Scalable and sustainable production of Ti(3)C(2)T(z) MXene and fluorine recovery from wastewater through cryolite precipitation

Treatment of HF or HCl/LiF etched Ti(3)C(2)T(z) with 0.05 M NaHCO(3) before water washing reduces the wastewater generated by 75%. When etched with HF, cryolite (Na(3)AlF(6)) 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 Ti(3)C(2)T(z) with 0.05 M NaHCO(3) allows for the production of delaminated Ti(3)C(2)T(z) colloidal suspensions, which typically requires the use of TBAOH or DMSO for intercalation and subsequent delamination. Ti(3)C(2)T(z) made with HCl/LiF and washed with 0.05 M NaHCO(3) yields a colloidal suspension with a concentration of 18 mg mL(−1) and a film conductivity of 1150 S cm(−1).