Design and application of a high-energy microplasma annular jet for colorimetric detection of Cr(III)

Microplasma jets (MPJs) are versatile tools widely applied in analytical chemistry, surface treatment, and environmental remediation. However, their utility is often constrained by their energy limitation. This restricts their efficiency and application potential. This study addresses this challenge by proposing a novel microplasma annular jet (MPAJ) design. The research aims to theoretically and experimentally characterize the properties of the MPAJ. The ultimate objective is to assess its potential for delivering enhanced performance, thereby overcoming a key constraint of conventional MPJs.

A two-dimensional axisymmetric model was developed to simulate the proposed MPAJ, focusing on electron density as a critical performance metric. The simulation results clearly indicated that the MPAJ achieves a significantly higher electron density compared to a conventional MPJ, confirming its superior energy capacity. To experimentally validate this enhancement, the MPAJ was applied to a colorimetric detection system for trivalent chromium ions (Cr(III)). The system demonstrated excellent analytical performance, exhibiting a linear response within the concentration range of 1-40 μmol L^-1 and achieving a notably low detection limit (LOD) of 0.7 μmol L^-1. Furthermore, the practicality and reliability of the MPAJ-based method were successfully confirmed through the accurate determination of Cr(III) in actual environmental water samples. These combined theoretical and experimental findings substantiate that the novel MPAJ design effectively mitigates the energy constraints of traditional microplasma jets, showcasing its strong potential for highly sensitive analytical applications.

The annular jet configuration offers greater flexibility, enabling precise and diversified energy application modes. By adjusting geometric parameters such as ring diameter and nozzle width, this design can be tailored to meet specific requirements. With its enhanced adaptability and elevated energy capacity, the MPAJ is a promising tool for advancing applications in analytical chemistry, materials processing, and other fields that depend on precise plasma delivery.