The Preparation, Characteristic Of Soft-Microreactor And Its Application In Wastewater Treatment

The toxic organic pollutants with lower concentration levels in wastewater, e.g.pesticide,dye,chlorine and hydroxybenzene compound,which may induce aberrance,cancer and female changes for propagation,will have potential harm to human body.The macroscopical reaction system still can not deal with pollutants in lower concentration until now.However,microreactor as micrometer-scale processing units in chemical reaction systems will provide a brand-new way for lower concentration wastewater treatment.The main objective of this thesis is to research a new dye wastewater treatment method which combines soft-microreactor(hollow polyelectrolyte microcapsules)and(like)-Fenton system.In this thesis,the preparation of melamine formaldehyde(MF)template is investigated.The MF particles which were prepared by dispersion polymerization,presented a state of monodisperse with diameter controlling in 1-10μm.The prepared MF particles provided high quality template for the subsequent preparation of hollow polyelectrolyte microcapsules.Then,the following research is based on polyelectrolyte microcapsules that were constructed by using melamine formaldehyde(MF)as template and using sodium alginate(ALG)and chitosan(CHI)as building blocks with the LBL self-assembly technique.The as-prepared polyelectrolyte microcapsules (ALG/CHI)with 5-7μm in diameter and several decade nanometer of the wall thickness first possessed good stability and permeability,and then non-biodegradable dye pollutants,e.g.rhodamine B(RhB)and fluorescein (Flu),from waste water could be accumulated in the interior of the as-prepared hollow microcapsules via the aggregation of permeable pollutants and/or the electrostatic drive force of the wall interior.Further,the photooxidative degradation of the accumulated dyes was examined in the presence of homogeneous Fenton system(Fe³⁺,H₂O₂)under visible radiation.The accumulated dyes were rapidly degraded.The assembled microcapsules maintain their intact spherical shape throughout the first photoreaction process, then the recycling degradation experiment can continue.In this thesis,the loading behavior of photocatalytic active component on the polyelectrolyte microcapsules and the subsequent process of accumulation and degradation have also been investigated.The photocatalytic active component Fe³⁺could load on the wall of microcapsules via the LBL self-assembly technique,and then dye pollutants,e.g.rhodamine B(RhB), methylene blue(MB)and acridine orange(AO),from waste water could be accumulated in the interior of the as-prepared Fe-immobilized hollow microcapsules(Fe/ALG/CHI).Further,the photooxidative degradation of the accumulated dyes was examined in the presence of heterogeneous like-Fenton system(loading Fe,H₂O₂)under visible radiation.The accumulated dyes were rapidly degraded.More importantly,the photooxidative reaction occurring in the Fe-immobilized microcapsules can be performed at a wide range of pH from acid to neutral media.The mechanism of the light-activated reaction process has also been studied and the results show that the photoreaction taking place in confined microshells in acid medium proceeds mainly through·OH radicals,and the·OOH/O₂·^- radicals in neutral medium.