Spectroscopic and microscopic characterization of humic acids from composts made by co-composting of green waste, spent coffee and OMWW sludge.

Due to its important role in the formation of humic acids (HA), improving lignin degradation during composting has usually been considered a challenge. One practice that could stimulate the biodegradation of this recalcitrant molecule is inoculation with exogenous lignolytic fungal strains. Two composts (C1) and (C2) from piles (H1) and (H2) were evaluated. H1 was the control pile and H2 was inoculated at maturity with Trametes trogii, resulting in a 35% increase in lignin degradation rate compared to H1. The aim of this study was to show the main effects of this increase on the humification process in the co-composting of green waste, coffee grounds and olive mill wastewater sludge (OMWWs). Microstructure of HA1 and HA2 extracted from C1 and C2, respectively, was also investigated by scanning electron microscopy (SEM) and SEM coupled with energy-dispersive X-ray spectroscopy (X-EDS). The results showed that there were several similarities between the compost samples tested. These included the mineral content, the degree of polymerization (PD)> 1 and the compact and rigid surface of the extracted HA. However, C2 was characterized by a higher humic content (HC), degree of polymerization (PD), humification index (HI) and percentage of humic acids (PHA) than C1. Carbon-13 nuclear magnetic resonance (13C-NMR) and Fourier transmission-infrared spectroscopy (FTIR) analysis showed that aliphatic groups such as hydroxyls, alcohols and carboxyls were predominant in both composts. SEM analysis in conjunction with X-EDS analysis of HA2 showed a higher proportion of carbon and potassium (18 and 7.93%) than in HA1 (14 and 0.95%).

Phase transitions in (C7 H12 N2 )2 [SnCl6 ]Cl2 ·1.5H2 O crystal, studied by NMR and infrared spectroscopy.

The (C7 H12 N2 )2 [SnCl6 ]Cl2 ·1.5H2 O complex is a new member of the family of hybrid organic-inorganic perovskite compounds. It exhibits two order-disorder phase transitions with changes in the conformation of aromatic cations at the two transition temperatures 360 and 412 K. Differential scanning calorimetry, nuclear magnetic resonance (NMR), and Fourier-transform infrared (FT-IR) spectroscopy were used to investigate these phase transitions. These transition mechanisms were investigated in terms of the spin-lattice relaxation times T1 for 1 H static NMR and the chemical shifts for 13 C CP-MAS. The temperature dependence of T1(1 H) and 13 C chemical shifts are changed near TC1 and TC2 . Furthermore, the splitting for 13 C NMR signals in Phases (II) and (III) indicated a ferroelastic characteristic of the compound. In addition, FT-IR results indicate that the ordered conformational structure of aromatic cations undergoes a remarkable disorder with increasing temperature. The NMR and FT-IR studies suggest that the phase transition mechanisms are related to the reorientational motion of [C7 H12 N2 ]2+ cations as a whole. Phase transition was examined in light of the interesting optical properties of this material.

Structural differences between chitin and chitosan extracted from three different marine sources.

Three marine sources of chitin from Tunisia were investigated. Structural differences between α-chitin from shrimp (Penaeus kerathurus) waste, crab (Carcinus mediterraneus) shells, and ß-chitin from cuttlefish (Sepia officinalis) bones were studied by the (13)C NMR, FTIR, and XRD diffractograms. The (13)C NMR analysis showed a splitting of the C3 and C5 carbon signals for α-chitin, while that of ß-chitin was merged into a single resonance. The bands contour of deconvoluted and curve-fit FTIR spectra showed a more detailed structure of α-chitin in the region of O-H, N-H and CO stretching regions. IR and (13)C NMR were used to determine the chitin degree of acetylation (DA). XRD analysis indicated that α-chitins were more crystalline polymorph than ß-chitin. Shrimp chitin was obtained with a good yield (20% on raw material dry weight) and no residual protein and salts. Chitosans, with a DA lower than 20% and relatively low molecular masses were prepared from the wet chitins in the same experimental conditions. They were perfectly soluble in acidic medium. Nevertheless, chitin and chitosan characteristics were depending upon the chitin source.