Abstract
In this study, we investigated the kinetics of arsenic removal from waste acid by the combination of zero-valent iron (ZVI) and CuSO4. ZVI samples were characterized by X-ray diffraction and scanning electron microscopy before and after arsenic removal; the results showed that after the arsenic removal reaction, As2O3 and magnetite phases were detected on the surface of these samples. Kinetic studies were carried out under different reaction temperatures, with different CuSO4 concentrations, and with different iron to arsenic molar ratios (Fe/As). The kinetic data of the arsenic removal were fitted to different kinetic models. The fitting results showed that the arsenic removal process could be described by the shrinking core model, controlled by residual layer diffusion. The apparent activation energy of the reaction was 9.0628 kJ/mol, the reaction order with the CuSO4 concentrations was −0.12681, and the reaction order with the molar ratio of iron to arsenic (Fe/As) was 3.152.
Highlights
Arsenic (As) is one of the most threatening elements in the environment, because it is highly toxic and carcinogenic
Prolonging the reaction time from 5 to 30 min increased the arsenic removal rate from 84.13% to 99.5% at a reaction temperature of 20 ◦ C, and increased the arsenic removal rate from 80.72% to 99.45% at a reaction temperature of 65 ◦ C. These results indicate that the reaction temperature has little effect on the arsenic removal rate in waste acid
The results show that the molar ratio of iron to arsenic has a great influence on the arsenic removal efficiency, and the arsenic molar ratio of iron towas arsenic has a great influence on the arsenic removal efficiency, and the arsenic removal control step the residual layer diffusion
Summary
Arsenic (As) is one of the most threatening elements in the environment, because it is highly toxic and carcinogenic. Long-term exposure to high concentrations of arsenic threatens human health [1,2]. Biological activities, and processes of human industrial production activities, a large amount of arsenic is drained into water supplies [3,4,5]. Has reduced the maximum concentration threshold of arsenic from 0.05 to 0.01 mg/L in drinking water. Nowadays, increasing numbers of scientists around the world are making great efforts to reduce the arsenic concentration in groundwater, drinking water, and wastewater, and to find the most efficient and cost-effective methods for arsenic removal [4,6]
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