Hyperbranched magnetic polymer: highly efficient removal of Cr(VI) and application in electroplating wastewater

By using a two-step hydrothermal method and trithiocyanuric acid (TTCA), 2,4,6-trihydrazino-1,3,5triazine (THT), and Fe3O4 as raw materials, a spherical magnetic adsorbent polymer (TTCA/THT@Fe3O4) was synthesized to achieve the efficient removal of Cr(VI) from wastewater. Under optimal adsorption conditions, the maximum adsorption capacity of TTCA/THT@Fe304 for Cr(VI) can reach 1340 mgg(-1). Notably, the removal efficiency can approach 98.9%, even at the lower concentration of 20 mgL-1 Cr(VI). For actual wastewater containing Cr(VI), the Cr(VI) concentration was reduced from 25.8 to 0.4 mgL-1, a remarkable 20% lower than the current industry discharge standard value. A mechanism for the high adsorption performance of Cr(VI) on TTCA/ THT@Fe3O4 was investigated using Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and density functional theory. It can be plausibly attributed to the formation of Cr/N and Cr/S coordination bonds. Additionally, surface electrostatic adsorption, reduction effects, and the spherical polymer structure increase the contact area with Cr(VI), maximizing adsorption. The synergistic effect of adsorption and reduction enhances the adsorption performance of TTCA/THT@Fe3O4 for Cr(VI) and total chromium in water. The resultant polymer has a simple preparation process, excellent adsorption performance, easy magnetic separation, and promising application for actual wastewater.

Automated summary

A spherical magnetic adsorbent polymer (TTCA/THT@Fe3O4) was synthesized using a two-step hydrothermal method, trithiocyanuric acid (TTCA), 2,4,6-trihydrazino-1,3,5-triazine (THT), and Fe3O4. The polymer showed high adsorption capacity for Cr(VI) in wastewater, reaching up to 1340 mgg(-1) under optimal conditions. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and density functional theory were used to investigate the mechanism behind the adsorption performance, attributing it to the formation of Cr/N and Cr/S coordination bonds. The polymer demonstrated excellent adsorption performance, easy magnetic separation, and promising application for actual wastewater.