The adsorption of As(Ⅲ) on a novel granular Fe-Cu-Mn trimetal oxide (GFCM): Behavior and mechanism

A novel sorbent of granular Fe-Cu-Mn trimetal oxide (GFCM) was fabricated by coating method,with chitosan as adhesive. The GFCM presents an incomplete spheric shape with a diameter of 0.7~ 1.0 mm. It can effectively oxidize As(Ⅲ) to As(V) and efficiently adsorb the new formed As(V). Its maximal sorption capacity on As(Ⅲ) is up to 56.5 mg&middot;g~(-1) at pH 7.0,which is superior to most of reported granular sorbents. The GFCB also shows excellent As(Ⅲ) sorption efficiency over a wide range of pH from 5.0 to 9.0,and is less affected by ionic strength. The coexisting anions would restrain the As(Ⅲ) sorption efficiency by the following order: PO~(3-)_4 &gt; SiO_3~(2-) &gt; CO_3~(2-) &gt; Cl~-&gt; SO_4~(2-). The arsenic-loaded sorbent could be effectively regenerated by using NaOH solution and reused again. During the process of As(Ⅲ) removal,Mn oxide in sorbent is mainly responsible for As(Ⅲ) oxidation,while both Fe and Cu oxides are dominant for adsorbing As(Ⅲ) and formed As(V). Moreover,Cu oxide contributes to enhance As(Ⅲ) sorption performance of the GFCM.</p

Adsorption of As (V) on Ce-Mn binary oxide: Behavior and mechanism

A novel Ce-Mn binary oxide adsorbent was synthesized via oxidation and co-precipitation method. As(V) adsorption behavior on Ce-Mn bimetal oxide was systematically investigated by batch experiments. As(V) adsorption mechanism was studied using FTIR and XPS techniques. The results indicated that the introduction of manganese oxides into CeO_2 emerged a synergistic effect on As(V) adsorption,which was evidently proved by the much higher adsorption capacity of Ce-Mn bimetal oxide than that of the pure CeO_2 and MnO_2,especially at the Ce/Mn molar ratio of 3 ∶ 1. The adsorption of As(V) was relatively fast and over 90.8% of the equilibrium adsorption capacity was obtained within 4 h. Ce-Mn bimetal oxide had good performance for As(V) adsorption,especially under acidic conditions. The maximum adsorption capacity was 77.8,63.5 and 39.0 mg·g~(-1) at pH 5.0,7.0 and 9.0,respectively. Freundlich model was more suitable to describe the adsorption isotherm data. The ionic strength had little influence on the adsorption. The coexisting anions PO_4~(3-) and SiO_2-3 inhibited As(V) adsorption,whereas the cations Ca~(2+) and Mg~(2+) slightly enhanced As(V) adsorption. Mechanism investigations suggested that As(V) was probably removed from the solution by forming monodentate mononuclear and didentate dinuclear complexes on the surface of Ce-Mn bimetal oxide