scholarly journals Effect of Humic Substances on Behavior of Ion Exchange Rate

1992 ◽  
Vol 3 (2) ◽  
pp. 61-68
Author(s):  
Wataru Agui ◽  
Masahiko Kondo ◽  
Masahiko Abe ◽  
Keizo Ogino
Keyword(s):  
Exchange Rate ◽  
Ion Exchange ◽  
Humic Substances

Removal of Humic Substances by Adsorption/Ion Exchange

1999 ◽  
Vol 40 (9) ◽  
pp. 173-182 ◽  
Author(s):  
Joachim Fettig
Keyword(s):  
Activated Carbon ◽  
Ion Exchange ◽  
Metal Oxides ◽  
Humic Substances ◽  
Predictive Models ◽  
Anion Exchange Resins ◽  
Sorption Equilibria ◽  
Exchange Resins ◽  
Favorable Conditions ◽  
Solution Parameters

This paper gives an overview over the ability of four different sorbent media, activated carbon, anion exchange resins, carbonaceous resins and metal oxides, for the removal of humic sustances. Both sorbent characteristics and solution parameters that affect the ultimate capacities are discussed, and approaches developed in order to describe sorption equilibria and rate of uptake are reported. In addition, successes and failures of predictive models are described. Some general conclusions about favorable conditions for the removal of humic substances by sorption processes are given.

scholarly journals Lithium Isotope Selectivity of Semicrystalline Titanium Phosphates with Rapid Ion Exchange Rate

2003 ◽  
Vol 14 (Supplement) ◽  
pp. 385-388 ◽  
Author(s):  
Hiroaki TAKAHASHI ◽  
Takao OI ◽  
Morikazu HOSOE
Keyword(s):  
Exchange Rate ◽  
Ion Exchange ◽  
Lithium Isotope ◽  
Titanium Phosphates

Diffusion Coefficients of Transition Metal Ion Complexes in Zeolites NaA, CaA, NaX

1992 ◽  
Vol 57 (5) ◽  
pp. 921-937
Author(s):  
Athanasios G. Vlessidis ◽  
Nicholaos P. Evmiridis
Keyword(s):  
Exchange Rate ◽  
Ion Exchange ◽  
Transition Metal ◽  
Diffusion Coefficients ◽  
Molecular Sieves ◽  
Metal Ion ◽  
Ion Exchangers ◽  
Metal Ion Complexes ◽  
Transition Metal Ion

Ion-exchange rate curves of aqueous and ammonia transition metal ion complexes are presented together with ion-exchange isotherms of the corresponding complexes using molecular sieves as ion-exchangers. The data are treated mathematically according to Danes and Wolf procedure and the diffusion coefficients for the specific transition metal ion complexes are obtained. Finally, the variation of diffusion coefficients with the extent of ion exchange is followed.

Substitution of Co2+ ions into CdS-based molecular clusters

2015 ◽  
Vol 51 (96) ◽  
pp. 17096-17099 ◽  
Author(s):  
Swamy Pittala ◽  
Michael J. Mortelliti ◽  
Fumitoshi Kato ◽  
Kevin R. Kittilstved
Keyword(s):  
Exchange Rate ◽  
Ion Exchange ◽  
Metal Ion ◽  
Molecular Clusters ◽  
Metal Ion Exchange

The metal ion exchange rate of Co2+ ions into CdS-based clusters is found to correlate with the ligand interconversion rate.

Natural Occurrence and Stability of Pyrochlore in Carbonatites, Related Hydrothermal Systems, and Weathering Environments

1995 ◽  
Vol 412 ◽  
Author(s):  
Gregory R. Lumpkin ◽  
Anthony N. Mariano
Keyword(s):  
Exchange Rate ◽  
Ion Exchange ◽  
Cation Exchange ◽  
Low Temperatures ◽  
Hydrothermal Systems ◽  
Hydrothermal Fluids ◽  
Natural Environments ◽  
Natural Occurrence ◽  
The Stability ◽  
A Site

AbstractStoichiometric and non-stoichiometric (defect) pyrochlores crystallize during the magmatic and late magmatic-hydrothermal phases of carbonatite emplacement (T > 450–550 °C, P < 2 kb). Defect pyrochlores can also form at low temperatures in laterite horizons during weathering. After crystallization, pyrochlore is subject to alteration by hydrothermal fluids (T ∼ 550-200°C) and ground water. Alteration occurs primarily by ion exchange of low valence A-site cations together with O, F, and OH ions. The high valence cations Th and U are generally immobile; however, we have documented one example of hydrothermal alteration involving loss of U together with cation exchange at the B-site in samples from Mountain Pass, California. During laterite accumulation, the cation exchange rate of pyrochlore greatly exceeds the rate of matrix dissolution. The exceptional durability of pyrochlore in natural environments is related to the stability of the B-site framework cations. In carbonatites, defect pyrochlores may contain significant amounts of Si (up to 7.6 wt% SiO2) which is negatively correlated with Nb.

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