Novel three-dimensional Ti3C2-MXene embedded zirconium alginate aerogel adsorbent for efficient phosphate removal in water

Excessive phosphorus in water causes environmental security problems like eutrophication. Advanced two-dimensional material MXene has attracted raising attention in aquatic adsorption, while lack of selectivity and difficult recovery limit its application in phosphate removal. In this study, Ti3C2-MXene embedded zirconium-crosslinked SA (MX-ZrSA) beads were synthesized and their phosphate adsorption performance under different conditions was assessed. Investigations using SEM/EDS, XRD, BET, TGA and contact angle meter reveal that the addition of Ti3C2-MXene enhanced the thermal stability, mechanical strength, hydrophilicity, and formed loose network-like mesoporous inner structure with large surface area. The theoretical maximum adsorption capacity was 492.55 mg P/g and was well fitted by Freundlich and optimized Langmuir models. The Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analysis showed that chemi-sorption was involved, and the formation of Zr-O-P and Ti-O-P complexes accounted for high selectivity and affinity to phosphate. The adsorption experiments in real waters and lab-scale continuous flow Anaerobic-Anoxic-Oxic reactor further indicated the application potential of MX-ZrSA beads. Our study will provide insight into MXene and SA aerogel synergistic adsorption of aquatic contaminants and help with the removal and recovery of finite phosphorus resource.

Automated summary

In this study, Ti3C2-MXene embedded Zr-crosslinked SA (MX-ZrSA) beads were synthesized and their phosphate adsorption performance was evaluated. The results showed that Ti3C2-MXene enhanced the thermal stability, mechanical strength, and hydrophilicity of the material, forming loose network-like mesoporous structure. The maximum adsorption capacity was 492.55 mg P/g and was well fitted by Freundlich and optimized Langmuir models. Chemi-sorption involving Zr-O-P and Ti-O-P complexes accounted for high selectivity and affinity to phosphate. The adsorption experiments in real waters and lab-scale continuous flow Anoxic-Anoxic-Oxic reactor demonstrated the potential application of MX-ZrSA beads for phosphate removal. This study provides insight into the synergistic adsorption of aquatic contaminants by MXene and SA aerogel, as well as the removal and recovery of finite phosphorus resource.