Research On The Preparation Of Magnetic Flocculants And The Flocculation

With the development of industry, the discharge amount of the wastewater was larger and larger. A large amount of wastewater entered water bodies, formed the pollution. There are many treatments of getting rid of wastewater, but their effects were limited. Nowadays, to develop high-efficient and practical products became more and more important on water pollution. This paper advanced a new program of dealing with wastewater by making full use of the advantages of HGMS which belonged to physical method and flocculation belonged to chemical method. And study on the treatment effect on wastewater.This study was conduced in two parts. In part 1, The first aim at the preparation of two magnetic flocculants that PSAC and PSAFC coating the surface of SiO₂/γ-Fe₂O₃-SiO₂ which acts as magnetic vector, and studying on the best preparation conditions of this two magnetic flocculants.The part 2 aims at the flocculation effects of the magnetic flocculants mentioned above, and discussed different effects on flocculation. The optimal technological condition of the PSAC magnetic flocculants of inorganic particle was: the initial pH is 3.5; n_Si:n_Al=6:1; the dosage of the magnetic flocculants is 220 mg·L^-1; reaction time is 6 min. The optimal technological condition of the PSAFC magnetic flocculants of inorganic particle was: n_Al:n_Fe=3:1; n_Al:n_Si=5:1; the initial pH is 3.0; the dosage of the magnetic flocculants is 210 mg·L^-1; reaction time is 5min. Meanwhile, this papers has used orthogonal design to find the relationship between primary and secondary factors for the magnetic flocculants of PSAC and PSAFC, the result was: pH>(n_Si:n_Al)>dosage >reaction time; (n_Al:n_Fe)>(n_Al:n_Si)>pH>dosage.The third part aims at the effects of the different factors(the total density of Al, temperature, B and ratio of adding alkaline matter)on preparation of Al₁₃, and the effects of the three factors (pH, time and temperature) on the flocculation effect of the magnetic flocculants under magnetic environment and environment without magnetic.The experimental results demonstrated the best condition of preparation for Al₁₃ was: the total concentration of Al is not more than 10^-2 mol·L^-1; the bath temperature is 85℃; the ratio of OH/Al is 2.5; the rate of dropwise add for NaOH is not more than 2 mL·min^-1; The mixing speed is 120 r/min. The best condition of flocculation was: the initial pH is 8.0; the dosage of the magnetic flocculants is 80 mg/L; the bath temperature is 25℃; the first mix is 1 min with 120 r/min, then the second mix is 4 min with 40 r/min, the ratio of elimination for feculence degree is at least 80%. By comparing the flocculation effect of the magnetic flocculants under magnetic environment and environment without magnetic, we can find that the flocculation effect of the magnetic flocculants under magnetic is better than that under environment without magnetic.We can find through the test contrast that the flocculation effects of PSAC magnetic flocculant is the best.These results represent a general phenomenon because the magnetic flocculants mentioned above are representative.