Study On The Adsorption Performance And Application Of New Covalent Organic Polymeric Materials For Ciprofloxacin

With the development of human society,the population is soaring,the drug consumption is increasing,and the problem of global environmental pollution is increasingly serious.Water pollution is an important factor hindering the sustainable development of human economy.Antibiotics,as one of the main components of a new class of pollutants such as pharmaceuticals/personal care products（PPCPs）,have the characteristics of large consumption,wide use,accumulation in the biological body,etc.At the same time,they can interfere with the endocrine system of the human body,thus destroying homeostasis and causing adverse effects,endangering human health.Conventional wastewater treatment process can not effectively remove such pollutants,and advanced oxidation process,which has attracted much attention,is costly.Antibiotic pollutants exist in trace amount in the environment and are easy to generate metabolic intermediates which are toxic to human body in the process of treatment.Adsorption method has unique advantages because of its lower operating cost,higher removal efficiency and no secondary toxic pollutants.Therefore,it is of great significance to develop a new adsorbent to effectively remove antibiotics.In recent years,Covalent Organic Polymers（COPs）have become new materials for environmental remediation,attracting high attention due to their chemical adjustability,high crystallity,adjustable pore structure,large surface area,low density and good stability.Aiming at quinolone antibiotics represented by ciprofloxacin as target pollutants,this paper developed a new type of covalent organic polymer,carried out adsorption research on it,and explored the adsorption behavior and mechanism.As the material is powdery,it is difficult to recover in practical application.Therefore,COPs adsorbent loaded on absorbent cotton was synthesized using absorbent cotton carrier,and stable filler was formed to continuously adsorb ciprofloxacin solution in adsorption bed.The main contents are as follows:Based on the physical and chemical properties and structure of ciprofloxacin,a porous amorphous covalent organic polymer（COP-SO₃H）with benzene ring as skeleton and hydrogen bond as electrostatic action site was designed.1,3,5-benzoylhydrazide（BTCH）,1,4-bis（4-aldehyde phenyl）benzene（TPDA）and 2,5-diaminobenzene sulfonic acid were synthesized by solvothermal method using the synthesis scheme of[C₃+C₂+C₁]and Schiff base reaction.A novel covalent organic polymer COP-SO₃H was synthesized.Then,the physical properties of COP-SO₃H were characterized and analyzed by various characterization methods.The characterization results showed that COP-SO₃H was successfully prepared,and COP-SO₃H was successfully loaded onto the surface of dehydrated cotton to synthesize COP-SO₃H@cotton.The covalent organic polymer COP-SO₃His an amorphous hydrophilic material,which is negative in the p H coverage range of 2～10.Its specific surface area is 39.096 m²·g^-1,the average pore size is 3.827 nm,and the pore distribution is irregular.It has micropore and mesoporous pore structure,which is stable under acid-base conditions and has good thermal stability.The influence factors on the adsorption of ciprofloxacin（CIP）by covalent organic polymer COP-SO₃H were investigated.The results showed that COP-SO₃H had a good adsorption effect on ciprofloxacin.When CIP concentration was 10mg·L^-1,COP-SO₃H quickly adsorbed ciprofloxacin for 4 hours and reached the adsorption equilibrium at 24 hours.The CIP removal rate of COP-SO₃H was more than 90%.The adsorption effect of COP-SO₃H on ciprofloxacin was related to p H.When p H=6,the adsorption effect of COP-SO₃H on CIP was the best.The adsorption force of COP-SO₃H on CIP depends not only on electrostatic force,but also onπ-πEDA,hydrophilic-hydrophobic equilibrium and hydrogen bonding.The adsorption of ciprofloxacin by COP-SO₃H was significantly inhibited by oxy-containing acid roots,and the increase of cation concentration also inhibited the adsorption,but the salt-out effect enhanced the hydrophilic and hydrophobic interaction between COP-SO₃H and CIP,and weakened the influence of cations and anions on the adsorption process.The COP-SO₃H adsorption material has no obvious structural change after five cycles,which proves that it has good stability and economic applicability in practical application.The amphoteric binding sites of sulfonic acid group and amide group in COP-SO₃H lead to strong affinity and selectivity for quinolones.COP-SO₃H@cotton was applied in the adsorption bed for CIP removal research,Thoams model and Yoon-Nelson model were used to fit the COP-SO₃H@cotton adsorption column penetration curve,q₀ andτwere 16.28 mg·g-1 and 299 min,respectively.Based on the experimental results,the adsorption capacity and half-life of the COP-SO₃H@cotton adsorption column are quantitatively analyzed,which provides a reference for the practical application of the COP-SO₃H@cotton adsorption column.The adsorption of ciprofloxacin by COP-SO₃H was investigated by various factors.The results show that the adsorption of ciprofloxacin by COP-SO₃H accords with pseudo-second-order kinetics.Langmuir isotherm model,Temkin isotherm model and thermodynamic calculation results show that CIP uniformly attached to the surface of a single layer belongs to spontaneous endothermic chemisorption.The results of internal ion diffusion model show that the adsorption process can be divided into three stages:external diffusion,internal diffusion and adsorption diffusion equilibrium.The maximum adsorption capacities of COP-SO₃H were 30.37,39.11and 44.96 mg·g^-1 at 10℃,20℃and 30℃,respectively.In conclusion,the adsorption of ciprofloxacin by COP-SO₃H mainly depends on void filling effect,electrostatic interaction,hydrogen bonding,π-πEDA interaction and hydrophilic-hydrophobic equilibrium.