HWAHAK KONGHAK, Vol.41, No.6, 744-748, December, 2003
화학적으로 표면처리된 활성탄소섬유 디스크에의한 코발트이온의 전기흡착
Electrosorption of Cobalt Ions by Chemically Treated ACF Discs
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초록
활성탄소섬유로 디스크를 만들고 NaOH 또는 HNO3로 처리하여 표면특성을 변화시킨 후 흑연봉에 연결하여 직류전기를 공급하면서 수용액으로부터 코발트이온을 전기흡착시켰다. 활성탄소섬유를 NaOH로 처리하면 미세공의 평균크기와 비표면적은 변화가 없으나 총산도가 감소되었고 HNO3로 처리하면 미세공의 평균크기는 변화가 없으나 비표면적은 약 20% 감소하고 총산도는 증가하며 특히 carboxyl 그룹이 많이 생성되었다. 약품처리에 의하여 활성탄소섬유의 등전점은 pH 3.1에서 pH 2.6, pH 2.2로 각각 낮아졌고 zeta 전위도 감소하였는데 이것은 표면에 음이온 하전밀도가 증가하였기 때문이다. NaOH처리된 활성탄소섬유 디스크에 의한 코발트이온의 흡착속도는 처리되지 않은 활성탄소섬유에 의한 흡착속도보다 2배 증가하였으나 HNO3처리 활성탄소섬유는 1/5로 감소하였다. 코발트 이온의 전기흡착능력은 0.2 N NaCl까지는 전해질의 농도에 비례하였으나 전해질의 농도가 더 증가하면 양이온의 경쟁으로 코발트 이온의 흡착속도는 감소하였다.
ACF discs were surface treated using NaOH, HNO3 and connected to a graphite bar, for the electrosorption of cobalt ions from an aqueous solution. The total acidity of ACF decreased by NaOH treatment which maintaining the same average pore size and specific surface area. The total acidity, specially carboxyl groups, increased by HNO3 treatment, although the specific surface area was reduced by co. 20%. The Point of Zero Charge (PZC) of ACF decreased from pH 3.1 to 2.6 and 2.2 by HNO3 and NaOH treatment, as a result of increases in anode ion density on ACF disc surface. Therefore, the adsorption rate of cabalt ion by NaOH treated ACF disc was twice larger than that of non-treated ACF disc, while that of HNO3 treated ACF disc was only one fifth of the non-treated ACF disc in electrosorption. The electrosorption rate increased with the electrolyte concentration, however, it slowly decreased above 0.2 N NaCl because of competition between Co2+ and Na+.
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