Investigation Of Solid-liquid Extraction Of Several Metal Ions With P2O4and Benzoyl Thiourea Derivatives In Molten Paraffin Wax System

In this paper, the extraction of manganese, chromium and palladium withdifferent extractants into molten paraffin wax at60℃was studied. The feasibility ofextraction and separation of manganese and iron with P2O4has been studied. Twokinds of benzoyl thiourea compounds were synthesized to extract palladium inhydrochloric acid solution.Chapter one: The extraction separation method and extraction kinetics method ofmetal ions were reviewed in this chapter. The latest development of extraction formanganese、chromium and palladium has been summarized. The commonly usedsolid-liquid extraction systems were also introduced. At last, the perspective ofsolid-liquid extraction technique in chemistry was described briefly.Chapter two: The extraction behavior of manganese withdi（2-ethylhexyl）phosphoric acid into molten paraffin wax has been studied. Theeffects of pH, P2O4concentration, phase ratio, manganese ion concentration,extraction time, temperature etc. on the extraction percentage were discussed indetails. The extraction reaction was given to be Mn^2＋+H₂A₂=MnA₂+2H⁺. Theextraction thermodynamics data were determined. The study has indicated that theiron ion can be separated from manganese ion in the pH range of0.5to1.2.Chapter three: The extraction thermodynamics and kinetics of chromium withdi（2-ethylhexyl） phosphoric acid into molten paraffin wax has been studied. Theeffects of pH, P2O4concentration, phase ratio, chromium ion concentration, P2O4concentration, extraction time, temperature etc. on the extraction percentage werediscussed in details. The extraction reaction was given to be2Cr³⁺+3H₂A₂=2CrA₃+6H⁺. The empirical rate equations have been derived and therate-controlling steps were discussed. The reaction is inverse second order withrespect to the hydrogen ion and first order for P2O4and Cr³⁺. The rate constant andactivation energy were caculated.Chapter four: Two kinds of of N-aryl-N’-benzoylthiourea compounds weresynthesized. The solid-liquid extraction of palladium with the two reagents into molten paraffin wax in hydrochloric acid solution was studied. The effects ofequilibrium concentration, extractant concentration, stirring time, phase ratio,palladium concentration and temperature on the extraction were determined in detail.The palladium loading capacity of organic phase was given. Palladium loaded in theorganic phase can be stripped with thiourea （1.5%） and H2SO4（0.5mol/L）. The singlestep stripping percentage was about75%. The extraction stage required wascalculated by using Mccabe-Thiele diagram.