Transformation of construction and demolition waste into high value zeolitic materials

Abstract

Zeolites, microporous crystalline materials composed mainly of silicon and aluminum, possess physicochemical properties that make them valuable in water treatment and catalysis applications. Using construction and demolition waste (CDW) as raw material for producing zeolites represents a sustainable strategy to reduce its environmental impact. Thus, the present work addresses the synthesis of zeolites from CDW within the framework of the circular economy. Crushed brick waste was used and subjected to a hydrothermal process in a stainless-steel reactor with 2 M KOH, at 160 °C, for 6, 8, 10, and 12 hours. After treatment, the products were characterized by powder X-ray diffraction to evaluate their crystallinity. The results showed a progressive evolution in the formation of crystalline phases: at 6 hours an amorphous material was obtained; at 8 hours the first signs of nucleation of ordered phases were identified; at 10 hours zeolitic structures were consolidated, including aluminosilicates typical of zeolites, such as phillipsite; and finally, at 12 hours secondary phases were observed. It is concluded that it is feasible to transform CDW into functional zeolites by hydrothermal synthesis, with an optimum reaction time of about 10 hours. This approach allows the valorization of solid waste and contributes to the production of high-value materials, promoting sustainable practices in the materials science field.