Detection of Cd2+ in Aqueous Solution by the Fluorescent Probe of CdSe/CdS QDs Based on OFF–ON Mode

Abstract

The detection of heavy metals in aqueous solutions has always attracted much attention from all over the world. A fluorescent probe of CdSe/CdS core-shell quantum dots (QDs) was designed to detect trace Cd2+ in aqueous solutions using the OFF–ON mode rapidly and efficiently, likely based on adsorption and desorption reactions between ethylenediaminetetraacetic acid disodium salt (EDTA) and CdSe/CdS QDs. In the OFF mode, the optical shielding function of EDTA results in fluorescence quenching owing to the strong adsorption ability of EDTA with Cd2+ on the sites of CdSe/CdS QDs surface. In the ON mode, the introduction of Cd2+ promotes the desorption of EDTA from the EDTA-CdSe/CdS QDs and restores the fluorescence intensity. There were two linear response ranges which were 0.1–20 µmol/L and 20–90 µmol/L for the EDTA-CdSe/CdS system to detect Cd2+. The detection limit was 6 nmol/L, and the standard deviation was below 4% for the detection of Cd2+ concentration in tap water.

Target-triggered dual signal amplification based on HCR-enhanced nanozyme activity for the sensitive visual detection of Escherichia coli

“…20,21 In a variety of signal outputs, such as uorescence and electrochemistry, colorimetry is ourishing because of its advantages of rapid response, easy operation, and low cost. [22][23][24] However, the limitations including low sensitivity and susceptibility hinder its applications in early monitoring and on-site detection. In recent years, several signal amplication techniques have been developed to obtain high-sensitivity analysis.…”

Novel Adsorbents and Adsorption Methods for Pollutant Removal

“…The advection and dispersion of tritiated water and pollutants such as iodine species (iodide: I − and iodate: IO 3 − ) and plutonium in deep geological repositories were studied in two respective articles [ 11 , 12 ]. In order to study the purification and detection technology of heavy metals in water, Dengpeng Wang, Chunlin He, and Yuling Zhao et al [ 13 , 14 , 15 ] discussed CdSe/CdS core–shell quantum dot tracing Cd 2+ in aqueous solutions, carbon adsorbent microwaves with waste amine–oxime removing Pb(II), and advanced Fe 3 O 4 @SFBC adsorbent removing As(III/V), respectively. Based on waste ore, two articles [ 16 ] studied the rational recovery process of radionuclides in tantalum–niobium slag and the adsorption effect of discarded coal gangue on the pollutant tetracycline hydrochloride, which reflected the important idea of turning waste into treasure.…”