Waste Valorisation into Zeolite and Their Potential Application in Water Treatment

Serious environmental issues have escalated as a result of urbanization, industrialization, and global population growth, caused by solid waste accumulation and water pollution. Tackling these challenges requires innovative strategies for waste reuse and pollution control, such as using solid wastes with high concentrations of Si and Al as raw materials for the development of emerging materials used for decontamination of waters (i.e. zeolites). Therefore, within this study two zeolites were synthesized using an easy, environmentally friendly and inexpensive method (sol-gel). The precursors were metallic waste (aluminium cans) for the sodium aluminate, and both pure precursor (pure sodium silicate) and agricultural waste (rice husks) for the sodium silicate. The synthesized samples were analyzed using different techniques, such as XRF, XRD, DTA and SEM. The results showed that the developed zeolites are faujasite and sodalite types, which are adequate for eliminating heavy metal ions from water. Additionally, the heavy metal removal efficiency for the two developed zeolites was higher than 95% for Cd, Ni after 24h testing, and only ~35% after 24h for Pb, emphasizing their good capacity to retain heavy elements. Thus, these findings demonstrate the great potential of waste-derived zeolites as sustainable adsorbents for reducing heavy metal pollution in aquatic environments, contributing to the advancement of resource recovery, waste reduction, and green remediation methods and aligning with the circular economy principles.