Synthesis Of Fe₃o₄/CPAM Composite Magnetic Flocculant

Flocculation is an efficient and widely applied wastewater treatment method.Flocculants play an irreplaceable role in the entire flocculation process.The final flocculation performance is usually deter mined by the choice of flocculants.Up to now,coagulation-flocculationdepend on gravity deposition to achieve solid-liquid separation in treatment process.The separation of traditional flocculants has some disadvantages such as long solid-liquid separation time,high production costs and low removal efficiency,especially when the particle size is reduced to such a nano-scale.A new type of flocculant is required to solve these difficulties.In this paper,a magnetic flocculant is prepared,which had obvious effect in accelerating separation,improving removal efficiency and shorteningsolid-liquid separation time,with the action of the external magnetic field assisted the gravity field.In this paper,theoptimal reaction conditions of preparing Fe₃O₄/CPAM composite magnetic flocculant,and the structure,composition and magnetic properties of Fe₃O₄/CPAM composite magnetic flocculant were analyzed in this study.The magnetic flocculation performance of Fe₃O₄/CPAM composite magnetic flocculant was studied.Specific research conents and results are as follows:Synthesis of CPAM by inverse emulsion polymerization:In order to make it more convenient to synthesize Fe₃O₄/CPAM composite magnetic flocculant,the effects of monomer concentration,initiator concentration,emulsifier concentration and reaction temperature on molecular weight were studied in synthesis of CPAM.The optimal reaction conditions to produce the CPAM with high molecular weight were obtained at O/W=1.6:1,C_M=25%,HLB=5,C_I=0.8%,C_E=15%,T_r=60°C,t=6 h.Under these reactions,CPAM with the molecular weight reaching up to 2.21×10⁶g·mol^-11 was obtained.Synthesis of Fe₃O₄/CPAM composite magnetic flocculant by inverse emulsion polymerization:On the basis of the optimal polymerization conditions in the previousstudies,the effects of the dosage of Fe₃O₄ nanoparticles,citric acid and gelatin on the synthesis of Fe₃O₄/CPAM composite magnetic flocculant were optimized by orthogonal experiment.The dosage of Fe₃O₄ nanoparticles had the greatesteffect on the removal rate in experiment,then followed bythe dosage of gelatin but the dosage of citric acid had the less effect.When the dosage of Fe₃O₄nanoparticles was 9%,the dosage of gelatin was 3%,the dosage of citric acid was 2%,the Fe₃O₄/CPAM composite magnetic flocculant with the maximum removal rate of90.31%of reactive red dye X-3B was obtained.The characterization of Fe₃O₄/CPAM composite magnetic flocculant:The structure,composition and magnetic properties of Fe₃O₄/CPAM composite magnetic flocculant were analyzed in this study.The Fe₃O₄/CPAM composite magnetic flocculant had core-shell structures,with the particle diameter size of Fe₃O₄/CPAM magnetic flocculant was about 10-15 nm.The FT-IR spectrums showed that Fe₃O₄nanoparticles was successfully coated with CPAM,and the Fe₃O₄/CPAM composite magnetic flocculant had a good magnetic response.The magnetic flocculation performance of Fe₃O₄/CPAM composite magnetic flocculant:The Fe₃O₄/CPAM composite magnetic flocculant synthesized by inverse emulsion polymerization had a good effect on the removal of dyes and turbidity.At the time of 5 min,the removal rate was improved to a maximum value of 90.31%by using the Fe₃O₄/CPAM composite magnetic flocculant to treat reactive red dye X-3B.At the time of 3 min,the turbidity removal rate was improved to a maximum value of99.99%by using the Fe₃O₄/CPAM composite magnetic flocculant to treat diatomite suspensions.Compared with CPAM,with the action of the external magnetic field assisted the gravity field,the Fe₃O₄/CPAM composite magnetic flocculant had obvious effect in accelerating separation,improving removal efficiency and shortening solid-liquid separation time.