Mineralization of SF 6 and NF 3 fluorinated compounds for greenhouse gas abatement by oxalates

• Published in: Chemosphere (Oxford) 2024-05, p.142186
• Main Authors: Mdlovu, Ndumiso Vukile, Lin, Kuen-Song, Tang, Cheng-Yang, Chen, Wei-Chung, Hussain, Jamshid
• Format: Article
• Language: English
• ISSN: 1879-1298

Fluorinated compounds (FCs) such as sulfur hexafluoride (SF ) and nitrogen trifluoride (NF ) have garnered attention due to their environmental impact. This study investigates the mineralization and removal of two potent FCs: SF and NF . The results confirm that utilizing various oxalate salts leads to the formation of corresponding metallic fluorides: lithium fluoride (LiF), sodium fluoride (NaF), and potassium fluoride (KF), validating the occurrence of mineralization reactions. Among the oxalate salts, sodium oxalate demonstrates the highest mineralization efficiency in both SF and NF removal. Real-time Fourier transform infrared spectroscopy (FT-IR) gas-phase analysis confirms rapid and complete gas removal within a short reaction time using the selected oxalate salts. Meticulous mass balance calculations revealed that oxalates (LiF, NaF, and KF) yielded sulfur (S) at rates of 92.09%, 91.85%, and 84.98% following SF mineralization. Additionally, the conversion rates of oxalates to the corresponding metallic fluorides (LiF, NaF, and KF) after SF mineralization were 98.18%, 95.82%, and 95.21%, respectively. Similarly, after NF mineralization, these conversion rates stood at 92.18%, 90.67%, and 90.02%, respectively. The removal efficiencies for SF (1,000 ppm) were 4.98, 12.01, and 7.23 L/g, while those for NF (1,000 ppm) were 14.1, 12.6, and 11.7 L/g, respectively. Notably, sodium oxalate exhibits superior effectiveness, achieving 100% SF conversion within 30 min and 100% NF conversion within 50 min. This work underscores the potential of oxalate mineralization as a promising strategy for efficient and rapid removal of potent fluorinated compounds, paving the way for environmentally benign FC remediation techniques with broader implications for sustainable gas treatment technologies.