[Adsorption properties of thiocyanate anion on granular Mg/Al mixed oxides]

Granular Mg/Al mixed oxides (G-Mg3.3 AlO4.8) was successfully synthesized by using Mg/Al layered double hydroxide (Mg/Al-LDH) as the precursor. Its structure was characterized by analytical methods of BET, XRD, SEM and FT-IR. Adsorption properties of thiocyanate anion (SCN-) on this new material were also investigated. Specific surface area and average pore width of G-Mg3.3 AlO4.8 are 269.4 m2 x g(-1) and 13.25 nm respectively. Molding and granulation retains the layer structure and generates no new phase. Freundlich isotherm equation and pseudo-second-order kinetic equation can describe the static adsorption process precisely and adsorption capacity reaches 165.8 mg x g(-1) at 25 degrees C and 500 mg x L(-1). Yoon-Nelson model can predict the breakthrough curves of SCN- on G-Mg3.3 AlO4.8 precisely. The breakthrough adsorption capacity reaches 50.73 mg x g(-1) under the conditions with initial concentration is 100 mg x L(-1), flow rate is 5 mL x min(-1), bed layer altitude is 10 cm and initial pH is 6. The removal rates of SCN- are all above 98% after reusing four times. Consequently, G-Mg3.3 AlO4. 8 is a reusable and high-efficient adsorbent.