Preparation of CNTs/MgAl-LDHs Composites and their Adsorption Properties for Chloride Ions

Abstract

Magnesium-aluminum hydrotalcite and carbon nanotube composites (CNTs/MgAl-LDHs) were prepared by one-step hydrothermal method using magnesium nitrate, aluminum nitrate and carbon nanotubes as raw materials and urea as precipitant. The samples were characterized by SEM, XRD, BET and other methods. The adsorption properties of CNTs/MgAl-LDHs on chloride ions and the factors affecting the adsorption of chloride ions were studied. The results show that the prepared CNTs/MgAl-LDHs exhibit a three-dimensional honeycomb structure with a specific surface area of 103.019 m2/g, which is larger than the specific surface area of MgAl-LDHs of 84.344 m2/g. The results showed that the optimal adsorption conditions were: adsorption temperature was 45°C, the pH value was 8, the adsorption time was 100 min, the Cl- concentration was 0.01 M (584 mg/L), and the adsorbent concentration was 1.0 g/L. CNTs/MgAl-LDHs has the best adsorption performance for chloride ions. The maximum adsorption capacity is 75.58 mg/g. The adsorption isotherms and adsorption kinetics are consistent with the Langmuir isotherm model and the quasi-secondary kinetic model.