Study On The Kinetics Of Isotropic Flocculation In Magnetic Field

Flocculation is an important process in the water treatment system.And flocculants are a key in achieving high flocculation efficiency in the aggregation process.In recent years,magnetic flocculants have been widely used in various fields.Although magnetic flocculants are widely used,their kinetics under the synergistic action of gravity and magnetic force are rarely studied.Published studies have focused on the flocculation behavior of conventional flocculants in gravitational fields.Therefore,the study of the isotropic flocculation kinetics in magnetic field is of great significance to understand the mechanism of magnetic flocculation and the solid-liquid separation process.In this paper,magnetic cationic polyacrylamide?MCPAM?was selected as the flocculant,and the diatomite suspension was used as the experimental object to study the flocculation kinetics under the synergistic action of magnetic and gravitational fields.The density of flocs was estimated by the determination of floc settlement velocity and image analysis.The frequency distribution of floc size was measured by the Malvern Mastersizer instrument.The kinetic constants for particle collisions and aggregation were calculated based on the bimolecular reaction model.Additionally,the flocculation rate equation of flocs was constructed under the synergistic action of magnetic and gravitational fields.It was found in the performance experiment that under the synergistic action of magnetic field and gravity field,the supernatant transmittance of the diatomite suspension treated by magnetic flocculant was higher than that of the conventional flocculant,and the flocculation speed was faster than that of the conventional flocculant.In the flocculation kinetic experiments,it was found that under the synergistic effect of the magnetic field and the gravity field,the magnetic field strength has an important effect on the floc formation process.The kinetic constant k and the floc density increased to 25.81×10^-11s^-1and 10–252 kg?m^-3,respectively.The size of magnetic floc increases faster than conventional floc and has a higher growth rate.Magnetic flocs attract each other under the synergistic action of magnetic field and gravity field,which significantly improves the collision frequency and collision efficiency between magnetic flocs.The above reason was that the magnetic flocculants have better effect in flocculation than conventional flocculants.On this basis,the flocculation rate equation,???,which under the synergistic effect of the gravity field and the magnetic field was obtained.