ADSORPTION OF POLYACRYLIC-ACID ON HYDROPHOBIC AND HYDROPHILIC SURFACES

In this paper the adsorption of polyacrylic acid (MW = 5000) on the hy drophobic mercury surface and on the hydrophilic gamma-Al2O3 surface a t pH = 3-4 in 0.55 M sodium chloride solution was investigated. Measur ements of change of the double layer capacitance by phase selective a. c. voltammetry were used for determination of the adsorption of polyac rylic acid on the mercury electrode. The same method was used for the determination of the polyacrylic acid remaining in the solution after the adsorption on hydrophilic particles (gamma-Al2O3 particles). The r esults obtained for adsorption of polyacrylic acid were compared to th e results of the adsorption of humic substance of similar molecular we ight under similar experimental conditions. The study has shown that p olyacrylic acid in acidic solution is strongly adsorbed on the mercury surface, which is comparable to the adsorption of humic substance on the mercury surface. At the same time, the adsorption/deposition of po lyacrylic acid on the gamma-Al2O3 surface is weaker compared to humic acid, indicating at a smaller degree of interaction of polyacrylic aci d with aluminium ions and with hydrophilic surface.