Novel 3D LP-C3N4@Ni-MOF-74-S selective adsorption and detection of mercury and reuse of waste materials as photocatalysts

Abstract

Herein, 3D aerogel PAN-C3N4 was prepared by hydrothermal method using polyacrylonitrile(PAN) and C3N4 as raw materials, and then a layer of Ni-MOF was grown on its surface, and 3D aerogel composites(LP-C3N4@Ni-MOF-74-S) co-doped with nitrogen and sulfur were prepared by vulcanization reaction. The adsorbent LP-C3N4@Ni-MOF-74-S can be applied to mercury (II) and elemental mercury adsorption with maximum adsorption capacities of to 1320.13 and 894 mg/g, respectively, exceeding all sulfur-functionalized adsorbent materials reported so far. More importantly, LP-C3N4@Ni-MOF-74-S showed excellent adsorption capacity in dynamic adsorption experiments on industrial wastewater to rapidly reduce the concentration of mercury (II) from 10.0 mg/L to <0.8 μg/L, which is far below the acceptable limit for drinking water(2 μg/L). Meanwhile, LP-C3N4@Ni-MOF-74-S can also be used as a sensor. After adsorption of mercury (II), TMB and H2O2 were added, and the amount of mercury (II) in the solution was detected in only 5 s with a detection line of 1 ppb. The adsorbent can also be used as a photocatalyst to avoid secondary contamination. LP-C3N4@Ni-MOF-74-HgS was able to completely degrade 100 mL of a solution with a concentration of 10 mg/L RhB in 15 min, showing good degradation ability.