Photocatalytic Degradation of Water Sample and On-line Monitoring of Cd2+ in Microreactor

doi:10.7517/j.issn.1674-0475.2016.05.444

Abstract

Abstract:

In this paper, a micro-analysis system integrated pretreatment of water sample by photocatalysis of organic matter with on-line monitoring of Cd²⁺ is established. Aphotocatalytic microreactor based on microfluidic chip coated with TiO₂ filmhas been fabricated and integrated with electrochemical detection system. The Cd-EDTA complex served as model system to demonstrate the on-line photocatalytic degradation of organic matter followed by the differential pulse stripping voltammetric determination of the metal ion in aqueous solution. The voltammetric signal of 0.1 mg/L Cd²⁺ in acetate buffer (pH 4.4) at the Bismuth Film Electrode is suppressed by EDTA. While irradiating the TiO₂-coated microfluidic chip with UV-LED at 365 nm causes the recovery of the Cd²⁺ signal, indicating the photocatalyticdegradation of EDTA.The effects of UV light intensity,flow rate,flow rate of oxygen and other factors on the photocatalytic degradation efficiency have been studied.Under the optimal condition of light intensity being 120 mW/cm², pH 4.4,flow rate of oxygen being 850 μL/h and the flow rate of water sample being 50 μL/h, the recovery of the Cd²⁺ signal rate up to 92.6%. When the flow rate of water sample is 300 μL/h, the recovery of the Cd²⁺ signal is 60.0%, and the RSD of the recovery of the Cd²⁺ signal is 5.2%. The sample volume needed for the electrochemical detection of Cd²⁺ is only 0.3 mL.The total analysis time for one measurement is about 60 min.

Key words: photocatalitic microreactor, degradation of EDTA, Cd²⁺, on-line detection

ZHU Zhexin, YE Meiying. Photocatalytic Degradation of Water Sample and On-line Monitoring of Cd²⁺ in Microreactor[J]. Imaging Science and Photochemistry, 2016, 34(5): 444-451.

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Photocatalytic Degradation of Water Sample and On-line Monitoring of Cd²⁺ in Microreactor

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