Study On Scaled Continuous Controllable Preparation Method Of Magnetic Nano-adsorbent For Wastewater Treatment

Superparamagnetic nanoparticles have been widely used in wastewater treatment,biological separation,detection,magnetic resonance imaging,targeted therapy and other fields.Magnetic nano-adsorbents,which are easy to recycle quickly and can be reused,are a research hotspot in the field of wastewater treatment in recent years.Although much progress has been made in its types and laboratory preparation methods,the preparation process has difficulty in continuous and amplification,which has become a bottleneck for its scaled application.Based on the new idea of coupling the separation process and the preparation process of magnetic nano-adsorbent,this paper proposes a continuous preparation method that can be easily scaled to capture the magnetic nano-adsorbent generated in the solution continuously and controllable.In this way,the nucleation growth process of the magnetic nano-adsorbent is regulated,thereby achieving the controllable and large-scale continuous preparation of the magnetic nano-adsorbent.?1?Firstly,a continuous synthesis device was designed and constructed.I have investigated the influence of key parameters on the particle size of Fe₃O₄,including temperature,nitrogen flow rate and concentration of NaOH solution.The obtained samples were characterized by FT-IR,XRD,TEM and VSM.Further preparation was carried out on a small pilot-scale device,followed by an adsorption performance test of the nanoparticles.The results show that the designed continuous preparation device can successfully prepare nanoparticles with superparamagnetism.Magnetic nanoparticles with a particle size of 2?10 nm and a saturation magnetization of 40?65 emu/g can be customized by adjusting parameters such as temperature and nitrogen flow rate;and the new method has the same adsorption performance as the magnetic nanoparticles prepared by the traditional batch method.The method has been proved to be feasible by a small pilot scale up to 0.573 kg/h,and the particle size is also controllable.?2?The preparation process of functionalized magnetic nanoparticles has the following problems: two-step,batch and difficult to enlarge.In order to further explore the feasibility of the new method for the continuous preparation of functionalized magnetic nanoparticles in one step,a small pilot scale one-step continuous preparation process was carried out.I have used the magnetic nano-adsorbent modified by sodium alginate as a model to investigate the effects of temperature,nitrogen flow rate,feed flow rate,sodium alginate addition and iron raw material concentration on the preparation process,and clarify the influence law and adjustment interval of each parameter on the synthesis process.I performed TEM,FT-IR,XRD,VSM,TGA characterization on the samples,and finally carried out Congo red adsorption experiments.The result is that the proposed method can successfully control the preparation of superparamagnetic Fe₃O₄/sodium alginate adsorbent in one step,which has a particle size of 6?9 nm and a saturation magnetization of 35?45 emu/g,the preparation scale reached 0.491 kg/h,they show good adsorption properties for Congo red in wastewater.The method was further confirmed to be successfully used in one-step continuous preparation of chitosan and sodium humate-modified magnetic nanoparticles with yields of 0.315 kg/h and 0.430 kg/h,respectively,which proved its versatility and high efficiency.