球状纳米纤维素基/氨基酸复合吸附材料的制备与应用

With the development of industry,a large amount of heavy metal ions are discharged into the environment,causing serious damage to water bodies and natural ecosystems.Cellulose is the main chemical component of forest resources and a renewable biomass resource.Its high-value conversion has been extensively studied.In recent years,spherical nanocellulose has gradually gained attention as a novel nanocellulose with great potential in chemical modification,biomedical,and other fields.The adsorbents composed of spherical nanoparticles exhibit excellent adsorption performance and have been widely studied in recent years.Using spherical nanocellulose could prepare all-biomass cellulose/amino acid spherical nanomaterials with high functional group density for adsorption,medical,catalytic,analytical chemistry,corrosion,and photochromic applications.In this study,corn straw was transformed into spherical nanocellulose with a cellulose II crystal structure by using NaOH/urea/thiourea solvent system via a bottom-up approach.Through sodium periodate oxidation and glutaraldehyde grafting,tri-aldehyde spherical nanocellulose-based adsorbent materials that coude be modified by various of functional groups were successfully prepared.Two representative amino acids were introduced into the pre-modification platform of trialdehyde spherical nanocellulose adsorbent,and two all biomass spherical nanocellulose adsorbents,whose namely cellulose/L-lysine(CTNAP-Lys)and cellulose/L-cysteine(CTNAP-Cys)were effectively prepared.Detailed studies were conducted on the microstructure,chemistry,and crystal structure of two adsorbents,in addition the adsorption mechanisms of CTNAP-Lys for Cr(VI)and CTNAP-Cys for Cu(II)were researched.The results shows that pre-modified platform of spherical nanocellulose adsorbent was successfully prepared,and the surface aldehyde group content up to 1.85±0.07 mmol/g.Two all-biomass spherical nanoadsorbents namely CTNAP-Lys and CTNAP-Cys were prepared,those exhibite two important characteristics,a spherical nanoparticle morphology and cellulose II crystal structure,which significantly enhanced their adsorption performance.The adsorption capacity of CTNAP-Lys adsorbent for Cr(VI)is 361.69 mg/g,and the adsorption mechanism involved three synergistic processes:electrostatic interaction between protonated amino groups and Cr(VI),chelation of amino and carboxyl groups with Cr(VI)/Cr(III),and partial reduction of Cr(VI)to Cr(III)by amino groups.The adsorption capacity of CTNAP-Cys adsorbent for Cu(II)is 252.38 mg/g,and the mechanism involved three synergistic processes:electrostatic interaction between deprotonated thiol and carboxyl groups and Cu(II),chelation of thiol and carboxyl groups with Cu(II)/Cu(I),and partial reduction of Cu(II)to Cu(I)by thiol groups.