One Step Preparation Of Solid Rare Earth Lanthanum Polymeric Ferric Sulfate High Efficient Flocculant And Its Application

Polyferric sulfate（PFS）was prepared by"one-step"method with industrial green alum as the main raw material.It was modified by lanthanum to prepare rare earth lanthanum polyferric sulfate（La-PFS）.In the experiment,the ratio of raw materials and reaction conditions were optimized by single factor experiment and box Behnken experiment.FT-IR,XRD and SEM were used to characterize the structure of rare earth flocculant,and the synthesis mechanism was analyzed;By comparing the changes of physical and chemical properties and flocculation effect before and after the introduction of rare earth lanthanum,the iron form of flocculant was determined by Fe-Ferron time-by-time complexing colorimetry,and the stability of product was determined by Turbiscan Lab dispersion stability analyze,so as to discuss the advantages and disadvantages and stability of flocculant performance;Through the research on the turbidity removal effect of various kinds of waste water,the use conditions and application scope of the products are preliminarily analyzed,and the economic and social benefits of La-PFS are analyzed.The results show that:1.When the polymerization temperature is 123℃,the molar ratio of La/Fe is 1:105.56,and the molar ratio of OH^-/Fe is 0.19,the turbidity removal rate of La-PFS is 99.41%.The flocculant performance meets the standard（GB-14951-2016）;The product is stable,and the stable time of solid product is more than 6 months.2.The introduction of lanthanum is not only a simple mixture,but also a kind of lanthanum iron polymer.The properties of lanthanum promote the chain structure to strengthen.The product is made of particles by polymerization,which are closely linked to form a network and cross-linked.The particles are integrated into a sponge structure,with a relatively tight texture and a high degree of polymerization.3.The flocculation process of La-PFS showed that the average particle size of flocs increased rapidly with time and the particle aggregation rate accelerated.The kinetic parameterΔTSI of the water with self-made flocculant is 941.95,which is significantly higher than that of the traditionalΔTSI of PFS which is 732.76,indicating that the water has poor stability and is easy to destabilize and precipitate.4.Study on the treatment of papermaking wastewater by La PFS:When the dosage is320 mg·L^-1and the flocculation settling time is 5 min,the turbidity removal rate can reach70%.When the precipitation time is 10 minutes,the removal rate of CODcr and chroma can reach 35%and 32%respectively;The study of La-PFS on the treatment of rainstorm flood:The applicable range of p H is 4-9;When the dosage is 300 mg·L^-1,the flocculation precipitation time is 15 minutes,and the p H value is 6,the turbidity removal rate of rainstorm flood basically reaches the optimal value of 99.34%.