Arsenic Removal from Water Using Various Adsorbents: Magnetic Ion Exchange Resins, Hydrous Ion Oxide Particles, Granular Ferric Hydroxide, Activated Alumina, Sulfur Modified Iron, and Iron Oxide-Coated Microsand

摘要

The equilibrium and kinetic adsorption of arsenic on six different adsorbents were investigated with one synthetic and four naturaludtypes (two surface and two ground) of water. The adsorbents tested included magnetic ion exchange resins (MIEX), hydrous ion oxideudparticles (HIOPs), granular ferric hydroxide (GFH), activated alumina (AA), sulfur modified iron (SMI), and iron oxide-coated micud-udrosand (IOC-M), which have different physicochemical properties (shape, charge, surface area, size, and metal content). The resultsudshowed that adsorption equilibriums were achieved within a contact period of 20 min. The optimal doses of adsorbents determinedudfor a given equilibrium concentration of Cudequd= 10 μg/L were 500 mg/L for AA and GFH, 520–1,300 mg/L for MIEX, 1,200 mg/L for HIOPs,ud2,500 mg/L for SMI, and 7,500 mg/L for IOC-M at a contact time of 60 min. At these optimal doses, the rate constants of the adsorbentsudwere 3.9, 2.6, 2.5, 1.9, 1.8, and 1.6 1/hr for HIOPs, AA, GFH, MIEX, SMI, and IOC-M, respectively. The presence of silicate significantlyudreduced the arsenic removal efficiency of HIOPs, AA, and GFH, presumably due to the decrease in chemical binding affinity of arsenicudin the presence of silicate. Additional experiments with natural types of water showed that, with the exception of IOC-M, the adsorbentsudhad lower adsorption capacities in ground water than with surface and deionized water, in which the adsorption capacities decreasedudby approximately 60–95ud%ud.