Scalable and sustainable production of Ti3C2T z MXene and fluorine recovery from wastewater through cryolite precipitation.

Abstract

Treatment of HF or HCl/LiF etched Ti3C2T z with 0.05 M NaHCO3 before water washing reduces the wastewater generated by 75%. When etched with HF, cryolite (Na3AlF6) precipitation from spent etching waste effectively removes fluorine from this waste stream, offers insight into the etching chemistry of MAX to MXene, and provides an effective analytical tool for optimization of MXene production. Additionally, washing HF etched multilayered Ti3C2T z with 0.05 M NaHCO3 allows for the production of delaminated Ti3C2T z colloidal suspensions, which typically requires the use of TBAOH or DMSO for intercalation and subsequent delamination. Ti3C2T z made with HCl/LiF and washed with 0.05 M NaHCO3 yields a colloidal suspension with a concentration of 18 mg mL-1 and a film conductivity of 1150 S cm-1.