The Synthesis Of New Silicon Metal Salt Composite Flocculants And Applied Research

The thesis belong to Composite Inorganic Polymer Flocculants study in the field of Functional Ecomaterials.By knowing development situation domestically and abroad of coagulant, we have prepared polysilicic acid-polyferric chloride containing boron and zinc (PSFZB) coagulant on the basis of preparing the polysilicic acid and polysilicic acid-polyferric chloride. PSFZB report has not be founded.Technical conditions for preparing polysilicate-metals(PSMS) coagulant and application characteristics were studied.On the basis of Conditions for polymerization of characteristic polymerized silicic acid and PSMS of complex-polymerize and Copolymerization, PSFZB coagulant was prepared with adding zinc sulfate and natrium tetraborate. By investigating the removing rate of turbidity and COD,the results show that the flocculation efficiency is influenced by the concentration of Na₂SiO₃, polymerization time,the Fe / Sk Zn / Si and B / Si malar rate. The optional thchnological conditions are got by experiment action temperature 20³0℃, polymerization time 50 min, C_si=0.5mol/L, Si/Fe=l:0.5, Si/Zn=l:4, B/Si=0.8,ageing reactions time 24 h.Flocculation efficiency of PSFZB were studied.(l)It has good stability effect. The form and flocculation efficiency of PSFZB almost have no more change with the condition of haning it placed at nature.(2)PSFZB dosage is more less than it of PAC and PFC. When dosage of PAC and PFC is 80mg/L, turbidity is no less than 5NTU.but PSFZB dosage 60mg/L, turbidity is just 2NTU.(3)flocculation efficiency have no effect on pH, it flocculation efficiency is almost no chang at pH from 4 to 10. (4)PSFZB crassitude and close-grained floc was observed. Settling velocity of it is 3.32 multiple PAC and 1.98 multiple PFC.(5) it has no evidence response to temperature.from 0℃ to 40℃. And property of turbidity removal in low temperature.Mechanism of flocculation and structure characterizations of PSFZB were studied.By XRD instrument analysis, PSFZB which is composed with B> Fe³⁺ Zn²⁺ and polysilicic acid is amorpHous polymer.By TME,different component have great effect on flocculant Structure.Fe and Si have trend to form Chainlike and Branched structure,Zn and B form anastomosing structure. Structure characterizations of PSFZB is different of common IPF,it has nicer flocculation efficiency and stabilitybecause of its special web-like stuucture.By studying flocculating mechanism it has abilities of charge neutralization absorbing and bridging > network, so it has the best flocculation effect.In order to test practice effect in sewage treatment ,domestic waste > dyeing waste waters heavy metal waste water were to get disposal by using PSFZB. COD removal rate of can attain 95.7%,colority of wastewater could reach to 91.2%.Remove rate of Cr(VI) may get to 66.9%,more 22.1% and 37.8% than its of PAC and PFC.According to the facts, PSFZB is a new-style and high effect coagulation.