Acoustic-Dependent Enhanced Functionalized Magnetic Nanomaterials for Purification of Chromium Containing Water

Magnetic nanomaterials typically exhibit good solid–liquid separation properties and surface modifiability, making them widely used in the separation and purification of highly toxic pollutants despite the problem of magnetic agglomeration. Herein, pure Fe 3 O 4 nanoparticles, graphene oxide (GO)-modified Fe 3 O 4 nanocomposites, polypyrrole (PPy)-modified Fe 3 O 4 nanocomposites, and GO and PPy-comodified Fe 3 O 4 nanocomposites were used as adsorbents to explore the universal and effective dispersion methods of functionalized magnetic nanoadsorbents from the perspective of acoustic parameters. System tests have shown that regardless of whether the surface of magnetic nanomaterials is modified or not, ultrasound radiation can significantly enhance the adsorption of Cr(VI) (2.1–7.3-folds). Detailed performance tests, ultrasonic parameters, and color development experiments show that the enhanced adsorption characteristics of magnetic nanomaterials with improved dispersion have a strong frequency/power dependence. Interestingly, a single modification layer, especially a combined modification layer, weakens this effect. After 5 cycles, the nanomaterial still has more than 90% adsorption efficiency, indicating that the nanoadsorbent has good cycle stability. In addition, this method exhibits excellent removal activity for Cr(VI) and other heavy metal ions (such as Pb 2+ ) in actual wastewater. This work confirms that ultrasound-assisted dispersion is a simple, efficient, and sustainable way to fully demonstrate the application characteristics of magnetic-based nanoadsorbents.