Template-free Synthesis of Mesoporous Silica with High Specific Surface Area from Natural Halloysite and Its Application in Methylene Blue Adsorption

Abstract

Avoiding the use of templates and employing natural minerals as raw materials could promote the cost-efficient preparation of mesoporous materials. This work demonstrated a template-free route to process natural halloysite into mesoporous silica with high specific surface area (SSA) up to 767 m 2 /g and pore size of about 5 nm.The halloysite was successively calcined, alkali-treated and acid-treated. The transformation of calcined halloysite into crystalline sodium aluminosilicate (zeolite LTA) by longtime alkali-treating, was found to be the key for obtaining high-SSA mesoporous silica in the final acid treatment. The optimized mesoporous silica showed a monolayer adsorption capacity as high as 741 mg/g for methylene blue, suggesting its great potential in adsorption applications.