Preparation And Water Treatment Performance Of Covalent Organic Framework Composite Materials

The industrialized society’s swift and unceasing growth,coupled with the population’s continual expansion,has made water contamination and lack of supply a pressing issue.Organic pollutants and heavy metal contamination of natural water sources have caused grave harm to the environment and human health.Consequently,it is essential to create and construct new materials for water treatment.A novel porous material,Covalent Organic Framework（COF）,boasts regular channels,a designable pore structure,and a high specific surface area.This material has great potential for water treatment applications.This paper investigates two aspects,based on the issues presented above,as follows.（1）Taking natural wood as raw material,after oxidation modification,COF is grown in situ to prepare Tp Pa-wood.Based on the size screening effect and electrostatic interaction of Tp Pa COF layer,organic pollutants in water can be filtered and removed.The overall hydrophilicity of the material can provide good water flux.The filtration experiment shows that Tp Pa-wood can effectively remove organic pollutants including dye molecules and drug molecules,and the removal efficiency of cationic dye methylene blue can reach 98.9%under the optimal filtration conditions.The material can maintain efficient removal under wide water flow rate(60-900L·m^-2·h^-1),p H（3-11）and temperature conditions.After 48 hours of long-term use and six cycles of regeneration,the removal performance has not significantly decreased.（2）With air-spinned nanofibers as the carrier,COF is grown on its surface by solvothermal method to prepare PAN/COF-SH.The adsorption of Hg²⁺by PAN/COF-SH,which is a chemical adsorption dominated by monolayer adsorption and can reach a capacity of 195.2 mg/g,is demonstrated by an experiment.This conforms to the quasi-second-order kinetic model and Langmuir isotherm model,due to the coordination of sulfhydryl groups on COF-SH with heavy metal ions and the high specific surface area of the material.Thus,the adsorption and removal of heavy metal ions in water can be achieved.Under acidic and alkaline conditions,adsorption performance will be affected by protonation and competitive complexation.The adsorption capacity of Hg²⁺increases with the increase of temperature.The material’s adsorption and desorption performance has remained satisfactory,despite six cycles of regeneration.