Full Description

The oxidation status of arsenic in source waters significantly affects the adsorptioncapacity of adsorbents. Many arsenic removal processes have been found to beineffective for arsenite, As(III), which is uncharged at the pH of drinking water.Removal of As(III) is generally accomplished by oxidizing it to arsenate, As(V),which can be removed by adsorption or ion-exchange mechanisms.Previous researchers have found that the TiO2/ultraviolet photocatalytic processeffectively converts As(III) to As(V). However, most of the research was performedwith TiO2 nano-particle suspensions. Removal of these particles later in the treatmentprocess could be problematic. During the authors' testing, a TiO2/Al2O3 mixed oxidewas developed which has been shown to effectively remove As(III) without requiringa separate oxidation process. A heterogeneous photocatalytic adsorbent (Al2O3/TiO2)was synthesized by sol-gel techniques. This composite acts as a photocatalyst thatcan oxidize As(III) to As(V), with the latter species being adsorbed by the adsorbent.The materials (Al2O3/TiO2) were mixed as a stable suspension (sol) that was used tocoat glass beads. After the coated beads were fired, the resulting thin films served asboth a photocatalyst and an adsorbent. Includes 24 references, figures.

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Edition: Vol. - No. Published: 06/15/2003 Number of Pages: 13File Size: 1 file , 380 KB