scholarly journals Caffeine Adsorption by Fique Bagasse Biochar Produced at Various Pyrolysis Temperatures

2019 ◽  
Vol 35 (2) ◽  
pp. 538-546 ◽  
Author(s):  
Yaned Milena Correa-Navarro ◽  
Juan Carlos Moreno-Piraján ◽  
Liliana Giraldo ◽  
Paola Rodríguez-Estupiñan
Keyword(s):  
Experimental Data ◽  
Hydrogen Bonding ◽  
Physicochemical Properties ◽  
Agricultural Residues ◽  
Layer Adsorption ◽  
Different Temperatures ◽  
Π Stacking Interaction ◽  
Ph Dependent ◽  
Bagasse Biochar ◽  
Adsorption Capability

Biochar obtained from agricultural residues is ever more recognized as a multifunctional porous solid for multiples applications. In this study, fique bagasse biochars were produced at different temperatures and their corresponding deashing. These materials were investigated about physicochemical properties and adsorption capability of caffeine. The pH solution was an influential parameter, and it was determined that a pH =2.0 for washed biochar and pH= 6.0 for not washed biochar were the best conditions for adsorption. Langmuir, Freundlich and Redlich-Peterson isotherms models provided a good fit for the experimental data, indicating a surface and multi-layer adsorption. From the adsorption capacity at equilibrium of fique bagasse biochars it was concluded that pH-dependent interactions, hydrogen bonding and π- π stacking interaction were found to be responsible for caffeine adsorption. The results allow to visualize the biochar obtained from fique bagasse as a sustainable alternative for the waste derived from the production of the cabuya.

Effect Of Elevated Temperatures On Complete Concrete Deformation Diagrams

2019 ◽  
pp. 9-14
Keyword(s):  
Experimental Data ◽  
Elastic Modulus ◽  
Elevated Temperatures ◽  
Peak Load ◽  
Relative Deformation ◽  
Deformation Characteristics ◽  
Compression Tests ◽  
Strain Behavior ◽  
Different Temperatures ◽  
Deformation Diagrams

The analysis of the previous results of the study on concrete stress-strain behavior at elevated temperatures has been carried out. Based on the analysis, the main reasons for strength retrogression and elastic modulus reduction of concrete have been identified. Despite a significant amount of research in this area, there is a large spread in experimental data received, both as a result of compression and tension. In addition, the deformation characteristics of concrete are insufficiently studied: the coefficient of transverse deformation, the limiting relative compression deformation corresponding to the peak load and the almost complete absence of studies of complete deformation diagrams at elevated temperatures. The two testing chambers provided creating the necessary temperature conditions for conducting studies under bending compression and tension have been developed. On the basis of the obtained experimental data of physical and mechanical characteristics of concrete at different temperatures under conditions of axial compression and tensile bending, conclusions about the nature of changes in strength and deformation characteristics have been drawn. Compression tests conducted following the method of concrete deformation complete curves provided obtaining diagrams not only at normal temperature, but also at elevated temperature. Based on the experimental results, dependences of changes in prism strength and elastic modulus as well as an equation for determining the relative deformation and stresses at elevated temperatures at all stages of concrete deterioration have been suggested.

scholarly journals Changes of Physicochemical Properties of Starch Syrups Recommended for Winter Feeding of Honeybees during Storage

Agriculture ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 374
Author(s):  
Teresa Szczęsna ◽  
Ewa Waś ◽  
Piotr Semkiw ◽  
Piotr Skubida ◽  
Katarzyna Jaśkiewicz ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Physicochemical Properties ◽  
Physicochemical Parameters ◽  
Storage Temperature ◽  
Storage Conditions ◽  
Different Temperatures ◽  
And Storage ◽  
Bee Colonies ◽  
Temperature Time ◽  
Winter Feeding

The aim of this study was to determine the influence of storage temperature and time on physicochemical parameters of starch syrups recommended for the winter feeding of bee colonies. The studies included commercially available three starch syrups and an inverted saccharose syrup that were stored at different temperatures: ca. 20 °C, 10–14 °C, and ca. 4 °C. Physicochemical parameters of fresh syrups (immediately after purchase) and syrups after 3, 6, 9, 12, 15, 18, 21, and 24 months of storage at the abovementioned temperatures were measured. It was observed that the rate of unfavorable changes in chemical composition of starch syrups and the inverted saccharose syrup, mainly the changes in the 5-hydroxymethylfurfural (HMF) content, depended on the type of a syrup and storage conditions (temperature, time). Properties of tested starch syrups intended for winter feeding of bees stored at ca. 20 °C maintained unchanged for up to 6 months, whereas the same syrups stored at lower temperatures (10–14 °C) maintained unchanged physicochemical parameters for about 12 months. In higher temperatures, the HMF content increased. To date, the influence of this compound on bees has not been thoroughly investigated.

scholarly journals Kinetics and thermodynamic properties related to the drying of 'Cabacinha' pepper fruits

2016 ◽  
Vol 20 (2) ◽  
pp. 174-180 ◽  
Author(s):  
Hellismar W. da Silva ◽  
Renato S. Rodovalho ◽  
Marya F. Velasco ◽  
Camila F. Silva ◽  
Luís S. R. Vale
Keyword(s):  
Experimental Data ◽  
Activation Energy ◽  
Free Energy ◽  
Thermodynamic Properties ◽  
Gibbs Free Energy ◽  
Removal Rate ◽  
Effective Diffusion ◽  
Drying Time ◽  
Three Samples ◽  
Different Temperatures

ABSTRACT The objective of this study was to determine and model the drying kinetics of 'Cabacinha' pepper fruits at different temperatures of the drying air, as well as obtain the thermodynamic properties involved in the drying process of the product. Drying was carried out under controlled conductions of temperature (60, 70, 80, 90 and 100 °C) using three samples of 130 g of fruit, which were weighed periodically until constant mass. The experimental data were adjusted to different mathematical models often used in the representation of fruit drying. Effective diffusion coefficients, calculated from the mathematical model of liquid diffusion, were used to obtain activation energy, enthalpy, entropy and Gibbs free energy. The Midilli model showed the best fit to the experimental data of drying of 'Cabacinha' pepper fruits. The increase in drying temperature promoted an increase in water removal rate, effective diffusion coefficient and Gibbs free energy, besides a reduction in fruit drying time and in the values of entropy and enthalpy. The activation energy for the drying of pepper fruits was 36.09 kJ mol-1.

scholarly journals Torrefaction of Almond and Walnut Byproducts

2021 ◽  
Vol 9 ◽  
Author(s):  
Zach McCaffrey ◽  
Lennard Torres ◽  
Bor-Sen Chiou ◽  
Saulo Rocha Ferreira ◽  
Luiz Eduardo Silva ◽  
...  
Keyword(s):  
Physicochemical Properties ◽  
Moisture Absorption ◽  
Calorific Value ◽  
Dynamic Vapor Sorption ◽  
Energy Applications ◽  
Thermochemical Process ◽  
Heat Treated ◽  
The Us ◽  
Torrefied Biomass ◽  
Different Temperatures

While the US nut industry is growing, markets for nut by-products, particularly nutshells and tree prunings, have not kept pace. Torrefaction is a thermochemical process used to improve physicochemical properties of biomass for energy and other applications. The goal of the paper was to characterize the effects of a range of torrefaction conditions on the properties of nut by-product feedstock. The process consists of thermal treatment of biomass at a temperature between 200 and 300°C in the absence of oxygen, where final material properties of the torrefied biomass depend on the temperature, heating rate, and residence time. In general, torrefied biomass exhibits higher hydrophobicity and calorific value with reduced moisture absorption compared to untreated biomass, making it an ideal fuel source for energy applications compared to raw biomass. In this study, almond shells of soft, semi-soft, and hardshell varieties, as well as walnut shells and almond wood, were torrefied at two different temperatures (230 and 290°C) and three different residence times (20, 40, and 60 min) in order to characterize the physicochemical properties. The thermal behavior of raw and heat-treated biomass was investigated by TGA analysis, elemental analysis, pH, helium pycnometry, FTIR spectroscopy, and dynamic vapor sorption analysis.

scholarly journals A Temperature Variation of Debye-Waller Factor for Alkali and Noble Metals

1983 ◽  
Vol 38 (5) ◽  
pp. 503-508 ◽  
Author(s):  
A. R. Jani ◽  
V. B. Gohel
Keyword(s):  
Experimental Data ◽  
Temperature Variation ◽  
Phenomenological Model ◽  
Noble Metals ◽  
Experimental Information ◽  
Waller Factor ◽  
Critical Examination ◽  
Debye Waller Factor ◽  
Different Temperatures ◽  
Experimental Findings

Debye-Waller factors at different temperatures of four alkali and three noble metals have been computed on the basis of a screened shell phenomenological model. The theoretical values are compared with existing experimental data. Particularly for lithium and potassium, most recent experimental information has been included. A critical examination of the results reveals a satis­factory agreement between the theoretical and experimental findings.

Fluorescence characteristic and molecular interaction in the excited state of 1,2,3,4-tetrahydroquinoline

1984 ◽  
Vol 62 (7) ◽  
pp. 1369-1372 ◽  
Author(s):  
Kakali Chatterjee ◽  
Santanu Laha ◽  
Sankar Chakravorti ◽  
Tapan Ganguly ◽  
Sukhendu B. Banerjee
Keyword(s):  
Hydrogen Bonding ◽  
Excited State ◽  
Electron System ◽  
Reaction Scheme ◽  
Ternary Mixtures ◽  
Probable Case ◽  
Electronic Delocalization ◽  
Diffusion Controlled ◽  
Binary And Ternary Mixtures ◽  
Different Temperatures

Fluorescence spectra of 1,2,3,4-tetrahydroquinoline (THQ) in binary and ternary mixtures in nonpolar and hydrogen bonding solvents at different temperatures are investigated. A probable case of partial protonation of THQ at 300 K due to hydrogen bonding in the excited state with ethanol is reported. At 77 K, there is no significant hydrogen bonding interaction between these molecules. Interaction between the n-orbital of triethylamine (TEA) and the π-electron system of excited THQ results in the formation of a CT-type complex which causes slow quenching of the fluorescence of THQ at 300 K. This quenching is not observed at 77 K because restriction of molecular orientation at 77 K prevents the formation of such complex In pyridine, the fluorescence is strongly quenched both at room temperature and at 77 K. This has been attributed to π-electronic delocalization interaction between the fluorescer THQ and the nonfluorescing quencher pyridine. Possibility of conformational change is suggested. Rate constants associated with suitable reaction scheme for depletion of excited state are estimated. It is indicated that the quenching of fluorescence may be largely diffusion controlled.

scholarly journals Drying kinetics of baru flours as function of temperature

2018 ◽  
Vol 22 (10) ◽  
pp. 713-719 ◽  
Author(s):  
Douglas R. Reis ◽  
Fabrício B. Brum ◽  
Eduardo J. O. Soares ◽  
Jessiana R. Magalhães ◽  
Fabrício S. Silva ◽  
...  
Keyword(s):  
Experimental Data ◽  
Activation Energy ◽  
Food Industry ◽  
Nutritional Value ◽  
Effective Diffusivity ◽  
Drying Kinetics ◽  
Statistical Parameters ◽  
Noticeable Effect ◽  
Different Temperatures ◽  
Kinetics Of

ABSTRACT Several types of seeds have been initially used in the food industry due to the great potential that vegetable proteins have. Baru is a fruit commonly found in the Cerrado biome, having a high nutritional value. This paper aimed to determine and analyze the drying kinetics of whole and defatted baru almond flours at different temperatures. The flour resulting from almond milling was defatted using petroleum ether. The drying processes were performed at temperatures of 40, 50 and 60 ºC. The mathematical models of Page, Henderson and Pabis, Midilli & Kucuk, Thompson and Approximation of Diffusion were fitted to the experimental data. The results showed a noticeable effect of air temperature on the drying kinetics of whole and defatted baru almond flours. According to the statistical parameters of analysis, the models Midilli & Kucuk and Page were the ones with the best fits to the experimental data. The effective diffusivity values found ranged from 8.02 × 10–10 to 19.90 × 10–10 m2 s-1 and for the activation energy were 22.39 and 39.37 KJ mol-1 for whole and defatted almonds, respectively.

Carbon nanospheres with dual-color emission and their application in ratiometric pyrophosphate sensing

The Analyst ◽  
2019 ◽  
Vol 144 (2) ◽  
pp. 550-558 ◽  
Author(s):  
Zhong-Xia Wang ◽  
Yuan-Fei Gao ◽  
Xian-He Yu ◽  
Fen-Ying Kong ◽  
Wen-Juan Wang ◽  
...  
Keyword(s):  
Physicochemical Properties ◽  
Carbon Nanospheres ◽  
One Pot ◽  
Aqueous Synthesis ◽  
Dual Color ◽  
Ph Dependent ◽  
The One ◽  
Solubility Equilibrium ◽  
Color Emission ◽  
Fluorescent Carbon

Herein, we employ pH-dependent solubility equilibrium to develop the one-pot aqueous synthesis of dual-color emission fluorescent carbon nanosphere (DFCSs) with novel physicochemical properties.

scholarly journals Correlations of the physicochemical properties of organosolv lignins from Broussonetia papyrifera with their antioxidant activities

2020 ◽  
Vol 4 (10) ◽  
pp. 5114-5119
Author(s):  
Lan Yao ◽  
Long Xiong ◽  
Chang Geun Yoo ◽  
Chengyu Dong ◽  
Xianzhi Meng ◽  
...  
Keyword(s):  
Physicochemical Properties ◽  
Antioxidant Activities ◽  
Broussonetia Papyrifera ◽  
Organosolv Pretreatment ◽  
Different Temperatures ◽  
Lignin Characteristics

To understand the influence of lignin characteristics on their antioxidant activities, lignins were isolated from Broussonetia papyrifera by organosolv pretreatment at different temperatures.

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