The Application of Self-Assembled of Meso-2,3-Dimercaptosuccinic Acid-Polydopamine-Zinc Oxide for Trace Cadmium Analysis

Abstract

Nanomaterials have been applied in the analysis of trace contaminants in aquatic samples; however, the adsorption affinity of heavy metal ions to metallic oxide nanoparticles is low. Meso-2,3-dimercaptosuccinic acid-polydopamine-zinc oxide (DMSA/PDA/ZnO) was synthesized through a facile self-assembly process for enhancing the adsorption capacity of ZnO to cadmium cation (Cd(II)). A method for the analysis of trace Cd(II) in water samples was developed while using dimercaptosuccinic acid/Polydopamine/zinc oxide (DMSA/PDA/ZnO) as an adsorbent and atomic absorption spectrometry (AAS) as a means of determination. The results demonstrate that the adsorption ratio of DMSA-PDA-ZnO to 1 mg/L Cd(II) is around 95% at pH 6.0–8.0 with a contact time of 31 h, and the enrichment rate can be more than 98% with the dosage of DMSA-PDA-ZnO exceeding 1.0 g/L. The adsorption isotherm of Cd(II) to DMSA/PDA/ZnO fits the Langmuir equation well, and the saturated adsorption of DMSA-PDA-ZnO to Cd(II) is 28.5 mg/g. The detection limit (3σ) of this method is 0.1 μg/L, with a relative standard deviation of 1%. Additionally, this method presents satisfactory performance with a recovery rate of 86−90% when applied to the detection of Cd(II) in environmental water samples.