Designed Synthesis Of Biomimetic Multifunctional Composites For Degradation Model

With the rapid rising of manufacture ability all around the world,the improving water treatment technology of factories has been paid great attention recently,（e.g.waste dyes treatment and waste antibiotics treatment）.Herein,we reported a green biomimetic multifunctional hollow polydopamine（PDA）-based composites which would be modified by in-situ reduce Ag precursor in the next step.The materials could efficiently remove dyes and antibiotics.Firstly,in-situ embedding of Fe₃O₄ nanoparticles and formation of PDA shell were achieved in a single system employing carboxylic-capped polystyrene（PS-COOH）spheres as hard template,which can be selectively dissolved by tetrahydrofuran.The prepared hollow PDA-based composites（Fe₃O₄@PDA）was applied to efficient removal of antibiotics.Then,Ag nanoparticles were anchored on PDA surface via in situ reduction by PDA layers,leading to multifunctional hollow Ag-based PDA composite,i.e.Fe₃O₄@PDA@Ag.The modified composites could efficiently catalyze the degradation of 4-nitrophenol（4-NP）and Rhodamine B（RhB）with NaBH4 as a reducing agent.In the section one,we reported a multifunctional hollow polydopamine（PDA）-based composites（Fe₃O₄@PDA）as a potential sorbent for tetracycline（TC）removal,In contrast to non-hollow counterpart of PS@Fe₃O₄@PDA,the designed Fe₃O₄@PDA hollow spheres exhibited much enhanced adsorption performance in removing TC at pH value（2 to 10）.TC molecule can present different ionic states by protonation/deprotonation at different pH values.The change of pH values also can affect the surface properties of Fe₃O₄@PDA hollow spheres,e.g.,the amount of hydroxyl moieties on its surfaces.The dominant electrostatic interaction between TC and Fe304@PDA hollow spheres should be repulsion at low pH.The adsorption of TC onto Fe₃O₄@PDA hollow spheres better fitted the pseudo-second-order kinetics model,and the maximum adsorption capacity was 151.7 mg·g^-1 calculated from Langmuir isotherm model at pH = 8.After adsorption,the Fe₃O₄@PDA hollow spheres could be quickly recovered from the TC solution,owing to the room-temperature paramagnetic property endowed by Fe₃O₄ nanoparticles that were pre-loaded into the interior surface of hollow PDA shells.Based on the first section,we reported a multifunctional hollow Ag-based PDA composite（Fe304@PDA@Ag）by in-situ reduce Ag precursor and anchored Ag nanoparticles on the surface of Fe₃O₄@PDA.This newly prepared composite could efficiently catalyze the degradation of 4-nitrophenol and Rhodamine B with NaBH4 as a reducing agent;and the reaction rate constants were calculated using the pseudo-first-order reaction equation.Compared to non-hollow PS@Fe₃O₄/PDA@Ag,the hollow composite exhibited enhanced performance toward both reactions,without significant loss even after ten cycles.This green biomimetic multifunctional hollow Ag-based PDA composites may find potential applications in other domains like medical,construction and manufacturing,etc.