Maria Lacalamita

The environmental and economic challenges stemming from fossil fuel dependence and climate change highlight the urgent need for sustainable biofuels. Wastewater treatment byproducts, such as sewage sludge (SS), represent a promising, yet underutilized, feedstock for biodiesel production within a circular economy. This research proposes a closed-loop valorization strategy for wastewater treatment byproducts, integrating solventless lipid extraction with the pyrolysis (at 400, 550, and 750 °C) of lipid-free residual biomass to produce the relevant biochars (BC). BCs can be functionalized (sulfonation run at 175 °C, 24 h), characterized (CHNS, FTIR, XRD, SBET, TPD, SEM), and used as catalysts for the esterification reaction of the previously extracted lipids with methanol to produce biodiesel. The extracted lipids were reacted with methanol (1:10 molar ratio, 80 °C, 5 h) using 3 wt.% of sulfonated catalysts per gram of grease, producing fatty acid methyl esters in high yield and conversion (>96%). Catalysts were easily and efficiently recoverable through centrifugation, rendering them stable and reusable for five cycles without losing their catalytic properties. This approach aims to transform SS into a valuable resource, fostering a more sustainable and efficient biofuel production system.

In Albania, the presence of high mountain chains and active fault systems favors the ascent of deep waters producing several thermo-mineral springs. The most important springs, rising from deep karst aquifers, are located in the Kruja tectonic zone (central Albania), that consists of elongated anticline structures of Cretaceous–Eocene limestones and dolomites covered by Oligocene flysch deposits, and is affected by longitudinal NW-SE faults intersected by transversal faults. The carbonate rocks have been buried up to ca. 10 km depth, and are underlain by Triassic-Permian evaporites. The geothermal gradient ranges from 7 to 11 mK/m. Five deep wells are present in the area (depth range 600-3000 m) tapping thermal waters of carbonate aquifer. Thermal waters in the central area of the Kruja province are mainly of the Cl–SO4 –Na–Ca type, with temperatures up to 56 °C for springs and 65 °C for wells, and high H2S concentrations. Recent scientific activities carried out at the Kruja Province focused on Kozan-8 well (1837 m depth) at Elbasan locality, including water and deposited minerals sampling. Thermal waters discharge exhibits EC = 6340 µS/cm, temperature of 55.4 °C, pH = 6.73, and reducing Eh. Water stable isotopes results (d18O = -8.4 ‰ and dD = -53.9 ‰) indicate a main meteoric origin of the water. Water composition shows similar high Na+ and Ca2+ contents among cations, and high Cl- and (SO4)2- among anions. Together with H2S, enrichment in CO2, CH4 and He has also been detected. This water composition may be related to the presence of deep fluids with long/deep circulation in the local anticline structures, involving Mesozoic carbonates and the underlying Triassic evaporites. At the emergence, the water results oversaturated with respect to Ca-Mg carbonates, and slightly undersaturated with respect to sulphates. Around the water discharge abundant mineral deposits are present, consisting of banded encrustations of different colours, formed from the outgoing hot fluids. Combined optical microscopy and X-ray powder diffraction analyses evidenced that the studied encrustations mainly consist of micrometric-sized crystals of Ca- and Mg-sulphates (gypsum, CaSO4·2H2O; bassanite, CaSO4·0.5H2O; epsomite, MgSO4·7H2O), calcium carbonates (aragonite and calcite, CaCO3), and sulphur (S8).

Amongst the various strategies studied to reduce polluting agents in water, both from anthropogenic and natural sources, adsorption processes are among the most widespread techniques. Layered double hydroxides (LDH, anionic adsorbers) play a fundamental role in the treatment of industrial wastewater, which often contains both anionic and cationic species. The objectives of the present study were to synthesize a (Mg, Zn)Al-NO₃ LDH, and a composite between the LDH and montmorillonite (Mnt, cationic exchanger), and to test their adsorption capacity for both cationic and anionic pollutants in two different samples of industrial wastewater. The compounds were characterized by means of inductively coupled plasma-atomic emission spectroscopy (ICP-AES), X-ray powder diffraction (XRPD), Fourier-transform infrared (FT-IR) spectroscopy, differential thermal analysis/thermogravimetry (DTA-TG), and transmission electron microscopy (TEM). Results of product yields and extraction performance provided evidence that the synthesized compounds were active in the removal of various kinds of pollutants from real wastewaters. The adsorption capacity, in the case of the removal of cations varied from ~85 to 100% and from ~92 to 100% when the LDH and the LDH-Mnt, respectively, were used. The 56–100% removal of anions was instead obtained for both the adsorbents.

The thermal behaviour of fluorcarletonite, KNa₄Ca₄Si₈O₁₈(CO₃)₄(F,OH)⋅H₂O, from the charoitites of the Severny district at the Malyy Murun massif, Murun complex, NW Aldan Shield, Siberia, Russia, has been investigated in order to understand the temperature-induced changes in the crystal structure of this rare silicate. The study has been carried out combining in situ high-temperature single-crystal X-ray diffraction (T range 25–550°C), ex situ high-temperature Fourier-transform infrared spectroscopy (25–700°C) and ab initio calculations. An increasing trend of lattice parameters and cell volume was observed in the 150–550°C temperature range, when the mineral underwent a progressive dehydration process. At 550°C ~40% water loss was detected. If compared with the fluorcarletonite structure at room temperature, the partially dehydrated fluorcarletonite shows: the same space group (P4/mbm); increased distances between the oxygens of the H₂O molecules (O11w and O12w) and their Na-centred octahedral cations (Na1 and Na2, respectively); distortion of the four- and six-member tetrahedral rings of the double silicate layer. The dehydration process mainly involves the oxygen at the O11w site which has a different local environment with respect to the oxygen at the O12w site. At T > 600°C, the complete dehydration is accompanied by deprotonation of the OH groups substituting for the F atoms and by the collapse of the structure when the CO₂ is released. The adopted approach allowed definition of the temperature thresholds at which modifications occur in the fluorcarletonite crystal structure when subjected to controlled heating conditions. Our findings contribute to assessment of stability, reactivity and, more generally, the thermal behaviour of sheet silicates with fluorcarletonite-like topology.

The controlled supply of bioactive molecules is a subject of debate in animal nutrition. The release of bioactive molecules in the target organ, in this case the intestine, results in improved feed, as well as having a lower environmental impact. However, the degradation of bioactive molecules’ in transit in the gastrointestinal passage is still an unresolved issue. This paper discusses the feasibility of a simple and cost-effective procedure to bypass the degradation problem. A solid/liquid adsorption procedure was applied, and the operating parameters (pH, reaction time, and LY initial concentration) were studied. Lysozyme is used in this work as a representative bioactive molecule, while Adsorbo^®, a commercial mixture of clay minerals and zeolites which meets current feed regulations, is used as the carrier. A maximum LY loading of 32 mg_LY/g_AD (LY(32)-AD) was obtained, with fixing pH in the range 7.5–8, initial LY content at 37.5 mg_LY/g_AD, and reaction time at 30 min. A full characterisation of the hybrid organoclay highlighted that LY molecules were homogeneously spread on the carrier’s surface, where the LY–carrier interaction was mainly due to charge interaction. Preliminary release tests performed on the LY(32)-AD synthesised sample showed a higher releasing capacity, raising the pH from 3 to 7. In addition, a preliminary Trolox equivalent antioxidant capacity (TEAC) assay showed an antioxidant capacity for the LY of 1.47 ± 0.18 µmol TroloxEq/g with an inhibition percentage of 33.20 ± 3.94%.

A synthetic approach to bond lysozyme (LY) to commercial natural carriers, namely clay minerals (bentonite, BN; and sepiolite, SP) and commercial zeolite (Phil 75^®, PH), already in use in feed formulation, is proposed. The synthetic route, which implies solid–liquid adsorption, is a simple and effective way for preparing hybrid materials characterized by LY loadings up to 37 mg_LY/g_carrier. By operating at pH 4.3, initial LY content of 37.5 mg_LY/g_carrier, and reaction time of 90 min, hybrid materials with LY loadings of 37, 35, and 12 mg_LY/g_carrier for LY-SP, LY-BN, and LY-PH, respectively were obtained. The LY initial concentration and pH, as well as the physico-chemical properties of the carries were found to be the parameters that govern the synthesis of the materials. The driving force for an effective LY adsorption and interaction is the combined Zero Point Charge (ZPC) of the carriers, always negative (in the range between −4 and −170 mV) and the positive ZPC of LY, as well as the carrier morphology, characterized by mesoporosity (pore dimensions in the range of 5–12 nm). However, it is the interaction of charges of opposite sign that mainly affects LY loadings and bond strength. Based on SEM-EDX analysis, LY molecules are quite homogeneously spread onto the carriers’ surface. TG-DTG analyses showed that the LY–carrier interaction in the hybrid materials is stronger than that in a simple mechanical mixture of the components. Specifically, in the hybrid materials, the phenomenon at 300 °C, associated to LY decomposition, is broadened and slightly shifted towards higher temperatures (320–350 °C), whereas in a mechanical mixture of the same composition, it occurs at temperatures closer to those of free LY, as if there were no or very weak interactions. At pH 3, a very little LY release, 0.03 and 0.01 mg_LY/g_carrier, was found for LY-BN and LY-PH, respectively. The latter became larger at pH 7, 0.06 mg_LY/g_carrier for both BN and PH carriers, suggesting that BN and PH are better modulators of LY release. The paper provides insights for the study and the development of new optimized feed formulations for the targeted delivery of natural compounds with antimicrobial activity, alternatives to antibiotics, and vaccinal antigens.

Strontium-substituted Ca₁₀(PO₄)₆(OH)₂ hydroxyapatite (HAp) powders, with Sr wt% concentrations of 2.5, 5.6 and 10%, were prepared by a solid-state synthesis method. The chemical composition of the samples was accurately evaluated by using inductively coupled plasma (ICP) spectroscopy. The morphology of the samples was analyzed via optical microscopy, while structural characterization was achieved through powder X-ray diffraction (PXRD) and infrared (FTIR) and Raman spectroscopy. The PXRD structural characterization showed the presence of the Sr dopant in the Ca1 structural site for HAp with a lower Sr concentration and in the Ca2 site for the sample with a higher Sr concentration. FTIR and Raman spectra showed slight band shifts and minor modifications of the (PO₄) bands with increasing the Sr doping rate.

The thermal behavior of melanterite from the Fornovolasco mine (Tuscany, Italy) has been investigated via differential thermal analysis (DTA), thermogravimetry (TG), in situ high-temperature X-ray powder diffraction (XRPD) and Fourier-transform infrared spectroscopy (FTIR). The DTA curve showed endothermic peaks at 70, 100, 260, 500–560 and 660 °C whereas the TG curve evidenced a total mass decrease of ~68%, in keeping with the loss of all H₂O and SO₄ groups. Rietveld refinements were performed for all the collected patterns in the 25–775 °C range and converged at 1.57 ≤ R (%) ≤ 2.75 and 1.98 ≤ R_wp (%) ≤ 3.74. The decomposition steps FeSO₄·7H₂O → FeSO₄·4H₂O (25 ≤ T ≤ 50 °C) → FeSO₄·H₂O (50 < T ≤ 100 °C) → FeOHSO₄ (75 < T ≤ 200 °C) → Fe₂(SO₄)₃ (400 < T ≤ 500 °C) → Fe₂O₃ (500 < T ≤ 775 °C) were obtained. The high-temperature infrared analysis confirmed that melanterite undergoes a three-step dehydration in the 25–300 °C temperature range. The FeOHSO₄ phase is stable over a wide range of temperature and transforms partially to Fe₂(SO₄)₃ without the formation of Fe₂O(SO₄)₂. The findings highlight a different behavior of the studied sample with respect to the synthetic salt.