Removal of Cu2+ from Aqueous Solution by Cement-Based Absorbent Incorporating Fly Ash

Cement-based materials containing abundant pores have the benefit of removing heavy ions. The absorbent from cement and fly ash (FA) is prepared, and its physical and mechanical properties and removal efficiency on Cu 2+ are investigated in this paper. The results indicate that the compressive strength of the adsorbent has a positive correlation with curing age and a negative correlation with the FA content. An 80% replacement ratio of FA enables the adsorbent to obtain a high water absorption and reaches a comparable compressive strength with the ceramsite for water purification. The removal rate of Cu 2+ increases while the adsorption capacity decreases as the solid–liquid ratio increases. With an initial Cu 2+ concentration of 10–55 mg/L, the Cu 2+ removal rate of the cement-based absorbent exceeds 95% and remains above 95% even after regenerated two times. Raising the ambient temperature positively impacts the adsorption of Cu 2+ . In addition, the adsorption mechanism adheres to the Langmuir isotherm and pseudo-second-order kinetics, demonstrating that single-layer adsorption and chemical adsorption are crucial to the adsorption process.