A green route to preparation of MCM-41 silicas with well-ordered mesostructure controlled in acidic and alkaline environments

E-waste is one of the rapidly growing environmental problems of the world. However, the utilization of e-waste to produce economically viable materials such as mesoporous silica molecular sieves has not been well studied to date. Electronic packaging resins have been used widely in semiconductor industry. This study uses resin waste from this packaging process as source of Si and cationic surfactant as a template for the synthesis of highly ordered mesoporous silica with large surface area. This investigation reports the effects of various conditions on the self-assembly process of silica including the duration and temperature of the hydrothermal treatment, the molar ratio of water to surfactant, gelation pH, and calcination temperature. Experimental results confirm that MCM-41 with a well-ordered mesostructure is synthesized in strongly basic conditions. These materials had pore structures ranging from 3 to 10 nm. The produced silica is free of sodium impurities and the purity is as high as 99.8 wt%. SEM reveals that the proposed process can be controlled to produce silica particles with various morphologies under acidic or basic media. TEM images clearly illustrate the hexagonal array of uniform meso-channels in the silica materials. The proposed method for synthesizing mesoporous MCM-41 using resin waste provides a viable alternative for recycling and utilizing silicon-containing industrial waste.

► Electronic packaging resin waste is used as Si precursor.
► Cationic surfactant is a template for the self-assembly process of silica.
► Silica materials have pore structures ranging from 3 to 10 nm.
► MCM-41 shows well-ordered hexagonal mesostructure in strongly basic conditions.
► Recycling and utilizing silicon-containing industrial waste.