Mineralogical, Geochemical, and Rock Mechanic Characteristics of Zeolite-Bearing Rocks of the Hatrurim Basin, Israel

The Hatrurim Basin, Israel, is located on the western border of the Dead Sea Transform. This is one of the localities of a unique pyrometamorphic complex whose genesis remains problematic. This paper deals with zeolite-bearing rock that is known in the Hatrurim Basin only. The strata subjected to zeolitization is called the “olive unit” and consists of anorthite–pyroxene (diopside–esseneite) hornfels. Zeolitization occurred in an alkaline environment provided by the interaction of meteoric water with Portland-cement-like rocks of the Hatrurim Complex. The resulting zeolite-bearing rocks contain 20–30% zeolitic material. The main zeolitic minerals are calcic: thomsonite-Ca ± Sr, phillipsite-Ca, gismondine-Ca, and clinoptilolite-Ca. The remainder is calcite, diopsidic pyroxene, garnets (either Ti-andradite and/or hydrogrossular), and less frequently, fluorapatite, opal, and others. Their major mineralogical and chemical compositions resemble carbonated zeolite-blended Portland mortar. Rocks show different values of porosity. Their mechanical characteristics are much better for samples with porosity values below 24%. The related parameters are like those of blended concretes. The minimal age of zeolitization is 5 Ka. The natural zeolite-bearing rocks are resistant to weathering in the Levant desert climate.

Silver-Modified Mexican Clinoptilolite-Rich Tuffs With Various Particle Sizes as Antimicrobial Agents Against Escherichia coli

Water disinfection was performed using Mexican clinoptilolite-rich tuffs from Oaxaca and Sonora with different particle sizes exchanged with silver ions. Samples of Escherichia coli (ATCC 8739) suspended in distilled water (wastewater-like) and municipal wastewater containing coliforms (E. coli as a representative microorganisms from the coliform consortium), were treated in this investigation. E. coli is considered an indicator of microbiological contamination of water, so levels of this microorganism after zeolite treatment indicate how well the disinfection process worked. It was found that particle size, the amount of silver in the modified zeolitic rocks, the origin of the zeolitic material and the type of aqueous media containing E. coli all play important roles in the wastewater disinfection process.

ADSORPTION STUDY OF CRYSTAL VIOLET AND MALACHITE GREEN DYES IN ZEOLITIC MATERIAL

Violet crystal and malachite green are dyes used in the textile industry. These organic compounds are toxic agents capable of polluting water resources as well as destroying the existing biota in this location. The decolorization of textile effluents has always been a global problem, but it has accentuated over time with increasing scale operation and changes in the origin of the dyes used. Decolorization of wastewater achieved by physically removing the dye from the water or by destroying its chromophore group. Adsorption is referred to as one of the most efficient and feasible methods for discoloring an effluent. Molecular sieves (zeolites) showed to be an efficient alternative in the discoloration of textile effluents when compared to other processes in the industry. Sodalite is a zeolite that has the ability to adsorb the azo functional groups related to color. The focus of this work is to use sodalite in the process of discoloration of a synthetic solution of crystal violet and malachite green. The experiments performed by varying the contact times between the zeolitic material and the synthetic solutions of the dyes. The results revealed that both dyes had a decolorization process. According to analyzes, greater times of contact (12, 24, 48, and 72 hours) with sodalite is more efficient in the removal color. A decisive factor in this process is the higher Si/Al ratio (2.5) of sodalite that potentiates the process and efficiency of the experiments.