环境地球化学国家重点实验室知识库

The removal of heavy metals from wastewater is one of the most important issues for the world, especially from industrial effluents. Pumice-nanoscale zero-valent iron (P-NZVI) was successfully prepared in different experimental conditions. Meanwhile, the shape, size and distribution of NZVI on P-NZVI were evaluated using a scanning electron microscope (SEM). At the optimum condition, NZVI with a mean diameter of 20.2 nm was distributed uniformly and consistently on the surface of pumice. Freundlich isotherm analysis suggested that the surface property of P-NZVI were heterogeneous. The removal of Hg (II) and Cr (VI) by P-NZVI could be well described by pseudo-first-order kinetic model. At equilibrium q(max) of Hg (II) and Cr (VI) was 107.1 and 106.9 mg/g, respectively. Thermodynamic investigation suggested that the removal of Hg (II) and Cr (VI) by P-NZVI was an endothermic and spontaneous process. The less values of Delta H-0 for Hg (II) than those for Cr (VI) demonstrated that more thermal energy was needed to remove Cr (VI) than Hg (II) at the same reaction rate.