Effect of stabilizers on As(III) and As(V) sorption by zirconium and aluminum hydroxide particles
Type of DegreeMaster's Thesis
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Arsenic is a highly toxic contaminant found in water, air, and soil; which is well recognized carcinogenic element. The groundwater contamination of arsenic has been reported in many countries such as Bangladesh, China, and some parts of the United States. Several studies have been done to develop new technologies for enhanced removal of arsenic. Recently, metal oxide nanoparticles, such as iron, aluminum, and zirconium oxide/hydroxide, have been considered to be effective technologies for removal of arsenic from water. Zirconium hydroxide stabilized with CMC or starch and aluminum oxide/hydroxide with CMC or starch adsorbents were used for enhanced removal of arsenic in this work. The experimental results reveal that starch stabilized zirconium hydroxide nanoparticles have an excellent adsorption capacity toward both As(III) and As(V). Zeta potential data shows that the surface charge of particles is highly dependent on stabilizers. The removal rate of As(V) is significantly decreased with increase in pH, while, solution’s pH effect is observed to be negligible on As(III) removal. Dissolved organic matter (DOM) decreases the arsenic uptake by zirconium hydroxide nanoparticles. Although starch or CMC are not able to effectively stabilize particles, yet, aluminum hydroxide coated with starch was found to enhance As(V) removal capacity. Calcination of freeze dried aluminum hydroxide with CMC or starch at 500 ˚C results in production of porous activated alumina, which displays high arsenic adsorption capacity.