Scalable and Chemical Free Activation Synthesis of High-Performance Microporous Carbon Adsorbents for Nuclear Waste Capture

Radioactive wastes, the byproduct of nuclear energy generation, need to be urgently captured due to their high volatility and well-established adverse effects on human health. Among the radioactive waste adsorbents, conventional activated carbon materials, which are used as industrial adsorbents, nevertheless exhibit low adsorption capacities. On the other hand, MOFs, COFs, and POPs are emerging as new effective adsorbents. However, due to their low production volume and complex manufacturing processes, they remain at the laboratory scale. One of the primary challenges associated with effective adsorption in practical applications is achieving both high processibility and adsorption performance.<br/>Herein, we present an effective activation method for generating a carbon-based pore structure in a scalable and low-cost absorbent. Specifically, compared to conventional activation methods for high porosity, we adopted a chemical-free physical activation method (carbon dioxide utilization), ultimately reaching a high specific surface area and total pore volume than conventional activated carbon. Furthermore, the adsorption capacities of iodine, one of the nuclear wastes, are comparable to those of MOFs, COFs, and POPs but also demonstrate higher adsorption rates.<br/>Our work makes several critical contributions: 1) These fiber types of large-scale sorbents can be used as a sorbent themselves without substrates due to their self-standing characteristics. 2) This processing method proposes a proper way to utilize captured carbon dioxide and even capture nuclear wastes, byproduct of low-carbon energy, for a carbon-neutral society. The nano/microstructure evolution of PAN-based activated carbon fiber during physical activation was investigated, and its correlation with radioactive waste adsorption performances will be discussed in detail.