PERLITE: CHARACTERIZATION, MODIFICATION AND APPLICATIONS

Perlite is a glass-like amorphous (non-crystalline) mineral created by nature. Its composition is made up of high amounts, mainly, pertaining to silicon oxide (SiO2) and aluminum oxide (Al2O3), coupled with a trivial amount of alkali metal oxides (Na2O and K2O, respectively) as well as other elements. It is produced by the rapid cooling of volcanic stone (obsidian), therefore, when heated, it undergoes expansion, which in turn is responsible for its lightweight and porous nature, making it a remarkable and versatile material with various applications. Presently, the broad horizon of uses, include but not limited to, construction and cryogenic insulation, thanks to its exceptional thermal characteristics; filtration and horticulture, due to its porous nature; as a fireproofing agent on account of it being non-combustible; even in various drug delivery systems as a carrier, in the preparation of catalysts, as a filler, aggregate for light cement etc. Another interesting use of perlite is in the production of cosmetics, where it is used as a gentle exfoliant in skincare products. In addition, perlite is a major constituent in ceramic production, as it effectively aids in reducing and preventing cracking/shrinkage during firing due to its ability to absorb water and expand, thus reducing stress within the ceramic, which in turn leads to improved overall quality of the finished pieces/products; as well as, the purifying of solutions by adsorbing heavy metals, attributed to it being a permeable and inert material, are noteworthy mentions. Consequently, through meticulous review, this paper provides an in-depth analysis of the modifications of perlite, the comparison of physical-chemical and mineralogical characteristics of both natural resources, and summarizes the utilization status of perlite.