Investigating the efficacy of metakaolin based alkali activated materials for efficient removal of nickel and lead ions

Abstract This study presents a comprehensive investigation into the efficacy of metakaolin based alkali activated materials for the efficient removal of nickel and lead ions from aqueous solutions. The synthesis process involved the preparation of porous structures with high porosity, leading to an expanded surface area and an increased number of sorption sites. By applying alkali activation to the metakaolin, the reactivity is enhanced, forming hydrated phases that exhibited exceptional adsorption properties. This study examined the ideal sodium hydroxide molarity and metakaolin/activator ratios for producing metakaolin-based alkali activated materials based on the physical properties and capacity to adsorb nickel and lead ions. The solution with 10M sodium hydroxide and a 0.8 solid-to-liquid ratio had the best nickel and lead ion removal efficiency. This ratio formed metakaolin-based alkali-activated materials with suitable physical properties and porosity for efficient adsorption. The results demonstrated an outstanding removal efficiency of nickel and lead ions of 95.78% and 93.7%, respectively within 60 min contact duration. Moreover, the optimal ratio revealed to a evolution of muscovite phases that enhances adsorption capacity and removal efficiency. The adsorption process was found to be rapid coupled with promising structural properties, highlighting the potential of the metakaolin-based alkali-activated materials as an adsorbent for efficient heavy metal removal.