Controlled Synthesis of Struvite Nanowires in Synthetic Wastewater

Controlled struvite crystallization is regarded as a promising route to phosphorus recovery from wastewaters, and has been the topic of extensive research in the last two decades. Most studies made great efforts to elevate the quantity of struvite recovered from various wastewaters, but little attention has been focused on the struvite quality which affects the agronomic response. The improvement of struvite quality can raise its value in fertilizer markets and improve the economical sustainability of struvite crystallization technology. In this study, we report a facile method for the synthesis of struvite nanowires by regulating NaCl concentration and initial pH (pHi) in synthetic wastewater. The identification and characterization of the synthesized products were done using X-ray powder diffraction, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, Raman spectroscopy, nuclear magnetic resonance spectroscopy, X-ray photoelectron spectroscopy, and Zeta potential Analyzer. Our results reveal that both NaCl concentration and pHi play important roles on the phase composition and morphology of products in the crystallization system. In particular, a mass of struvite nanowires with high yield can be obtained at NaCl concentration ranging from 3.5 to 4.5 wt % at pHi 11.0, and the mechanism for the formation of struvite nanowires was systematically investigated. As struvite has been regarded as a fertilizer, struvite nanowires can potentially act as a new kind of nanofertilizer with higher efficiency.