scholarly journals Effect of degree of crystallinity and the contents of aluminium oxide and sodium oxide on water sorption capacity in NaY zeolite

2016 ◽  
Vol 70 (4) ◽  
pp. 399-407 ◽  
Author(s):  
Dragana Keselj ◽  
Dragica Lazic ◽  
Zivan Zivkovic ◽  
Branko Skundric ◽  
Jelena Penavin-Skundric ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Regression Analysis ◽  
Sorption Capacity ◽  
Water Sorption ◽  
Linear Regression Analysis ◽  
Degree Of Crystallinity ◽  
Quadratic Model ◽  
Nay Zeolite ◽  
The Degree Of Crystallinity ◽  
Water Sorption Capacity

The paper presents mathematical models which describe the dependence between water sorption capacity, on one hand, and the degree of crystallinity and the content of Na2O and Al2O3 in NaY zeolite, on the other. NaY was synthesized from sodium aluminate solution, water glass and sulfuric acid under different conditions of crystallization. The obtained zeolite powders underwent chemical analysis (Na2O, Al2O3), water sorption capacity (WSC), as well as diffraction analysis which served to determine the degree of crystallinity (CD). Zeolite powder samples had the following values: for the content of Na2O from 13.81 to 16.14%, for Al2O3 from 21.58 to 27.17%, degree of crystallinity from 58.70 to 114.00 and WSC from 21.32 to 36.59%, and regression analysis lead to the conclusion that there is a significant correlation between water sorption capacity and the degree of crystallinity, unlike the contents of Na2O and Al2O3 in the zeolite powder, whose correlation with water sorption capacity was neglibile. The mathematical model obtained by linear regression analysis had a high R2= 0.796, where as non-linear regressional analysis produced a better mathematical model R2= 0.912, where water sorption capacity was expressed through a quadratic model.

Experimental Design of Surface Modification of Expanded Obsidian and Determination of Water Sorption Capacity

2014 ◽  
Vol 1020 ◽  
pp. 823-826
Author(s):  
G.Sh. Hovsepyan ◽  
M.A. Kalantaryan ◽  
T.V. Yedoyan
Keyword(s):  
Experimental Data ◽  
Surface Modification ◽  
Sorption Capacity ◽  
Water Sorption ◽  
Structural Changes ◽  
Ir Spectrometry ◽  
Water Capacity ◽  
Series Of Experiments ◽  
Water Sorption Capacity

The aim of this paper is to study the possibility of expanded obsidian and its modified product use for oil sorption, in that tetraethoxisilane (TEOS) has been used as a modifier. The optimal concentration of the modifier was determined by 50 per cent weight of expanded obsidian. The expanded obsidian was previously activated with 0,1 M solution of hydrochloric acid. IR spectrometry was used to characterise structural changes in the modified expanded obsidian samples. To determine water sorption capacity a series of experiments has been carried out. The analysis of obtained experimental data showed that after surface modification of expanded obsidian water capacity is reduced 3 times after the surface modification of EO.

scholarly journals Assessment of Performance of Posidona oceanica (L.) as Biosorbent for Crude Oil-Spill Cleanup in Seawater

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Senda Ben Jmaa ◽  
Amjad Kallel
Keyword(s):  
Crude Oil ◽  
Sorption Capacity ◽  
Water Sorption ◽  
Pure Water ◽  
Water System ◽  
Oil Concentration ◽  
Oil Water ◽  
Mixed Oil ◽  
The Impact ◽  
Water Sorption Capacity

The marine environment is constantly at risk of pollution by hydrocarbon spills that requires its cleanup to protect the environment and human health. Posidonia oceanica (L.) (PO) beach balls, which are characteristic of the Mediterranean Sea and abundant on the beaches, are used as biosorbent to remove hydrocarbons from the sea. The impact of several factors such as oil concentration, time sorption, and weight sorbent was investigated to determine the oil and water sorption capacity for raw and milled P. oceanica fibers. The study of kinetic models for initial crude oil concentration of 2.5, 5, 8.8, 10, 15, 20, 30, and 40 g/L revealed that crude uptake followed the pseudo-first-order model while, for isotherm models, the crude uptake onto the P. oceanica tended to fit the Langmuir model. Experiments were performed according to two systems: a pure oil and pure water system and a mixed oil/water system. For the dry system (pure oil and pure water), the maximum oil and water sorption capacity of raw and milled fibers was found to be 5.5 g/g and 14 g/g for oil and 14.95 g/g and 15.84 g/g for water, respectively, whereas, in the mixed oil/water system, the maximum oil and water sorption capacity was estimated as 4.74 g/g, 12.80 g/g and 7.41 g/g, 8.31 g/g, respectively. The results showed that, in spite of their absorbency of a lot of water, the milled fibers with grain size ranging between 0.5 mm and 1 mm might be the relevant sorbent for the elimination of crude oil from seawater thanks to its efficient sorption capacity and low cost.

Cervix cancer regression measured using weekly MR imaging during fractionated radiotherapy: Radiobiologic modeling and correlation with tumor hypoxia

2007 ◽  
Vol 25 (18_suppl) ◽  
pp. 5547-5547
Author(s):  
K. S. Lim ◽  
P. Chan ◽  
R. Dinniwell ◽  
A. Fyles ◽  
M. Haider ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Regression Analysis ◽  
Linear Regression ◽  
Mr Imaging ◽  
Tumor Volume ◽  
Tumor Regression ◽  
Linear Regression Analysis ◽  
Tumor Hypoxia ◽  
Cervix Cancer ◽  
Pre Treatment

5547 Background: To utilize cervix cancer volumetry, as measured with MR imaging during definitive chemoirradiation (RT-CT), to derive radiobiological parameters using a mathematical model of tumor regression, and compare them to pre-treatment measurements of tumor hypoxia. Methods: Twenty-eight patients receiving RT-CT for cervix cancer underwent weekly magnetic resonance imaging (MRI) scans. Tumor volume was assessed on each of these scans and the rate of regression plotted. A mathematical model of tumor regression was formulated to simulate the relationship between three independent radiobiological parameters, 1) surviving fraction of cells after 2 Gy, SF2, 2) the cell clearance constant Tc, and 3) the cellular proliferation constant Tp. Non-linear regression analysis was applied to fit the MR-derived tumor volumes to the mathematical model and to derive SF2 and Tc values for each patient. These were compared to pre-treatment hypoxia measurements. Results: Initial tumor volume ranged between 8 and 209 cm3. Relative reduction in volume during treatment was 0.02 to 0.79. Simulations using representative values of the independent biologic variables derived from the literature showed SF2 and Tc to strongly influence the shape of the volume response curves. Non-linear regression analysis yielded a median SF2 of 0.71 and median Tc of 10 days. Radioresistant tumors (SF2 >0.71) were significantly more hypoxic at diagnosis (p=0.02). Conclusion: Based on serial MR imaging during treatment, a marked variation in cervix tumor regression is seen from patient to patient. Through our radiobiological model, tumors can be classified as radioresistant or radiosensitive, which correlates with hypoxia [Table: see text] No significant financial relationships to disclose.

scholarly journals Application of Linear Regression Mathematical Model in the Evaluation of Teachers’ Informatization Quality

Complexity ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Shuping Li ◽  
Xinlei Yuan
Keyword(s):  
Mathematical Model ◽  
Regression Analysis ◽  
Linear Regression ◽  
Evaluation System ◽  
Linear Regression Analysis ◽  
School Education ◽  
Main Body ◽  
Widespread Application ◽  
Important Indicator ◽  
The Impact

With the widespread application of information technology and the continuous deepening of my country’s education informatization construction, the educational field has increasingly higher requirements for teachers’ informatization quality. The advancement of the process of education informatization depends to a large extent on the level of teachers’ own level of informatization and has gradually become an important indicator to measure the informatization of education. The main body of education and the decisive factor are teachers. The scientific and reasonable evaluation of informatization education is an important content of today’s education informatization. This paper uses regression analysis to evaluate the teacher education information system and uses mathematical statistics to establish a linear regression model for the city and analyze and calculate it. Through the quantitative analysis of the evaluation index system of the education informatization level, the multiple linear regression analysis method was used to establish the linear regression mathematical model of the school education informatization level on each secondary index, and the influence of various indicators on the school education informatization level was analyzed to establish a scientific evaluation system to evaluate the literacy of teachers’ informatization education and to give suggestions for improving the level of school education informatization. The design of the evaluation system is more scientific and reasonable, the regression error is small, the results obtained are more accurate, and the impact of nonlinear errors is basically eliminated.

Research on Several Problems in Partial Least Squares Regression Analysis

2014 ◽  
Vol 8 (1) ◽  
pp. 754-758 ◽  
Author(s):  
Ju Wu
Keyword(s):  
Mathematical Model ◽  
Regression Analysis ◽  
Linear Regression ◽  
Least Squares ◽  
Partial Least Squares ◽  
Partial Least Squares Regression ◽  
Linear Regression Analysis ◽  
Multiple Linear Regression Analysis ◽  
Least Squares Regression ◽  
Analysis Method

Purpose: preliminary discussion on model prediction precision in the partial least squares regression analysis method; Method: introduce current development conditions of partial least squares regression analysis, analyze problems of traditional regression analysis method such as multiple linear regression analysis, introduce the mathematic principle and modeling method of the partial least squares regression analysis method, and conduct detailed analysis on the partial least squares regression analysis modeling and prediction by using the classical Linnerud data. Result: The partial least squares regression analysis has the basic features of the multiple linear regression analysis and principal component analysis, can precisely predict multiple data and establish a precise mathematical model; Conclusion: The partial least squares regression analysis can provide precise mathematical model and can reserve the explaining variants remarkably associated to explained variants to most extent, so it is feasible to some extent and can meet the general requirements of engineering, economy, biology and medical statistical analysis.

scholarly journals The influence of the ammonia concentration and the water content on the water sorption behavior of ambient pressure dried silica xerogels

2020 ◽  
Vol 96 (1) ◽  
pp. 197-206
Author(s):  
Lukas Huber ◽  
Silvia Paz Comesaña ◽  
Matthias M. Koebel
Keyword(s):  
Water Content ◽  
Sorption Capacity ◽  
Water Sorption ◽  
Ambient Pressure ◽  
Ammonia Concentration ◽  
Silica Xerogel ◽  
Sorption Behavior ◽  
Relative Pressure ◽  
Silica Xerogels ◽  
Water Sorption Capacity

Abstract Porous silica xerogels were synthesized within 10 h by a two-step sol–gel process under atmospheric conditions. In the first step, tetraethylorthosiloxane (TEOS) was hydrolyzed with water using sulfuric acid as a catalyst. In the second step, water and ammonia were added to the prehydrolyzed silica sol prior to the drying of the samples at 150 °C. The influence of the ammonia concentration and the water content on the physicochemical properties and the water sorption behavior of silica xerogels produced in the aforementioned way was investigated. The resulting silica xerogels were characterized by helium pycnometry, scanning electron microscopy, fourier-transform infrared spectroscopy, nitrogen sorption, and water sorption. It was shown that a higher ammonia concentration leads to an increased pore size of the silica xerogel which starts to adsorb water at a higher relative pressure. With an increased water content during gelation, the silica xerogel has a higher specific surface area and a higher water sorption capacity. Furthermore, silica xerogels can be tailored by a controlled addition of ammonia and water to have a higher water sorption capacity than the reference silica gel over the whole range of relative pressure.

scholarly journals New Composite Water Sorbents CaCl2-PHTS for Low-Temperature Sorption Heat Storage: Determination of Structural Properties

Nanomaterials ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 27 ◽  
Author(s):  
Alenka Ristić ◽  
Nataša Zabukovec Logar
Keyword(s):  
Electron Microscopy ◽  
Calcium Chloride ◽  
Structural Properties ◽  
Sorption Capacity ◽  
Water Uptake ◽  
Water Sorption ◽  
Heat Storage ◽  
Impregnation Method ◽  
Sorption Heat ◽  
Water Sorption Capacity

Sorption heat storage, as one of low-energy consuming technologies, is an approach to reduce CO2 emissions. The efficiency of such technology is governed by the performance of the applied sorbents. Thus, sorbents with high water sorption capacity and regeneration temperature from 80 to 150 °C are required. Incorporation of hygroscopic salt such as calcium chloride into porous materials is a logical strategy for increasing the water sorption capacity. This work reports the study on the development of composites with PHTS (plugged hexagonal templated silicate) matrix with an average pore size of 5.7 nm and different amounts of calcium chloride (4, 10, 20 wt.%) for solar thermal energy storage. These composites were prepared by wetness incipient impregnation method. Structural properties were determined by X-ray diffraction (XRD), nitrogen physisorption, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). CaCl2 was confined in micro- and mesopores of the matrix. The resulting CaCl2-PHTS materials were used for water sorption at 40 °C, showing an increase of maximal water uptake with higher amount of calcium chloride from 0.78 g/g to 2.44 g/g of the dry composite. A small reduction in water uptake was observed after 20 cycles of sorption/desorption between temperatures of 140 °C and 40 °C, indicating good cycling stability of these composites under the working conditions.

An “on–off” switchable cubic phase with exceptional thermal stability and water sorption capacity

2017 ◽  
Vol 53 (99) ◽  
pp. 13217-13220 ◽  
Author(s):  
K. N. Grafskaia ◽  
D. V. Anokhin ◽  
B. I. Zimka ◽  
I. A. Izdelieva ◽  
X. Zhu ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Sorption Capacity ◽  
Water Sorption ◽  
Columnar Structure ◽  
Cubic Phase ◽  
Water Sorption Capacity

A wedge-shaped mesogen reveals structural bistability; the gyroid phase exhibits exceptional water sorption capacity whereas the columnar structure does not swell.

Sign in / Sign up

Export Citation Format

Share Document