Application of construction and demolition waste (gypsum and mortar) for the removal of metal ions, Pb2+, Cu2+, and Ni2+

Abstract

The intensification of human activities, consumption, production, and exploitation of raw materials, coupled with rapid population growth and industrial activity development, has led to significant environmental impacts. As civilization progresses, the level of environmental pollution with toxic metals has also intensified. The ability to quickly detect heavy metal pollution in wastewater and find its source is critical for environmental monitoring and protection. In the search for cheaper and more economical materials to be used as precipitants, civil construction waste has been used for this application. In this context, the present study aimed to evaluate the utilization of construction and demolition waste (gypsum and cementitious mortar) in the retention of Copper, Lead, and Nickel metal ions. The assessment of the removal capacity of these metal ions using gypsum powder and cementitious mortar was conducted through chemical precipitation using batch experiments. The results obtained for Pb²⁺ ions showed that increasing the mass of gypsum from 10 to 100 g resulted in precipitation rates ranging from 97.29 to 98.31 %. Gypsum also proved to be a viable alternative for Cu²⁺ precipitation with rates of 92.99 to 96.65 %, while the most significant retention rate for Ni²⁺ was observed for the mass of 100 g, reaching 94.63 %. In experiments using different types of cementitious mortar (ACI, ACII, ACIII, and common) as precipitants in a solution contaminated with copper at a constant concentration of 600 mg/L, it was found that the precipitation rates were practically the same, with ACIII mortar showing the highest percentage of precipitation. Therefore, the results obtained demonstrated that construction and demolition waste by-products rich in gypsum and cementitious mortar are efficient in removing toxic metals, representing promising alternatives for wastewater decontamination.