Nanoscale zero-valent iron (NZVI) has a high adsorption capacity for heavy metals, but easily forms aggregates. Herein, preprocessed undulating venus shell (UVS) is used as support material to prevent NZVI from reuniting. The SEM and TEM results show that UVS had a porous layered structure and NZVI particles were evenly distributed on the UVS surface. A large number of adsorption sites on the surface of UVS-NZVI are confirmed by IR and XRD. UVS-NZVI is used for adsorption of Pb 2+ and Cd 2+ at pH = 6.00 in aqueous solution, and the experimental adsorption capacities are 29.91 and 38.99 mg g −1 at optimal pH, respectively. Thermodynamic studies indicate that the adsorption of ions by UVS-NZVI is more in line with the Langmuir model when Pb 2+ or Cd 2+ existed alone. For the mixed solution of Pb 2+ and Cd 2+ , only the adsorption of Pb 2+ by UVS-NZVI conforms to the Langmuir model. In addition, the maximum adsorption capacities of UVS-NZVI for Pb 2+ and Cd 2+ are 93.01 and 46.07 mg g −1 , respectively. Kinetic studies demonstrate that the determination coefficients ( R 2 ) of the pseudo first-order kinetic model for UVS-NZVI adsorption of Cd 2+ and Pb 2+ are higher than those of the pseudo second-order kinetic model and Elovich kinetic model. Highly efficient performance for metal removal makes UVS-NZVI show potential application to heavy metal ion adsorption.

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Heavy metal ions such as Cr(VI) pose great hazards to the environment, which requests materials and methods for decontamination. Nano zero-valent iron (nZVI) has emerged as a promising candidate for Cr(VI) removal. Herein, harnessing the merits of marine biomass, a heterogeneous water treatment system for the decontamination of Cr(VI) is developed based on the in situ immobilization of nZVI on the seashell powder (SP)-derived porous support. A response surface methodology (RSM) study involving three independent factors is designed and conducted to direct material synthesis and reaction design for products with optimal performances. Under optimal synthetic conditions, the nZVI-loaded seashell powder (SP@nZVI), which is characterized in detail by scanning electron microscope (SEM), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR), results in a 79% increase in the removal efficiency of Cr(VI) compared to free nZVI. Mechanism studies show that the removal of Cr(VI) by SP@nZVI conforms to the Langmuir adsorption model with a quasi-second order kinetic equation, in which redox reactions between nZVI and Cr(VI) occurred at the SP surface. The results of this work are expected to benefit the reuse of bioresource waste in developing environmental remediation materials.