Effect of Additives on the Sorption Kinetics of a Silica Gel Bed in Adsorption Chiller

The article presents experimental results of the metal-based and carbon nanotube additives influence on sorption kinetics of a silica-gel-based adsorption bed in an adsorption chiller. The purpose of the doping is to improve the efficiency of sorption processes within the bed by use of metallic and non-metallic additives characterized by higher thermal diffusivity than basic adsorption material. The higher the thermal conductivity of the bed, the faster the sorption processes take place, which directly translates into greater efficiency of the refrigerator. In this study, sorption kinetics of pure silica gel sorbent doped with a given amount of aluminum (Al) and copper (Cu) powders and carbon nanotubes (CNT) were analyzed. The tests were performed on DVS Dynamic Gravimetric Vapor Sorption System apparatus used for dynamic vapor sorption measurements. A decrease in the amount of adsorbed water was observed with an increase in the mass share of the additives in the performed studies. Experimental results show that, CNTs seems to be the most promising additive as the sorption process time was reduced with the smallest decrease in water uptake. Any significant reduction of adsorption time was noted in case of the Al addition. Whereas, in case of Cu doping, delamination of the mixture was observed.

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Effect of Metal Additives in the Bed on the Performance Parameters of an Adsorption Chiller with Desalination Function

Energies ◽

10.3390/en14217226 ◽

2021 ◽

Vol 14 (21) ◽

pp. 7226

Author(s):

Karol Sztekler ◽

Wojciech Kalawa ◽

Łukasz Mika ◽

Marcin Sowa

Keyword(s):

Silica Gel ◽

Electricity Consumption ◽

Sorption Kinetics ◽

Coefficient Of Performance ◽

Cooling Power ◽

Adsorption Chiller ◽

Cycle Times ◽

Metal Additives ◽

Low Performance ◽

Kinetics Of

Adsorption chillers with desalination functionality, being devices characterised by very low electricity consumption, provide an alternative to conventional sources of cooling and water. The option of desalinating water means that the use of a single device enables obtaining two useful products. Adsorption chillers are not widely used at present. due to their low performance characteristics; these are, however, constantly being improved. This paper presents a verification of the possibility of increasing the cooling coefficient of performance (COP) and specific cooling power (SCP) of a laboratory adsorption chiller by optimising the length of cycle times and using a copper additive to silica gel with a mass fraction of 15% to increase heat transport in the bed. The choice of copper among other considered additives was determined by the conclusions from the research on the sorption kinetics of various mixtures, price and availability, and a high thermal conductivity. The device was operated in a two-bed mode aimed at producing cooling. The adsorbate was distilled water. The results were compared with those obtained under similar conditions when the beds were only filled with silica gel. As a result of the testing, it was found that the use of the copper additive with the sorbent increased both the COP and SCP. The tests were performed for different cycle times, of 100, 200, 300 and 600 s. With increasing cycle time COP also increased. In contrast, the specific cooling power increased only up to a certain point, whereafter its value decreased.

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Effect of the concentration of 5,5'-dithiobis(2-nitrobenzoic acid) on parameters of the kinetics of its chemisorption on thiol derivatives of cellulose

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19860545 ◽

1986 ◽

Vol 51 (3) ◽

pp. 545-552 ◽

Cited By ~ 6

Author(s):

Albert Breier ◽

Peter Gemeiner ◽

Milan J. Beneš

Keyword(s):

Ethyl Cellulose ◽

Chemical Structure ◽

Sorption Process ◽

Sorption Kinetics ◽

Cellulose Derivatives ◽

Experimental Conditions ◽

Nitrobenzoic Acid ◽

Kinetics Of ◽

Derivatives Of ◽

Sorbate Concentration

Equations describing the dependence of parameters of sorption kinetics on the sorbate concentration have been determined. The validity of the equations has been verified for the chemisorption of 5,5'-dithiobis(2-nitrobenzoic acid) on bead O-(2-mercaptoethyl)-, O-(3-mercapto-2-hydroxy-propyl)- and O-[2-(4-mercaptophenylsulfonyl)ethyl]cellulose. Isothermic constants obtained from the equations can be calculated also under experimental conditions unfavourable for their determination. These constants may be utilized for characterizing relations between the chemical structure of cellulose derivatives and the sorption process. The equation which provides a complete time-concentration description of sorption is suggested.

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Kinetics of Water Vapor Sorption in Wood Cell Walls: State of the Art and Research Needs

Forests ◽

10.3390/f10080704 ◽

2019 ◽

Vol 10 (8) ◽

pp. 704 ◽

Cited By ~ 8

Author(s):

Emil Engelund Thybring ◽

Samuel V. Glass ◽

Samuel L. Zelinka

Keyword(s):

Water Vapor ◽

State Of The Art ◽

Theoretical Models ◽

Sorption Process ◽

Sorption Kinetics ◽

Water Vapor Sorption ◽

Fundamental Aspect ◽

Vapor Sorption ◽

Transfer Resistance ◽

New Models

Water vapor sorption is the most fundamental aspect of wood-moisture relations. It is directly or indirectly related to the physical properties of wood and the onset of wood-damage mechanisms. While sorption properties of cellulosic materials have been utilized since antiquity, the time-dependent transition from one moisture content to another (i.e., sorption kinetics) has received much less attention. In this critical review, we present the state-of-the-art of water vapor sorption kinetics in wood. We first examine different experimental methods that have been used to measure sorption kinetics, from the quartz helix vacuum balance beginning in earnest in the 1930s, to automated sorption balances used recently. We then give an overview of experimental observations and describe the physical phenomena that occur during the sorption process, which potentially govern the following kinetics: boundary layer mass transfer resistance, heat of sorption, cell wall diffusion, swelling, and polymer mobility. Finally, we evaluate theoretical models that have been proposed for describing sorption kinetics, considering both experimental data and the physical processes described in the previous section. It is clear that no previously developed model can phenomenologically describe the sorption process. Instead, new models are needed. We conclude that the development of new models will require more than simple gravimetric measurements. In addition to mass changes, complementary techniques are needed to probe other important physical quantities on multiple length scales.

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Enhanced copper selectivity and faster sorption kinetics of poly(4-vinylpyridine) crosslinked in presence of copper(II) as template on silica gel

Reactive Polymers ◽

10.1016/0923-1137(92)90022-t ◽

1992 ◽

Vol 16 (2) ◽

pp. 149-158 ◽

Cited By ~ 5

Author(s):

M. Chanda ◽

G.L. Rempel

Keyword(s):

Silica Gel ◽

Sorption Kinetics ◽

Kinetics Of

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Sorption and desorption kinetics of Np(V) on magnetite and hematite

Radiochimica Acta ◽

10.1524/ract.2000.88.8.453 ◽

2000 ◽

Vol 88 (8) ◽

Cited By ~ 10

Author(s):

K. Nakata ◽

S. Nagasaki ◽

S. Tanaka ◽

Y. Sakamoto ◽

T. Tanaka ◽

...

Keyword(s):

Crystalline Phase ◽

Acidic Solution ◽

Sorption Process ◽

Sorption Kinetics ◽

Chemical Form ◽

Alkaline Solutions ◽

Desorption Kinetics ◽

Chemical Forms ◽

Kinetics Of ◽

Desorption Method

Sorption kinetics of Np(V) on magnetite and hematite were investigated, and a sequential desorption method was applied to investigate changes in the chemical form of Np sorbed according to the amount of time they were in contact with the Np solution. It was found that the sorption process consists of fast sorption and slow sorption which reaches equilibrium in 1 h. According to the desorption results, it was conjectured (i) that fast sorption is attributable to sorption on/into the surface and non-crystalline phases of iron oxides for magnetite and hematite in both acidic and alkaline solutions, (ii) that sorption on/into the crystalline phase also contributes to fast sorption for hematite in an alkaline solution, and (iii) that slow sorption represents sorption into the crystalline phase of magnetite in both acidic and alkaline solutions and that of hematite in an acidic solution. From the results of sorption and desorption kinetics, it was concluded that the equilibrium between various chemical forms of sorbed Np was achieved in about 1 week, although the amount of sorbed Np reached an equilibrium in only 1 h.

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Equilibrium and Kinetic Study of Ammonium Sorption by Raphia farinifera

Water Air & Soil Pollution ◽

10.1007/s11270-019-4301-z ◽

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.

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