Synthesis Of Cellulose-based Double Network Hydrogel And Its Adsorption On Copper Ions

Hydrogel is a polymer material with porous network structure,which can be used as an adsorbent to remove heavy metal ions in liquid waste.However,traditional chemical cross-linked hydrogels have such defects as low strength and poor toughness due to the uneven stability of their cross-linked structures,which limit the application of hydrogels.In this paper,In this paper,high-strength double-network hydrogels with pH sensitivity were prepared by the"one-pot method",among which the hydrogel prepared by cellulose and chitosan was used as the first network to improve the mechanical properties of double-network hydrogels,the functional polymer polyacrylamide?PAAM?cross-linked with chemical cross-linking agent was used as the second network.The adsorption test of Cu²⁺on the hydrogel was carried out,and adsorption process and mechanism were analyzed.The main contents and results are as follows:In this paper,ionic liquid was used as a solvent to dissolving cellulose and chitosan,and epichlorohydrin was used as crosslinking agent to form cellulose chitosan?Ce-Cs?hydrogel.The adsorption capacity of Ce-Cs hydrogel to Cu²⁺at different temperatures was tested.The results showed that the adsorption capacity of Ce-Cs hydrogel decreased with the increase of temperature.The adsorption capacity at 15?and 35?were 37.74 mg/g and 31.06 mg/g,respectively.Cellulose?Ce?,chitosan?Cs?and acrylamide?AAM?were used as the main raw materials to prepare banana cellulose-chitosan/polyacrylamide?CE-CS/PAAM?double network hydrogel by“one-pot”method.The structure,mechanical properties,swelling and adsorption properties of the hydrogel were investigated and applied to the adsorption of metal ions in water.The experimental results show that the Ce-Cs/PAAM hydrogel has a three-dimensional porous and double network structure with excellent mechanical strength and toughness.The maximum compressive stress can reach 60 MPa under 90%compressive strain,the swelling degree of the Ce-Cs/PAAM hydrogel is 9.56 mg/mg in water,and it reaches 15.34 mg/mg in the solution of pH12;The result of Ce-Cs/PAAM double network hydrogel adsorption Cu²⁺test indicated that the maximum adsorption capacity Qe was 312.4 mg/g when the initial concentration of Cu²⁺was350 mg/L,pH value was 5.5 and adsorption time t was 90 min.The adsorption process and mechanism of Cu²⁺by Ce-Cs/PAAM double network hydrogel were studied in depth.The adsorption isotherm model analysis showed that the adsorption of Cu²⁺on Ce-Cs/PAAM double network hydrogel accords with the Langmuir model,and the value of n is greater than 1,which means the adsorption of Cu²⁺by hydrogel can not only ensure the effective removal of Cu²⁺,but also facilitate the adsorption separation,namely preferential adsorption.According to the model analysis results of adsorption kinetics,the adsorption of Cu²⁺by Ce-Cs/PAAM double network hydrogel conforms to the quasi-secondary mechanical model,that is,the adsorption rate is controlled by chemical adsorption.