Current aspects regarding the ecological impact of some wastewater recycling procedures and of zeolitic adsorption mechanisms
S.I. Ognean, M. Senila, V. Micle, D. Boloș, O. Tamas-Krumpe, F. Daria-Maria-Ecaterina* and L. Ognean
Due to their specific properties, such as the ability to conduct ion exchange, their big internal surface, and their highly porous structure, natural and synthetic zeolites alike are successfully used to attach and remove heavy metals (Cd, Cr, Cs, Cu, Fe, Hg, Mn, Ni, Pb, Sr, W, Zn) and ions (ammonium) from wastewaters, industrial residues, contaminated soils, and industrial sludge. These volcanic tuffs are also excellent sorbent environments for permeable reactive barriers and systems used to decontaminate wastewater. This review includes an ensemble of relevant scientific studies regarding the analysis of the treatment and recycling of wastewater and heavy metal contaminated soils, with specific reference to the use of zeolites from Rupea and Baia-Mare. The compositional analysis of the zeolites revealed insignificant variations of SiO2 (56.85-59.31%), Al2O3 (11.94-12.88%), and a Si/Al ratio 4 times bigger, which is specific to clinoptilolite, as opposed to the ratio that is usually found in the structure of other zeolites. Other major constituents that were identified in the chemical structure of clinoptilolite are CaO (2.67-2.83%), K2O (2.30-2.40%), and Fe2O3 (1.24-1.59%), MgO (1.42-1.62%). Compositionally, the zeolite from Baia-Mare is very similar to the clinoptilolite from Rupea. Based on data resulting from the treatment of heavy metal contaminated soil (Cd, Cr, Cu, Pb, Zn) with clinoptilolite from Rupea some studies assign this type of zeolite an efficient ecological amendment.