Montmorillonite and AgNPs modified corn stalk-based filling material with fire retardancy and antibacterial activity

Abstract

At present, the reuse of corn stalk (CS) or other biomass stalk generally requires crushing or dissolution, which leads to waste of energy and use of toxic chemicals. In this work, porous CS was directly utilized without any pretreatment as furniture and building materials by loading silver nanoparticles (AgNPs) and montmorillonite (MMT), which endowed excellent flame retardant and antibacterial properties. Firstly, CS was delignified (DLCS) to expose more porous structures. Then, DLCS was used to in situ reduce and immobilize AgNPs, and MMT particles was further loaded into holes of DLCS to prepare antibacterial and flame-retardant CS (DLCS/MMT/AgNPs). Due to the oxygen barrier layer formed by MMT in the combustion process, the time DLCS/MMT/AgNPs started combustion delayed to 5 s while that of CS was 1 s. The combustion residue of DLCS/MMT/AgNPs retained after burning under nitrogen and air atmosphere at 800 °C were 65.8% and 61%, respectively, and basically maintained its original morphology. Furthermore, AgNPs endowed DLCS/MMT/AgNPs with the inhibition zone of 3.5 mm and 2.0 mm for E. coli and S. aureus, respectively, as well as long-lasting antibacterial property for at least 7 days. This work laid a theoretical foundation for agricultural waste CS to realize the high-value utilization in an economical and environmentally friendly way.