Preparation Of Polyiron-based Flocculant By Bmed Reactor And Its Safety Analysis

In recent years,with the continuous development of chemical technology,water treatment technology is also in rapid progress.As an inorganic polymer flocculant,polyferric based flocculant has been widely used,but its alkalinity and safe preparation have always been the factors restricting its application.In this project,the application of bipolar membrane electrodialysis technology was extended to the level of chemical reactor.Based on the process characteristics of electrodialysis,a process of preparing polymeric ferric sulfate by coupling electrodialysis and bipolar membrane electrodialysis was designed,which improves the efficiency and safety of the preparation process of polymeric ferric sulfate flocculant.The main research contents are as follows:（1）The purification solution containing high concentration of Fe²⁺and Cl O₃^-was prepared by electrodialysis.Fe SO₄·7H₂O and KCl O₃of certain concentration were added into the feed tank respectively.The change of voltage drop,current efficiency,energy consumption and purification effect were investigated by changing current density and feed concentration,The results show that the best experimental conditions were the current density of 20m A/cm²,the feed concentration of Fe SO₄·7H₂O and KCl O₃of 4.2mol/L and0.7mol/L respectively.（2）Bipolar membrane electrodialysis was used to produce concentrated and purified solution prepared in H⁺acidizing electrodialysis process,so as to promote the oxidation of Fe²⁺to Fe³⁺.Then,OH^-dissociation on bipolar membrane was hydrolyzed and polymerized with Fe³⁺to form liquid polymeric ferric sulfate flocculant.The effects of current density,feed flow rate and sulfuric acid addition on voltage drop,p H value in acid chamber,energy consumption and quality and performance of liquid PFS flocculant were studied.The microstructure and morphology of solid products were characterized and analyzed by SEM,XRD and FT-IR.The results showed that when the current density was 20m/cm²,the feed flow rate was 0.2L/min,and the acid dosage was 0.100mol/L,the turbidity removal ability of the liquid PFS flocculant is the strongest,and the energy consumption in the preparation process was lower,and other indicators of the product were also in the range of first-class indicators.（3）Firstly,MIL-53（Fe）was prepared by hydrothermal solvent method.Then,the self-made MIL-53（Fe）was added into the sulfonated polyphenylene oxide by ultrasonic spraying technology to prepare the modified bipolar membrane.The surface morphology of the modified bipolar membrane was tested by SEM,FT-IR and I-V curve.The experimental results showed that different spraying amount and different MIL-53（Fe）have certain effects on the electrical properties of the films.（4）The modified bipolar membrane was used in the experiment of preparing polymeric ferric sulfate flocculant by bipolar membrane electrodialysis.The effects of spraying amount and addition amount of MIL-53（Fe）on the process of bipolar membrane electrodialysis were tested,and the quality and microstructure of the prepared polymeric ferric sulfate flocculant were characterized and analyzed.The results show that when the spraying amount is 4 unit and the addition amount of MIL-53（Fe）is 7%,the performance of the modified film was the best,and the energy consumption can be reduced by about 10%.