Molecular configuration of amylose and its complexes in aqueous solutions. Part II. Relation between the DP of helical segments of the amylose-iodine complex and the equilibrium concentration of free iodine

Biopolymers ◽  
1967 ◽  
Vol 5 (1) ◽  
pp. 5-16 ◽  
Author(s):  
J. Szejtli ◽  
M. Richter ◽  
S. Augustat
Keyword(s):  
Aqueous Solutions ◽  
Equilibrium Concentration ◽  
Molecular Configuration ◽  
Iodine Complex ◽  
Free Iodine

scholarly journals A study of adsorption isotherms for the removal of herbicide Atlantis WG from aqueous solutions by using Bentonite clay

2015 ◽  
Vol 12 (1) ◽  
pp. 148-156
Author(s):  
Baghdad Science Journal
Keyword(s):  
Aqueous Solutions ◽  
Adsorption Process ◽  
Equilibrium Concentration ◽  
Bentonite Clay ◽  
Langmuir Model ◽  
Effect Of Temperature ◽  
Isotherm Models ◽  
Sorption Data ◽  
Freundlich Model ◽  
The Subject

The subject of this research involves studying adsorption to removal herbicide Atlantis WG from aqueous solutions by bentonite clay. The equilibrium concentration have been determined spectra photometry by using UV-Vis spectrophotometer. The experimental equilibrium sorption data were analyzed by two widely, Langmuir and Freundlish isotherm models. The Langmuir model gave a better fit than Freundlich model The adsorption amount of (Atlantis WG) increased when the temperature and pH decreased. The thermodynamic parameters like ?G, ?H, and ?S have been calculated from the effect of temperature on adsorption process, is exothermic. The kinetic of adsorption process was studied depending on Lagergren ,Morris ? Weber and Rauschenberg equations.

scholarly journals EQUILIBRIA PROCESSES IN AQUEOUS SOLUTIONS OF K2CrO4 – HNO3 – KNO3 – H2O AND K2Cr2O7 – NaOH – KNO3 – H2O SYSTEMS

2021 ◽  
Vol 26 (2(78)) ◽  
pp. 56-72
Author(s):  
Yu. A Oleksii ◽  
O. Yu. Mariichak ◽  
G. M. Rozantsev ◽  
S. A. Shyshkanov ◽  
S.V. Radio
Keyword(s):  
Mathematical Modeling ◽  
Aqueous Solutions ◽  
Equilibrium Constants ◽  
Equilibrium Concentration ◽  
Quantitative Composition ◽  
Anion Formation ◽  
Chromium Vi ◽  
Vis Spectroscopy ◽  
Pitzer Method ◽  
Quasi Newton

The equilibria processes in aqueous solutions of CrO42– – H+ – H2O and Cr2O72– – OH– – H2O systems were studied by pH‑potentiometric titration, mathematical modeling and UV–Vis. spectroscopy. It was established that in the CrO42– – H+ – H2O systems with acidity ZН = ν(H+)/ν(Cr(VI)) = 0–2.5 the processes of dichromate and hydrochromate anion formation and hydrolytic conversion of dichromate to hydrochromate take place, for which the logarithms of the equilibrium concentration constants were calculated by the quasi-Newton method (CLINP 2.1 software; 95 % confidence probability). The calculated values of the logarithms of the concentration equilibrium constants lgKC reliably agree with the literature data. The calculated lgKC were used to build of chromium(VI) anions distribution diagrams depending on ZH, and ZOH in solutions. For the first time, by the Pitzer method the thermodynamic equilibria constants of hydrochromate HCrO4– (lgK10 = 6,94), the dichromate anion Cr2O72– (lgK20 = 15,49) formation processes from the CrO4 2– and H+ ions, and the logarithm of equilibrium constant of the interconversion of the dichromate anion to the hydrochromate anion (lgK30 = –1,61) were calculated. Mathematical modeling and UV–Vis. spectroscopy show that the composition of anions in Cr2O72– – OH– – H2O solutions with alkality ZOH = ν(OH–)/ν(Cr(VI)) = 0–2.5 is identical to CrO42– – H+ – H2O systems. It is established that the experimental dependencies pH = f(Z) for the Cr2O72– – OH– – H2O system can be reliably reproduced by hydrolysis reactions of dichromate anion to hydrochromate anion and by subsequent neutralization to chromate anion with equilibrium constants calculated for processes in CrO42– – H+ – H2O solutions with same ionic strengths. The quantitative composition of chromium(VI) solutions was confirmed qualitatively by UV–Vis. spectroscopy.

Removal of Pb(II), Zn(II), Sn(II) and Cu(II) Ions from Aqueous Solutions by Linear Alternating Poly(4,4'-biphenol oxalate) Oligomer

2020 ◽  
Vol 15 (2) ◽  
pp. 73-85
Keyword(s):  
Aqueous Solutions ◽  
Metal Ions ◽  
Metal Ion ◽  
Ph Value ◽  
Equilibrium Concentration ◽  
Ion Uptake ◽  
Uptake Capacity ◽  
Concentration Data ◽  
Hno3 Solution ◽  
Metal Ion Uptake

Poly(4,4′-biphenol oxalate) oligomer was synthesized and characterized by FT-IR, elemental analysis XRD and thermal analysis. The capability of the oligomer to take away Pb(II), Zn(II), Sn(II) and Cu(II) metal ions from aqueous solutions was considered by the known batch and column techniques in terms of concentration, pH value, contact time and temperature. The results indicated that a high initial rate of metal-ion uptake by the oligomer was observed throughout the first 30 minutes, which enlarged slightly amid rising the pH value and then reached its greatest value at pH=5.00 for Pb(II) and Zn(II), pH=4.00 for Cu(II) and pH=6.00 for Sn(II). The oligomer exhibited a high metal-ion uptake capacity to Pb(II) and Zn(II), but a little metal-ion uptake capacity to Cu(II) and Sn(II). Linearized forms of the Langmuir, Freundlich and Dubinin–Radushkevich adsorption isotherms were used to investigate the experimental equilibrium concentration data of Pb(II), Zn(II), Cu(II) and Sn(II). ΔG values demonstrated that the adsorption process of these metal ions on the oligomer is favored while the ΔH values indicated that this process is endothermic. On the other hand, the entropy of the process is positive. In addition to batch experiments, column experiments were performed, where the metal ions were efficiently recovered by treatment of the metal-loaded oligomer with 1.0 M HNO3, 1.0 M HCl and 0.5 M EDTA. The best results were obtained with 1.0 M HNO3 solution.

Adsorption of Copper (II) from Solution by Wheat Husk in Batch Mode

2011 ◽  
Vol 393-395 ◽  
pp. 1093-1097
Author(s):  
Ya Li Liu ◽  
Xiu Rong Zhao ◽  
Dan Ma ◽  
Yu Fei Li ◽  
Run Ping Han
Keyword(s):  
Aqueous Solutions ◽  
Salt Concentration ◽  
Contact Time ◽  
Copper Concentration ◽  
Ph Value ◽  
Equilibrium Concentration ◽  
Batch Mode ◽  
Freundlich Model ◽  
Equilibrium Data ◽  
Wheat Husk

Wheat husk, an agriculture byproduct, was used to adsorb copper (II) from aqueous solutions. Variables of the system, including contact time, pH, salt concentration, and equilibrium copper concentration, were adopted to study their effects on copper (II) adsorption. The results showed that coexisted salt was not favor of adsorption and pH value near 5 was favor of adsorption. Adsorbent quantity of copper onto wheat husk increased with the equilibrium concentration increasing. The kinetic process can be predicted by Elovich model while the equilibrium data was fitted better by Freundlich model.

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