title: Use of Mg-Al oxide for boron removal from an aqueous solution in rotation: Kinetics and equilibrium studies.
abstract: Mg-Al oxide prepared through the thermal treatment of [Formula: see text] intercalated Mg-Al layered double hydroxides (CO3·Mg-Al LDH) was found to remove boron (B) from an aqueous solution. B was removed by the rehydration of Mg-Al oxide accompanied by combination with [Formula: see text] . When using twice the stoichiometric quantity of Mg-Al oxide for Mg/Al = 4, the residual concentration of B dropped from 100 to 2.8 mg/L in 480 min, and for Mg/Al = 2, it decreased from 100 to 2.5 mg/L in 240 min. In both cases, the residual concentration of B was highlighted to be lower than the current Japanese effluent standards (10 mg/L). The removal of B can be explained by way of pseudo-first-order reaction kinetics. The apparent activation energy of 63.5 kJ mol(-1), calculated from the Arrhenius plot indicating that a chemical reaction dominates the removal of B by Mg-Al oxide (Mg/Al = 2). The adsorption of B acts upon a Langmuir-type phenomena. The maximum adsorption (qm) and equilibrium adsorption constants (KL) were 7.4 mmol g(-1) and 1.9 × 10(3), respectively, for Mg-Al oxide (Mg/Al = 2). [Formula: see text] in B(OH)4·Mg-Al LDH produced by the removal of B was observed to undergo anion exchange with [Formula: see text] in solution. Following regeneration, the Mg-Al oxide maintained the ability to remove B from an aqueous solution. This study has clarified the possibility of recycling Mg-Al oxide for B removal.
authors.affiliation: Graduate School of Environmental Studies, Tohoku University, 6-6-07 Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Japan. Electronic address: kameda@env.che.tohoku.ac.jp.
authors.forename: Tomohito
authors.initials: T
authors.lastname: Kameda
authors.affiliation: Graduate School of Environmental Studies, Tohoku University, 6-6-07 Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Japan.
authors.forename: Jumpei
authors.initials: J
authors.lastname: Oba
authors.affiliation: Graduate School of Environmental Studies, Tohoku University, 6-6-07 Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Japan.
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Yoshioka
mesh_terms: D000327:Adsorption; D000537:Aluminum Oxide / Q000737:chemistry*; D001895:Boron / Q000032:analysis / Q000737:chemistry*; D007700:Kinetics; D008277:Magnesium Oxide / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*
chemical_list: D014874:Water Pollutants, Chemical; D008277:Magnesium Oxide; D000537:Aluminum Oxide; D001895:Boron
keywords: Boron; Cyclic usage; Equilibrium; Kinetics; Mg–Al oxide; Removal