Engineering 2D nano-sheet struvite by ethanol regulation for boosting flame retardant properties

Abstract

Struvite exhibits versatile applications as both a slow-release fertilizer and an inorganic flame-retardant material. In this study, we present a successful synthesis method for producing nano-sheet struvite with a remarkably thin nanoscale thickness of 63 nm and an impressive specific surface area of 128.4 m2·g−1. Our approach involves a combination of ethanol supplementation and ammonia diffusion. By employing MgCl2·6H2O and NaH2PO4·2H2O as reactants, with a Mg2+:PO43- molar ratio of 1:2, and incorporating 50 vol% ethanol, we achieved optimal preparation conditions. Moreover, we determined that a reaction time of 20 min and a reaction pH ranging from 9.3 to 9.5 yielded the best results. The experimental results revealed that the nano-sheet variant of struvite exhibited exceptional physical barrier properties achieving a flame retardance rate of 92.6 %, surpassing other morphologies such as rod-like, butterfly-like, and needle-like variants. And the optimal usage amount of nano-sheet struvite on the wood surface was determined to be 8.5 × 10−3 g·cm−2. Furthermore, the mechanism of the ethanol solvent in the formation process of 2D nano-sheet struvite was preliminarily discussed, offering a viable approach for the preparation of struvite with high flame retardant performance.