| Summary: | 碩士 === 嘉南藥理大學 === 環境資源管理系 === 107 === This research determined the effect of the complexing agents, EDTA and citrate, on the recovery of cobalt and copper from synthetic wastewater by the fluidized bed homogeneous granulation process using phosphate as the precipitant. In the absence of the complexing agent, the removal and granulation efficiencies of cobalt at the optimum pH of 7.75 were 99.34%, 98.87% and of copper at the optimum pH of 6.50 were 99.59%, 89.09%, respectively. In the presence of EDTA, the removal and granulation efficiencies of cobalt dropped by 5.28% to 30.45% and 8.63% to 31.10%, respectively, as the EDTA to Co2+ molar ratio increased from 0.1 to 0.5. The adverse impact slightly lessened for citrate by which the efficiencies decreased 4.17% to 28.00% and 7.72% to 29.02%, respectively. Both complexing agents hindered the precipitation of copper as well. As the EDTA to Cu2+ molar ratio increased from 0.1 to 0.5, the removal and granulation efficiencies deteriorated by 4.94% to 29.29% and 4.38% to 34.41%, respectively. In the case of citrate, both efficiencies drastically decreased up to 25.69 % and 36.93 %, respectively, at the citrate to Cu2+ molar ratio of 0.1. As the molar ratio increased, no copper phosphate precipitated out. In addition, it was found that EDTA and citrate significantly reduced the granule sizes. Chloride which can form complexes with cobalt and copper interfered the precipitation of both cobalt and copper phosphate as well.
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