Giulia Cimo

Effect of heating time and temperature on the chemical characteristics of biochar from poultry manure.

Poultry manure (PM) chars were obtained at different temperatures and charring times. Chemical-physical characterization of the different PM chars was conducted by cross-polarization magic angle spinning (CPMAS) (13)C NMR spectroscopy and thermal analysis. CPMAS (13)C NMR spectra showed that the chemical composition of PM char is dependent on production temperature rather than on production duration. Aromatic and alkyl domains in the PM chars obtained at the lowest temperatures remained unchanged at all heating times applied for their production. The PM char obtained at the highest temperature consisted only of aromatic structures having chemical nature that also appeared invariant with heating time. Thermogravimetry revealed differences in the thermo-oxidative stability of the aromatic domains in the different PM chars. The PM char produced at the highest temperature appeared less stable than those produced at the lowest temperatures. This difference was explained by a protective effect of the alkyl groups, which are still present in chars formed at lower temperature. The analysis of the chemical and physicochemical character of poultry manure chars produced at different temperatures can increase understanding of the role of these materials in the properties and behavior of char-amended soils.

Structure alteration of a sandy-clay soil by biochar amendments

PurposeThe aim of the present study was to investigate structure alterations of a sandy-clay soil upon addition of different amounts of biochar (fbc).Materials and methodsAll the fbc samples were analyzed by high energy moisture characteristic (HEMC) technique and 1H nuclear magnetic resonance (NMR) relaxometry. HEMC was applied in order to evaluate aggregate stability of biochar-amended soil samples. 1H NMR relaxometry experiments were conducted for the evaluation of the pore distributions through the investigation of water dynamics of the same samples.Results and discussionThe HEMC technique revealed improvement in aggregate stability through measurements of the amount of drainable pores and the stability ratio. The latter increased as the amount of biochar was raised up. The 1H NMR relaxometry revealed a unimodal T1 distribution for both the sole sandy-clay soil and the biochar. Conversely, a bimodal T1 distribution was acquired for all the different fbc samples.ConclusionsImprovement in aggregate stability was obtained as biochar was progressively added to the sandy-clay soil. A dual mechanism of water retention has been hypothesized. In particular, intra-aggregate porosity was indicated as the main responsible for molecular water diffusion when fbc comprised between 0 and 0.33. Conversely, inter-aggregate porosity resulted predominant, through swelling processes, when fbc overcame 0.33.

Mechanisms of Water Interaction with Pore Systems of Hydrochar and Pyrochar from Poplar Forestry Waste

The aim of this study was to understand the water-surface interactions of two chars obtained by gasification (pyrochar) and hydrothermal carbonization (hydrochar) of a poplar biomass. The two samples revealed different chemical compositions as evidenced by solid state (13)C NMR spectroscopy. In fact, hydrochar resulted in a lignin-like material still containing oxygenated functionalities. Pyrochar was a polyaromatic system in which no heteronuclei were detected. After saturation with water, hydrochar and pyrochar were analyzed by fast field cycling (FFC) NMR relaxometry. Results showed that water movement in hydrochar was mainly confined in very small pores. Conversely, water movement in pyrochar led to the conclusion that a larger number of transitional and very large pores were present. These results were confirmed by porosity evaluation derived from gas adsorption. Variable-temperature FFC NMR experiments confirmed a slow-motion regime due to a preferential diffusion of water on the solid surface. Conversely, the higher number of large pores in pyrochar allowed slow movement only up to 50 °C. As the temperature was raised to 80 °C, water interactions with the pore surface became weaker, thereby allowing a three-dimensional water exchange with the bulk liquid. This paper has shown that pore size distribution was more important than chemical composition in affecting water movement in two chemically different charred systems.

Preliminary identification and quantification of steroid hormones in the red palm weevil, Rhynchophorus ferrugineus

In the present preliminary study, we used a gas chromatography–mass spectroscopy (GC-MS) method to identify and quantify steroid hormones, their precursors and metabolites in whole body of red palm weevil (RPW) R. ferrugineus adults. We identified a total of seven steroids by single ion monitoring mode (SIM) analysis and compared them to the National Institute of Standards and Technology (NIST) library. The steroids include: dehydroepiandrosterone (DHEA), estrone, estradiol-17β, testosterone, progesterone, cortisol and cholesterol, whereas pregnenolone, pregnan-20-one-17-hydroxy and corticosterone were not detected. This study shows that some invertebrate groups seem to use partially or totally comparable hormones to vertebrates and produce vertebrate-type steroids with functional roles. However, some steroids of the endocrine system of invertebrates are still lacking or yet to be identified in most phyla.

Conformational Redistribution of Honey Components following Different Storage Conditions

The present study aims at the investigation of the changes in water distribution among the organic components of selected honey samples following honey storage at different temperatures. Results, achieved by application of fast field cycling NMR relaxometry, revealed that the organic constituents were homogeneously distributed within the whole samples stored at room temperature. Conversely, after four months of refrigeration at 4°C, the organic systems were included in persistent clusters, as a consequence of the water release due to the larger stability of the intramolecular interactions over the intermolecular ones. The new conformational arrangements of the honey constituents entailed enhancement of honey moisture content. For this reason, it can be suggested that honey refrigeration prior to storage at room temperature may be detrimental for its long-term storage. In fact, higher risk of fermentation may occur once the sample is warmed after the first refrigeration step.