Preliminary Studies of the Development of Arsenic Pre-Concentration Technique Using Iron (III) Modified Montmorillonite

Gan, Teck Kang (2017) Preliminary Studies of the Development of Arsenic Pre-Concentration Technique Using Iron (III) Modified Montmorillonite. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

Arsenic is an element that found widely in earth’s crust. In natural water, the concentration of arsenic are less than 1-2 μg/L, but the concentration can be significantly elevated in groundwater where there are sulfide mineral deposits and sedimentary deposits deriving from volcanic rocks. Soluble inorganic arsenic is acute toxic and ingestion of large doses leads to gastrointestinal symptoms, disturbances of cardiovascular and nervous system functions, and eventually death The limit of detection was 0.1 μg/L by ICP-MS: 2 μg/L by hydride generation atomic adsorption spectrometry (HG-AAS) or flame atomic adsorption spectrometry (Flame-AAS). This project aim to determine the adsorption and preconcentration of arsenic using Ferric hydroxide (Fe(OH)3) and Iron (III) modified montmorillonite. The adsorption and desorption ability was tested. Desorption was tested in the condition of 2% nitric acid. Preconcentration was tested by reducing the amount of acid to 5mL. The Fe(OH)3 was showing moderate adsorption and low desorption ability where only 45.99% to 76.49% of adsorption and only 37.59% of recovery. Fe(OH)3 was found to be unable dissolve completely in the 2% acid solution. Iron (III) modified montmorillonite was showing higher adsorption of arsenic range from75% to 90% with recovery approximately 50%. There are some effect of acid concentration on the recovery of arsenic, where 4% of HNO3 showing the higher recovery which is 50.26% for preconcentration technique. At the same time, the type of acid also affect the recovery of arsenic. 7.95%, 68.09%, and 73.60% of arsenic was recovered with 2%, 4%, and 6% H2SO4 respectively