH 3 and 9. Studies on the effect of pH showed that the ion exchange mechanism might be involved in the sorption process. The percentage of nitrate removed increased with increasing sorbent concentration, and the ideal sorbent dose was found to be 20 g?L-1. Four isotherm models-Langmuir, Freundlich, Redlich-Peterson and Sips-were used to fit the experimental data. The Redlich-Peterson isotherm model explained the sorption process well and showed the best coefficient of determination (0.9979) and Chi-square test statistic (0.0079). Using the Sips isotherm model, the sorption capacity (qe) was found to be 1.93 mg nitrate per g of sorbent. Kinetic experiments indicated that sorption was a fast process, reaching equilibrium within 120 min. The nitrate sorption kinetic data were successfully fitted to a pseudo-second-order kinetic model. The overall results demonstrated potential applications of modified GAC for nitrate removal from aqueous solutions.

scholarly journals Equilibrium isotherm studies for the sorption of Nickel ions onto coal fly ash

2014 ◽  
Vol 15 (1&2) ◽  
pp. 153-159
Author(s):  
Ajay K. Agarwal ◽  
Mahendra S. Kadu ◽  
Chandrashekhar P. Pandhurnekar ◽  
Ishwardas L. Muthreja
Keyword(s):  
Fly Ash ◽  
Adsorption Isotherm ◽  
Coal Fly Ash ◽  
Coefficient Of Determination ◽  
Equilibrium Isotherm ◽  
Chi Square ◽  
Linear Coefficient ◽  
Nickel Ions ◽  
Chi Square Test ◽  
Best Fit

The objective of the present study was to study equilibrium isotherm for the sorption of Nickel ions onto coal fly ash. In this study, BET adsorption isotherm was found to be best fitted among  Langmuir, Freundlich, BET, Temkin and Harkins Jura adsorption isotherms using lest square fit method. The best fit adsorption isotherm   is assessed by the linear coefficient of determination (R2) and non-linear Chi-square test. The theoretical value of qe calculated from the best fit linear equation of each adsorption isotherm and the experimental values of qe (0.08) are plotted against Ce, to compare the experimental and Theoretical value of qe.

scholarly journals Methods and techniques of research motivation and satisfaction of employees

2021 ◽  
Vol 9 (2) ◽  
pp. 53-63
Author(s):  
Dragana Pešić-Jenačković
Keyword(s):  
Analysis Of Variance ◽  
Employee Motivation ◽  
Test Point ◽  
Coefficient Of Determination ◽  
Business Success ◽  
Chi Square ◽  
Methods And Techniques ◽  
Chi Square Test ◽  
Using Data ◽  
The Impact

Motivation and employee satisfaction are very important precondition for the effectiveness of work and the achievement of set goals for individuals and organizations. Consequently, continuous measurement of employee motivation and satisfaction is essential to improve company's efficiency and improve human resource use. The results of a well-planned, detailed and adequate methods and techniques of research on employee motivation and satisfaction can be applied to the design of various schemes in order to reduce absenteeism and employee turnover and overall business success. In this paper, the emphasis is on the methodology of researching employee motivation and satisfaction. In addition to the elaboration of questionnaires with scales for measuring the motivation and satisfaction of employees, it is explained in which situations, in which types of questions and answers, respectively, types of data, and how certain statistical techniques are applied, such as: T-test, One-factor analysis of variance (ANOVA), Chi-square test, Point-two-series correlations. Also, the importance of using the subsequent post hoc test (LSD comparison) in the analysis of variance, as well as the indicators of correlation, the strength of the impact, such as: phi correlation coefficient, Kramer's coefficient and contingency coefficient, is pointed out in the Chi-square test. In addition to the mentioned techniques and indicators from SPSS, the role of certain indicators (eta squared and coefficient of determination) is calculated, which are calculated using data from research results and with the help of certain formulas

scholarly journals Drying kinetics of crushed mass of ‘jambu’: Effective diffusivity and activation energy

2018 ◽  
Vol 22 (7) ◽  
pp. 499-505 ◽  
Author(s):  
Francileni P. Gomes ◽  
Resende Osvaldo ◽  
Elisabete P. Sousa ◽  
Daneil E. C. de Oliveira ◽  
Francisco R. de Araújo Neto
Keyword(s):  
Experimental Data ◽  
Activation Energy ◽  
Agricultural Research ◽  
Effective Diffusion ◽  
Effective Diffusivity ◽  
Information Criterion ◽  
Drying Kinetics ◽  
Coefficient Of Determination ◽  
Chi Square ◽  
Chi Square Test

ABSTRACT The aim of this paper was to analyze the drying kinetics, test the Akaike information criterion (AIC) and Schwarz’s Bayesian information criterion (BIC) in the selection of models, determine the effective diffusivity and activation energy of the crushed mass of ‘jambu’ leaves for different conditions of temperature and layer thicknesses. The experiment was carried out at the Food Laboratory of the Brazilian Agricultural Research Corporation (Embrapa) in Macapá-AP. Drying was carried out in air circulation oven with speed of 1.0 m s-1 at various temperatures (60, 70 and 80 ºC) and layer thicknesses (0.005 and 0.010 m). The experimental data were fitted to 11 mathematical models. Coefficient of determination (R2), mean relative error (P), mean estimated error (SE), Chi-square test (χ2), AIC and BIC were the selection criteria for the models. For the effective diffusivity, the Fick’s diffusion model was used considering the flat plate geometry. It was found that Midilli and Logarithmic models showed the best fit to the experimental data of drying kinetics. Effective diffusion coefficient increases with increment in the thickness of the material and with the temperature elevation. Activation energy of the material was of 16.61 kJ mol-1 for the thickness of 0.005 m, and 16.97 kJ mol-1 for the thickness of 0.010 m. AIC and BIC can be additionally included to select models of drying.

scholarly journals Comparison of adsorption of Cd(II) and Pb(II) ions on pure and chemically modified fly ashes

2016 ◽  
Vol 37 (2) ◽  
pp. 215-234 ◽  
Author(s):  
Eleonora Sočo ◽  
Jan Kalembkiewicz
Keyword(s):  
Fly Ash ◽  
Water Solution ◽  
Coal Fly Ash ◽  
Mixing Time ◽  
Sorption Process ◽  
Particle Model ◽  
X Ray Scattering ◽  
Equilibrium And Kinetics ◽  
Pseudo Second Order ◽  
Polluted Waters

Abstract The study investigates chemical modifications of coal fly ash (FA) treated with HCl or NH4HCO3 or NaOH or Na2edta, based on the research conducted to examine the behaviour of Cd(II) and Pb(II) ions adsorbed from water solution on treated fly ash. In laboratory tests, the equilibrium and kinetics were examined applying various temperatures (293 - 333 K) and pH (2 - 11) values. The maximum Cd(II) and Pb(II) ions adsorption capacity obtained at 293 K, pH 9 and mixing time 2 h from the Langmuir model can be grouped in the following order: FA-NaOH > FA-NH4HCO3 > FA > FA-Na2edta > FA-HCl. The morphology of fly ash grains was examined via small-angle X-ray scattering (SAXS) and images of scanning electron microscope (SEM). The adsorption kinetics data were well fitted by a pseudo-second-order rate model but showed a very poor fit for the pseudofirst order model. The intra-particle model also revealed that there are two separate stages in the sorption process, i.e. the external diffusion and the inter-particle diffusion. Thermodynamics parameters such as free energy, enthalpy and entropy were also determined. A laboratory test demonstrated that the modified coal fly ash worked well for the Cd(II) and Pb(II) ion uptake from polluted waters.

scholarly journals Mathematical modeling of the foam-mat drying curves of guava pulp

2017 ◽  
Vol 21 (10) ◽  
pp. 721-725 ◽  
Author(s):  
Roberta M. G. Maciel ◽  
Marcos R. A. Afonso ◽  
José M. C. da Costa ◽  
Leandro S. Severo ◽  
Natália D. de Lima
Keyword(s):  
Experimental Data ◽  
Coefficient Of Determination ◽  
Drying Rate ◽  
Albumin Concentration ◽  
Mean Square ◽  
Liquid Food ◽  
Chi Square ◽  
Foaming Agent ◽  
Chi Square Test ◽  
Drying Curves

ABSTRACT In foam-mat drying, the liquid food is foamed by the addition of a foaming agent, for example, albumin. The aim of this study was to evaluate the adjustment of mathematical models to foam mat drying curves of guava pulp. The fits were evaluated using samples with 4 and 8% albumin (m m-1) and drying temperatures of 75, 80 and 85 °C. The samples were placed on aluminum trays. Drying was carried out in a tray dryer. The Lewis, Page, Midilli and Logarithmic models were fitted to the experimental data and evaluated based on the coefficient of determination (R2), root-mean-square error (RMSE) and chi-square test. All models fitted well to experimental data and Midilli was the best. Albumin concentration and temperature influenced the drying rate; the lowest drying times occurred for the highest albumin concentration and highest drying temperature.

scholarly journals Kinetic, equilibrium and thermodynamic studies of Ni(II) ions sorption on sulfuric acid treated Lagenaria vulgaris shell

2016 ◽  
Vol 22 (3) ◽  
pp. 235-247 ◽  
Author(s):  
Danijela Bojic ◽  
Goran Nikolic ◽  
Jelena Mitrovic ◽  
Miljana Radovic ◽  
Milica Petrovic ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Sorption Process ◽  
Sorption Kinetics ◽  
Significant Loss ◽  
Isotherm Models ◽  
Pseudo Second Order ◽  
Na Ions ◽  
Ph Range ◽  
Rate Limiting ◽  
Lagenaria Vulgaris

Chemically modified Lagenaria vulgaris shell (ccLVB) was tested as a new sorbent for the removal of Ni(II) from aqueous solution, in batch conditions. The sorption process was very fast reaching equilibrium in about 20 min. Ni(II) sorption is almost invariant in the pH range from 3 to 6. Sorption kinetics followed pseudo-second order, intraparticle diffusion and Chrastil?s models, which suggest that both surface reaction and diffusion were the rate-limiting steps. Equilibria experimental results are well fitted by Langmuir and Temkin sorption isotherm models, indicating mixed adsorption process. The maximum biosorption capacity of ccLVB for Ni(II) was found to be 84.51 mg g-1. The calculated thermodynamic parameters showed that the biosorption of nickel on ccLVB was feasible, spontaneous and exothermic at 25-45?C. The desorption experiments showed that the ccLVB could be reused for five cycles without significant loss in sorption capacity. Release of Na+ ions from the biosorbent during sorption of Ni(II) reveals that the main sorption mechanism is ion exchange. Presented study suggests that ccLVB can be used effectively for the removal of Ni(II) ions from aqueous solution.

scholarly journals Study of Knowledge, Attitude and Action of Buffalo Breeders in the Villages Around Nagan Raya Power Plant on the Impact of Fly Ash Exposure

2018 ◽  
Vol 3 (2) ◽  
pp. 43-48
Author(s):  
Ira Susanti ◽  
Rinidar Rinidar ◽  
Sugito Sugito
Keyword(s):  
Fly Ash ◽  
Power Plant ◽  
Coal Fly Ash ◽  
Animal Health ◽  
Low Rank ◽  
Chi Square ◽  
Cross Sectional ◽  
Chi Square Test ◽  
Cross Sectional Design ◽  
The Impact

One of the biggest contributors of air pollution is the production of coal fly ash from power plant industry. Fly ash has an immediate impact on human and animal health around the power plant. Many buffaloes in Nagan Raya usually grazing near the 110-megawatt steam power plant that using low rank coal. This action raises concerns about buffalo’s health due to exposure to fly ash. This study aimed to examine the relationship of knowledge, attitude and action of buffalo breeders to the impact of fly ash exposure on the buffaloes. This research used analytical survey with cross sectional design. This study was conducted in February 2018 with 30 respondents from four villages around Nagan Raya Power Plant to evaluate their knowledge, attitudes and actions by using questionnaires. The data were analyzed statistically with Chi Square Test with SPSS for Windows version 17.0. The results showed that there was no significant correlation between the knowledge of buffalo breeders and the impact of fly ash exposure (P> 0.05), while the attitude and actions of buffalo breeders had a significant correlation with the impact of fly ash exposure (P <0.05). These results concluded that the buffalo breeders in the villages around the power plant did not realize the impact of fly ash arising from coal of power plant. It is expected that the associated institution would conduct a counseling about the impact of fly ash exposure as well as good management of buffaloes.

scholarly journals Equilibrium and Kinetic Study of Ammonium Sorption by Raphia farinifera

2019 ◽  
Vol 230 (10) ◽  
Author(s):  
Paweł Staroń ◽  
Paulina Sorys ◽  
Jarosław Chwastowski
Keyword(s):  
Chemical Nature ◽  
Sorption Process ◽  
Sorption Kinetics ◽  
Second Order ◽  
Isotherm Models ◽  
Mechanism Analysis ◽  
Order Model ◽  
Sorption Model ◽  
Pseudo Second Order ◽  
Kinetics Of

Abstract The study investigated the sorption capacity of biosorbent-raphia sp. against ammonia. Raphia fibers were used without and with the modification of its surface with NaCl, NaNO3, and K2SO4. The data was analyzed in the state of equilibrium using four isotherm models such as Langmuir, Freudlich, Temkin, and Dubinin-Radushkevich. The equilibrium of ammonia sorption for all studied systems was best described by the Freudlich isotherm model. On its basis, it can be assumed that the studied process is of chemical nature, which results from the value of the coefficient 1/n < 1. In order to confirm the sorption mechanism, analysis of the kinetics of the ammonia sorption process on raphia fibers was performed. Four kinetic models of sorption were calculated: pseudo-first-order model, pseudo-second-order model, Elovich model, and Webber-Morris intermolecular diffusion model. The sorption kinetics of the modeled ammonia waste were carried out using unmodified palm fibers and all kinds of surface modification. This process was best described by the pseudo-second-order sorption model, which can be considered as a confirmation of the chemical nature of ammonia sorption on raphia sp. fibers.

Comparison of methods in estimating Weibull parameters for wind energy applications

2017 ◽  
Vol 11 (4) ◽  
pp. 650-663 ◽  
Author(s):  
Ijjou Tizgui ◽  
Fatima El Guezar ◽  
Hassane Bouzahir ◽  
Brahim Benaid
Keyword(s):  
Weibull Distribution ◽  
Empirical Method ◽  
Likelihood Method ◽  
Coefficient Of Determination ◽  
Average Error ◽  
Chi Square ◽  
Content Type ◽  
Weibull Parameters ◽  
Energy Applications ◽  
Chi Square Test

Purpose The purpose of this study is to select the most accurate and the most efficient method in estimating Weibull parameters at Agadir region in Morocco. Design/methodology/approach In this paper, Weibull distribution is used to model the wind speed in hourly time series format. Since several methods are used to adjust the Weibull distribution to the measured data, in reporting and analyzing the easiest and the most effective method, seven methods have been investigated, namely, the graphical method (GM), the maximum likelihood method (MLM), the empirical method of Justus (EMJ), the empirical method of Lysen (EML), the energy pattern factor method (EPFM), Mabchour’s method (MMab) and the method of moments (MM). Findings According to the statistical analysis tools (the coefficient of determination, root mean square error and chi-square test), it was found that for five months, the MLM presents more efficiency, and for four months, EMJ is ranked first and it is ranked second for February. To select only one method, the selected methods (MLM and EMJ) were compared by calculating the error in estimating the power density using Weibull distribution adjusted by those methods. The average error was found to be −0.51 and −4.56 per cent for MLM and EMJ, respectively. Originality/value This investigation is the first of its kind for the studied region. To estimate the available wind power at Agadir in Morocco, investors can directly use MLM to determine the Weibull parameters at this site.

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