The effects of magnesium hydroxide dosage, PH, temperature and adsorption time on the adsorption effect were investigated by one-way experiments using magnesium hydroxide as adsorbent material. The thermodynamic and kinetic properties of adsorption of As(Ⅲ) by Mg hydroxide were investigated, and the mechanism of action was discussed.
The results showed that the removal rate of arsenic ions by magnesium hydroxide could reach more than 99% under the conditions of initial arsenic concentration between 0.5 and 100 mg/L, temperature of 25℃, pH of 3, magnesium hydroxide dosage of 0.5-4 g, and adsorption time of 1 h. The removal rate of arsenic ions by magnesium hydroxide could reach more than 99% under the same conditions. Under the same conditions, the adsorption equilibrium time of magnesium hydroxide on As(Ⅲ) in water was 80 min. The adsorption isotherm conformed to the Freundlich model, and the double constant model and parabolic kinetic equation better characterized the kinetic properties of magnesium hydroxide adsorption of As(Ⅲ). The free energy of adsorption, ΔGo, was negative, indicating that the adsorption of As(III) by Mg hydroxide was spontaneous.
The adsorption of magnesium hydroxide on arsenic ions in water is mainly reflected in its efficient adsorption capacity and spontaneous adsorption process. Research shows that the adsorption effect of magnesium hydroxide on As(Ⅲ) in water is remarkable, and the removal rate can reach more than 99%.
Adsorption conditions
The removal rate of arsenic ions by magnesium hydroxide can reach more than 99% under the conditions of initial arsenic concentration between 0.5 and 100 mg/L, temperature of 25°C, pH 3, magnesium hydroxide dosage of 0.5-4 g, and adsorption time of 1 h.12 Under the same conditions, the equilibrium time of magnesium hydroxide adsorption on As(Ⅲ) in water is 80 min. The adsorption equilibrium time for As(III) in water is 80 minutes.
Adsorption mechanism
The adsorption isotherm of As(Ⅲ) by magnesium hydroxide conforms to the Freundlich model, and the kinetic properties of adsorption of As(Ⅲ) by magnesium hydroxide are better characterized by the double constant model and parabolic kinetic equation. The free energy of adsorption, ΔGo, was negative, indicating that the process of adsorption of As(III) by Mg hydroxide was spontaneous.
Practical application
Magnesium hydroxide as an adsorbent material is suitable for arsenic ion removal in wastewater treatment with the advantages of simple operation and low cost. The adsorption effect of magnesium hydroxide can be further improved by optimizing the experimental parameters such as pH, temperature and solid-liquid ratio. In addition, magnesium hydroxide can be treated by surface modification to enhance its dispersion stability and lipophilic hydrophobicity, thus improving its adsorption capacity.