Hard and Soft Acid-Base Behavior in Aqueous Solution: Steric Effects Make Some Metal Ions Hard: A Quantitative Scale of Hardness-Softness for Acids and Bases

1996 ◽  
Vol 73 (7) ◽  
pp. 654 ◽  
Author(s):  
Robert D. Hancock ◽  
Arthur E. Martell
Keyword(s):  
Aqueous Solution ◽  
Metal Ions ◽  
Steric Effects ◽  
Acid Base ◽  
Acids And Bases ◽  
Soft Acid

scholarly journals PHYTIC ACID: AN ANALYTICAL INVESTIGATION

1961 ◽  
Vol 39 (6) ◽  
pp. 1290-1297 ◽  
Author(s):  
E. C. Brown ◽  
M. L. Heit ◽  
D. E. Ryan
Keyword(s):  
Aqueous Solution ◽  
Aqueous Solutions ◽  
Metal Ions ◽  
Phytic Acid ◽  
Titration Curve ◽  
Analytical Investigation ◽  
Acid Base ◽  
Acid Structure

Acid–base titrations in aqueous and non-aqueous solutions, titrations with metal ions, and analyses of various metal phytates support beyond question the 18-acid structure of phytic acid. Six of the hydrogens are too weakly acidic to be ordinarily titratable in water; in aqueous solution, two distinct breaks occur in the titration curve corresponding to the titration of 8 and 12 protons of phytic acid.

REMOVAL OF HEAVY METAL Cr (II), Ni (II), Cu (II), Zn (II), Cd (II), Pb (II) IONS FROM AQUEOUS SOLUTION BY MENTHA PIPERITA EXTRACT

2020 ◽  
pp. 15-20
Author(s):  
Ersin Yucel ◽  
Mine Yucel
Keyword(s):  
Aqueous Solution ◽  
Metal Ions ◽  
High Efficiency ◽  
Correlation Coefficients ◽  
Langmuir Model ◽  
Mentha Piperita ◽  
Freundlich Model ◽  
Biosorption Capacity ◽  
Peppermint Extract ◽  
The Stability

In this study, the usage of the peppermint (Mentha piperita) for extracting the metal ions [Mg (II), Cr (II), Ni (II), Cu (II), Zn (II), Cd (II), Pb (II)] that exist at water was investigated. In order to analyze the stability properties, Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherms were used at removing the metal ions and the highest correlation coefficients (R2) were obtained at Langmuir isotherm. Therefore, it is seen that the Langmuir model is more proper than the Freundlich model. However, it was found that the correlation coefficients of removing Ni and Cd is higher at Freundlich model than Langmuir and low at Dubinin-Radushkevich isotherm. It is established that the biosorption amount increase depends on the increase of biosorbent and it can be achieved high efficiency (95%) even with small amount (0.6 mg, peppermint extract) at lead ions. It is also determined that the peppermint extracted that is used at this study shows high biosorption capacity for metal ions and can be used for immobilization of metals from polluted areas.

Comparative Bio-sorption of Cadmium and Nickel Ions from Aqueous Solution onto Fibers of Date Palm using Fluidized Bed Column

2019 ◽  
Vol 70 (5) ◽  
pp. 1507-1512
Author(s):  
Baker M. Abod ◽  
Ramy Mohamed Jebir Al-Alawy ◽  
Firas Hashim Kamar ◽  
Gheorghe Nechifor
Keyword(s):  
Aqueous Solution ◽  
Heavy Metal ◽  
Metal Ions ◽  
Fluidized Bed ◽  
Removal Efficiency ◽  
Heavy Metal Ions ◽  
Date Palm ◽  
Operating Conditions ◽  
Initial Concentration ◽  
Bed Height

The aim of this study is to use the dry fibers of date palm as low-cost biosorbent for the removal of Cd(II), and Ni(II) ions from aqueous solution by fluidized bed column. The effects of many operating conditions such as superficial velocity, static bed height, and initial concentration on the removal efficiency of metal ions were investigated. FTIR analyses clarified that hydroxyl, amine and carboxyl groups could be very effective for bio-sorption of these heavy metal ions. SEM images showed that dry fibers of date palm have a high porosity and that metal ions can be trapped and sorbed into pores. The results show that a bed height of 6 cm, velocity of 1.1Umf and initial concentration for each heavy metal ions of 50 mg/L are most feasible and give high removal efficiency. The fluidized bed reactor was modeled using ideal plug flow and this model was solved numerically by utilizing the MATLAB software for fitting the measured breakthrough results. The breakthrough curves for metal ions gave the order of bio-sorption capacity as follow: Cd(II)]Ni(II).

Stabilization of Hazardous Materials into Ferrites

1991 ◽  
Vol 23 (1-3) ◽  
pp. 399-404 ◽  
Author(s):  
Y. Tamaura ◽  
P. Q. Tu ◽  
S. Rojarayanont ◽  
H. Abe
Keyword(s):  
Aqueous Solution ◽  
Heavy Metal ◽  
Metal Ions ◽  
Present Method ◽  
Hazardous Materials ◽  
Precipitation Process ◽  
Waste Waters ◽  
Formation Reaction ◽  
Coating Method ◽  
Hazardous Metal

Stabilization of the hazardous materials by the Fe3O4-coating method was studied. In the ferrite-formation reaction in the aqueous solution, the adsorption of the metal ions and the oxidation of the adsorbed Fe(II) ions are repeated on the surface of the ferrite particles. This reaction was adopted to the coating of the hazardous materials with the Fe3O4(or ferrite). By repeating the two steps of l)the addition of the Fe(II) aqueous solution into the suspension of the hazardous materials, and 2)the oxidation by passing air through the reaction suspension, with the Fe3O4 layer, we could coat the surfaces of the hazardous materials, such as the heavy metal sludge from the neutralization-precipitation process, the CaF2 precipitates in the treatment of the waste waters containing fluoride ion along with hazardous metal ions, and the soils containing Cd(II) ion. These Fe3O4-coated hazardous materials are very stable and no heavy metal ions are leached under the normal environmental conditions. The ferrite sludges formed in the “Ferrite Process” were highly stabilized by the present method, and by the heat-treatment.

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