Decrease in Cation Exchange Capacity of Zeolites at Neutral pH: Examples and Proposals of a Determination Method

Munthali, Moses Wazingwa; Kabwadza-Corner, Ponyadira; Johan, Erni; Matsue, Naoto

doi:10.4236/msce.2014.28001

Cited by 13 publications

(8 citation statements)

References 12 publications

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“…This finding has been contrary to what has been thought all along: that the CEC of zeolites does not change with change in aqueous pH. This concept has been inferred from the fact that the CEC of 2:1 type layer silicate clay minerals such as montmorillonite is constant even at acidic conditions such as pH 4 [30,32]. Such logic possibly led to the determination of CEC without considering the effect of H + adsorption.…”

Section: Introductionmentioning

confidence: 90%

“…In some of the aforementioned applications, zeolites are used in a wide range of pH from acidic to alkaline conditions in aqueous media. However, our recent study showed that cation exchange capacity (CEC) Na + retention by zeolites is greatly affected by the adsorption of H + , even in the neutral pH region [30]. The adsorption of H + into zeolites results in the loss of the negative charge due to neutralization forming covalent bonds from the Lewis acid-base reaction [29,31].…”

Section: Introductionmentioning

confidence: 99%

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Proton Adsorption Selectivity of Zeolites in Aqueous Media: Effect of Exchangeable Cation Species of Zeolites

2015

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The saturation of negative charges of zeolites by specific cations to modify their physicochemical and catalytic properties has broadened the applications of zeolites. The adsorption behavior of H + to Li + , Na + , K + , Rb + and Cs +-saturated Linde-type A, Na-P1, mordenite, X type and Y type zeolites was evaluated at different pH-pM, where pH-pM is equal to log {(M +)/(H +)} and M + represents either Li + , Na + , K + , Rb + , or Cs +. In all cases, with decreasing pH-pM, the amounts of alkali metal retention decreased due to the adsorption of H + via cation exchange reaction. The adsorption selectivity of H + into the zeolites had a negative correlation with the Si/Al ratio of the zeolites. In each zeolite species, Cs +-saturated zeolite showed the lowest H + selectivity, and this suggested that Cs + had the strongest adsorption energy in the alkali metal cations. The adsorption of H + was strongly affected by diameter and hydration energy of the alkali metal cations, and was also affected by the framework type and Si/Al ratio of the zeolites. The adsorption of H + into zeolites decreases the amount of cation retention other than with H + and may cause the elution of Si and Al into aqueous solutions.

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Section: Introductionmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Proton Adsorption Selectivity of Zeolites in Aqueous Media: Effect of Exchangeable Cation Species of Zeolites

2015

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“…In this set of measurements we made samples that contained soil as blank, zeolites only and soil with zeolites and redistilled water was added up to 500 g. Concentrations of zeolites added to samples were 0.5%, 2% and 5% calculated relativ to 500 g mixture as presented in table 1 and table 2 Table 2 shows pH values that remain constant after zeolite addition in soil, for all the three cases (concentration of zeolite in the mixture of 0.5 %, 2 % and 5 % respectively. Natural zeolites generally have the capacity to decrease soils pH [7]. However, given the bufferig capacity of soils, if small quantities of zeolite are added, soil mixture pH does not significantly change.…”

Section: 1mentioning

confidence: 99%

Evaluation of Ammonium Exchange Capacity for Agricultural Soils Treated With Zeolites

Bumbac¹,

Nicolescu²,

Gheboianu³

et al. 2016

Simi 2016

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Natural zeolites are crystalline hydrated aluminosilicates formed by the deposition of volcanic ash in lakes with salted water. They are characterized by their ability to lose and gain water reversibly and to exchange some of the constituents without changing their structure. These properties recommend them as useful additives for agricultural soils as buffer matrix for the process of nutrients translocation.Present study aims to evaluate the ammonium exchange capacity (AEC) of treated and untreated soils with natural zeolites as an indicator of quality soil improvement. The zeolites used in this study (with a content of approx. 60% clinoptilolite) were purchased from Cemacom, the exploiting company of volcanic tuff from Zalau, Salaj County. The soil samples were collected at various time intervals during one year. Furthermore, we collecteded soil samples from unprotected and protected (greenhouses) sources where soil had different degree of organic fertilization in order to obtain information on the effect of zeolites addition on AEC.

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“…The available protons are the ones that contributed to the wider range of pH change at equilibrium. In their study on the decrease in the CEC of zeolites at neutral pH, Munthali et al [26] highlighted the pH dependence of Na + -saturated A4 and Na-P1 zeolites. With increasing the amount of HCl addition to the zeolites, equilibrium pH decreased, and CEC or the amount of Na + retained of the two zeolites decreased.…”

Section: Ph Dependence Of Pb Adsorptionmentioning

confidence: 99%

pH Dependence of Lead Adsorption on Zeolites

Kabwadza-Corner¹,

Johan²,

Matsue³

2015

JEP

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The adsorption of Pb on zeolites A4, X, Y and mordenite was studied at various initial pH with the purpose of assessing the pH dependence of Pb adsorption. The adsorption was conducted using 0 -0.6 mM Pb(NO3)2 in the presence of 100 mM NH4NO3 and pH adjustment done using HNO3. The coexisting NH4NO3 served as a representative of other cations available in nature. The study was conducted at initial solution pH ranging from 3 -5. Adsorption results were analyzed using Langmuir isotherm analysis. Adsorption was noted to be dependent on pH with increasing adsorption as pH increased from 3 -5 for zeolites A4, X and Y. The adsorption of Pb on mordenite on the other hand did not show any dependence on pH since it was almost constant within the studied pH range. The adsorptive capacities were 2500, 2000, 588 and 179 mmol•kg −1 for A4, X, Y and mordenite, respectively. The results of this study can be used in designing or planning for the clean-up of polluted water using adsorption techniques. An important attribute of these findings was that the samples studied were shown to have the capacity of removing even very low concentration of Pb, a property which is hardly achievable by most adsorbents.

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Decrease in Cation Exchange Capacity of Zeolites at Neutral pH: Examples and Proposals of a Determination Method

Cited by 13 publications

References 12 publications

Proton Adsorption Selectivity of Zeolites in Aqueous Media: Effect of Exchangeable Cation Species of Zeolites

Proton Adsorption Selectivity of Zeolites in Aqueous Media: Effect of Exchangeable Cation Species of Zeolites

Evaluation of Ammonium Exchange Capacity for Agricultural Soils Treated With Zeolites

pH Dependence of Lead Adsorption on Zeolites

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