Comments on using of “initial adsorption rate” [J. Hazard. Mater. 173]

2010 ◽  
Vol 179 (1-3) ◽  
pp. 1165 ◽  
Author(s):  
Yuh-Shan Ho
Keyword(s):  
Adsorption Rate ◽  
Initial Adsorption ◽  
Initial Adsorption Rate

scholarly journals Kinetics of Phenol Removal from Aqueous Solution by Adsorption onto Peanut Shell Acid-Activated Carbon

2005 ◽  
Vol 23 (4) ◽  
pp. 289-302 ◽  
Author(s):  
Elio E. Gonzo ◽  
Luis F. Gonzo
Keyword(s):  
Activated Carbon ◽  
Adsorption Capacity ◽  
Rate Constant ◽  
Equilibrium Adsorption ◽  
Phenol Removal ◽  
Peanut Shell ◽  
Pseudo Second Order ◽  
Equilibrium Adsorption Capacity ◽  
Initial Adsorption ◽  
Initial Adsorption Rate

A pseudo-second-order rate equation describing the kinetic adsorption of phenol onto peanut shell acid-activated carbon at different initial concentrations, carbon dosages and particle sizes has been developed. The adsorption kinetics were followed on the basis of the amount of phenol adsorbed at various time intervals at 22°C. The rate constant and the equilibrium adsorption capacity were calculated. From these parameters, empirical correlations for predicting the equilibrium adsorption capacity as a function of the C0/D ratio, and for estimating the rate constant as a function of the relation D/(C0dp)0.5, were derived. This allowed a general rate expression for design purposes to be obtained which was valid for C0/D ≤ 1.5. The operation line for each case studied was constructed and the equilibrium adsorption capacity obtained. A comparison was undertaken with the experimental adsorption isotherm as previously determined. The effect of the initial phenol concentration, the carbon dose and the particle size on the initial adsorption rate was also analyzed.

scholarly journals Modified Vermiculite as Adsorbent of Hexavalent Chromium in Aqueous Solution

Minerals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 749
Author(s):  
Celia Marcos ◽  
Valeria Medoro ◽  
Alaa Adawy
Keyword(s):  
Adsorption Capacity ◽  
Adsorption Energy ◽  
Maximum Adsorption Capacity ◽  
Order Kinetic ◽  
Ion Chemistry ◽  
Solution Ph ◽  
Cooperative Process ◽  
Order Kinetic Model ◽  
Initial Adsorption ◽  
Initial Adsorption Rate

The aim of this study was to investigate the efficiency of removing Cr6+ from aqueous solutions using two exfoliated vermiculite: (1) heated abruptly at 1000 °C and (2) irradiated with microwave radiation. The effects investigated were contact time, adsorbate concentration and initial Cr6+ concentration. The adsorption with both exfoliated vermiculites was well described by the DKR isotherm, indicative of a cooperative process and with the pseudo second order kinetic model. The Kd value for the two exfoliated vermiculites was similar, 0.2 ·1010 μg/Kg. The maximum adsorption capacity of Cr6+ with thermo-exfoliated vermiculite, 2.81 mol/g, was much higher than with microwave irradiated vermiculite, 0.001 mol/g; both values were obtained with 0.5 g of vermiculite in contact with distilled water enriched with 1 ppm of Cr6+ for 24 h. Factors such as ion chemistry, the solution pH and ionic strength, influence the values of capacity, adsorption energy and initial adsorption rate values of the exfoliated vermiculite. In addition, these values depended on the exfoliation process, being the adsorption capacity highest with abrupt heating of vermiculite, while the adsorption energy and rate values showed just a slight increase with microwave irradiation. This aspect is important to select the most suitable vermiculite modification treatment to use it as an adsorbent.

scholarly journals Nanoporous Activated Carbon Derived via Pyrolysis Process of Spent Coffee: Structural Characterization. Investigation of Its Use for Hexavalent Chromium Removal

2020 ◽  
Vol 10 (24) ◽  
pp. 8812
Author(s):  
Georgios Asimakopoulos ◽  
Maria Baikousi ◽  
Vasilis Kostas ◽  
Marios Papantoniou ◽  
Athanasios B. Bourlinos ◽  
...  
Keyword(s):  
Activated Carbon ◽  
Surface Area ◽  
Hexavalent Chromium ◽  
Chemical Activation ◽  
Micropore Volume ◽  
Industrial Applications ◽  
Nitrogen Atmosphere ◽  
Pyrolysis Process ◽  
Initial Adsorption ◽  
Initial Adsorption Rate

Hexavalent chromium (Cr(VI)) is a heavy metal that is highly soluble and exhibits toxic effects on biological systems. Nevertheless, it is used in many industrial applications. The adsorption process of Cr(VI), using activated carbon (AC), is under investigation globally. On the other hand, around six million tons of spent coffee is sent to landfill annually. In the spirit of cyclic economy, this research investigated the production of AC from spent coffee for the removal of Cr(VI) from wastewater. The AC was produced via pyrolysis process under a nitrogen atmosphere. Chemical activation using potassium hydroxide (KOH) occurred simultaneously with the pyrolysis process. The produced AC was tested as an absorber of Cr(VI). The best fitted kinetic model was the diffusion–chemisorption model. A 24-h adsorption experiment was carried out using a solution with a pH of 3 and an initial Cr(VI) concentration of 54.14 ppm. This resulted in an experimental maximum capacity of 109 mg/g, while the theoretical prediction was 137 mg/g. It also resulted in an initial adsorption rate (ri) of 110 (mg/(g h)). The Brunauer–Emmett–Teller surface area (SgBET) was 1372 m2/g, the Langmuir surface area (SgLang.) was 1875 m2/g, and the corrugated pore structure model surface area (SgCPSM) was 1869 m2/g. The micropore volume was 84.6%, exhibiting micropores at Dmicro1 = 1.28 and Dmicro2 = 1.6 nm. The tortuosity factor (τ) was 4.65.

THE SHORT-TERM UPTAKE OF ZINC AND CELL MORTALITY OF THE SEAGRASS HALOPHILA STIPULACEA (FORSK.) ASCHERS.

1995 ◽  
Vol 43 (1) ◽  
pp. 21-30 ◽  
Author(s):  
P. Malea ◽  
T. Kevrekidis ◽  
S. Haritonidis
Keyword(s):  
Sea Water ◽  
Mesophyll Cells ◽  
Halophila Stipulacea ◽  
Zn Uptake ◽  
Cell Mortality ◽  
Zn Content ◽  
Zinc Concentrations ◽  
Equilibrium Concentrations ◽  
Initial Adsorption ◽  
Initial Adsorption Rate

Zinc uptake in the upper (leaves) and lower ground parts (roots, stems, rhizoids) of Halophila stipulacea (Forsk.) Aschers, and leaf cell mortality were examined in laboratory experiments. The seagrass was incubated for 12 days in zinc concentrations between 10−4 and 10−7 M. At 10−6 and 10−7 M Zn concentrations, uptake was characterized by a rapid initial adsorption rate slowly decreasing up to the 4th day, after which an equilibrium was reached; the ‘equilibrium’ concentrations increased as the Zn in sea water increased. At the higher Zn concentrations (10−5 and 10−4M)the content in the plant continued to increase after the 4th day, perhaps due to the development of necrotic effects mainly evident in the teeth and epidermal cells as well as in the mesophyll cells of the leaves. A positive correlation between Zn content in the upper and lower parts of H. stipulacea was also found, whereas Zn uptake in leaves was significantly higher than in the root-rhizomes-rhizoids. It was also demonstrated that some zinc can leak from the tissues of this seagrass.

Kinetics of Peach Clarified Juice Discoloration Process with an Adsorbent Resin

2008 ◽  
Vol 14 (5_suppl) ◽  
pp. 57-62 ◽  
Author(s):  
A. Ibarz ◽  
S. Garza ◽  
A. Garvín ◽  
J. Pagan
Keyword(s):  
Type Equation ◽  
Adsorbent Resin ◽  
Different Temperatures ◽  
Colored Product ◽  
Peach Juice ◽  
Initial Adsorption ◽  
Initial Adsorption Rate ◽  
Adsorption Desorption ◽  
Desorption Step ◽  
Kinetics Of

This paper deals with the effects of adsorbent resin upon kinetic process of peach juice adsorption de-coloration at different temperatures ranged from 10 °C to 50 °C. The adsorption equilibrium was quantified by means of adsorption isotherms in the range from 10 °C to 50 °C. Absorbance data at 420 nm were used to plot all the isotherms, which correlated reasonable well with the Freundlich and Langmuir isotherms. Also, the efficiency of the adsorption process was studied for different resin/juice ratios at different temperatures, from which it was observed that there was a notable improvement in efficiency as the resin content increased, while the increase in temperature was not so important in the process. The adsorption kinetics was also studied at 30 °C, for relationships of 1, 2, and 3 g resin/100g juice. A kinetic adsorption— desorption model in two simultaneous steps was proposed, where the adsorption step is considered as zero order and the desorption step as first order. This allows a global expression to be obtained that fits the experimental data appropriately to this kinetic type equation. The initial adsorption rate depended on the resin/juice relationship in such a way that the higher its value, the lower this relationship was. It was also shown that the equilibrium constant showed a similar tendency, its value being superior to the unit, which indicates that the retention stage over the resin prevails over the colored product desorption stage.

scholarly journals Kinetics and thermodynamics of adsorption of congo red on cellulose

2010 ◽  
Vol 8 (4) ◽  
pp. 906-912 ◽  
Author(s):  
Babak Samiey ◽  
Mohammad Dargahi
Keyword(s):  
Congo Red ◽  
Kinetics Of Adsorption ◽  
First Order ◽  
Rate Limiting Step ◽  
Pseudo Second Order ◽  
Initial Adsorption ◽  
Initial Adsorption Rate ◽  
Rate Limiting ◽  
Kinetics Of ◽  
Cellulose Surface

AbstractThermodynamics and kinetics of adsorption of congo red (CR) on cellulose are studied at 308–328 K. In the used concentration range of CR, interaction of CR with cellulose is exothermic and CR molecules adsorb chemically on cellulose surface. The effects of contact time, temperature and initial concentration of CR on kinetics of its adsorption on cellulose were investigated. The process proceeds according to the pseudo-second-order equation. Initial adsorption rate of adsorption is first-order in CR and the intraparticle diffusion of CR molecules within cellulose is identified as the main rate-limiting step.

Polyaniline/reduced graphene oxide/Fe3O4 nano-composite for aqueous Hg(II) removal

2015 ◽  
Vol 72 (11) ◽  
pp. 2062-2070 ◽  
Author(s):  
Renjie Li ◽  
Lifen Liu ◽  
Fenglin Yang
Keyword(s):  
Graphene Oxide ◽  
Adsorption Capacity ◽  
Reduced Graphene Oxide ◽  
Test Results ◽  
Nano Composite ◽  
Transmission Electron ◽  
Reduced Graphene ◽  
Initial Adsorption ◽  
Initial Adsorption Rate ◽  
Optimal Ph

To ease the adsorbent recovery and to increase the adsorption capacity of polyaniline (PANI), aniline was polymerized in the presence of a solvothermally prepared nano-composite of reduced graphene oxide and Fe3O4 (RGO/Fe3O4). The polyaniline was formed along the RGO/Fe3O4 composite in transmission electron microscope (TEM). The thus formed PANI/RGO/Fe3O4 adsorbent was tested and applied in removing Hg(II) in aqueous solution. The initial adsorption rate as well as the adsorption capacity increases with the incorporation of RGO/Fe3O4. The magnetic separation of PANI/RGO/Fe3O4 was easy, and its regeneration can be carried out at the optimal pH of 2. Test results proved the competence of the prepared adsorbent in pollution remediation applications for safer water quality and environmental protection.

Development of Bentonite-Alginate Films for Enhancement in Cd(II) Removal

2009 ◽  
Vol 1219 ◽  
Author(s):  
Wah Tzu Teoh ◽  
Takuma Tsuritani ◽  
Kazunori Sato
Keyword(s):  
Adsorption Isotherm ◽  
Adsorption Capacity ◽  
Kinetic Models ◽  
Kinetic Studies ◽  
Alginate Beads ◽  
Order Kinetic ◽  
Langmuir Isotherm Model ◽  
Isotherm And Kinetic Models ◽  
Initial Adsorption ◽  
Initial Adsorption Rate

AbstractThe comparison between bentonite-alginate beads and bentonite-alginate films in Cd(II) removal from aqueous solution was investigated. The experimental Cd(II) adsorption data were fitted to adsorption isotherm and kinetic models. Results showed that both bentonite-alginate film and beads were fitted better to the Langmuir isotherm model, the calculated saturation adsorption capacity for bentonite-alginate film was 59.9 mg/g as compared to 17.9 mg/g for the beads. The kinetic studies indicated that both samples followed the pseudo-second-order kinetic. The bentonite- alginate film showed higher adsorption capacity, rate constant as well as initial adsorption rate. This investigation showed that the adsorption behavior of both samples, in terms of adsorption isotherm and kinetic models, did not deviate significantly. The bentonite-alginate film has better performance in Cd(II) removal, attributed to the larger surface area which is exposed to the Cd(II) solution.

Study on the Absorption Action of Modified Activated Carbon for Phenol

2010 ◽  
Vol 113-116 ◽  
pp. 1981-1985
Author(s):  
Chun Sheng Ding ◽  
Fang Ming Ni ◽  
Hui Ye Cai ◽  
Qian Fen Zhu ◽  
Ying Long Zou
Keyword(s):  
Activated Carbon ◽  
Removal Rate ◽  
Copper Nitrate ◽  
Langmuir Model ◽  
Absorption Properties ◽  
Modified Activated Carbon ◽  
Adsorption Time ◽  
Initial Concentration ◽  
Initial Adsorption ◽  
Initial Adsorption Rate

To improve the adsorption efficiency of activated carbon for phenol, copper nitrate was used to modify activated carbon. In detail, the absorption properties of modified activated carbon was studied by investigating the effects of adsorption time, pH, amount of modified activated carbon and initial concentration of phenol on the adsorption. And the dynamic and adsorbent model were obtained and explored. It shows that the removal rate of modified activated carbon for phenol was higher than the unmodified carbon, and the best removal rate can be obtained under the conditions of pH about 5, adsorption time of 2h, modified activated carbon dosage of 1.0g. The quasi-two rate equation was better to reflect the dynamics of modified activated carbon for phenol, with the initial concentration of phenol increased, equilibrium adsorption capacity and initial adsorption rate were greater. Both Freundlich and Langmuir model could reflect the adsorption behavior of modified activated carbon for phenol, while the Langmuir model was more properly.

On the Understanding of the Adsorption of 2-Phenylethanol on Polyurethane-Keratin based Membranes

2017 ◽  
Vol 15 (5) ◽  
Author(s):  
Itza Cordero-Soto ◽  
Olga Rutiaga-Quiñones ◽  
Sergio Huerta-Ochoa ◽  
Veronica Saucedo-Rivalcoba ◽  
Alberto Gallegos-Infante
Keyword(s):  
Low Cost ◽  
Polymeric Membranes ◽  
Operating Conditions ◽  
Maximum Adsorption Capacity ◽  
Hybrid Membranes ◽  
Alternative Source ◽  
Adsorption Mechanisms ◽  
Before And After ◽  
Initial Adsorption ◽  
Initial Adsorption Rate

Abstract Polymers and specifically hybrid polymeric membranes have been identified as effective formulations in adsorption processes. Nevertheless, the adsorption mechanisms associated with their thermodynamics and kinetics are not fully understood, particularly when these polymeric membranes are used to adsorb 2-Phenylethanol (2-PE) to intensify its production in a specific bioconversion process. This work was aimed at giving phenomenological insights on the adsorption of 2-PE on a set of novel porous hybrid membranes based on polyurethane and keratin biofiber obtained from chicken feathers. Feathers, considered as a waste by-product of the poultry industry, represent an alternative source of keratin, a biopolymer that can be used to design low-cost materials from natural resources. Two types of hybrid membranes were prepared. i. e. composite and copolymer. Firstly, these materials were characterized by scanning electron microscopy (SEM), infrared spectroscopy (FT-IR) (before and after the adsorption process) and X-Ray (WAXD) analysis. Secondly, these materials, including the reference ones (keratin biofiber and polyurethane), were evaluated during the removal of 2-PE, relating their adsorption capabilities to physiochemical properties elucidated during the characterization. Particularly a composite with 0.1 g of chicken-feather-keratin (C1) presented the highest removal percentage (60.68%), a significant initial adsorption rate (0.2340 mgPE.h−1.gA −1), the maximum adsorption capacity (12.13 mgPE.gA −1) and the best stability and mechanical properties at studied operating conditions. In comparison with results reported in literature, in this composite carbonyl functional groups from polyurethane showed rather major affinity to 2-PE than amino groups from the keratin biofiber. To this end, parameters associated with its industrial application were obtained, namely thermodynamic and kinetic information was obtained from a proper design of experiments and phenomenological models based on adsorption macroscopic fundamentals.

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