DETERMINATION OF ADSORPTION CHARACTERISTICS OF METAL OXIDE NANOMATERIALS: APPLICATION AS ADSORBENTS

The application of metal oxide nanomaterials as adsorbents for the removal of methylene blue (methylene blue) and As(V) were studied. Two adsorption models were applied to fit the adsorption data. The results showed that the systems followed a Langmuir model, and the maximum adsorption capacities of nano-Al2O3, -CuO, -TiO2, and -ZnO were 229.09, 220.52, 206.60, and 182.39mg/g for methylene blue, and 36.81, 36.39, 29.24, and 18.21mg/g for As(V). The adsorption behavior of As(V) on the metal oxide nanomaterials was pH dependent with higher adsorbed rates occurring at lower pH conditions. The adsorption capacities were increased by 40%, 34%, 25%, and 29% for nano-TiO2, -Al2O3, -CuO, and -ZnO, when pH decreased from 9 to 3. The effects of adsorption and photodegradation enhanced the degradation rates of methylene blue with highest rate of 90.5% in the nano-Al2O3 adsorption experiment. The kinetics investigations suggested that methylene blue and As(V) adsorption on metal oxide nanomaterials were adequately fitted by a pseudo-second-order model, with faster equilibrium achieved with As(V) than methylene blue. Nano-ZnO and -TiO2 presented faster methylene blue removal behavior.