Highly efficient iodine capture and ultrafast fluorescent detection of heavy metals using PANI/LDH@CNT nanocomposite

• Published in: Journal of hazardous materials 2023-04, Vol.447, p.130732, Article 130732
• Main Authors: Salem, Mansour A.S., Khan, Amjad Mumtaz, Manea, Yahiya Kadaf, Qashqoosh, Mohsen T.A., Alahdal, Faiza A.M.
• Format: Article
• Language: English
• Subjects: Adsorption; Carbon nanotubes; CHEF effect; Fluorescent probe
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2023.130732

Here, the hybrid material of polyaniline/layered double hydroxide@carbonnanotubes (PANI/LDH@CNT) is considered a multifunctional material. Instrumental methods, including FTIR, XRD, TEM, SEM, and TGA/DTA were utilized to characterize PANI/LDH@CNT. The polymerization method created PANI/LDH@CNT as an adsorbent to remove toxic iodine in hexane solution with a capture capacity of 303.20 mg g−1 during 9 h. It is 900 mg g−1 in the vapor phase within 24 h. After three cycles, the PANI/LDH@CNT could be regenerated while maintaining 91.90 % iodine adsorption efficiency. Due to the presence of free amine (-N) groups, OH−, CO2H, and π-π conjugated structures in the PANI/LDH@CNT, it is also explored for efficient iodine uptake. It was demonstrated that the pseudo-first-order (PFO) and Langmuir model had the optimum correlation with the kinetic and isotherm data, respectively. Moreover, the use of PANI/LDH@CNT is not only limited to iodine capture; it can also be utilized as a sensitive sensor that displays a fluorescence “turn-off” response for Mn7+ and Cr6+ ions and a fluorescence “turn-on” response in the case of Al3+ ions. The fluorescence intensity of the PANI/LDH@CNT was turned off in the presence of Mn7+ and Cr6+ because of the fluorescence inner filter effect (IFE) mechanism. In contrast, the fluorescence intensity was turned on in the case of Al3+, relying on the chelation-enhanced fluorescence (CHEF) effect mechanism. Under optimal conditions, the limit of detection (LOD) of 51, 59, and 81 nM for Mn7+, Cr6+, and Al3+, respectively. According to the literature, this is probably the first example based on PANI/LDH@CNT as a multifunctional hybrid material employed as an adsorbent for capturing radioactive iodine and as a chemosensor for detecting heavy metal ions in aqueous solutions. [Display omitted] •Ex-situ oxidative polymerization was used to synthesize PANI/LDH@CNT.•The adsorption capacity for I2(aq) was 303.20 mg g−1 and 900 mg g−1 in I2(vap).•PANI/LDH@CNT showed a high sensitivity for heavy metal ions detection at ppb levels.