Adsorption of arsenic onto Kemiron in a landfill leachate

Abstract

Samples of Class I landfill of North Central Polk County contained high level of arsenic (As) above 10 µg L⁻¹, the permissible concentration levels in drinking water. By the method of addition, it was determined that the natural leachate samples contained 29 ± 2 µg L⁻¹ of dissolved As and 126 ± 6 µg L⁻¹ of total As. The sorption capacity of Kemiron fell from 85–90% of the initial 5 mg L⁻¹ As(V) concentration in DI water to 40–50% of 1 mg L⁻¹ initial As(V) concentration in the real landfill leachate system. The age of the landfill leachate exerted no significant influence on the sorption density of As(V) onto Kemiron. There were however small changes in the sorption density of As(III) onto Kemiron. The presence of selenite Se(IV) was the main controlling component in terms of the sorption density of the adsorption of As in the synthetic landfill leachate. Ca²⁺, –N, , and ions exerted no significant impact on the sorption density of As onto Kemiron. The oxidation reduction potential (ORP) and pH were the most influencing elements besides Se(IV) in the sorption of As onto Kemiron. Changes of ORP also produced changes in pH of the solution systems. In the experiment, the maximum As(V) sorption density acquired was 47.5 mg As g⁻¹ Kemiron at the following: ORP of 320–350 mV at pH of 7–8, ORP of 200 mV at pH of 8, or at ORP of −300 or 0 mV and at pH of 11.

Keywords:

• arsenic
• landfill leachate
• limestone
• adsorption
• aquifer