Preparation Of Dopamine Modified Hollow Polymer Particles And Their Adsorption Performance For Antibiotic

Owing to increasing awareness of environmental protection,the treatment of antibiotic wastewater has attracted wide attentions,and the adsorption process is currently considered to be one of the most effective methods.However,the conventional adsorbents have the disadvantages of complex preparation procedures,low adsorption performance and difficult in regeneration.The development of high-performance adsorbent that has fast adsorption rate,high adsorption capacity and excellent regeneration ability has become an urgent problem to be solved.In this work,a novel kind of polydopamine-modified hollow polymer particles(HPP-PDA)have been successfully designed and prepared based on self-stabilized precipitation polymerization,which can be used for the removal of antibiotic.Due to the synergistic effect of carboxylate groups and polydopamine layer,the HPP-PDA showed excellent adsorption performances for norfloxacin.The main contents are divided into the following four parts1.Anhydride functionalized hollow polymer particles(HPPs)with cross-linked shell layer were synthesized by self-stabilized precipitation polymerization.These HPPs were further modified with ethylenediamine,leading to the formation of various ammonium-functionalized hollow polymer particles(HPP-NH3+).The effects of crosslinking degree on the adsorption performance of HPP-NH3+were investigated in detail.The experimental results indicated that the adsorption rate and capacity increased dramatically with decreasing cross-linking degree of the shell layer.HPPs with a reasonable cross-linking degree were chosen for the preparation of high-performance adsorbent via chemical modification process.2.Subsequently,dopamine was used for the modification of these HPPs,and a series of HPP-PDA were successfully prepared.The chemical composition,surface morphology and specific surface area of HPP-PDA were characterized in detail by FT-IR,XPS,SEM and TEM to confirm the formation of PDA layer on the surface of the HPPs.The effect of dopamine concentration,modification time and temperature on the composition,morphology and specific surface area of the HPP-PDA were discussed systematically.3.Norfloxacin(NOR)was selected as the model antibiotic to study the effects of preparation conditions,including dopamine concentration,reaction time temperature,on the adsorption capacity of the as-prepared HPP-PDA.The experimental results showed that the adsorption capacity(qmax)of HPP-PDA decreased gradually with increasing concentration of dopamine.With the prolonging of reaction time,the qmax of HPP-PDA showed a trend of increasing firstly and then decreasing gradually and slightly.As the reaction temperature increased,the qmax of HPP-PDA increased accordingly.Furthermore,the influences of initial concentration of NOR,pH value of the solution and contact time on the adsorption performance were also investigated.The experimental result demonstrated that the adsorption process followed the Langmuir thermodynamic model and the pseudo-second-order kinetic model,and the maximum adsorption capacity is 498 mg/g.Due to the presence of pH-sensitive groups such as carboxyl groups,catechol and amine groups,the HPP-PDA exhibited a dramatically pH-responsive qe.4.Regeneration and reuse of HPP-PDA was investigated by adjusting the pH value of the solution.Experiment results indicated that NOR-adsorbed HPP-PDA can be facilely desorbed under mild condition of pH=10.After five adsorption-desorption cycles,the desorption efficiency of NOR was still higher than 88%,which indicated that HPP-PDA had excellent cycle regeneration performance.