Aqueous interactions of zeolitic material in acidic and basic solutions

Abstract

a b s t r a c tAqueous interactions of natural zeolitic material in as-received and modified forms were studied. The zeolitic materials was interacted with acidic (hydrochloric acid, lactic acid, acetic acid) and basic (sodium hydroxide) solutions. Ion exchange, adsorption, complex formation, precipitation and cation hydrolysis were possible interaction mechanisms affected by the amount and cation content of zeolite and pH. The dominant mechanisms seemed to be ion exchange and adsorption in HCl solution when zeolite was used in the as-received form, but dissociation of outer-sphere complexes when modified zeolite was used. In lactic acid, acetic acid as well as the basic solution, cation hydrolysis and complex formation were additional mechanism in the interactions.

Investigation of structural properties of clinoptilolite rich zeolites in simulated digestion conditions and their cytotoxicity against Caco-2 cells in vitro

“…However, results showed that characteristic peak intensities of the clinoptilolite were almost same compared to the control sample after the gastric treatment. It implied that crystal structure of zeolites were stable after gastric treatment where similar results were also reported [30]. On contrary, a significant change was observed in the quartz.…”

“…It was reported that the proton pumps in the Caco-2 cells did not rapidly reverse the effect of pH, and the buffering capacity of the cytoplasm was not strong enough to prevent the pH change [42]. Since zeolites have amphoteric behavior, they alter the pH of the aqueous growth media [30] thus reduction in cell proliferation compared to control sample might be achieved. Other possible reasons for the inhibition of cancer cell proliferation with zeolite treatment might due to its effect on cancer cell signaling pathways, or possibility of weak interactions such as van-der Waals, hydrogen bonding, electrostatic interactions between zeolite and some protein like structures in cell culture media (such as aminoacids, or growth hormones secreted by the cells) due to zeolite's ion exchange and adsorptive properties.…”

Effects of Thermal Treatment on Natural Clinoptilolite-Rich Zeolite Behavior in Simulated Biological Fluids

“…However, a significant increase of the intensity of peaks characteristic to quartz for samples exposed to SGF was observed. A possible explanation could be the purification effect of HCl by solubilization of mineral impurities from the quartz crystal lattice structure [26,28]. Arcoya et al reported a decrease of the characteristic peaks by HCl treatment, however our results show no modification of the characteristic peak intensities, probably due to the stability of crystal structure [26,29].…”

Zeolite Waste Characterization and Use as Low-Cost, Ecofriendly, and Sustainable Material for Malachite Green and Methylene Blue Dyes Removal: Box–Behnken Design, Kinetics, and Thermodynamics

“…However, a definitive explanation of this point cannot be established on the basis of pH values only, because pH can be influenced, separately or together, by the surface charge of the adsorbent, the degree of ionization of the adsorbate, and the extent of dissociation of functional groups at the adsorbent active sites [44,54]. Lower sorption of dyes obtained at very acidic pH values can be explained through the behavior of the zeolite in acidic and basic mediums, as reported elsewhere [55].…”