SuFEx Reaction Modified Silk Fibroin Aerogel For Pollutants Adsorption

With the progress of various industries,the danger of low concentration pollutants in water bodies is becoming more and more obvious.Low-concentration pollutants in water bodies mainly include various industrial dyes,heavy metal ions,various toxic and harmful organic substances.Although the concentration is low,it is difficult to degrade and result in long-term pollution,through the role of enrichment threatens human life and health,causing cancer,teratogenic,mutagenic and other human harm.The removal of such low-concentration pollutants has become a new challenge for environmental management technology.Adsorption method is to build up the interaction between pollutants and adsorbent surface by some specific driving force,so that the pollutants are enriched on the adsorbent surface and removed.With the advantages of high removal efficiency,regeneration,simple operation and low price,adsorption has become a widespread and efficient pollutant removal method.However,the general adsorbent materials on the market still have some problems:（1）the stability of the adsorbent is poor;（2）a single type of pollutant cannot deal with complex pollutants;（3）the recycling efficiency of adsorbent is low and their recovery is difficult;（4）the adsorbent will cause secondary pollution to the environment.Therefore,it is of great importance to prepare stable,easily recyclable and environmentally friendly and multifunctional adsorbent materials for the treatment of pollutants.Based on the above problems,we selected natural biomass materials that are non-toxic and non-hazardous to the environment for various post-modifications and then prepared into aerogels for the adsorption treatment of pollutants.That is,the silk protein was modified by SuFEx reaction to make it specific for the adsorption of different pollutants,including anionic dyes and some harmful anions,heavy metal ions,and organic iodine.This type of aerogel not only achieves the adsorption treatment of different pollutants,but also the morphology of the aerogel facilitates the recycling.The paper focuses on the following works.（1）Modification of the filamentous protein by SuFEx click reaction,which introduced quaternary ammonium salts on the filamentous protein.The modified silk protein was then reacted with tetraethyl orthosilicate（TEOS）to form a silica-based bioaerogel.The aerogel showed a maximum adsorption capacity of 845.92 mg g^-1 for anionic dyes such as methyl orange in water,and also had good adsorption performance for some anionic pollutants such as chromate manganate and phosphate.The aerogel has a good circulation efficiency along with some adsorption resistance to interference.In addition,the material has a sterilization capacity of more than 99.5%against bacteria such as E.coli and S.aureus in the water column.Therefore,the material has good application potential for treating integrated wastewater.（2）The silk protein was modified by SuFEx click reaction,and an iminodiacetic acid fragment was introduced on the silk protein,and then the modified silk protein was reacted with glutaraldehyde to form a composite silk aerogel.The maximum adsorption capacities of the aerogel for heavy metal ion contaminants such as Pb²⁺,Hg²⁺,Cr³⁺and Cd²⁺were 1.399mmol g^-1,1.520 mmol g^-1,1.631 mmol g^-1 and 1.290 mmol g^-1,respectively.In addition to the improved mechanical strength,the material also had better recycling efficiency.（3）The filamentous protein was modified by SuFEx click reaction to increase the nitrogen content of the filamentous protein.The modified silk protein was then reacted with2,2-bipyridine-5,5dialdehyde to form a composite aerogel.The aerogel effectively increases the surface area of the material while increasing the number of reaction sites.The presence of a large number of pyridine active sites gives the material good adsorption properties for iodine,which can be used for the adsorption of radioactive iodine.The maximum adsorption capacity for iodomethane is 724.3 mg g^-1 and the maximum adsorption capacity for iodine monomers is 347.8 mg g^-1 In addition,the material has good stability,heat resistance and high recyclability...