Macro-preparation,Performance And Continuous Recovery Of Superparamagnetic Nanomaterials For Congo Red Wastewater Treatment

Superparamagnetic nanomaterials have outstanding advantages such as high adsorption efficiency and easy recovery by magnetic field.They have wide applications in the field of wastewater treatment and show attractive prospects.Although the laboratory preparation of superparamagnetic nanomaterials has matured at present,there are still two outstanding bottleneck problems in the large-scale application of wastewater in wastewater treatment:the large-scale preparation of the material and the large-scale recovery from wastewater.In order to solve these large-scale application problems,this paper uses dye wastewater as a model,based on the long-term accumulation of the gas-assisted low-gradient magnetic separation recovery method and continuous preparation method in the early stage of the research group,a small-scale pilot-scale superparamagnetic nanomaterials step The continuous preparation and large-scale continuous recovery of these nano-materials from wastewater are intended to provide a demonstration for the large-scale application of this material in wastewater treatment and lay a solid foundation for its industrial application.（1）First,based on the idea of preparation while separation,a large-scale preparation method was constructed and a small-scale pilot plant with continuous controllable preparation was built.The main parameters temperature,nitrogen flow rate,feed rate of Fe source,Fe²⁺concentration,carboxymethyl were investigated The effect of sodium cellulose concentration on the continuous preparation process.The boundary conditions of the continuous preparation process are clarified.Three kinds of superparamagnetic nanoparticles have been successfully prepared,and the preparation scale can reach 1.06-2.92 Kg/h.The prepared magnetic particle samples were characterized by TEM,XRD,FT-IR,VSM,TG,etc.The results show that the prepared magnetic particles have good dispersibility,high purity,narrow particle size distribution,and average particle size of about 8 nm,which is excellent Superparamagnetic,the magnetic saturation strength can reach 56 emu/g,and the modification amount of carboxymethyl cellulose is about 5%.（2）The adsorption properties of the prepared CMC-Fe₃O₄ material for Congo red dye were further studied,and the influence of the main factors such as the amount of magnetic particles,initial concentration of Congo red,initial p H,ion concentration,and adsorption time on the adsorption performance of magnetic particles was investigated.p H and ion concentration have the greatest influence on the adsorption performance.The thermodynamic model and kinetic model were fitted to the adsorption data.The fitting results showed that the adsorption behavior was more in line with the Langmuir isotherm adsorption model（R²>0.99）and quasi-second-order kinetic model（R²>0.99）,and the maximum saturated adsorption capacity was 609.76mg/g,the initial adsorption rate is extremely fast,and basically reaches equilibrium after shaking adsorption for 2 h.A cycle adsorption experiment was carried out,and the adsorption performance remained stable after 6 cycles of use.（3）Finally,in order to achieve continuous and efficient recovery of CMC-Fe₃O₄nanoparticles adsorbing dyes in wastewater,a small continuous gas-assisted low-gradient magnetic separation was built.Based on the determination of the steady-state time corresponding to the different feed liquid feed flow rates,the effect of the main parameters on the recovery process of superparamagnetic nanoparticles is described.Optimized operating conditions:p H=7,magnetic particle concentration=0.5 g/L,Congo red concentration=200 ppm,adsorption time 4 h,gas velocity=500 m L/min,magnetic roller speed=32 rpm,Na Cl concentration=0.5mol/L.The concentration is 500 mg/L of raw material liquid.When the recovery rate of magnetic particles reaches 94.38%,the continuous processing capacity of the device can reach 12 L/h.