Preparation of a highly porous clay‐based absorbent for hazard spillage mitigation via two‐step expansion of vermiculite

Abstract

Expanded vermiculite (eVMT) has been studied as a risk‐free, general‐purpose absorbent for liquid hazards due to its excellent thermal and chemical stability. Here, vermiculite was expanded by two steps: exfoliation by 30 wt% H2O2 treatment at 60 °C and subsequent expansion by microwave heating. This two‐step expansion produced more homogenously separated concertina-like eVMTs with a higher total pore volume of 7.75 cm3 g−1 than the conventional thermal method. The two‐step eVMT was found to be greatly superior to the thermal and commercial silver counterparts in hazardous liquid‐uptake performance. The uptake was simply interpreted as a physical infilling process of a liquid into the eVMT pores, and the spontaneous hazard removal with a great capacity was discussed with the large pore volume of two‐step eVMT and its suitable pore dimensions for capillary action. As a practical device, a prototype absorbent assembly made of these eVMTs demonstrated the successful mitigation of liquid hazards on an impermeable surface.