Melamine/MIL-101(Fe)-derived magnetic carbon nanotube-decorated nitrogen-doped carbon materials as sorbent for rapid removal of organic dyes from environmental water sample

In this work, a magnetic carbon nanotube-decorated nitrogen-doped carbon (CNT/Fe@N-C) composite was successfully prepared by carbonization of melamine and MIL-101(Fe) under inert atmosphere at 900 °C. In order to study the removal performance of adsorbents for the organic dyes, different mass ratios melamine/MIL-101-derived CNT/Fe@N-C were prepared. The results show that the as-prepared CNT/Fe@N-C material delivers a high performance for removal of organic dyes (Rhodamine B, malachite green, and methyl orange) with mass ratio of MIL-101(Fe) and melamine at 1:3. The experimental parameters including amount of adsorbent, pH, contact time, and initial concentration of organic dyes were investigated. Under the optimized conditions, the maximum adsorption amount of CNT/Fe@N-C for three dyes are in the range of 182.1–196.5 mg/g. The adsorption process of three dyes on the CNT/Fe@N-C material was consistent with Langmuir isotherm model and pseudo-second-order model. The results indicate that the adsorption may be the monolayer chemisorption process. The adsorption mechanism of organic dyes on the adsorbent material is may be due to the electrostatic interactions and π-π stacking interaction. Finally, the CNT/Fe@N-C material can be reused 5 times without a significant reduction in the removal rate. The results indicate that the CNT/Fe@N-C material is a promising sorbent for removing organic dyes. This work provides a new strategy to prepare CNT/metal@N-doped carbon material with excellent adsorption properties from nitrogen-free raw MOF materials by calcining a mixture of MOF and melamine at high temperature.