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Benjawan Ninwong, Speaker at Chemical Engineering Conferences
King Mongkut’s University of Technology Thonburi, Thailand
Title : Carbon nanodots for mercury ions detection


In this research work, carbon nanodots were developed for determination of mercury ions. CDs were performed according to a simple one-step by microwave method. In the synthesis of CDs, citric acid was added in ultrapure water followed by ethylenediamine for produced nitrogen doped on CDs surface. The mixed solution was then put in microwave within 5 min. It was appeared the red-brown foamy solid and purified by using centrifugal filter unit. Characterization of carbon nanodots was studied by XRD, UV-vis, Fluorescence spectroscopy, TEM and FTIR. For the optical properties, the absorption spectra were shown at 350 nm which was the n-π* electron spectra of C=O and the sp3 hybridization. The emission wavelength was presented in a high intensity at 450 nm. The structure and functional group of carbon nanodots were studied by spectroscopic method using FTIR. The appearing peaks at the 1400 and 1320-1100 cm-1 wave positions were shown the bending vibration of C-N and C=N in the structure and the surface of the carbon nanodots. From the TEM image, it has good dispersion with a narrow size distribution in the range of 2 to 5 nm. The average diameter of the CDs was shown in 3 nm. The Hg2+-CDs complex was provided bigger size of CDs at 90 nm. In the presence of mercury ions, the fluorescence emission of CDs was gradually quenched by photo-induced electron transfer. The fluorescence turn-off of carbon nanodots obtained by Hg2+-CDs complex which didn’t interfere from other metal ions. The occurring interaction of mercury ions and CDs was applied on paper-based device by control with the black-light. The application on paper-based device provided several advantages that are simple, inexpensive material and the fabrication is cost effective. Moreover, it will be suitable for on-site environmental monitoring.

Audience Take Away:

  • Synthesis of carbon nanodots.
  • Characterization of carbon nanodots.
  • Application for mercury detection and alternative method using paper-based device.


Benjawan Ninwong studied Chemistry at the Chulalongkorn University, Thailand and graduated as MS in 2012. Now, she studying in PhD at King Mongkut’s University of Technology Thonburi. She received a scholarship from Royal Thai Government Scholarship for PhD. She joined the research group of Asst. Prof. Wijitra Dungchai at the Organic Synthesis, Electrochemistry & Natural Product Research Unit.