Transition Metal Dichalcogenide–Silk Nanofibril Membrane for One-Step Water Purification and Precious Metal Recovery

Abstract

With the rapid worldwide industrial development, large amounts of pollutants such as heavy metals are discharged into the water sources, causing a huge threat to living beings. To mitigate this issue, there is an urgent need for new water treatment strategies. Inspired by a natural shell nacre structure and a multidimensional hybrid concept, we demonstrate multilayered inorganic–organic hybrid membranes using metallic molybdenum disulfide (MoS2) as two-dimensional transition metal dichalcogenide nanosheets and one-dimensional silk nanofibrils for water purification. Because of its possessing negatively charged layers and interaction sites, the hybrid film could adsorb metal ions and dyes from water. The separation performance can be tuned by changing the component ratios of these two nanomaterials. During filtration, due to the reducing effect of the MoS2 nanosheets, precious metal ions are reduced to their nanoparticle form without any further thermal or chemical treatments. In addition to the one-step removal and recovery of metal ions, the hybrid membranes exhibit excellent potential for the determination and removal of different dyes from water. The results of this research can open up an effective and green avenue for water purification and recovery of metal ions dissolved in water.

Protein nanofibrils for next generation sustainable water purification

“…Unlike other technologies such degradation, which can give rise to secondary pollution by generating toxic metabolites 80 , in each protein nanofibrils technology the pollutants are adsorbed without release of potentially harmful chemical substances into water. Furthermore, as discussed earlier, in recovery applications, adsorbed precious metal ions on protein nanofibrils can be reduced to their elemental forms 8,22,33 , increasing the sustainability value of the technology. Industrial and agricultural waste and byproducts can be used as the source for protein nanofibrils.…”

“…For instance, hybrid amyloid fibrils-activated carbon hybrid membrane can simply be prepared by vacuum-assisted deposition on the surface of a support cellulose filter a homogenous aqueous mixture of β-lactoglobulin fibril (2 wt%) and activated carbon (10 wt%) solutions 22 . The fabrication method is general and extends to other types of protein nanofibril hybrids: for example, amyloid fibrils can be replaced by silk nanofibrils and activated carbon by metallic molybdenum disulfide 33 to generate diversified organic/inorganic hybrid membranes for water purification.…”

“…Multilayered inorganic−organic hybrid membranes can also be obtained by hybridizing metallic molybdenum disulfide (MoS 2 ), as two-dimensional transition metal dichalcogenide nanosheets, and silk nanofibrils 33 . The composite membrane removal performance can be tuned by altering the component ratios of the two nanomaterials.…”

“…The maximum adsorption capacity of the optimally designed hybrid membrane reaches 759 and 425 mg/g for gold and palladium, respectively. Furthermore, during filtration, the adsorbed precious metal ions were reduced in situ to their elemental nanoparticle form, thanks to the reducing properties of MoS 2 nanosheets 33 .…”

Progress in the design of nanoporous adsorbent materials containing transition metals for the removal of contaminants of emerging concern

“…This encompasses a wide range of strategies, from the addition of specific surface chemical species that serve as unique uptake sites to the preparation of composites that display multi-functional character. For instance, the inclusion of transition metals as the material active sites or structural element in catalysts [24][25][26][27][28][29][30][31][32], functionalization of membranes [33][34][35][36][37][38], or adsorbents [39][40][41][42]. Some of the enhancements in chemical activity are principally due to the capacity of the metal d subshell to form specific bonds (e.g.…”