Adsorption equilibrium of polyethylene glycol in the copper electroplating solution on activated carbon

Polyethylene glycol (PEG) used as a brightening and stabilization agent at the concentration of 30 mg dm(-3) is a major organic additive in the copper electroplating solution. Activated carbon, Calgon Filtrasob 400, is used as the adsorbent to remove the PEG from the used electroplating solution in order to broaden the appeal of recycling it. The equilibrium of adsorption is attained within 14 days. The effect of the temperature on the amount of PEG adsorbed on the activated carbon is insignificant for the temperatures ranged from 288 to 313 K. The adsorption isotherm of PEG conforms to the Langmuir isotherm, q(e) = Q(L)K(L)C(e)/(1 + KLCe), With a high correlation coefficient of 0.9979. The large values of the monolayer adsorption capacity, Q(L), of 303 mg g(-1) and the equilibrium constant, K-L, of 0.273 dm(3) mg(-1) show a great adsorption potential of PEG on the activated carbon. A high removal efficiency would be expected at such a low original concentration of PEG. From the results mentioned above, it is feasible to use activated carbon for removing PEG from the electroplating solution, thereby achieving the appeal of recycling. (C) 2000 Academic Press.