scholarly journals Chlorates(VII) removal on Dowex™PSR-2 resin

2016 ◽  
Vol 71 (1) ◽  
pp. 105
Author(s):  
Dorota Kołodyńska ◽  
Aleksandra Łyko ◽  
Marzena Gęca ◽  
Zbigniew Hubicki
Keyword(s):  
Solution Concentration ◽  
Intraparticle Diffusion ◽  
Optimum Conditions ◽  
Order Model ◽  
Experimental Conditions ◽  
Freundlich Model ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Pseudo Second Order ◽  
Rate Limiting

<p>Lately there has been observed the increased presence of chlorates(VII) in the natural environment which can affect human health negatively. Therefore the removal of chlorate(VII) ions using the gel type resin functionalized with the tri-n-butyl ammonium (Dowex<sup>™</sup>PSR-2) from waters was studied. The main aim was to evaluate the effects of experimental conditions including contact time, initial solution concentration, pH and temperature on chlorate(VII) ions removal as well as the anion exchanger properties on chlorate(VII) ions sorption. It was found that only the pseudo second order model described the experimental data well and the intraparticle diffusion was not the rate-limiting step. According to the Freundlich model, the q<sub>e</sub> value was to be 69.26 mg/g at optimum conditions (pH 7.0 at 25 <sup>o</sup>C).<strong></strong></p>

Kinetics and Isotherm Studies on Nd(III) Adsorption onto Xanthated Chitosan

2016 ◽  
Vol 857 ◽  
pp. 530-534 ◽  
Author(s):  
Noorul Farhana Md Ariff ◽  
Megat Ahmad Kamal Megat Hanafiah ◽  
Zurhana Mat Hussin ◽  
Shariff Che Ibrahim ◽  
Wan Saime Wan Ngah
Keyword(s):  
Metal Ion ◽  
Adsorption Process ◽  
Earth Metal ◽  
Hydroxyl Groups ◽  
Optimum Conditions ◽  
Order Model ◽  
Adsorbent Dosage ◽  
Rate Limiting Step ◽  
Pseudo Second Order ◽  
Rate Limiting

Xanthated chitosan (XC) beads synthesized from the reaction between sulphur and hydroxyl groups were applied to adsorb rare earth metal ion, Nd (III). Adsorption of Nd (III) was found to be a function of pH of initial solution, adsorbent dosage and contact time. The optimum conditions for Nd (III) adsorption were at pH 3 and adsorbent dosage of 0.02 g. Rapid adsorption process was observed as it took only 10 min for reaching the equilibrium state. Chemisorption was identified as the rate limiting step and the kinetics data correlated well with the pseudo-second-order model.

scholarly journals Removal of copper from an electroplating industrial effluent using the native and modified spirogyra

2018 ◽  
Vol 78 (1) ◽  
pp. 147-155 ◽  
Author(s):  
Nimra Ilyas ◽  
Sadia Ilyas ◽  
Sajjad-ur-Rahman ◽  
Sidra Yousaf ◽  
Aqsa Zia ◽  
...  
Keyword(s):  
Industrial Effluent ◽  
Order Kinetic ◽  
Sorption Data ◽  
Freundlich Model ◽  
First Order ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Intra Particle Diffusion ◽  
Pseudo Second Order ◽  
Rate Limiting

Abstract In the present study, biosorption behavior of a green filamentous alga, spirogyra in its native and modified states was investigated for copper removal from an electroplating industrial effluent. For this, the effluent containing 194 mg·L−1 Cu2+ in sulfate medium was contacted with both forms of spirogyra, under the parametric variations of effluent pH, adsorbent dosage, contact time, and sorption temperature. The study revealed spirogyra as a prominent candidate for removing contaminant metal cation; however, at the same condition, biosorption capacity of modified biomass in gel form was higher than the native spirogyra. At the optimized condition with 6 g sorbent dosage treated to 100 mL effluent for 30 min at pH 6.0 and temperature 20 °C, the maximum 82.8% and 96.4% copper could be adsorbed by the native and modified spirogyra, respectively. The batch sorption data using native biomass followed pseudo-first-order kinetic; exhibiting the multilayer sorption mechanism via surface diffusion could be defined by the Freundlich model. In contrast, the sulfuric acid treated modified spirogyra followed pseudo-second-order kinetics and intra particle diffusion as the rate-limiting step.

Study of Adsorption of Cu2+ and Ni2+ from Aqueous Solutions Using β-Cyclodextrin Modified Zeolites

2014 ◽  
Vol 955-959 ◽  
pp. 3509-3513
Author(s):  
Xiao Hong Li ◽  
Xue Kui Hao
Keyword(s):  
Contact Time ◽  
Physical Adsorption ◽  
Kinetic Studies ◽  
Order Model ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Adsorption Processes ◽  
Pseudo Second Order ◽  
Modified Zeolites ◽  
Rate Limiting

Adsorption of Cu2+ and Ni2+ from aqueous solution on CCDMZ was investigated. The adsorption capacity of Cu2+ and Ni2+ on CCDMZ was found to have a much higher enhance than that of NZ and to be obviously influenced by contact time, initial concentration and pH. The kinetic studies showed that the adsorption processes of Cu2+ and Ni2+ on CCDMZ were complex, including chemical adsorption and physical adsorption. The adsorption followed the pseudo-second-order model, which suggested that the rate-limiting step might be mainly chemisorption.

scholarly journals Kinetics of the diamine oxidase reaction

1973 ◽  
Vol 131 (3) ◽  
pp. 459-469 ◽  
Author(s):  
William G. Bardsley ◽  
M. James C. Crabbe ◽  
Julian S. Shindler
Keyword(s):  
Diamine Oxidase ◽  
Experimental Conditions ◽  
Ph Values ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Deuterium Substitution ◽  
Effects Of Temperature ◽  
Rate Limiting ◽  
Kinetics Of ◽  
Oxidase Reaction

1. The oxidation of p-dimethylaminomethylbenzylamine was followed spectrophotometrically by measuring the change in E250 caused by the p-dimethylaminomethylbenzaldehyde produced under a wide variety of experimental conditions. 2. The effect of variations in concentrations of both substrates (amine and oxygen) and all products (aminoaldehyde, hydrogen peroxide and ammonia) on this reaction was studied and the results used to develop a formal mechanism. 3. The nature of the rate-limiting step was elucidated by studying the effects of alterations in ionic strength, dielectric constant and deuterium substitution on the velocity of the forward reaction. 4. Thermodynamic activation energy parameters were obtained at several pH values from the effects of temperature on the reaction.

Physical Modeling of Backside Gettering

1984 ◽  
Vol 36 ◽  
Author(s):  
Gary B. Bronner ◽  
James D. Plummer
Keyword(s):  
Experimental Data ◽  
Physical Modeling ◽  
Equilibrium Concentration ◽  
Order Model ◽  
Phosphorus Diffusion ◽  
First Order ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Buried Layer ◽  
Rate Limiting

ABSTRACTTo understand gettering action we have modeled the diffusion of metal to a backside getter. A first order model describing the diffusion of metals to an infinite backside sink is found not to fit experimental data. To fit the data for phosphorus gettering at 1000°C and argon implantation gettering at 800°C it is necessary to also hypothesize the injection of silicon interstitials. Assuming that the diffusion of the silicon interstitials is the rate limiting step in gettering, allows one to extract the diffusion coefficient and equilibrium concentration of the interstitial. The hypothesis of silicon interstitial injection agrees with recent work on phosphorus diffusion by Fahey et. al. To test this hypothesis for heavily damaged regions we have looked at the effect of an argon implanted region on the diffusion of a phosphorus buried layer. At both 800°C and 700°C, during nitrogen anneals we see significant enhancement of the phosphorus diffusion.

Absorption Behavior of a Modified Cellulose Hydrogel for both Fluoride and Arsenic

2013 ◽  
Vol 726-731 ◽  
pp. 733-738 ◽  
Author(s):  
Ling Die Meng ◽  
Min Wu ◽  
Ye Tian ◽  
Shigenori Kuga ◽  
Yong Huang
Keyword(s):  
High Efficiency ◽  
Adsorption Process ◽  
Intraparticle Diffusion ◽  
Order Model ◽  
Arsenic Adsorption ◽  
Freundlich Model ◽  
Intraparticle Diffusion Model ◽  
Cellulose Hydrogel ◽  
Pseudo Second Order ◽  
Modified Cellulose

This work reports a cationic modified cellulose hydrogel for fluoride and arsenic adsorption. This adsorbent had a high efficiency in removal of F-, AsO2- and AsO43- simultaneously from aqueous solutions, even at low initial concentrations. Adsorption kinetics showed the relatively rapid rate to reach equilibrium, as could be explained by the pseudo-second-order model and the intraparticle diffusion model within 20 min before the equilibrium. Freundlich model could fit the adsorption process best, and the results showed the improved arsenic adsorption performances especially for AsO43-, much larger than other reported absorbents.

scholarly journals Adsorptive Removal of Aqeous Disperse Dye by using Flocs

2020 ◽  
Vol 9 (6) ◽  
pp. 767-771
Keyword(s):  
Ferric Chloride ◽  
Ferrous Sulphate ◽  
Aluminium Sulphate ◽  
Colour Removal ◽  
Adsorptive Removal ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Equilibrium Data ◽  
Pseudo Second Order ◽  
Rate Limiting

Ferric chloride, Aluminium sulphate, and Ferrous sulphate flocs were used as an adsorbent in the decolourisation of aqueous dye C.I. Disperse yellow 3. To evaluate the potentiality of adsorbents, non-flow agitated experiments were carried out to find the equilibrium contact time, optimum equilibrium adsorbent dose. Preformed flocs at pH:: 4 rather than pH:: 10 produced excellent colour removal. Adsorption capacity of flocs of Ferric chloride, Aluminium sulphate and Ferrous sulphate was obtained as 500 mg/g, 333mg/g and 23.3mg/g at pH:4. The equilibrium data sorption follows Langmuir Isotherm and kinetic data follows pseudo second order stating that chemisorptions is the rate limiting step.

Inhibition and activation of Na+-Ca2+ exchange activity by quinacrine

1987 ◽  
Vol 252 (1) ◽  
pp. C24-C29 ◽  
Author(s):  
P. de la Pena ◽  
J. P. Reeves
Keyword(s):  
Inhibitory Effects ◽  
Experimental Conditions ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Amiloride Derivatives ◽  
High Concentrations ◽  
Rate Limiting ◽  
Sarcolemmal Vesicles ◽  
Stimulation Of ◽  
Exchange Activity

Quinacrine either inhibited or stimulated Na-Ca exchange in cardiac sarcolemmal vesicles, depending on the experimental conditions. When present in the assay medium for Na-Ca exchange, quinacrine inhibited both Nai-dependent Ca2+ uptake (Ki = 50 microM) and Nao-dependent Ca2+ efflux. Quinacrine's inhibition of Ca2+ efflux was attenuated by high concentrations of Na+. Quinacrine also blocked Na-Na and Ca-Ca exchange activities in the vesicles. The inhibitory effects of quinacrine on Na-Ca exchange activity are qualitatively similar to those reported previously for amiloride derivatives. When Na-loaded vesicles were preincubated with quinacrine and then assayed for Na-Ca exchange in a quinacrine-free medium, stimulation of exchange activity was observed. This stimulation was reversible on the removal of bound quinacrine and involved in a reduction in the apparent Km for extravesicular Ca2+. Stimulation of exchange activity under these conditions was also observed with the lipophilic cation tetraphenylphosphonium. Since Ca2+, quinacrine and tetraphenylphosphonium all bind strongly to sarcolemmal membranes, it is suggested that the observed stimulation of exchange activity involves a local electrostatic effect of the bound cations in accelerating a rate-limiting step in the reaction mechanism for Na-Ca exchange.

Preparation of cationic starch microspheres and study on their absorption to anionic-type substance

2015 ◽  
Vol 71 (10) ◽  
pp. 1545-1553 ◽  
Author(s):  
Jie Zheng ◽  
YaNan Wang ◽  
ZuoShan Feng ◽  
ZeMin Kuang ◽  
DeZhou Zhao ◽  
...  
Keyword(s):  
Iminodiacetic Acid ◽  
Freundlich Isotherm ◽  
Isotherm Model ◽  
Cationic Starch ◽  
Order Model ◽  
Chemical Absorption ◽  
Rate Limiting Step ◽  
Langmuir Isotherm Model ◽  
Pseudo Second Order ◽  
Rate Limiting

Cationic starch microspheres (CSMs) were prepared from lab-made neutral starch-based microspheres using a cationic adsorbent, namely 3-chloro-2-hydroxypropyltrimethyl ammonium chloride, as the cationic etherifying agent. Detection by scanning electron microscopy, Fourier transform infrared spectroscopy (FTIR), and laser diffraction techniques revealed that CSMs had coarse surfaces with good sphericity and dispersibility. Differential thermal analysis showed the lower thermostability of the CSMs’ main chains. Furthermore, scores of experiments confirmed that CSMs are capable of absorption to N-(phosphonomethyl) iminodiacetic acid (PMIDA), a type of anionic substance, which is the intermediate to the preparation of glyphosate, maximally up to 95.24 mg/g. Compared with the Freundlich isotherm model, the Langmuir isotherm model can better describe the absorption process. The kinetic study showed that the pseudo-second-order model demonstrated a better correlation of the experimental data in contrast with the pseudo-first-order model. It can be therefore concluded that the rate-limiting step was the chemical absorption rather than the mass transport.

scholarly journals Drying of polymer powder in fluidized bed: Modeling of multizone dryer

2014 ◽  
Vol 68 (6) ◽  
pp. 661-671
Author(s):  
Nickolay Ostrovskii
Keyword(s):  
Fluidized Bed ◽  
Intraparticle Diffusion ◽  
Porous Polymer ◽  
Rate Limiting Step ◽  
Limiting Step ◽  
Polymer Powder ◽  
Large Particles ◽  
Two Stages ◽  
The Mathematical Model ◽  
Rate Limiting

The process of drying of porous polymer powder (polypropylene) intended to remove the solvent (heptane) is analyzed. The dryer consists of two stages (apparatus) with multizone fluidized bed. The mathematical model of the process in multizone fluidized bed is proposed. The rate-limiting step, depending on diameter of polymer particles, is determined. It was found that in relatively large particles (>200 ?m) the rate of drying is limited by intraparticle diffusion. A way to decrease the energy consumption in drying has been also discussed and verified in experiments.

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