Study on the extraction mechanism and thermodynamics of Pb(II) with a o-phenylendiamine tetraacetic acid

摘要

The extraction mechanism and thermodynamics of Pb(II) with a novel o-phenylendiamine tetraacetic acid (H(4)PDTA) were studied by high performance liquid chromatography with UV detector. The effects of extraction time, reciprocating oscillation frequency, Pb(II) concentration, H(4)PDTA concentration and Pb(II) solution acidity on Pb(II) extraction were investigated. The results showed that the extraction ratio of Pb(II) increased with an increase of pH and H(4)PEDTA concentration with a reciprocating oscillation frequency of 120 CPM (cycles per minute). The composition of the extraction complex was determined by slope methods and UV spectral analysis. The extraction mechanism of Pb(II) was proved to be a chelate extraction reaction and the values of thermodynamic function at 25A degrees C were determined: , Delta G (r) = -19.05 kJ mol(-1), Delta H (r) = -9.965 kJ mol(-1) and Delta S (r) = 30.47 J mol(-1) K-1.