Ti3C2Tx MXene@MOF decorated polyvinylidene fluoride membrane for the remediation of heavy metals ions and desalination

Nowadays, the evolution of two-dimensional materials like transition metal carbides (MXene) prepares a novel path to surpass the trade-off between the membrane permeation and rejection rates. Based on water swelling and oxidation vulnerability, MXene membranes showed vivid defects such as inadequate stability, detrimental adsorption, and haphazardly stacked nanosheets. Here, we prepared Ti3C2Tx MXene@metal-organic frameworks nanosheets from aminated metal-organic framework-101 (NH2-MIL-101(Al)) via the in-situ growth method and incorporated them into the thin-film polymer to acquire desirable MXene nanosheets with tailor-made structures. The earned modified thin-film nanocomposite membrane showed high salt rejection for Na2SO4 (98.6 +/- 0.5%), MgSO4 (96.9 +/- 0.7%), MgCl2 (84.5 +/- 0.8%), and NaCl (82.5 +/- 0.8%), and also showed an improved permeation rate by three times (17.1 +/- 0.2 L m- 2. h-1. bar-1). Concurrently, the rejection rate of five different types of heavy metal ions (Ni2+, Cd2+, Mn2+, Cu2+, and Zn2+) was tested and denoted more than a 95.2 +/- 0.5% rejection rate for all of them, notably high for Mn2+ (97.6 +/- 0.4%). After modification, the flux recovery rate was as high as 95.3 +/- 0.4%, denoting more than 30% improvement; besides, anti-compactness features enhanced by nearly 34 +/- 0.7%. The long-term water permeation kept 91.5 +/- 0.9% of its initial rate indicating almost 40 +/- 0.8% enhancement. In addition, the rejection performance of Na2SO4 for the optimized membrane was more than 97% even after two weeks.

Automated summary

By synthesizing modified thin-film nanocomposites using metal-organic frameworks and MXene nanosheets, the performance of the membranes in terms of salt rejection and permeability was significantly improved. The membranes also exhibited excellent rejection performance for heavy metal ions and maintained sustainable water permeation.