Abstract
Magnetite prepared by adding the aqueous sodium hydroxide solution to the mixture solution of Fe2+: Fe3+ = 1 : 2 was investigated on the adsorptive properties for arsenic(V) anion and cations such as cobalt(II), copper(II), cadmium(II), lead(II), nickel(II) and zinc(II) at 303K. Especially, arsenic(V) and lead(II) with high toxicity were studied in detail. Adsorption of arsenic(V) and lead(II) was dependent on equilibrium pH. The adsorption percentages of arsenic(V) and lead(II) showed the optimum values at around pHeq 4-5 and pHeq 5, respectively. From their chemical species existing at each pH and pH of zero point of charge on the magnetite surface, arsenic(V) and lead(II) were probably adsorbed on the surface of the magnetite by electrostatic force and ion exchange, respectively. The adsorption of arsenic(V) and lead(II) was the Langmuir type. The adsorption capacity and the adsorption equilibrium constant for arsenic(V) were 2.28 x 10-1 mmol g-1 and 1.21 dm3 mmol-1, respectively and those for lead(II) were 2.13 x 10-1 mmol g-1 and 5.03 dm3 mmol-1, respectively, at 303K. The adsorption of lead(II) was an endothermal reaction from the effect of the temperature on the adsorption. An aqueous sodium hydroxide solution was useful as an agent for desorption from arsenic(V)-loading magnetite.
