Mesoporous silica derived from kaolin: Specific surface area enlargement via a new zeolite-involved template-free strategy

• A template-free process to prepare mesoporous silica (MS) from kaolin was designed.
• The process simply consists of calcination, alkali- and acid-treatment.
• MS has an improved SBET of 751.5 m2/g and DBJH of ~ 4 nm.
• MS has a high monolayer adsorption capacity of 756.5 mg/g towards methylene blue.

A novel zeolite-involved template-free strategy is proposed and demonstrated to process natural kaolin into mesoporous silica with enlarged specific surface area (SBET). Kaolin was calcined and alkali-treated into aluminosilica zeolite, and then transformed into amorphous mesoporous silica with SBET of 751.5 m2/g and pore size of ~ 4.0 nm at the maximum probability in a subsequent acid-treatment. The alkali-treatment and the formation of zeolite intermediate were found to be the key for the SBET enlargement. The mechanisms were studied by XRD, XRF, SEM, TEM and N2 adsorption/desorption. The mesoporous silica shows favorable adsorption ability towards methylene blue with a monolayer adsorption capacity of up to 756.5 mg/g, indicating its promising potential in adsorption application.

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