Study On Treatment Of P-aminophenol Wastewater Based On Complexation Extraction

P-aminophenol(PAP) is typical polarity organic compound with amphoteric functional groups. In this thesis, trioctylamine (TOA), tri-n-butyl phosphate (TBP) and di(2-ethylhexyl)phosphoric acid (P204) have been used as complexing agents respectively. Through studying on complexation extraction of imitate wastewater of p-aminophenol, equilibrium time of extraction was determined; it was discussed how ratio of oil and aqua, pH value of aqueous solutions, kind of diluents, concentration of PAP, concentration of complexing agents and extraction temperature influenced p-aminophenol to extraction ratio; Anti-extraction of loaded organic phase with pH-swing effects has been researched. According to optimized experiments, actual wastewater was extracted through three adverse current steps with 10%P204 - 90% kerosene(volume percentage), extraction percentage of p-aminophenol could reach 98.50%, and complexing agents could be regenerated with aqueous solutions of 3.6%HCl(volume percentage).The complexation extraction mechanism of p-aminophenol was also studied. Thermodynamics process of extraction was assumed as macro-process, The extraction reaction enthalpy of three system P204, TOA TBP were respectively -9.20kJ/moh -5.57kJ/moK -3.47kJ/mol; The composition of extracted species was deduced by means of double-logarithmic coordinates. Molecule ratio of PAP:TOA , as well as PAP:TBP, is 1:1. Molecule ratio of PAP:(HP)2 is 2:1, where (HP)2 is the dimer of P204; The mechanism of complexation reaction and structure of extracted species were investigated by infrared spectra of the loaded organic phase. There is an electrovalent bond between TOA and PAP as well as between P204 and PAP, structure of extracted species is (RO)2POO- + NH3-Ar-OH and R3NH+ -O-Ar-NH2. There is a hydrogen bond between TBP and PAP, structure of extracted species is (C4H9O)3 P = O- HO -Ar -NH 2.The complexation extraction mechanism of organic compound with amphoteric functional groups is as follows: acidic complexing agents and alkaline complexing agents react with alkaline functional group and acidic functional group respectively to form extracted species with an electrovalent bond; neutral complexing agents react with proper functional group according to complexation function with a hydrogen bond.