Arsenic(III,V) Adsorption on Iron-Oxide-Coated Manganese Sand and Quartz Sand: Comparison of Different Carriers and Adsorption Capacities

摘要

This research aimed at improving the effectiveness of arsenic (As) (III,V) adsorption to iron-oxide-coated sand bynfirst using a manganese sand carrier instead of a quartz sand carrier. Although both adsorbents had similarnadsorption rates of As(III,V), the maximum adsorption capacities (qm) of As(III) (2.216 mg/g) and As(V)n(5.452 mg/g) by iron-oxide-coated manganese sand (IOCMS) were nearly 3 and 10 times higher than those byniron-oxide-coated quartz sand (IOCQS), respectively. Based on the analysis of scanning electron microscope andntotal Brunauer-Emmett-Teller surface area, IOCMS exhibited a rougher surface and a larger surface arean(9.18m2/g) than IOCQS (1.03m2/g). Coated Fe content in IOCMS and IOCQS were 48.7 and 10.2mg/g, respectively.nLarger Brunauer-Emmett-Teller value and Fe content may be responsible for the greater adsorptionncapacity of IOCMS. Results of X-ray diffraction and X-ray photoelectron spectroscopy analysis confirmed thenexistence of Fe2O3, MnO, MnO2 and FeOOH on the surface of IOCMS. In addition, IOCQS surfaces onlyncontained SiO2 and FeOOH. X-ray photoelectron spectroscopy results indicated that the MnO2 in IOCMS did notnoxidize As(III) in the adsorption process. Moreover, the optimum pH for As(III) removal by IOCMS was aboutnpH 7. In contrast, the As(V) removal efficiency by IOCMS decreased with pH, increasing from pH 4 to 10.nFurther, the influences of anions on the removal of both As(III) and As(V) by IOCMS followed the samensequence of phosphate > silicate > carbonate. In conclusion, IOCMS showed a considerable potential to treat Aspollutednwater in engineering application.