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As we all know, lead has been introduced into the soil and ground water from the industry such as storage batteries, mining, plating, paint and dyes, ammunition and so on [1-3]. The amount of excess lead in the soil and ground water is threatening for human beings as well as ecosystem [2,3]. The permissible limit of lead in drinking water and ground water regulated by WHO is 0.01 mg/L, which is the same as the limit in Japan [1]. Heavy metals in aqueous solution can be removed by chemical precipitation, ion exchange, liquid membrane extraction, electrode deposition, biological processes and adsorption [2,3]. Adsorption by activated carbon (AC) is one of the attractive options for the removal of noxious substances in the process of water purification due to its simple operation, low cost, easiness for scale-up and most importantly able to remove trace pollutants [4]. Thereby, AC has been widely used in water treatments especially for organic pollutants, because of its high affinity, large specific surface area and durability [5]. In recent years, considerable attention has been paid to a new category of activated carbon in the form of fiber [6]. Activated carbon fiber (ACF) can possess a large bulk volume, faster adsorption and desorption rates than other ordinary ACs such as granular activated carbons [3]. However, widely used ACs are hydrophobic and the adsorption ability of AC for hydrophobic organic pollutants should be higher than that of hydrophilic heavy metals. In order to enhance the adsorption ability for hydrophilic heavy metals, surface modification to introduce the hydrophilic acidic functional groups onto the surface has been conducted through heating treatment under air circumstance, oxidation of acid solution, ozone and electrochemical treatments [13,15]. In general, the oxidation of acid solution is more effective and easier than other methods because special device are not needed. The solution for oxidation is used as nitric acid, hydrogen peroxide, ammonium persulfate and so on, of which nitric acid is most widely and frequently used [3,15]. The objectives of this study are to enhance the adsorption ability of AC through oxidation treatment and elucidate the effects of the concentration of oxidant and contact time on the degree of oxidation. Commercially available ACF was oxidized by different concentrations of HNO3solution and contact time. The properties of ACFs were characterized by the measurements of the surface area, surface functional groups, the pH of the point of the zero charge (pHpzc) and elemental analysis. The adsorption of Pb(II) from aqueous solution by oxidized ACFs was examined comparing with the original ACF. Moreover, the effects of equilibrium solution pH, temperature and contact time on Pb(II) adsorption were also investigated. Adsorption of Pb (II) from Aqueous Solution on Oxidized Activated Carbon Fibers

Adsorption of Pb(II) from Aqueous Solution on Oxidized Activated Carbon Fibers