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Solid-Liquid Phase Equilibria For The Conversion Process Of Aluminum Hypophosphite Production

Posted on:2017-09-13Degree:MasterType:Thesis
Country:ChinaCandidate:F J LiuFull Text:PDF
GTID:2321330518993066Subject:Salt science and engineering
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Using conversion reaction(6NaH2PO2+A12(SO4)3=2Al(H2PO2)3+3Na2SO4)to produce aluminum hypophosphite involved the solid-liquid equilibrium researchs of interactive quaternary system(Na+,Al3+//SO42-,H2PO2-H2O)and its sub systems.In this paper we have got solid liquid equilibrium of one binary system(Al(H2PO2)3-H2O),four ternary systems(Al(H2PO2)3-Al2(S04)3-H20,Al(H2PO2)3?NaH2PO2-H2O,NaH2PO2-Na2SO4-H2O Al2(SO4)3-Na2SO4-H2O)and one interactive quaternary system(Na+,Al3+//S042-,H2PO2--H2O)at 298.15K experimentally via the classical isothermal solubility equilibrium method.The results proved that:(1)In Al(H2PO2)3-H2O binary system,balance solid phase was Al(H2PO2)3.From 0 ? to 100 ?,with the increased of temperature,the solubility of aluminum hypophosphite decreased from 1.88%to 0.8%,PH increased from 2 to 2.88.(2)Both of the NaH2PO2-Na2SO4-H2O and Al(H2PO2)3-NaH2PO2-H2O ternary systems belonged to hydrate phase diagram.NaH2PO2-Na2SO4-H2O ternary system belonged to hydrate ? phase diagram,there were three kinds of solid phase:NaH2PO2·H2O,Na2SO4,Na2SO4·10H2O,and the area of NaH2PO2·H2O was very small.Al(H2PO2)3-NaH2PO2-H2O ternary system belonged to hydrate I phase diagram,there were two kinds of solid phase:Al(H2PO2)3,NaH2PO2·H2O.The solubility in water was small,but with the increased of concentration of sodium hypophosphite it increased.Both of the Al2(S04)3-Na2SO4-H20 and Al(H2P02)3-A12(S04)3-H20 ternary systems belonged to the complex systerm,and the double-salt respectively NaAl(SO4)2·12H2O and Al(H2PO2)3·Al2(SO4)3·16H2O.In Al(H2PO2)3-Al2(SO4)3-H2O ternary system,there were two parts of metastable area,three kinds of solid phase:Al(H2PO2)3,Al(H2PO2)3·Al2(SO4)3·16H2O,Al2(SO4)3·16H2O,and the phase region of Al(H2PO2)3·Al2(SO4)3·16H2O was the largest.In Al2(SO4)3-Na2SO4-H2O ternary system,there were three kinds of solid phase:Na2S04·10H2O,Al2(SO4)3·18H2O,NaAl(SO4)2·12H2O.Compared the system of 298.15K and 323.15K,we can find that with the increase of temperature the existence of solid have changed,and the phase region of double-salt have became bigger,and the syetem was easier to appear double-salt.(3)According to Na+,Al3+//SO42-,H2PO2--H2O quaternary system study,it contented five invariant points,eight univariant curves,four solid phase regions.Al(H2PO2)3 and Al(H2PO2)3·Al2(SO4)3·16H2O had a large part of zone.We came the conclusion that we must observe Al(H2PO2)3·Al2(SO4)3·16H2O affected to Al(H2PO2)3.
Keywords/Search Tags:Solid-liquid equilibria, Phase diagram, Aluminum hypophosphite, Sodium hypophosphite, Conversional producing
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