Sequestration of some biogenic amines and poly(allyl)amine by high molecular weight polycarboxylic ligands in aqueous solution

Abstract

The interactions of two high molecular weight polycarboxylic ligands [polyacrylic- co-maleic, MW = 70 kDa, and poly(methyl vinyl ether- co-maleic acid), MW = 15 kDa] with some polyamines [1,4-diaminobutane (or putrescine), histamine and poly(allyl)amine, MW = 15 kDa] were studied, at t = 25 °C and at low ionic strength ( I = 0.015 mol L − 1 ) by potentiometric measurements. For all investigated systems, the formation of (am)(L)H i species was found (am = amine, L = polycarboxylic ligand, i = 1…4); the stability of polyammonium–polycarboxylate complexes is fairly high and the formation percentage of most species reaches ∼ 90% in the experimental conditions (mmolar concentration of reactants). The dependence on temperature and ionic strength of the stability of polyamine–polycarboxylate species was studied using some semiempirical equations and enthalpy data for the protonation of both components. The sequestering ability of polyelectrolytes towards amines was modeled by a sigmoid Boltzman type equation and was defined by calculating the parameter p L 50 (the total ligand concentration, as − log C L, able to bind 50% of cation); this parameter gives an objective representation of this ability. The dependence of p L 50 on pH, ionic strength and temperature was studied too.