| dc.description.abstract | The electroless nickel plating is widely used for the metal finish process of electronic component in various industries. In the waste nickel-containing solution produced from the process, high-concentration of nickel metal ions, hypophosphite and citrate acid organic compounds may result in high COD (40,000 ~ 70,000 mg/L), and cause difficulty for its biodegradation. Chemical precipitation is the most commonly used method for the treatment of waste nickel-containing solution, but it produces precipitation sludge which may lead to heavy loading of the secondary treatment process. However, waste nickel-containing solution, consists of high-concentration nickel metal ions which are indispensable raw material for the steel industry, and so it will bring about economic value if the nickel metal ions can be treated and recovered properly. Therefore, this study aims to develop an effective method for treating waste nickel-containing solution. The chemical reduction method was employed to remove the nickel ions and reclaim the nickel metal. And the effects of the operational conditions on Ni2+ removal rate and nickel metal recovery efficiency are investigated, as well as the efficiency of COD degradation by using Fenton oxidation procedure. Finally, the ultrasonic Fenton method is applied for comparison. The results of the study showed that with the chemical reduction method, the highest removal efficiency of the Ni2+ from the waste nickel-containing solution was 78%. And the most influential factors are the reaction monomer, pH value and [NaH2PO2]. The optimum operating condition was to use the polyimide as the reaction monomer, and to control the pH = 6 of the waste nickel-containing solution. The dosage was as [NaH2PO2] = 10 g/L and the [PdSO4] = 0.3 g/L. Under the optimum operating conditions, the highest nickel metal recovery efficiency could be realized. In the Fenton system, the reactive hydroxyl radicals (OH．) were generated in the initial 30 minutes reaction time, and the maximum COD degradation efficiency was up to 40%. The dosage of [Fe2+] should be precisely controlled to be lower than [H2O2], and H2O2 could be effectively catalyzed to generate hydroxyl radicals (OH．). Otherwise, a large amount of sludge containing Fe(OH)3 would be produced. The optimum operating condition was [Fe2+]/[H2O2] = 30/1800 mM, and it resulted in the maximum COD degradation efficiency up to 45%, which meant the dosing ratio of [Fe2+] and [H2O2] was 1:60. Under the same operation condition of [Fe2+]/[H2O2]=30/1200 mM, the performance of ultrasonic Fenton method was better than traditional Fenton method. Providing higher [H2O2] dosage would generate more hydroxyl radicals (OH．), resulting in higher COD degradation efficiency. | en_US |