Plasma-assisted synthesis of nano-sulfur adsorbent for efficient removal of mercury from flue gas

Adsorbents injection technology is one of the most promising strategies to control mercury emission from flue gas. However, existing literature has shown leaching risk of mercury and halogen from commercial halogen impregnated adsorbents. Therefore, we proposed a novel and convenient fabrication method for nano-sulfur adsorbent assisted with nonthermal plasma technology in order to address these issues. The morphology, number concentration and size distribution of as-obtained nano-sulfur particles was determined by High Resolution Transmission Electron Microscopy (HRTEM) and Scanning Mobility Particle Sizer (SMPS). The mercury adsorption experiments showed nano-sulfur adsorbent (removal efficiency: 88.2 %) was more effective than micron-sized elemental sulfur (less than 10 %). Furthermore, the chemical composition of elemental sulfur allotropes (S6, S7 and S8) was determined using High-performance Liquid Chromatography-Mass Spectrometry (HPLC-MS). It was found that nano-sulfur particles contained higher proportions of S6 (1.53 %) and S7 (1.29 %) allotropes, which are the active materials in elemental sulfur. To investigate the effects of adsorption temperature and simulated flue gas on the performance of nano-sulfur adsorbent, the optimal adsorption temperature of 110 degrees C was determined, indicating its suitability for coal-fired power plants equipped with a low-temperature electrostatic precipitator system. Additionally, it was observed that simulated flue gas had slight inhibitory effects on the adsorbent performance, with a reduction of approximately 5 % in Hg0 removal efficiency. In summary, this research proposed a novel method for synthesizing nano-sulfur adsorbent and revealed the differences in sulfur allotropes' reactions with mercury, thereby deepening our understanding of the mercury-sulfur reaction mechanism.

Automated summary

Adsorbents injection technology is an effective strategy for controlling mercury emission from flue gas. This study proposed a novel method for synthesizing nano-sulfur adsorbent and demonstrated its higher efficiency compared to micron-sized elemental sulfur adsorbent. Furthermore, the research revealed the differences in sulfur allotropes' reactions with mercury.