| Summary: | 碩士 === 高苑科技大學 === 化工與生化工程研究所 === 102 === In this study, the oyster shell powder was adopted to remove heavy metal Cd, Pb, Cu, Ni, and Cr from synthetic wastewater. The control factories of experiment were calcination temperature of oyster shell powder, particle size, dosage of oyster shell powder, reaction time, and agitating speed. Taguchi method L18 orthogonal array was conducted to evaluate the removal efficiency.
The results showed that the effect on heavy metal removal by oyster shell powder is as follow: dosage of oyster shell powder> calcination temperature > removal time = particle size > agitating speed. The higher temperature, finer particle size, more dosage, more reaction time, the higher removal. The conduction of experiments were: calcination of oyster shell powder: 300 ℃, 600 ℃, 1000 ℃; particle size: 6, 20, 42 mesh; dosage: 1, 2, 3 g; reaction time: 30, 60, 90 min; agitating speed: 30, 60, 100rpm. In case of calcination of oyster shell powder 300 ℃, 600 ℃and 1000 ℃, the concentration of heavy metal was 10 mg/L, the removal reached 95% by dosage of 3g, 2g and 1g, respectively. On the other hand, the results showed that the removal mechanism is owing oyster shell powder produced alkalinity in the water and raised pH higher than 10. The high pH led precipitation of metal hydroxide. Therefore, before the discharge of effluent, the pH adjusted to neutral is necessary. Thus, the heavy metal Cd, Pb, Cu, Ni, Cr could be removed effectively from wastewater by oyster shell powder.
Keywords: Oyster shell, Taguchi, heavy metal
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