Engineering Lignin Nanoparticles Deposition on Melamine Sponge Skeleton for Absorbent and Flame Retardant Materials

Abstract

Lignin is the second-most abundant natural organic material after cellulose and the richest aromatic organic biopolymer on earth. It was typically burned for energy generation with low economic benefits. To date, it remains still challenging to valorize lignin with a simple and straightforward strategy in an industrial scale-up. Here, we fabricate two highly hydrophobic melamine sponges with excellent adsorption performance and flame retardancy through a facile spontaneous deposition of lignin and/or acetylated lignin nanoparticles onto the MF sponge skeleton. Two targeted sponges show micro-nano structure with high porosity and robust properties for absorbing oils and organic solvents from contaminated water. Over 85% of the absorbed oils and solvents can be harvested by either batch squeezing way or continuous operating mode with the assistance of constant-flow pump. Interestingly, the targeted sponges exhibit satisfactory flame retardancy property to diminish the risk of fire and explosion when ignited. More importantly, the targeted sponges endorse excellent recyclability and robust stability after 60 repetitions with neglective lignin leaching. It is worthy to point out that the findings in our work opens up a new way for lignin valorization, which is a promising cost-effective and facile scalability processing to fabricate oil/water separation absorbent, since it requires neither hazard modifier agents nor sophisticated equipment.