In situ growth of Mg-MOF-derived dendritic carbon on lignin nanofibers for efficient capacitive defluorination

Fluoride contamination has become a global public health problem due to its adverse health effects. The search for efficient and environmentally friendly fluoride removal technology is an urgent issue. Capacitive deionization (CDI) technology has attracted much attention because of its high efficiency, easy operation and environmental friendliness. Electrode materials are crucial for CDI systems. Herein, Mg-MOF-derived dendritic carbon materials (MMCNF) are successfully grown in situ on lignin nanofibers via solvothermal synthesis. Due to the high specific surface area of Mg-MOF and the structural stability of lignin nanofibers, it has a high specific capacitance of 158 F·g −1 at a current density of 1 A·g −1 . And the capacitance retention of 93.13 % is obtained after 5000 charge/discharge cycles. The CDI unit equipped with MMCNF electrodes effectively reduced the fluoride ion concentration to 1.21 mg·L −1 in a 10 mg·L −1 simulated fluoridated wastewater, exhibiting a maximum adsorption capacity of 20.64 mg·g −1 . It is lower than the drinking water standard of 1.5 mg·L −1 set by the World Health Organization. This work offers new electrode materials and technological options for the removal of fluoride ions from wastewater in the future.