La roca magica: Uses of natural zeolites in agriculture and industry

Abstract

For nearly 200 years since their discovery in 1756, geologists considered the zeolite minerals to occur as fairly large crystals in the vugs and cavities of basalts and other traprock formations. Here, they were prized by mineral collectors, but their small abundance and polymineralic nature defied commercial exploitation. As the synthetic zeolite (molecular sieve) business began to take hold in the late 1950s, huge beds of zeolite-rich sediments, formed by the alteration of volcanic ash (glass) in lake and marine waters, were discovered in the western United States and elsewhere in the world. These beds were found to contain as much as 95% of a single zeolite; they were generally f lat-lying and easily mined by surface methods. The properties of these low-cost natural materials mimicked those of many of their synthetic counterparts, and considerable effort has made since that time to develop applications for them based on their unique adsorption, cation-exchange, dehydration-rehydration, and catalytic properties. Natural zeolites (i.e., those found in volcanogenic sedimentary rocks) have been and are being used as building stone, as lightweight aggregate and pozzolans in cements and concretes, as filler in paper, in the take-up of Cs and Sr from nuclear waste and fallout, as soil amendments in agronomy and horticulture, in the removal of ammonia from municipal, industrial, and agricultural waste and drinking waters, as energy exchangers in solar refrigerators, as dietary supplements in animal diets, as consumer deodorizers, in pet litters, in taking up ammonia from animal manures, and as ammonia filters in kidney-dialysis units. From their use in construction during Roman times, to their role as hydroponic (zeoponic) substrate for growing plants on space missions, to their recent success in the healing of cuts and wounds, natural zeolites are now considered to be full-f ledged mineral commodities, the use of which promise to expand even more in the future.The discovery of natural zeolites 40 years ago as large, widespread, mineable, near-monomineralic deposits in tuffaceous sedimentary rocks in the western United States and other countries opened another chapter in the book of useful industrial minerals whose exciting surface and structural properties have been exploited in industrial, agricultural, environmental, and biological technology. Like talc, diatomite, wollastonite, chrysotile, vermiculite, and bentonite, zeolite minerals possess attractive adsorption, cation-exchange, dehydration-rehydration, and catalysis properties, which contribute directly to their use in pozzolanic cement; as lightweight aggregates; in the drying of acid-gases; in the separation of oxygen from air; in the removal of NH 3 from drinking water and municipal wastewater; in the extraction of Cs and Sr from nuclear wastes and the mitigation of radioactive fallout; as dietary supplements to improve animal production; as soil amendments to improve cation-exchange capacities (CEC) and water sorption capacities; as soilless zeopon...

High-pressure synthesis of a polyethylene/zeolite nano-composite material

“…Their large-scale applications are, among others, fine gas separation, gas storage and catalysis [1][2][3][4][5][6][7][8][9] . More emerging applications of these materials, once properly functionalized, are also in sight in diverse fields such as nano-electronics, nanosensoring and nano-photonics 10,11 .…”

Diffractive hygrochromic effect in the cuticle of the hercules beetleDynastes hercules

“…Since optical properties can be transferred to other radiative spectral ranges by scaling the structure lengths up or down, hygrochromic materials could also find thermal uses. Microporous materials, such as natural zeolites, have been used as building blocks [36], with the added benefit of temperature stabilization.…”

Passive remediation of coalbed natural gas co-produced water using zeolite

“…Zeolites have also been shown to be effective in removing ionic substances from polluted waters (Colella, 1996;Pansini, 1996;Mumpton, 1999;Wingenfelder et al, 2005). There are approximately 40 natural (Inglezakis, 2005) and 150 synthesized (Eyde and Holmes, 2006) zeolites that have the potential for use as an ion-exchange material.…”