Preparation Of Bio-based Molecularly Imprinted Material And Its Removal Of Methylene Blue And Salicylic Acid From Wastewater

Environmental pollution is one of the key issues affecting the development of human society today,and the treatment of water pollution is urgent.The preparation of green materials that efficiently remove toxic pollutants from wastewater has become one of the research focuses in water pollution control.Biomass material is a cheap,non-toxic,and easily decomposable raw material,which is widely used in agriculture and energy,as well as in environmental governance（such as pollutant removal）.Molecular imprinting technology is an excellent selectivity technology for pollutants and has gradually become an important means of wastewater treatment.However,the process of green preparation of materials,high adsorption capacity and selectivity of pollutants are still difficulties and key points.Meanwhile,the combination of molecular imprinting technology and biomass materials for water pollution treatment is also a new research field.In this paper,using biomass materials（sodium lignosulfonate and chitosan）as raw materials to prepare molecularly imprinted polymers with different biological bases through molecular imprinting technology.FT-IR,SEM,EDX,TGA,XPS,etc.were used to analyze the structure of the prepared bio-based molecularly imprinted polymer,focusing on single-factor adsorption,selective adsorption of mixed pollutants,material recycling and mechanism.The research contents and results are as follows:（1）A novel amino TiO₂/sodium lignosulfonate molecularly imprinted polymer（ATMIP）was successfully prepared using methylene blue as a template molecule,sodium lignosulfonate as a functional monomer,and amino TiO₂ as a carrier using molecular imprinting technology to effectively remove methylene blue from wastewater.The BET analysis indicated that ATMIP possessed a mesopore structure with a high specific surface area of 56.3266 m²/g and a good visible light absorption property with a bandgap of 2.90 eV by UV-vis DRS.The adsorption of methylene blue by ATMIP is well fit for the pseudo second order model and Freundlich isotherm model,and the adsorption equilibrium can be reached quickly in 10 minutes.In methylene blue/crystal violet and methylene blue/rhodamine B binary systems,ATMIP has good adsorption capacity and selectivity for methylene blue.The FI-IR analysis before and after adsorption of methylene blue by ATMIP showed that the interaction mechanism of ATMIP and methylene blue was electrostatic interaction,hydrogen bonding andπ-πinteraction.（2）Chitosan-acrylamide molecularly imprinted hydrogel（CAMIH）was successfully prepared using deep eutectic solvents as synthetic solvent to remove salicylic acid from wastewater with high efficiency.The optimal material ratio was determined through response surface methodology（the volume of glutaraldehyde is 1 mL,the molar ratio of acrylamide and chitosan,and ethylene glycol and choline chloride are 1:2 and 4:1,respectively）.The molecular imprinted hydrogel prepared with choline chloride-ethylene glycol as the synthetic solvent has the highest adsorption capacity for salicylic acid,indicating that choline chloride-ethylene glycol is the most suitable eutectic solvent for preparing CAMIH.CAMIH has a mesoporous and irregular sheet like structure,and its BET surface area is 5.2 times that of non-molecularly imprinted materials（CANIH）.The selective adsorption capacity of CAMIH for salicylic acid was higher than that of the CANIH in single system,binary system,and ternary system,respectively.FT-IR and XPS analysis of CAMIH before and after adsorption of salicylic acid showed that the removal of salicylic acid by CAMIH was related to electrostatic attraction and hydrogen bonding.In addition,CAMIH reached the adsorption equilibrium with 20 min and the maximum adsorption capacity of CAMIH for SA was 106.5 mg/g,which was 1.2 times that of CANIH.