Ferromagnetic exchange interaction in a new Ir(IV)-Cu(II) chain based on the hexachloroiridate(IV) anion

The iridium(IV) complex (NBu4)2[IrCl6] (1) has been synthetised, characterised and used as a precursor to prepare the new chloro-bridged heterobimetallic IrIV-CuII chain of formula {IrCl5(μ-Cl)Cu(viim)4}n (2) [viim = 1-vinylimidazole]. The crystal structure and magnetic properties of 1 and 2 have been investigated. Both compounds crystallise in the monoclinic system with space group C2/c. Each Ir(IV) ion in both 1 and 2 is six-coordinate and bonded to six chloride ions in a regular octahedral geometry. In compound 2, the Cu(II) ion exhibits an axially elongated octahedron with four N atoms, from four monodentate viim ligands, that form the equatorial plane, and two chloride ions that occupy the axial positions. The way in which the anionic [IrCl6]2− units are arranged in the crystal packing of 1, well separated from each other by means of the bulky NBu4+ cations, avoids significant intermolecular Ir-Cl⋯Cl-Ir interactions. The crystal lattice of 2 shows adjacent Ir(IV)-Cu(II) chains that are connected through π⋯π stacking interactions, and are organized adopting perpendicular arrangements. The study of the magnetic properties of 1 and 2 through dc magnetic susceptibility measurements reveals that 1 shows magnetic behaviour typical of noninteracting mononuclear centres with S = 1/2, whereas 2 exhibits ferromagnetic exchange coupling between the Cu(II) and Ir(IV) metal ions linked through chloride ligands. In addition, ac magnetic susceptibility measurements show a field-induced slow relaxation of the magnetisation for 1, indicating single-ion magnet (SIM) behaviour for this mononuclear Ir(IV) system

Anaerobic membrane bioreactor (AnMBR) scale-up from laboratory to pilot-scale for microalgae and primary sludge co-digestion: Biological and filtration assessment

This research work proposes the scale-up evaluation in terms of biological and filtration performance from laboratory to pilot-scale of an anaerobic membrane bioreactor (AnMBR) co-digesting raw microalgae and primary sludge. Best operating conditions for this scale-up were energetically and economically assessed based on laboratory results. Economic balance showed 3% higher annual costs when operating a reactor at 100 d solids retention time (SRT) compared to 70 d SRT. Energetic balance showed a 5.5-fold increase in heat demand working at thermophilic temperature comparing to mesophilic. The AnMBR operating conditions were set at 70 d SRT and 35 °C. The pilot-scale and lab-scale co-digesters performed similarly in terms of biogas production andsystem stability. 154 mLbiogas·d−1·L−1 reactor were produced at pilot-scale, corresponding to methane yield of 215 mLCH4·gCODinf −1. AnMBR filtration at both laboratory and pilot-scale showed stability working at permeate fluxes of 4.2-5.8 L·m−2·h−1