Preparation of sodium lignosulfonate adsorption materials and their adsorption properties for Congo red
[Objective]Aminated sodium lignosulfonate(SLS)and covalent organic framework polymer/aminated sodium lignosulfonate composites were prepared with SLS as raw materials,and their adsorption properties for the Congo red(CR)were investigated.[Method]Aminated sodium lignosulfonate(ASLS)was prepared by Mannich reaction of sodium lignosulfonate with formaldehyde and diethylenetriamine.The surface functional groups and morphology of ASLS were characterized by infrared spectroscopy(FTIR)and scanning electron microscopy(SEM).The effects of initial concentration of CR,ASLS dosage,the pH value of the solution,and the adsorption time on the adsorption efficiency of the materials were investigated.The adsorption kinetics and regeneration performance of ASLS were analyzed.The AQ-COF was prepared,and the ASLS,AQ-COF,AQ-COF/ASLS on the adsorption for CR was compared.[Result]FTIR and SEM characterization results showed that sodium lignosulfonate was successfully aminated,and rod-like nanostructures were self-assembled after the combination of ASLS and AQ-COF.ASLS adsorption experiment showed that when the initial concentration of CR was 200 mg·L-1,the dosage of ASLS was 70 mg,and the pH was 1-5,the adsorption rate reached above 95%,and adsorption equilibrium was achieved within 80 minutes.The adsorption process was in line with the quasi second order adsorption kinetics model and Langmuir isotherm adsorption model,and the adsorption process was mainly chemical adsorption.When a small amount of AQ-COF(2 mg)was added to 30 mg ASLS,the adsorption rate of the composite adsorbent could reach more than 80%.[Conclusion]The modified aminated lignin has good adsorption effect on CR and excellent regeneration property,which can be used as an excellent adsorbent for CR.The composite adsorbent prepared by combining covalent organic framework polymer AQ-COF with ASLS can significantly improve the adsorption capacity of ASLS for CR,indicating that covalent organic frame polymers have good application prospects in the adsorption of organic pollutant CR.[Ch,9 fig.2 tab.25 ref.]