In situ construction of green multiscale nanosilicon-based sponges for stable oil-water separation

Oil and industrial wastewater spills have caused serious ecological impacts, thus superhydrophobic materials are paid much attention for their unique oil/water selective adsorption properties. Herein, we propose a green and efficient method for preparing superhydrophobic adsorbents for oil/water separation. Superhydrophobic melamine sponges (SMS) were prepared by in situ growth of nanosilica on melamine sponge skeletons followed by surface modification with hexadecyltrimethoxysilane (HTMS). The contact angle, oil-water separation, oil absorption, recyclability, acid resistance and alkali resistance of SMS were characterised to evaluate its performance. These results showed that the prepared SMS not only exhibits superhydrophobicity with a water contact angle of 152 degrees, but also has a strong adsorption capacity of 42-105 times its own weight for various oils and organic reagents, and outstanding recoverability with a retention of adsorption capacity of about 98% after 20 repeated cycles. In addition, it exhibits excellent environmental tolerance over a wide pH range. These excellent properties make it valuable for practical applications in the field of oil-water separation.