Synthesis of rambutan-like MnCo2O4 and its adsorption performance for methyl orange

A hierarchical rambutan-like MnCo 2 O 4 precursor is synthesized by a co-precipitation method in water–ethanol at room temperature. After being calcined at 400 °C in air for 10 min with a heating rate of 1 °C min −1 , the precursor MnCo 2 (C 2 O 4 ) 3 ·5.54H 2 O is transformed into the rambutan-like MnCo 2 O 4 microspheres composed of end-connected nanorods, which has a large specific surface area (155 m 2 g −1 ). When evaluated as adsorbent for methyl orange (MO), the rambutan-like MnCo 2 O 4 microspheres show excellent adsorption ability for methyl orange. The adsorption capacity of methyl orange on rambutan-like MnCo 2 O 4 is 185.14 mg g −1 under the conditions of initial MO concentration 12 mg L −1 and pH 2.09. Adsorption kinetics of methyl orange on rambutan-like MnCo 2 O 4 follows the pseudo-second-order kinetic model. The values of adsorption activation energy E a and enthalpy Δ H # are 5.71 ± 0.056 and 9.30 kJ mol −1 , respectively. Methyl orange adsorption on rambutan-like MnCo 2 O 4 is an endothermic and physical adsorption process.