Kinetics of decomposition of polyethylene glycol in electroplating solution by ozonation with UV radiation

The kinetics of the ozonation of polyethylene glycol (PEG) with ultraviolet (UV) radiation in the acid-based electroplating solution of the printed wi ring board industry is studied. The substrate prescription of a typical ele ctroplating solution is with pH of 0. 18-0.42, [CuSO4 . 5H(2)O] of 200 g/L, [H2SO4] of 60 g/L, and [Cl-] of 0.03 g/L. Certainly, the discarded electro plating solution is hard to treat with the common chemical and biological p rocesses because of its acidic and metallic compositions. In addition, it c ontains valuable substances suitable for recovery and reutilization. One of the most important processes for reviving it is to remove the aged organic additives such as PEG. A two-step reaction mechanism in terms of ozone A a nd total organic carbon is proposed to express the reaction kinetics of PEG ozonation with UV radiation with intensity [I-uv]. The initial concentrati on of PEG is 30 mg/L, according to the recipe of a typical electroplating s olution, which is equivalent to total organic carbon of 16.3 mg/L. The reac tion rate r expressions of the concentrations of the liquid phase ozone C-A Lb, PEG C-BLb, and intermediates C-ILb are r(A) (=dC(ALb)/dt) = -(k(Am) + k (t)[I-uv)C-ALb (k(R1) + k(RI1)[I-uv])CALbCBLb - (k(R2) + k(RI2)[I-uv])CALbC ILb, r(B) (=dC(BLb)/dt) = -(k(R1) + k(RI1)[I-uv])CALbCBLb, r(int) (=dC(ILb) /dt) (k(R1) + k(RI1)[I-uv])CALbCBLb - (k(R2) + k(RI2)[I-uv])CALbCILb, with k(Am) = 0.0036 s(-1), k(1) = 4.654 X 10(-5)s(-1)/(Wm(-2)), k(R1) = 13.525 M (-1)s(-1), k(R2) = 0.751 M(-1)s(-1), k(RI1) = 0.683 M(-1)s(-1)/(Wm(-2)), an d k(RI2) = 0.042 M(-1)s(-1)/(Wm(-2)). These reaction kinetic expressions ar e useful and referable for the proper design of an ozonation system with UV radiation for the treatment of PEG in the printed wiring board electroplat ing solution.