Comparison of As(III) Adsorption by Nanomagnetic Fe3O4, Activated Carbon and Modified Activated Carbon

Abstract

As a kind of new material, nanomagnetic Fe3O4 (NMF) has many advantages in water and wastewater treatment. In this paper, the adsorption characteristic for arsenic(III) (As) by NMF was studied, and the adsorption was compared with the traditional adsorbent of activated carbon (AC) and modified activated carbon (MAC). The results showed that the NMF had high adsorption performance for As, and the adsorption performance of modified activated carbon and activated carbon were far lower than that of magnetic nanomagnetic Fe3O4. The adsorption capacity for As with NMF, MAC, and AC was 0.189 mg.g-1, 0.023 mg.g-1 and 0.013 mg.g-1 in 0.25 mg.L-1 As solution, respectively. The adsorption rate for As was different from the three adsorbents. For NMF, it needs only 10 minutes to reach an adsorption balance, while the time to balance was 20 minutes for MAC and more than 120 minutes for AC. The adsorption for As by the three adsorbents all conform to Langmuir adsorption isotherm, and the adsorption kinetics for As by the three adsorbents were in accordance with the pseudo-second-order kinetics model. The adsorption efficiency of MAC and AC was lower than nanomagnetic Fe3O4. The nanomagnetic Fe3O4 was an effective adsorbent for arsenic.