Abstract
The interactions of Cu(II) and Ni(II) with mono-, di- and triethanolamine over all possible ranges of pH values and amine concentrations in aqueous solution, have been described in this thesis. Copper was released to the outer solution when the copper form resin was equilibrated with all the three aqueous ethanolamine solutions. Model curves, explaining the reason why the copper was extracted with all the three amines, were constructed successfully from the experimental findings and equilibrium constants derived by other methods. The factors involved in swelling in the three forms of Mea-salt, Dea-salt and Tea-salt, have been studied for comparison. It was found that the addition of each C2H4OH group was accompanied by an increase in 34 units in volume, while the anomaly with 2% cross-linked resin suggests ion-association in the order TeaH+ > DeaH > MeaH+ with the charged group of the resin. Some conductimetric, potentiometrie and spectrophotometric studies were carried out to study the influence of ionised -OH groups in the ligand molecule towards Cu(II) and Ni(II) ions in dilute solutions. Such studies revealed the presence of hydroxy, chelate, mixed and polynuolear complexes in addition to normal amine complexes with cupric ions. Nickel formed normal ammine complexes and showed no tendency to form hydroxy complexes. The several stepwise dissociation constants of CuTea2+, CuDea2+ and CuMea2+ were determined. Further, a Martell plot was used to estimate the dimerisation in solution. With Cu(II)-diethanolamine, K(MLOH)2 = 1 X 10-13, where K = [ (CuDeaOH)22+] [H+]2/ [CuDea2+]2, was obtained. With nickel, the values of log K1 and log K2 of the complexes of the general formula [NiX]2+ and [NiX2]2+ formed below pH 9, have been determined by the method of potentiometry.