Quantitative Determination of Clinoptilolite in Soils by a Cation-Exchange Capacity Method

Abstract

Abstract--A cation-exchange capacity (CEC) method based on ion-sieving properties was developed for the quantitative determination of clinoptilolite in soils. In this method, both zeolitic and non-zeolitic exchange sites in the soil sample are saturated with Na t. The CEC of the non-zeolitic exchange sites is determined by replacing the Na-in these sites with tert-butylammonium ions. The tert-butylammonium ion cannot be exchanged into the zeolitic exchange sites because it is too large to pass through the channels in the clinoptilolite structure. The sample is next washed with NH4OAc to replace the Na + in the zeolitic exchange sites. The amount of soil zeolite is then estimated by comparing the CEC of zeolitic exchange sites to the total zeolite CEC ( 175 meq/100 g for pure clinoptilolite). Prior to the CEC analyses, carbonates and organic matter must be removed to minimize interference with the exchange process. A high correlation (r-' = .96) was observed between the abundance of clinoptilolite estimated using the CEC method and the abundance estimated by semiquantitative X-ray powder diffraction analysis.The CEC procedure was used to quantify clinoptilolite in an Aridic Calciustoll soil from south Texas. About 2-5% clinoptilolite occurs in the A and B horizons, and concentrations progressively increase with soil depth to as much as 20% in the CBk2 horizon.

Characterization and Utilization of Natural Zeolites in Technical Applications

“…This value is in good accordance to literature data for clinoptilolite rich zeolites [7], although it is difficult to compare CEC-results for different zeolite samples published in literature as the applied methods are not standardized [28]. Given a CEC for pure clinoptilolite of 1.75 meq g -1 [29], the clinoptilolite content of the sample was estimated to be around 73%. Nevertheless, ammonium uptake did not obtain constant values even at the highest initial concentrations as a result of single batch equilibration [28].…”

Zeolites versus Lead Toxicity

“…A greater weight gain has been reported of 17% and 3.6% in young beef cattle and broilers when clinoptilolite at 4.3% and, 0.5%, 1% and 1.5% by weight was added to cattle's and chickens' regular diet, respectively [129]. In comparison to a regular diet, the clinoptilolite at 5% and 10% levels by weight in hog's diet resulted in a weight gain of 27% [130][131][132][133][134] and 8% [129], respectively.…”

Removal of cadmium and humic acid from aqueous solutions using surface modified nanozeolite A

“…The materials were washed to achieve a Cl -free solution, using silver nitrate solution as an indicator. The resultant materials were dried at 110 o C for 24 h (Ming and Dixon, 1987;Diaz-Nava et al, 2005).…”