Preparation Of Silk Fibroin/cellulose Composite Aerogel And Its Ion Adsorption Performance

As the degree of industrialization continues to advance,the environmental problems derived from it are constantly warning people.Among them,the treatment of a large number of chemical substances generated by chemical,textile,mining,agriculture,cosmetics,metal plating,papermaking and tanning operations has always been one of the concerns.The heavy metal ions contained in these chemicals cannot be removed by the self-purification of water due to their high toxicity and non-biodegradability.Several commonly used methods for removing heavy metal ions from industrial wastewater include chemical precipitation,membrane filtration,adsorption,coagulation/flocculation,photocatalysis and biological treatment.Studies have shown that adsorption is one of the most effective and easy to handle treatments.Common adsorbent materials can be mainly divided into two categories:synthetic polymers and natural materials.In this experiment,silkworm cocoons and microcrystalline cellulose were selected as raw materials,and novel silk fibroin aerogel,cellulose aerogel and silk fibroin/cellulose composite aerogel were prepared.Further,using Pb(?)and Cu(?)as heavy metal sources,the ion adsorption performance of the above three aerogel materials was studied by using adsorption time,sample,solution concentration and solution pH as a single variable.(1)Preparation of novel silk fibroin aerogel and its ion adsorption performanceTaking silkworm cocoons as raw materials,silk fibroin solution was first obtained by degumming and dissolving.Secondly,a novel silk fibroin aerogel material was prepared by high-speed dispersion and freeze-drying methods,and its ion adsorption performance was further explored.The results of preparation experiments showed that a series of novel silk fibroin aerogel materials with three-dimensional porous structure were prepared with the concentration of silk fibroin solution and dispersion speed as the variables,which were mainly ?-sheet structure and had good structural stability,porosity,swelling ratio and water absorption.Silk fibroin aerogels exhibited high adsorption properties of both Pb(?)and Cu(?),and the adsorption of Pb(?)was higher than that of Cu(?).Samples SFA153 and SFA151 had better Pb(?)adsorption properties and Cu(?)adsorption properties,respectively.An increase in the concentration of the ionic solution or an increase in the pH value of the solution in an acidic environment would raise the amount of ionic adsorption of the SFA sample.(2)Preparation of cellulose aerogel and its ion adsorption performanceThe cellulose aerogel material was prepared by microcrystalline cellulose as raw material via low temperature dissolution and freeze-drying methods,and its ion adsorption performance was further studied.The results showed that a group of cellulose aerogels prepared using dissolved concentration as a single variablea was mainly composed of amorphous structure,with relatively good porosity,high swelling ratio and water absorption.Cellulose aerogel had high adsorption capacity for both Pb(?)and Cu(?),and it was higher for Pb(?).The increase of the solution concentration had a promoting effect on the adsorption performance of the material.In the acidic environment,the increase of the pH value of the solution could provide greater number of free hydroxyl groups for adsorption to promote adsorption.(3)Synthesis of silk fibroin/cellulose composite aerogel and its ion adsorption performanceUsing silkworm cocoons and microcrystalline cellulose as raw materials,silk fibroin/cellulose composite aerogel materials were prepared via low temperature dissolution,high speed dispersion and freeze-drying techniques.The effects of adsorption time,sample,solution concentration and solution pH on ion adsorption performance were investigated.The results showed that silk fibroin/cellulose composite aerogel had rich three-dimensional porous structure and the roughness of the surface of the wall was increased with the increase of silk fibroin solution concentration and dispersion speed.The composite aerogel had a high porosity,and its hydrophilicity,swelling ratio and water absorption were also improved compared with the silk fibroin aerogel material.In the adsorption experiment,it exhibited better ion adsorption adsorption performance than silk fibroin aerogel and cellulose aerogel.In summary,silk fibroin/cellulose composite aerogel had high ion adsorption performance and could regulate its morphology by the concentration ratio of two materials and high-speed dispersion rotation speed,which was expected to become a new type of adsorbent materials for using in fields such as water treatment.