抄録
In this study, Ni2+ removal from electroless nickel plating wastewater (A. co., Ltd.) by reduction crystallization was investigated, to make clear the effect of seeds specific surface area on the Ni2+ removal characteristics. Although the main reaction in this research is the same as the one in electroless nickel plating, the authors have proposed reduction crystallization in which wastewater from electroless nickel plating contacts with suspended nickel powder, to remove and recover Ni2+. The results could be obtained on the relationship between the pH change profile and recovery efficiency in the reaction process, in which nickel powders having various specific surface area were used as seeds. Experimental results were discussed, considering surface conditions of grown nickel and the behavior of produced fines. With a constant 10% NaOH solution feed rate, the pH profile changed in the process of Ni2+ reduction, by changing the specific surface area of seeds, which means that Ni2+ removal efficiency was affected by the specific surface area of seeds. When constant pH7 was maintained, higher removal efficiency (0.99; Ni2+ concentration in the treated water 2.5×10-2g·dm-3) could be obtained, although the specific surface area of Ni seed powder varied. Specific surface of seeds, based on the roughness of seed crystal, was suggested to be an effective factor on the Ni metal coating behavior on the seed surface and also the phenomena of fines production in the process of Ni deposition.
