The Comparision Of Flocculation Performance Between M-Al₁₃ And K-Al₁₃, The Crystal Structure Of Tridecamertc Polyaluminum Iodide

In various polyaluminum forms, who are the key coagulation patterns remains controversial. Some scholars believe that the crucial form is moderate degree of polymerization'Alb, while Alb and K-Al13 have better correlation, which the content higher means better flocculation performance, so K-Al13 attract much attention. Others deem that polycation's charge is higher, the coagulation performance is better. But the study has not been reported about contrast between "keggin-Al13" with seven positive charge and "flat-Al13" with fifteen positive charge of flocculation performance.In this paper, prepared almost pure crystal chloride M-Al13, and synthesized nearly pure chloride K-Al13 solutions by ultrasound replacement experiment both BaCl2 solution and insoluble K-Al13 sulfate, that of distribution of aluminum species and flocculation performances have been compared.The experiment of distribution of aluminum species shows that this two Al13 specise have equivalent Alb content, from 97.35% of K-Al13 to 90.26% of M-Al13belonging Alb category. Based on the kinetic difference of reactions between Ferron with M-Al13 and K-Al13, k(M-Al13) is larger than k(K-Al13).Many schoolers figure that the faster reacting polymers is Alb1, and the slower reacting polymers is Alb2, so M-Al13 belongs Alb1.Coagulation contrastive experiments indicate that compared to chloride K-Al13, the chloride M-Al13 represent excellent power removing turbidity and broad dose range when the pH values of Kaoline simulated suspending water is 6.5,7.0 and 7.5, especially in the lower dose area, the ability of removing turbidity of chloride M-Al13 is better than chloride K-Al13 apparently. All researches reveal that chloride M-A113 is a high performance flocculation.A novel tridecameric polyaluminum iodide has been obtained in this paper and its crystal structure has been determined by X-ray structure analysis.The structure of polycation is an octahedral AlO6 core is surrounded by a "hexameric ring" through edge-sharing, then six octahedral AlO6 units are suspended onto the peripher of the ring upper and lower alternately by sharing two neighboring corners with an average turn angel of 23.6°entad, that is similar to structure of chloride M-Al13 obtained our laboratory which has a "tortoise-like"sturcture with turnup "forefeet"and "tail". As the structure of polyaluminum iodide's confirmation, furthe has ascertained "flat-Al13"sturcture which is universal in exsistence, and will be bound to add a new member for crystal data-base.