High adsorption capacity of ammonia nitrogen on hexagonal porous aluminosilicate derived from solid-waste bagasse bottom ash

Abstract

This study investigates the use of a hexagonal-porous aluminosilicate (HAS) adsorbent derived from bagasse bottom ash (BBA), an agricultural solid waste, for the adsorption of ammonia nitrogen (NH3–N)—a key water pollutant from agricultural and farming activities. Sodium silicate derived from BBA via the alkaline fusion method was employed, resulting in energy savings due to a synthesis temperature 1.53 times lower than that of commercial sodium silicate synthesis. The sol-gel method was utilized to successfully synthesize HAS featuring a high surface area and porosity using the sodium silicate prepared from BBA. However, an increase in aluminum content resulted in a decrease in surface area and hexagonal porosity. In performance tests, the HAS(5) adsorbent exhibited the most efficient NH3–N removal, outperforming other adsorbents by 4.54–25.19 times across all initial concentrations. This enhanced efficiency can be attributed to its numerous acidic surface sites, enabling the bonding of NH3–N molecules through monolayer adsorption on the HAS surface.