The adsorption and decomposition of methanol on clean Ru(0001) were investigated by reflection−absorption infrared spectroscopy (RAIRS). At low temperature (90 K) and coverage (0.1 L), it was confirmed that methanol adsorbs dissociatively as methoxide (CH3O−). No experimental evidence was obtained of an alternative decomposition for high coverage. Different bonding sites and geometries, depending on temperature and coverage, were proposed for methoxide and correlated with the corresponding CO stretching wavenumbers. Methoxide may either undergo complete dehydrogenation into CO(ads) and H(ads), if annealed in small temperature steps (in the range between 110 and 320 K), or partial dehydrogenation into very stable η2-formaldehyde, by a one-step thermal activation (from 130 K to at least 190 K), in the presence of previously formed products (CO and atomic species). At high temperatures (≥190 K), methanol undergoes O−H, C−H, and C−O bond scission, leaving surface fragments undetectable by RAIRS. However, in a sequential dosing, the fragments from the first methanol molecules that hit the surface seem to have a passivating effect on Ru(0001). Subsequent doses undergo only partial dehydrogenation, yielding η2-formaldehyde, which was isolated on the surface in two bonding configurations: bridging [μ2-η2(C,O)-H2CO] and chelating [μ1-η2(C,O)-H2CO], characterized by the νCO mode at 1262 and 1277 cm-1, respectively. This assignment was confirmed by adsorbing CD3OH. The bridging form is favored at lower coverage. Formaldehyde prepared by sequential dosing is stable on the surface up to at least 290 K, although some dehydrogenates to CO(ads) above 190 K.
Industrial production of novel microalgal isolates is key to improving the current portfolio of available strains that are able to grow in large-scale production systems for different biotechnological applications, including carbon mitigation. In this context, Tetraselmis sp. CTP4 was successfully scaled up from an agar plate to 35- and 100-m3 industrial scale tubular photobioreactors (PBR). Growth was performed semi-continuously for 60 days in the autumn-winter season (17th October – 14th December). Optimisation of tubular PBR operations showed that improved productivities were obtained at a culture velocity of 0.65–1.35 m s−1 and a pH set-point for CO2 injection of 8.0. Highest volumetric (0.08 ± 0.01 g L−1 d−1) and areal (20.3 ± 3.2 g m−2 d−1) biomass productivities were attained in the 100-m3 PBR compared to those of the 35-m3 PBR (0.05 ± 0.02 g L−1 d−1 and 13.5 ± 4.3 g m−2 d−1, respectively). Lipid contents were similar in both PBRs (9–10% of ash free dry weight). CO2 sequestration was followed in the 100-m3 PBR, revealing a mean CO2 mitigation efficiency of 65% and a biomass to carbon ratio of 1.80. Tetraselmis sp. CTP4 is thus a robust candidate for industrial-scale production with promising biomass productivities and photosynthetic efficiencies up to 3.5% of total solar irradiance.
Cellulose acetate films dyed with pseudoisocyanine iodide (1,1'-diethyl-2,2'-cyanine iodide) have been produced by spin coating and their structures characterized by FTIR spectroscopy. The aggregation of the cyanine during the spinning process was induced by addition of KI to the precursor solution, and the formation of J-aggregates was observed by UV-vis spectroscopy. The detailed analysis of the O-H stretching mode of cellulose acetate allowed us to understand the types of hydrogen bonds existing in the pure matrix films, in films containing just cyanine monomers and J-aggregates as well. It has been shown that cyanine monomers, even in a large concentration, have a small influence on the cellulose acetate structure, by favoring the replacement of some intermolecular by intramolecular hydrogen bonds. On the contrary, the presence of cyanine J-aggregates remarkably modifies the arrangement of the polymer chains, inducing an extensive formation of intermolecular hydrogen bonds in the C2, C3, and/or C6 positions of the glucopyranose rings. These intermolecular bonds do not involve the carbonyl groups, as the CdO stretching mode is not affected. This effect has been interpreted in terms of a higher degree of packing of the cellulose acetate amorphous phase, due to the presence of J-aggregates. The infrared spectra of the cyanine, in the wavenumber windows where the matrix does not absorb, have shown that the pseudoisocyanine molecule keeps the all-trans conformation upon aggregation. The modifications in the quinolines out of plane C-H deformations have indicated that the J-aggregates are formed by overlap of the phenyl rings of neighbor cyanines, leaving the heterocyclic moieties unperturbed.
Biological treatment with dissimilatory sulphate-reducing bacteria has been considered the most promising alternative for decontamination of sulphate rich effluents. These wastewaters are usually deficient in electron donors and require their external addition to achieve complete sulphate reduction. The aim of the present study was to investigate the possibility of using food industry wastes (a waste from the wine industry and cheese whey) as carbon sources for dissimilatory sulphate-reducing bacteria. The results show that these wastes can be efficiently used by these bacteria provided that calcite tailing is present as a neutralizing and buffer material. A 95 and 50 % sulphate reduction was achieved within 20 days of experiment by a consortium of dissimilatory sulphate-reducing bacteria grown on media containing waste from the wine industry or cheese whey respectively. Identification of the dissimilatory sulphate-reducing bacteria community using the dsr gene revealed the presence of the species Desulfovibrio fructosovorans, Desulfovibrio aminophilus and Desulfovibrio desulfuricans. The findings of the present study emphasise the potential of using wastes from the wine industry as carbon source for dissimilatory sulphate-reducing bacteria, combined with calcite tailing, in the development of cost effective and environmentally friendly bioremediation processes.
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