Adsorption of As(III) and As(V) by using the Fenton reaction modified kapok fiber

Abstract

The hydrophilic kapok fiber was obtained by Fenton reaction via a cost-effective and controllable solution-dipping process. The adsorption performances of Fenton reaction modified kapok fiber (FRKF) were evaluated in terms of pH, time, pollutant concentration, temperature, co-existing anions, and reusability, so as to find the optimum adsorption conditions for removing As(III) and As(V) from the aqueous solution. The results showed that FRKF was stable at a relatively wide range of pH for As(III) and As(V), the optimal pH of As(III) and As(V) were 7.0 and 4.0, respectively, and the adsorption equilibrium time of As(III) was shorter than that of As(V). The effect of temperature on the adsorption of As(III) by FRKF was negligible, but it has an obvious effect on the adsorption of As(V). As the temperature increased from 293 K to 313 K, the adsorption uptakes of FRKF for As(V) increased from 18.7 mg g−1 to 30.0 mg g−1. Compared with NO3−, and SO42−, the co-existing anion of PO43− has a serious inhibitory effect on the adsorption of arsenic due to its high content of negative charge and a tetrahedral structure similar to As(V). Based on the XPS analysis, the functional groups of hydroxyl and/or carboxyl on FRKF play a major role by forming C-O-As bond with arsenic in the adsorption process. Finally, the adsorption-desorption experiments demonstrated that FRKF has good stability and reusability, thus FRKF can be used an effective and practical adsorbent for the treatment of arsenic or other heavy metals.