Optimization of boric acid extraction from ulexite mineral by using supercritical carbon dioxide

• Published in: The Journal of supercritical fluids 2020-12, Vol.166, p.104998, Article 104998
• Main Authors: İpeksever, Sercan, Gönen, Mehmet
• Format: Article
• Language: English
• Subjects: Boric acid; Box-Behnken design; Reactive extraction; Sequestration; Supercritical CO2
• ISSN: 0896-8446; 1872-8162
• DOI: 10.1016/j.supflu.2020.104998

[Display omitted] •Boric acid extraction from ulexite using supercritical CO2.•Development of green and sustainable process.•Dissolution of ulexite mineral in an aqueous phase by carbonic acid.•Box-Behnken experimental design for optimizing reaction conditions. The utilization of carbon dioxide (CO2) in chemical processes is one plausible solution for decreasing greenhouse gases in the atmosphere. Herein, a boric acid extraction process was developed utilizing CO2 as a leaching agent. Three-factor three-level Box-Behnken design model was employed to investigate and optimize process variables of temperature, pressure and reaction time for reactive extraction from ulexite mineral using carbon dioxide. A 91.8 % boric acid extraction yield was obtained at 70 °C and 9 MPa with a reaction time of 170 min. At the end of reaction, the heterogeneous mixture was separated by vacuum filtration. The presence of Na (8.72% wt.) in EDX analysis confirmed the crystallized powder has sodium borate. The filter cake was determined as calcium carbonate from the XRD and FTIR analyses. Utilizing supercritical CO2 as a leaching agent is a viable solution to sequester CO2 collected as calcium carbonate while also producing commercially relevant boric acid.