Photocatalytic materials for environmental remediation of organic pollutions and heavy metals require not only a strong visible light response and high photocatalytic performance, but also the regeneration and reuse of catalysts. In this work, a ternary hybrid structure material of Nanoscale Zero Valent Iron(Fe 0 ) doped g-C 3 N 4 /MoS 2 layered structure (GCNFM) was synthesized by a facile strategy. Compared with the pure GCN, GCNM and Fe-GCN, the photodegradation efficiency of the GCNFM toward the RhB and Cr(VI) under visible light are considerably enhanced to 98.2% for RhB and 91.4% for Cr(VI),respectively. In addition, the reaction rate constants (K RhB and K Cr ) of GCNFM are much higher than those of GCN, GCNM and Fe-GCN. attributing to that Fe 0 and MoS 2 composited with GCNM promotes the separation of photogenerated electron-hole pairs. Moreover, with the loading of MoS 2 and/or Fe 0 , the holes could displace the ·O 2as the main reactive oxygen specie in GCN. GCNFM maintains an efficient degradation ability to both the RhB and Cr(VI) after several cycles, in spite that normally Fe 0 will be consumed and deactivated with the reduction proceeding as previously reported. It suggests that the photogenerated electrons, in response, can reduce the Fe(III)/Fe(II) to Fe 0 , inducing a regeneration and reuse of Fe 0 . We anticipate this work can provide a good example for the design of efficient, visible light driven and recyclable photocatalysts for environmental remediation of both the organic pollution and heavy metals.

Inorganic hierarchical nanostructures have remarkable potential applications in environmental metal remediation; however, their applications usually suffer from low capacity, high cost, and difficulties in the recycling of adsorbents. We previously reported a facile strategy to synthesize acid-insoluble calcium silicate hydrates (CSH) from oyster shells, a representative kind of biowaste. However, little is known of the structure, size, and morphology of the as-prepared CSH, which hampers the improvement of their adsorption capacities. In this work, systematic investigation of the structures of as-generated CSH demonstrate that they have a hierarchically porous structure composed of thin nano-sheets, where each nano-sheet is assembled by nano-fibers with width of around ten nanometers. The hierarchical nanostructures with pore size of ∼12 nm provide a significant amount of active sites to graft polyethyleneimine (PEI), which enables the efficient extraction of both Cu(ii) cations and Cr(vi) anions from the aqueous solution. Batch experiments further indicate that the PEI-modified PCSH exhibit a maximum adsorption capacity of 203 and 256 mg g(-1) for Cu(ii) and Cr(vi), respectively, much higher than that of CSH, OS and many other adsorbents in literature. The adsorption of Cu(ii) and Cr(vi) proved to be spontaneous and exothermic. Combining the pH-dependent experiments with X-ray photoelectron spectroscopy analysis, the underlying mechanism is discussed. PCSH derived from OS biowaste maintains an efficient extraction ability toward Cu(ii) and Cr(vi) after five adsorption-desorption cycles. It is also applicable for treating various kinds of heavy metal ions and organic pollutants, showing potentially wide applications in water treatment.

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