The Influence Of Four Ions On The Hydrolysis Behavior Of Aluminum Salt Water And The Structure Analysis And Flocculation Performance Evaluation Of Crystal Products

The morphology chemistry of aluminum salt hydrolysis products has become the focus and difficulty of many disciplines such as environmental chemistry,biochemistry,water treatment chemistry,catalytic chemistry,soil chemistry,and geochemistry.However,due to the complicated and changeable hydrolysis process of aluminum（Ⅲ）in aqueous solution and the severe shortage of information about the morphological structure of polyaluminum,so far it has not been possible to reach a unified consensus on how the monomer aluminum in the solution evolves into the hydrolysis mechanism of aluminum hydroxide.The preparation of solid pure crystalline polyaluminum morphology and structural analysis of its crystals to obtain the exact polyaluminum structure is of great significance for perfecting the aluminum salt solution polymerization theory and the polyaluminum morphological transformation evolution model.In this paper,an aqueous solution of P-Al₁₃ and ScCl₃·6H₂O was reacted in an oil bath at 150℃.The product was successfully analyzed by combining three-dimensional electron diffraction method（3D ED）with APEX-Ⅲsoftware analysis of crystal structure to analyze the product[Al₁₀（OH）₂₄（H₂O）₄]Cl₆and its crystal structure.3D ED can automatically drive the transmission electron microscope（TEM）sample stage to rotate along single-axis,the position and intensity information of the spots on the electron diffraction photographs of the selected area was automatically collected to reconstruct the reciprocal point array space and achieve indexing.After data reduction and absorption correction,a large number of three-dimensional electron diffraction spots’diffraction index and intensity information are obtained,and then the data is analyzed using APEX-Ⅲsoftware for crystal structure analysis to obtain crystal information and crystal structure.The structure analysis shows that the crystal is crystallized in the monoclinic system,P2₁/c space group,and its unit cell parameters:a=7.900?,b=17.900?,c=11.766?,α=90.0°,β=115.43°,γ=90.0°,V=1502.62（60）?³,D_c=2.12778 g/cm³,Z=2.This structure is that 7 AlO₆octahedrons are connected together to form a seven-aluminum flat plate.The periphery of the flat plate is connected with 2 AlO₆octahedrons and 4AlO₅polyhedrons by sharing O atoms,and polyhedrons are connected to each other.The seven aluminum plates continue to circulate and reciprocate,forming a three-dimensional infinitely extending inorganic polycation network framework material.This material also has a larger pore structure.The analysis of this structure enriches the structure of infinitely extending polyaluminum compounds,which is of great significance for in-depth understanding of the formation law of infinitely extending polyaluminum structures,and at the same time promotes the derivation of the mechanism of hydrolysis and polymerization of aluminum species.In this paper,the four ions Ga³⁺,Ge⁴⁺,Sc³⁺ and Cr³⁺ are introduced into the P-Al₁₃solution and the spontaneous hydrolysis reaction process to explore the influence of the four ions Ga³⁺,Ge⁴⁺,Sc³⁺and Cr³⁺on the hydrolysis of aluminum salt and the formation of polyaluminum compounds.The introduction of Ga³⁺can promote the transformation of P-Al₁₃from the Planner type to the Keggin type.Ga can replace the Al in the Keggin type central AlO₄tetrahedron to form a Ga O₄tetrahedron,and the substitution in the water system will generate[Ga O₄Al₁₂（OH）₂₄（H₂O）₁₂]Cl₇·10H₂O or others（unobtained structure）,[Ga O₄Al₁₂（OH）₂₄（H₂O）₁₂]Cl₇·10.5H₂O is formed when substituted in methanol system,both crystals are soluble in water;the introduction of Ge⁴⁺can change the aluminum salt.The polymerization law of polyaluminum compounds is formed during the hydrolysis process,which affects the phase diagram distribution of the phase and is not easy to enter the polyaluminum structure;The introduction of Sc³⁺has obtained the structure of the three-dimensional infinite inorganic cation network framework material[Al₁₀（OH）₂₄（H₂O）₄]Cl₆,and the structure of Al₂₉is expected to be resolved by the three-dimensional electron diffraction method;the introduction of Cr³⁺has discovered a new phase,and it is hoped that the new structure can be analyzed by the three-dimensional electron diffraction method and new compound.This paper also compares P-Al₁₃and K-GaAl₁₂ with laser diffraction particle size analyzer,turbidity meter,ultraviolet spectrophotometer and other instruments at C(Al³⁺)=10^-4.5,C(Al³⁺)=10^-4.0,C(Al³⁺)=10^-3.5.The flocculation characteristics of simulated water samples to remove humic acid under different dosages.The results show that for humic acid simulated water samples,P-Al₁₃flocculant is better than K-GaAl₁₂flocculant in removal effect,which may be due to the high charge of P-Al₁₃.