Adsorption of Arsenic to Titanium Dioxide Nanoparticles, and Nano-Composites: Study of Isotherms, Kinetics, Photo-Oxidation, and Individual Metal Effects

Date

2017

Authors

Wagle, Dipendra

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Abstract

Arsenic contamination in drinking and groundwater is of great challenge due to its toxic effect to human and the environment. The purpose of this study was to investigate the removal of arsenic from water via adsorption process by using nanomaterials and novel nanocomposites. The adsorption behavior of arsenic to four different sorbents: TiO2 NPs, zeolite (ZSM5), TiO2-ZSM5, and TiO2-ZSM5-MoS2 was studied. TiO2 NPs and nano composites were characterized by using surface morphology, surface area, and point of zero charge. Scanning electron microscopy (SEM) images showed that TiO2 NPs was about 20 nm, and zeolite (ZSM5) was several microns. The surface area of TiO2-ZSM5, and TiO2-ZSM5-MoS2 were 132.9 m2/g, and 106.8 m2/g respectively. The PZCs of TiO2 NPs, ZSM5, TiO2-ZSM5, and TiO2-ZSM5-MoS2 were 5.1, 4.6, 5.9, and 5.1 respectively. The isotherm and kinetic study showed that the adsorption capacity of sorbents to As (V) was greater than As (III), and As (V) adsorption rate was greater than As (III). As (V) adsorption was increased at pH below the PZC. The photocatalytic behavior of TiO2 NPs, and TiO2-ZSM5-MoS2 nano composite to oxidize As (III) to As (V) was investigated. TiO2 NPs oxidized 80% As (III) within 180 min of UV irradiation; whereas, TiO2-ZSM5-MoS2 oxidized 100% As (III) within 150 min of UV irradiation. The competitive study showed that Pb (II) was more favorable for As (V) adsorption to TiO2 NPs, and TiO2-ZSM5; whereas Zn (II) was more favorable for As (V) adsorption to TiO2-ZSM5-MoS2. Multi contaminants adsorption spiking heavy metals and As (V) to San Antonio tap water showed that TiO2-ZSM5-MoS 2 has high potential to adsorb multiple contaminants simultaneously.

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Keywords

Adsorption, Arsenic, Heavy metals, Nano composites, Nanomaterials, Nanotechnology

Citation

Department

Civil and Environmental Engineering