1. BackgroundFor thousands of years, ** has been at the center of social development, first due to its *** and inert metal properties, and more recently in human history, due to its technological applications in electronics, catalysis, aerospace, electroplating, nanotechnology, medicine and biotechnology. **Excellent electrical conductivity, ductility, reflectivity, biocompatibility, and stability make it an integral part of the microelectronics industry, while driving advances in green chemistry and fuel innovation. As a non-renewable resource that is in high demand due to technological development, it is particularly important to obtain waste from municipal solid waste, waste electrical and electronic equipment (e-waste) and industrial wastewater. E-waste is the world's fastest-growing solid waste, with production expected to reach 61.3 million tonnes in 2023. It is one of the most valuable components of e-waste and can be highly profitable; However, current methods are resource-intensive, so more efficient extraction materials need to be developed to cope with the steadily increasing demand from e-waste.
Second, the content of the studyRecently,ETH Zurichraffaele mezzengaProtein starch nanofibers extracted from whey, a by-product of the dairy industry, were exploredaf), asA novel adsorbent from e-wasteMedium ** goldThe results show that:AF aerogels have a significant gold adsorption capacity (166.).7mg g) and selectivity, is a highly effective gold** adsorbent。In addition, since AU grows along the (111) plane, AF aerogels are an effective template for converting gold ions into single crystal lamellae. When used as a template for ** gold from an e-waste solution (computer board dissolved in a suitable solvent), 21-22 carats (about 90.) can be obtained8wt.%) of high-purity gold nuggets. The life cycle assessment and techno-economic analysis of the process ultimately cemented the potential of protein nanofiber aerogels as an environmentally friendly and economically viable method to extract e-waste. Related research work to:Gold Recovery from E-Waste by Food-Waste Amyloid Aerogels" was published in top international journalsadvanced materialsAbove. 
3. Research contentThis study shows how whey, a major dairy industry by-product, can be processed as AF aerogel for selectivity from e-waste (Figure 1). The two major wastes** (e-waste and food waste) are sustainably remediated, reducing their environmental impact and generating net value from circular economy principles. 
Figure 1A schematic diagram of the route for the extraction of pure gold from food waste (whey) and e-waste is shown in Figure 2a, and the resulting AF aerogel is lightweight (density 33.).18mg·cm-3, porosity 97%), with excellent mechanical stability and water stability. Figure 2b shows that the gold concentration of the mixture decreased from 950 ppm to 130 ppm after treatment with AF aerogel, indicating that the AF aerogel adsorbed 3320 g of gold. In addition, with the exception of **, the concentrations only changed slightly. It has been observed that the efficiency of the aerogel for the removal of gold is 933%, the adsorption capacity is 1667mg/g。Conversely, for Cu, Ni, Pb, Zn, Cr, Fe, and Mn, the removal efficiencies were 19% (Figure 2c). The adsorption capacities of Cu, Ni, Pb, Zn, Cr, Fe and Mn were respectively. 3 and 0 mg g (Figure 2D). These results were obtained from the passive adsorption of extremely high concentrations of heavy metal solutions, demonstrating the superior selectivity of AF aerogels for gold ions compared to other metal ions. The adsorption isotherm plotted by the Swillens and Motulsk methods exhibits an L-curve pattern, and locating the vacancy binding site becomes increasingly challenging as the gold concentration increases (Figure 2E). The saturation limit and binding constant were determined to be 54., respectively64mm and 11832m-1。Notably, the maximum adsorption capacity of AF aerogels for gold ranges from 012 mg g to 1887 mg g at 100,000 ppm. At 1000ppm, the gold adsorption capacity reached 190 mg g, which is slightly higher than the adsorption capacity in a mixed metal environment at the same concentration. As shown in Figure 2F, the gold concentration decreased by 77% to 143 mg of adsorption capacity within only 5 minutes of contact with AF aerogel, and plateaued after 30 minutes. This abrupt drop implies rapid mass transfer of gold ions, as well as their rapid interaction with the binding site of AF aerogel. Figure 2g shows that this rapid adsorption process follows a quasi-second-order reaction, indicating that chemisorption is the primary mechanism of the adsorption reaction. 
Figure 2Fig. 3A shows the formation of gold nanoparticles on the surface of AF aerogels during treatment with a low concentration of gold solution (10 ppm). When the concentration of the gold solution is increased to 1000 ppm, the AF aerogel not only adsorbs the gold, but also reduces it to a single crystal form (Figure 3B). This is supported by light microscopy images of AF aerogel samples (Figure 3C). In Figure 3D, SEM shows the formation of a gold microplate on the inner surface of an AF aerogel. Microplates maintain triangles and hexagons of various sizes, but always have 120° angular symmetry. Changes in the size and properties of the resulting gold (nanoparticles and nanosheets) can be attributed to complex interactions of amino acids, which affect the reduction and capping effects as well as the concentration of gold. The XRD in Figure 3E is shown with the 2 corners located. 6 ° and 77The presence of four distinct peaks at 6° corresponds to the characteristic Bragg reflection of the (111), (200), (220) and (311) crystal planes of the face-centered cubic (fcc) lattice structure of the elemental gold (AU0) metal, confirming the formation of crystalline gold nanoplates. Using the Scherrer equation, the average grain size was determined to be 32 nm. Topographic height analysis shows that the polygonal single crystals appear very flat and remain at a consistent height of around 55 nm (Figure 3f). Figure 3G-I shows the STEM of the flake layer, AF facilitates the formation of flakes. The HAADF images clearly show the significant polycrystalline morphology of the faceted particles throughout the TEM sample (Figure 3G). Figure 3H shows a colored overlay of the Au-LA and C-Ka signals of the particles in Figure 3G and confirms that the very regularly shaped polygon is an AU sheet located on a mesh amorphous carbon foil of the TEM support grid. As can be seen from Figure 3i, SAD stands for very thin lamellae, with the very characteristic of lamellae, the most prominent [111] out-of-plane crystal orientation of lamellae. 
Figure 3The gold nanoparticles and crystals formed using AF aerogels are shown in Figure 4 with a gold concentration of 1 in the solution prior to AF treatment44ppm, well below other metals such as copper (2711ppm) or iron (5033ppm). Even under these conditions, the AF aerogel has a significant adsorption capacity, and the gold content in the solution drops to 0 after treatment48 ppm (Figure 4a). Figure 4b shows that the reduction in gold concentration is equal to 66The removal efficiency is 8%, while the removal efficiency of copper (the second largest adsorbed metal) is only 156%, indicating the high gold selectivity of AF aerogels. 
Figure 4The performance of AF aerogel treatment and gold in e-waste solution is shown in Figure 5a, after adsorption of gold ions, AF aerogel is heat-treated, and finally from this process ** mass is 05g of gold nuggets. Figure 5b shows that the nugget contains mainly gold (908wt.% copper and nickel contain 109 and 0018wt.%, the content of the remaining metal is less than 0025wt.%。Proof of high purity of ** gold nuggets, equivalent to approximately 21-22 carats. In Figure 5b, the carbon footprint of AF aerogel in Au** is approximately 87 g CO2eq, while for activated carbon deployment, the amount reaches 116g CO2eq. Using AF aerogel as an adsorbent for gold** resulted in a 71% reduction in freshwater eutrophication and a 64% reduction in fossil consumption compared to activated carbon (Fig. 5c and d). As shown in Figures 5E and G, AF aerogels are consistently less damaging to human health and resources than activated carbon. However, AF aerogels are more damaging to ecosystems than activated charcoal (Figure 5F). In fact, LCA analysis showed that changing the protein type from whey to pea and potato protein resulted in a 41% and 53% reduction in ecosystem damage, respectively, and less damage to the ecosystem than activated carbon. Taken together, these results highlight the economic viability and environmental advantages of AF aerogels in terms of separating them from e-waste. 
Figure 5Technical-economic analysis and life cycle assessment of AF aerogel from e-waste4. Conclusions and prospectsThis study demonstrates the successful application of AF aerogel extraction from food side streams, such as whey protein, as a highly efficient and selective adsorbent for the extraction of gold from e-waste. AF aerogels exhibit significant gold adsorption capacity and selectivity compared to other metals present in e-waste, making them promising materials for sustainable mining. In addition, AF aerogels are able to convert gold ions into gold nanoparticles and elemental crystal flakes during the adsorption process. AF aerogel is used to dissolve gold in the e-waste solution of computer motherboards, resulting in high-purity nuggets of approximately 21-22 carats. These findings, along with the life cycle assessment and techno-economic analysis of the process, run on realistic benchmarks, demonstrate the potential of AF aerogel as a new environmentally friendly method to address the growing demand from e-waste, contributing to circular economy principles and sustainable resource management. Literature Links: