Ultrasonic disaggregation of dioctahedral palygorskite crystal bundles for enhancing the stability and antibacterial properties of Pickering emulsion

Abstract

The disaggregation of palygorskite (Pal) crystal bundles and stable dispersion of Pal rod crystals have been the crux of its high-value and functionalized application. Herein, the scale-up ultrasonication and thermosonication were employed to disaggregate dioctahedral Pal crystal bundles, and the effects of sonication time and temperature on the physicochemical features of Pal were systematically investigated. The results showed that the highly dispersed individual Pal nanorods could be continuously produced by sonicating Pal dispersion at 30 °C for 8–12 min, retaining the original nanorod crystal morphology and layered-chain microstructure. It also greatly improved the specific surface area, electronegativity, suspensibility, and colloid performance of Pal. Furthermore, the disaggregated one-dimensional Pal nanorods (2 wt%) were applied to stabilize carvacrol (CAR) and thereby fabricate antibacterial Pickering emulsion (PEs), which showed outstanding storage stability with little change in emulsion volume over 270 days and excellent antibacterial activity against E. coli and S. aureus even after 210 days of storage. This work provides a feasible and efficient ultrasonic process for large-scale industrialized disaggregation of dioctahedral Pal crystal bundles, and the obtained high dispersed individual Pal nanorods lay a foundation for the functional utilization of Pal, especially for the fabrication plant essential oils-based antibacterial PEs.