Abstract

Arsenic (As) is one of the most toxic elements found in water resources. The As contamination in the ground water and its adverse effects on human health have been receiving much attention in various countries whole the world, including Vietnam. This paper presented the fact that the iron mining waste, collected at the tailings dam of Trai Cau mine, Thai Nguyen province (STC), was investigated for its performance in removing both arsenite [As(III)] and arsenate [As(V)] in an aqueous environment through a series of batch adsorption experiments under various conditions (i.e., solution pH, contact time, and initial arsenic concentrations). Results of the effect of pH solution indicated that both the As(III) and As(V) adsorption processes were insignificantly affected by the initial pH solution (pH 2−10). The adsorption process of STC toward both As(III) and As(V) increased quickly in the first hour of contact and then reached equilibrium at about 400 minutes of contact. The kinetic study showed that both As(III) and As(V) adsorption processes onto STC adsorbent were represented by the second−order model (PSO) with the R2 = 0.94 and 0.94, respectively. The equilibrium adsorption isotherm study suggested that the adsorption process of As(III) and As(V) were adequately described by the Langmuir model. The maximum adsorption capacity (qmax) of STC toward As(III) and As(V), calculated by the Langmuir model, were 0.49 and 0.54 mg/g, respectively. In addition, the adsorption capacity of STC toward As ions was generally higher than those reported in the literature where many other adsorbents were used, i.e., natural materials (laterite, zeolite), industrial wastes, or even their modified forms (iron mining waste, red mud). The results suggest that STC would be considered as a promising adsorbent for the removal of As ions from water media.