Preparation and evaluation of a novel Fe–Mn binary oxide adsorbent for effective arsenite removal

Abstract

Adsorbent OxidationArsenite Removal a b s t r a c t Arsenite (As(III)) is more toxic and more difficult to remove from water than arsenate (As(V)).As there is no simple treatment for the efficient removal of As(III), an oxidation step is always necessary to achieve higher removal. However, this leads to a complicated operation and is not cost-effective. To overcome these disadvantage, a novel Fe-Mn binary oxide material which combined the oxidation property of manganese dioxide and the high adsorption features to As(V) of iron oxides, were developed from low cost materials using a simultaneous oxidation and coprecipitation method. The adsorbent was characterized by BET surface areas measurement, powder XRD, SEM, and XPS. The results showed that prepared Fe-Mn binary oxide with a high surface area ð265 m 2 g À1 Þ was amorphous. Iron and manganese existed mainly in the oxidation state þIII and IV, respectively. Laboratory experiments were carried out to investigate adsorption kinetics, adsorption capacity of the adsorbent and the effect of solution pH values on arsenic removal. Batch experimental results showed that the adsorbent could completely oxidize As(III) to As(V) and was effective for both As(V) and As(III) removal, particularly the As(III). The maximal adsorption capacities of As(V) and As(III) were 0:93 mmol g À1 and 1:77 mmol g À1 , respectively. The results compare favorably with those obtained using other adsorbent. The effects of anions such as SO 2À 4 , PO 3À 4 , SiO and humic acid (HA), which possibly exist in natural water, on As(III) removal were also investigated. The results indicated that phosphate was the greatest competitor with arsenic for adsorptive sites on the adsorbent. The presence of sulfate and HA had no significant effect on arsenic removal. The high uptake capability of the Fe-Mn binary oxide makes it potentially attractive adsorbent for the removal of As(III) from aqueous solution.

Removal of phosphate from water by a Fe–Mn binary oxide adsorbent

“…Chemical composition analysis (figures not presented) revealed that Fe and Mn were evenly distributed on the surface and the Fe/Mn molar ratio on the surface was in the range of 5.9-6.1, which is very close to the value of 6:1 of the bulk Fe/Mn molar ratio. The material has a high BET specific surface area of 309 m 2 /g with a pore volume of 0.42 cm 3 /g, which is in agreement with previous results [32,34].…”

“…9. For the Fe-Mn binary oxide sample, the band at 1625 cm À1 was assigned to the deformation of water molecules and indicated the presence of physisorbed water on the oxides; three peaks at 1123, 1051, and 974 cm À1 could be primarily attributed to the bending vibration of hydroxyl groups of iron (hydr)oxides (Fe-OH) vibration [34].…”

Arsenic removal from aqueous solution using ferrous based red mud sludge

“…2. 2 × 10 −4 mol/l iron (ferrous or ferric) and 7.7 × 10 −2 g/l RM were added in arsenic water, meanwhile, research done before had shown that Cl anion has little effect on As(V) removal [20]. Arsenic removal efficiency for ferrous based red mud was higher than ferric based red mud (91.7 ± 2.3% compared to 81.2 ± 3.9%) when the initial As(V) concentrations were varied in the range of 0.16-1.4 mg/l.…”

Research progress of novel adsorption processes in water purification: A review

“…E-mail: jhqu@rcees.ac.cn. numerous approaches have been investigated for the development of cheaper and more effective novel composite adsorbents (Oliveira et al, 2004;Gu et al, 2005;Machado et al, 2006;Zhang et al, 2007b). These composite materials deserve particular attention because they combine the properties and advantages of each of their components.…”