Chitosan-Derived Synthetic Ion Exchangers: Characteristics and Applications

In this study the use of zeolites as ion-exchangers for equalization of ammonia peak loadings in aerated biological activated filters was investigated. For this use zeolites were mixed with a filter medium and the nitrifying filter was loaded with ammonia peaks for two hours at different flow rates. It could be demonstrated that during the phase of higher inflow concentrations the zeolite was collecting ammonia. When the influent concentration decreased ammonia was desorbed from the zeolite and could be nitrified by the bacteria growing on the filter medium. It was shown that additional zeolites can equalize variations of ammonia, especially in filter units which are working at a high nitrification rate and which are very sensitive to varying influent conditions. During the operation time of the filter no separation of the zeolite by higher hydraulic loading or by backwashing could be recognized. So the upgrading of nitrifying filters with zeolite represents an additional security for effluents containing oscillating ammonia concentrations.

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Polymer structure and catalytic activity of ion exchangers

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19811577 ◽

1981 ◽

Vol 46 (7) ◽

pp. 1577-1587 ◽

Cited By ~ 8

Author(s):

Karel Jeřábek

Keyword(s):

Catalytic Activity ◽

Ethyl Acetate ◽

Active Sites ◽

Crosslinking Agent ◽

Reaction Medium ◽

Polymer Structure ◽

Local Concentration ◽

Ion Exchangers ◽

Styrene Divinylbenzene ◽

Kinetics Of

Catalytic activity of ion exchangers prepared by partial sulphonation of styrene-divinylbenzene copolymers in reesterifications of ethyl acetate by methanol and propanol, hydrolysis of ethyl acetate and in synthesis of bisphenol A has been compared with data on polymer structure of these catalysts and with distribution of the crosslinking agent, divinylbenzene, calculated from literature data on kinetics of copolymerisation of styrene with divinylbenzene. It was found that the polymer structure of ion exchangers influences catalytic activity predominantly by changing the local concentration of acid active sites. The results obtained indicated that the effect of transport phenomena on the rate of catalytic reactions does not depend on the degree of swelling of the ion exchangers in reaction medium but it is mainly dependent on the relative affinity of reaction components to the acid groups or to the polymer skeleton.

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Sorption of Cadmium and Lead by Chelating Ion Exchangers Ostsorb OXIN, Ostsorb DETA, and Ostsorb DTTA

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19941311 ◽

1994 ◽

Vol 59 (6) ◽

pp. 1311-1318 ◽

Cited By ~ 5

Author(s):

Ladislav Svoboda ◽

Petr Vořechovský

Keyword(s):

Ionic Strength ◽

Aqueous Solutions ◽

Sodium Perchlorate ◽

Exchange Capacity ◽

Chloride Ions ◽

Point Of View ◽

Alkaline Media ◽

Ion Exchangers ◽

Acidic Media ◽

Cadmium And Lead

The properties of cellulose chelating ion exchangers Ostsorb have been studied in the sorption of cadmium and lead from aqueous solutions. The Cd(II) and Pb(II) ions are trapped by the Ostsorb OXIN and Ostsorb DETA ion exchangers most effectively in neutral and alkaline media but at these conditions formation of stable hydrolytic products of both metals competes with the exchange equilibria. From this point of view, Ostsorb DTTA appears to be a more suitable sorbent since it traps the Pb(II) and Cd(II) ions in acidic media already. Chloride ions interfere with the sorption of the two metals by Ostsorb DTTA whereas the ionic strength adjusted by the addition of sodium perchlorate does not affect the exchange capacity of this ion exchanger.

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