title: Kinetics and equilibrium studies on the treatment of nitric acid with Mg-Al oxide obtained by thermal decomposition of NO3(-)-intercalated Mg-Al layered double hydroxide.
abstract: Mg-Al oxide obtained by thermal decomposition of NO(3)(-)-intercalated Mg-Al layered double hydroxide (NO(3)·Mg-Al LDH) was found to treat HNO(3), acting as both a neutralizer and fixative for NO(3)(-). The degree of NO(3)(-) removal increased with time, Mg-Al oxide quantity, and temperature. The NO(3)(-) removal could be represented by a first-order reaction. The apparent activation energy was 52.9 kJ mol(-1), confirming that NO(3)(-) removal by Mg-Al oxide proceeded under chemical reaction control. Furthermore, the adsorption of NO(3)(-) on Mg-Al oxide could be expressed by a Langmuir-type adsorption isotherm. The maximum adsorption amount and equilibrium adsorption constant were 3.8 mmol g(-1) and 1.33, respectively. The Gibbs free energy change was -18 kJ mol(-1), confirming that the uptake of NO(3)(-) from HNO(3) by Mg-Al oxide proceeded spontaneously.
authors.affiliation: Graduate School of Environmental Studies, Tohoku University, 6-6-07 Aoba, Aramaki, Sendai 980-8579, 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