Removal of fluoride ions from aqueous solution at low pH using schwertmannite

2008 ◽  
Vol 152 (2) ◽  
pp. 571-579 ◽  
Author(s):  
Akbar Eskandarpour ◽  
Maurice S. Onyango ◽  
Aoyi Ochieng ◽  
Shigeo Asai
Keyword(s):  
Aqueous Solution ◽  
Low Ph ◽  
Fluoride Ions

LDH-MgAl-NO3 synthesis with the intervention of ethylenediamine intended for the removal of fluoride ions from aqueous solution

MRS Advances ◽  
2021 ◽  
Author(s):  
J. C. Coyote-Jiménez ◽  
R. E. Zavala-Arce ◽  
M. L. Jiménez-Núñez ◽  
J. L. García-Rivas ◽  
N. A. Rangel-Vázquez ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Fluoride Ions

scholarly journals Adsorption of Cr6+ Onto Unmodified and Hydrochloric Acid Modified African Nutmeg Pod (Monodora myristica) from Aqueous Solution

2019 ◽  
pp. 1-8
Author(s):  
F. U. Okwunodulu ◽  
H. O. Chukwuemeka-Okorie ◽  
N. M. Mgbemena ◽  
J. B. I. Kalu
Keyword(s):  
Aqueous Solution ◽  
Metal Ion ◽  
Correlation Coefficients ◽  
Freundlich Isotherm ◽  
Low Ph ◽  
Ion Concentration ◽  
Isotherm Models ◽  
Particle Sizes ◽  
Monodora Myristica ◽  
Best Fit

The removal of Cr6+ from aqueous solution using unmodified and hydrochloric modified African nutmeg pod was studied. The effects of particle size, pH and initial metal ions concentration adsorbed were investigated. The amount of metal ion adsorbed increased as the initial metal ion concentration increased and also decreased at low pH of 2 for both modified and unmodified African nutmeg pod.  400 µm and 250 µm were the optimum particle sizes for both modified and unmodified African nutmeg pod respectively, values given as 75.8 mg/g for the modified and 93.39 mg/g for the unmodified. Generally, it was observed that the unmodified African nutmeg pod showed greater adsorption capacity than the modified African nutmeg pod. The equilibrium experimental data were examined via Langmuir and Freundlich isotherm models.  Freundlich isotherm model gave the best fit for the data in both unmodified and modified African nutmeg pod based on the correlation coefficients (R2 values) gotten. The results of the study showed that the African nutmeg pod is efficient for the removal of Cr6+ from aqueous solutions especially when unmodified.

Kinetic and equilibrium studies of fluoride sorption onto surfactant-modified smectites

Clay Minerals ◽  
2012 ◽  
Vol 47 (4) ◽  
pp. 429-440 ◽  
Author(s):  
S. Gamoudi ◽  
N. Frini-Srasra ◽  
E. Srasra
Keyword(s):  
Aqueous Solution ◽  
Thermodynamic Parameters ◽  
Adsorption Kinetics ◽  
Equilibrium Constants ◽  
Second Order ◽  
Operating Conditions ◽  
Polluted Water ◽  
Isotherm Models ◽  
Fluoride Ions ◽  
Pseudo Second Order

AbstractThe use of organoclays as adsorbents in the remediation of polluted water has been the subject of many recent studies. In the present work, a Tunisian smectite modified with two cationic surfactants was used as an adsorbent to examine the adsorption kinetics, isotherms and thermodynamic parameters of fluoride ions from aqueous solution. Various pH values, initial concentrations and temperatures have been tested. Two simplified kinetic models, first-order and pseudo-second-order, were used to predict the adsorption rate constants. It was found that the adsorption kinetics of fluoride onto modified smectites at different operating conditions can best be described by the pseudo-second-order model. Adsorption isotherms and equilibrium adsorption capacities were determined by the fitting of the experimental data to well known isotherm models including those of Langmuir and Freundlich. The results showed that the Langmuir model appears to fit the adsorption better than the Freundlich adsorption model for the adsorption of fluoride ions onto modified smectites. The equilibrium constants were used to calculate thermodynamic parameters, such as the change of free energy, enthalpy and entropy. Results of this study demonstrated the effectiveness and feasibility of organoclays for the removal of fluoride ions from aqueous solution.

Rare Earth Ion from Aqueous Solution Removed by Polymer Enhanced Ultrafiltration Process

2011 ◽  
Vol 233-235 ◽  
pp. 959-964 ◽  
Author(s):  
Gui E Chen ◽  
De Sun ◽  
Zhen Liang Xu
Keyword(s):  
Aqueous Solution ◽  
Rare Earth ◽  
Low Ph ◽  
Water Soluble ◽  
Rare Earth Ion ◽  
Water Soluble Polymers ◽  
Soluble Polymers ◽  
Ion Rejection ◽  
Ultrafiltration Process ◽  
Added Salt

An efficiency of rare earth (europium, Eu) removal from aqueous solutions by polymer enhanced ultrafiltration (PEUF) process was investigated using two water-soluble polymers polyacrylic acid (PAA) and polyethylenimine (PEI). The effects of loading ratios of Eu to PAA or PEI, pH of solution and the added salt on Eu removal were evaluated. It was shown that the binding capacities for PAA and PEI to Eu ions were 0.8g Eu/g PAA and 0.5g Eu/g PEI, respectively. Eu ion rejection R decreased significantly at a low pH compared to the results at high pH, regardless of using PAA or PEI. Compared to the PAA case, PEI enhanced UF was more sensitive with changing pH. The effect of the added salt was slightly weak at pH 4-5.At the decomplexation stage, when permeate volume was equal to three times than that of the retentate, Eu removal efficiency (X) of Eu-PAA enhanced UF was 79.5% while that of Eu-PEI enhanced UF was 76.1%, and the polymer PAA and PEI could be recovered more than 97% and 93%, respectively. Eu in the retentate could be extracted effectively and the purified PAA and PEI solution were obtained. The recovered PAA and PEI solution was same as the fresh PAA and PEI solution in PEUF processes carried out by using the recovery recovered PAA and PEI as complex agents.

Rapid and efficient removal of fluoride ions from aqueous solution using a polypyrrole coated hydrous tin oxide nanocomposite

2016 ◽  
Vol 476 ◽  
pp. 103-118 ◽  
Author(s):  
Kamya Parashar ◽  
Niladri Ballav ◽  
Sushanta Debnath ◽  
Kriveshini Pillay ◽  
Arjun Maity
Keyword(s):  
Aqueous Solution ◽  
Tin Oxide ◽  
Efficient Removal ◽  
Fluoride Ions

Synthesis of carboxymethyl-chitosan/acrylic acid hydrogel using silane crosslinker

e-Polymers ◽  
2008 ◽  
Vol 8 (1) ◽  
Author(s):  
Tariq Yasin ◽  
Nadia Rasool ◽  
Zareen Akhter
Keyword(s):  
Drug Delivery ◽  
Aqueous Solution ◽  
Small Intestine ◽  
Acrylic Acid ◽  
Low Ph ◽  
Carboxymethyl Chitosan ◽  
Mass Ratio ◽  
Pyranose Ring ◽  
Ir Analysis ◽  
The Stability

AbstractNovel pH sensitive carboxymethyl (CM) chitosan/acrylic acid hydrogels were prepared. CM-chitosan and acrylic acid (AA) in aqueous solution were copolymerized and crosslinked by using vinyltriethoxysilane (VTESi). Different amounts of AA and crosslinker were incorporated in CM-chitosan/AA hydrogel. IR analysis confirmed the presence of pyranose ring as well as Si-O-Si linkage within the hydrogel. Thermogravimetric analysis showed an increase in the stability of hydrogel either having high AA ratio or high crosslinker ratio. The swelling of the hydrogels was carried out by investigating the effect of time, pH (buffered and nonbuffered) and ionic media. In non-buffered media the overall swelling was found to be high as compared to buffered media. Maximum swelling was observed in hydrogel having mass ratio of 7.0 (AA : CM-chitosan). This hydrogel showed low swelling in low pH similar to that of the stomach and high swelling in neutral pH similar to that of the small intestine and can be used in drug delivery applications

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