Arsenate adsorption onto iron oxide amended rice husk char

In this study, rice husks were charred at 550 degrees C in a partially sealed ceramic vessel for 30 minutes to create a high specific surface area (SSA) rice husk char (RHC). The RHC was then amended with iron oxides using dissolved ferric nitrate, Fe(NO3)(3) center dot 9H2O, to provide a surface chemistry conducive to arsenic adsorption. The 550 degrees C iron oxide amended rice husk char's (550 IOA-RHC's) SSA was nearly 2.5 orders of magnitude higher and the arsenate adsorptive level was nearly 2 orders of magnitude higher than those reported for iron oxide amended sand, thus indicating a positive relationship between post-amendment SSA and arsenate adsorptive levels. Rice husks were then charred at temperatures ranging from 450 degrees C to 1050 degrees C to create an even higher SSA material, which might further increase arsenate adsorptive levels. The 950 degrees C RHC was chosen for amendment due to its high SSA and feasibility of being produced in the field. Once amended, the 950 degrees C iron oxide amended rice husk char (950 IOA-RHC) improved the arsenate adsorption capacity by thus confirming a positive relationship, though not a linear relationship, between post-amendment SSA and arsenic adsorptive capacity. Further study demonstrated that post-amendment mesoporous volume and mesoporous surface area appear to be better indicators of arsenic adsorptive capacity than SSA or iron content. (C) 2014 Elsevier B.V. All rights reserved.