Cadmium adsorption on goethite-coated sand in the presence of humic acid.
Heat was employed to coat crystalline goethite onto a quartz sand surface so that the adsorbent properties of the coating could be utilized. The adsorption characteristics of cadmium and humic acid onto goethite-coated sand were examined. Results show that the goethite-coated sand surface had a higher specific surface area and more mesopores than the uncoated sand. The adsorption of both cadmium and humic acid was highly pH-dependent: cadmium adsorption increased with pH, but humic acid adsorption decreased as pH increased. The presence of humic acid resulted in increasing cadmium adsorption in a specific pH range. The order of reacting humic acid with cadmium was found to have a noticeable effect on the final adsorption capacity. The adsorption capacity of cadmium for humic acid that is adsorbed onto goethite-coated sand before reacting with a cadmium system, exceeds that of humic acid that is mixed with cadmium ions before goethite-coated sand is added.
Lai
Chin-Hsing
CH
Department of Environmental Engineering and Sanitation, Fooyin Institute of Technology, Ta-Liao Hsiang, Kao-Hsiung Hsien, Taiwan. chlai@mail.fy.edu.tw
Chen
Chih-Yu
CY
Wei
Bai-Luh
BL
Yeh
Shu-Hsing
SH
D000327:Adsorption; D002104:Cadmium / Q000032:analysis / Q000737:chemistry*; D006812:Humic Substances / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D012822:Silicon Dioxide; D013696:Temperature; D014873:Water Pollutants / Q000032:analysis*
D006812:Humic Substances; D014873:Water Pollutants; D002104:Cadmium; D012822:Silicon Dioxide