title: Treatment of waste H₂SO₄ with Mg-Al oxide obtained by calcination of NO₃⁻-intercalated Mg-Al layered double hydroxide: Kinetics and equilibrium.
abstract: Mg-Al oxide obtained by calcination of NO(3)(-)-intercalated Mg-Al layered double hydroxide (NO(3)•Mg-Al LDH) was used to treat H(2)SO(4), acting as both a neutralizer of the acid and a fixative for SO(4)(2-). The fraction of SO(4)(2-) removed increased with time and with increasing Mg-Al oxide quantity and temperature. The rate of SO(4)(2-) removal followed first-order kinetics with apparent rate constants of 2.0 × 10(-3), 4.4 × 10(-3), and 5.3 × 10(-2) min(-1) at 10, 30, and 60°C, respectively. The apparent activation energy was 52.1 kJ mol(-1), confirming that the SO(4)(2-) removal by Mg-Al oxide proceeded under chemical reaction control. Furthermore, the adsorption isotherm of SO(4)(2-) by Mg-Al oxide obeyed the Langmuir equation. The maximum adsorption amount was 2.0 mmol g(-1), or 4.0 meq g(-1), indicating that Mg-Al oxide has a large capacity for uptake of SO(4)(2-) from H(2)SO(4).
authors.affiliation: Graduate School of Environmental Studies, Tohoku University, Aramaki, Aoba-ku, Sendai, Japan. kameda@env.che.tohoku.ac.jp
authors.forename: Tomohito
authors.initials: T
authors.lastname: Kameda
authors.forename: Yuki
authors.initials: Y
authors.lastname: Fubasami
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Yoshioka
mesh_terms: D000327:Adsorption; D017607:Aluminum Compounds / Q000737:chemistry*; D000536:Aluminum Hydroxide / Q000737:chemistry*; D007220:Industrial Waste; D007700:Kinetics; D017616:Magnesium Compounds / Q000737:chemistry*; D008276:Magnesium Hydroxide / Q000737:chemistry*; D009566:Nitrates / Q000737:chemistry; D013464:Sulfuric Acids / Q000737:chemistry*; D014865:Waste Disposal, Fluid / Q000379:methods*; D014961:X-Ray Diffraction
chemical_list: D017607:Aluminum Compounds; D007220:Industrial Waste; D017616:Magnesium Compounds; D009566:Nitrates; D013464:Sulfuric Acids; C110424:aluminum magnesium oxide; D000536:Aluminum Hydroxide; D008276:Magnesium Hydroxide; C033158:sulfuric acid