Removal of Cu(II) from aqueous solution using a composite made from cocoa cortex and sodium alginate.

The aim of this work was to prepare a composite material based on cocoa cortex and sodium alginate and test it to remove Cu(II) ions in aqueous solution in batch conditions. The composite was characterized using elemental analysis, scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA/DTG), and point of zero charge. The highest amount of adsorbed Cu(II) for the composite was 19.54 mg/g, i.e., 95.32% of an initial concentration of 100 mg/L. Under the same conditions, the cocoa cortex untreated exhibited extremely low adsorption, while when it was treated with hot soda, it adsorbed 13.67 mg/g. Adsorption by the composite reached the equilibrium after 220 min. Kinetic data analysis suggested that the process was governed by adsorption (pseudo-second-order model) and diffusion through macropores and/or mesopores (intra-particle model). The adsorption isotherm that best described the system was Langmuir's. The maximum adsorption capacity of Cu(II) was 76.92 mg/g. The values of the thermodynamic parameters indicated that the process was spontaneous, with ΔG° values between (- 7.886 and - 9.458 kJ/mol) and endothermic, with ΔH° = 7.728 kJ/mol. Graphical abstract.

Atomistic models for CeO(2)(111), (110), and (100) nanoparticles, supported on yttrium-stabilized zirconia.

Ceria is an important component in three-way catalysts for the treatment of automobile exhaust gases owing to its ability to store and release oxygen, a property known as the oxygen storage capacity. Much effort has been focused on increasing the OSC of ceria, and one avenue of exploration is the ability to fabricate CeO(2)-based catalysts, which expose reactive surfaces. Here we show how models for a polycrystalline CeO(2) thin film, which expose the (111), (110), and dipolar (100) surfaces, can be synthesized. This is achieved by supporting the CeO(2) thin film on an yttrium-stabilized zirconia substrate using a simulated amorphization and recrystallization strategy. In particular, the methodology generates models which reveal the atomistic structures present on the surface of the reactive faces and provides details of the grain-boundary structures, defects (vacancies, substitutionals, and clustering), and epitaxial relationships. Such models are an important first step in understanding the active sites at the surface of a catalytic material.