Авторы: Masue Y., Loeppert R., Kramer T.

2007 г.

Env.Sci.Techn.

       Although arsenic adsorption/desorption behavior on aluminum and iron (oxyhydr)oxides has been extensively studied, little is known about arsenic adsorption/desorption behavior by bimetal Al:Fe hydroxides. In this study, influence of the Al:Fe molar ratio, pH, and counterion (Ca2+ versus Na+) on arsenic adsorption/desorption by preformed coprecipitated Al:Fe hydroxides was investigated. Adsorbents were formed by initial hydrolysis of mixed Al3+/ Fe3+ salts to form coprecipitated Al:Fe hydroxide products. At Al:Fe molar ratiose1:4, Al3+ was largely incorporated into the iron hydroxide structure to form a poorly crystalline bimetal hydroxide; however, at higher Al:Fe molar ratios, crystalline aluminum hydroxides (bayerite and gibbsite) were formed. Although approximately equal AsV adsorption maxima were observed for 0:1 and 1:4 Al:Fe hydroxides, the AsIII adsorption maximum was greater with the 0:1 Al: Fe hydroxide. AsV and AsIII adsorption decreased with further increases in Al:Fe molar ratio. AsV exhibited strong affinity to 0:1 and 1:4 Al:Fe hydroxides at pH 3-6. Adsorption decreased at pH > 6.5; however, the presence of Ca2+ compared to Na+ as the counterion enhanced AsV retention by both hydroxides. There was more AsV and especially AsIII desorption by phosphate with an increase in Al:Fe molar ratio.

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