| For treatment of heavy metal pollution in natural water, anenvironmental friendly adsorbent, of high removal rate and high adsorptioncapacity and can be reused, is needed. In this study, a low-cost andenvironmentally friendly raw material of chitosan is chosen as anadsorbent, and nanosized Fe3O4@SiO2@Chitosan (magnet chitosannanoparticles, MCNPs for short) is synthesized through hydrothermaloxidation and sol-gel methods. This new adsorbent can adsorb Cd2+andCu2+extremely rapidly (within2min), and has a high adsorption capacity(above110.0and89.1mg/g, respectively). Besides, the adsorbed MCNPscan easily regenerate by simple acid pickling, and the adsorption capacityis still92.2and79.8mg/g after three times of regeneration, which standsfor an fine recycling stability. The MCNPs is also stable after a bath of60℃(decreased1.9and1.4mg/g, respectively). Furthermore, with a saturationmagnetization of13.3emu/g and a coercivity of only1.4mT, this newmaterial can be rapidly trapped by magnets, and will not aggregate in water.On the basis above, MCNPs is an recyclable and renewable material for heavy metal pollution emergency treatment in natural water.When the magnetic field height is H,the force analysis of magnet particles in turbid liquid—whose flow is Q,cross-sectional area is A, density is p0,viscosity is μ,and the efficient cross-sectional area of suspended particles of which is S—is given as follow: π/6(ρ-ρ0)gd3+KSBH-3πμvd=m dv/dt.Further,to trap all the magnetic particles,a magnetic field whose length is L≥2.38Q、AKS√∫H O m/f(h)g(h) dh is required.In this formula,f(h)is the function of magnetic field intensity, and it is related with the characteristic of the magnet field;g(h)is the function of magnetization,and it is related with the magnetic field intensity and the characteristic of magnetic particles.Moreover, the trap efficiency equation given as η=2Q/1whKS√∫H O m/f(h)g(h)dh... |
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