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Removing carbon dioxide from industrial effluents (i.e. flue gas) via solid sorbents is a potential greenhouse gas mitigation strategy. Lithium orthosilicate (Li4SiO4) is one of the most promising materials for CO2 capture at high temperature (500-700 °C). In this study, the non-hydrolytic sol-gel technique was used to synthesized Li4SiO4 nanoparticles for improving lithium silicate features as solid sorbent for carbon dioxide. The CO2 sorption properties of the obtained nanoparticles were investigated by using a thermal gravimetric analyzer (TGA) in a controlled gas flow environment at CO2 partial pressure of 0.6 atm and at 700 °C. Li4SiO4 nanoparticles with average diameter less than 100 nm aggregated in clusters less than 500 nm were obtained. An amount of adsorbed carbon dioxide of 6.9 mmol of CO2/g sorbent, corresponding to an 82.4 % conversion of lithium orthosilicate, was reached. The promising results could be related to high surface area of nano-size material synthesized by sol- gel process.

Hydrothermal carbonization (HTC) is a thermo-chemical process for recovery and valorization of biomass and organic waste that uses sub-critical liquid water as a reaction medium for converting feedstock into value- added products.. HTC treatment produces a carbonaceous solid, named hydrochar, with attractive characteristics that can be used in a variety of applications, such as activated carbon or soil amendment. In this study, activated carbons were prepared by KOH chemical activation of hydrochars obtained from hydrothermal carbonization of green waste and municipal solid waste. The effects of precursors and different KOH/char mass ratios on physical characteristics of the activated carbon were investigated. Methylene blue and iodine numbers were determined to evaluate the adsorption properties of obtained activated carbons. The results have shown a significant increase of porosity and a change in hydrochar structure by KOH activation method. The amount of mesopores and micropores increase with increasing KOH/char ratio. In particular, the sample by treatment of hydrochar from green waste activated with a 2:1 KOH/char weight ratio presented good mesoporosity, with a methylene blue number of 385 mg/g, and a well-developed micropore structure, with iodine number of 747 mg/g. Therefore, the application of KOH activated hydrochar as activated carbon appears to be promising.

In recent years, small scale cogeneration systems (< 500 kWe) distributed in different geographical locations using biomass has received special attention as economically competitive and environmentally friendly ways of producing energy. These systems can be integrated to industrial and agricultural activities where biomass residues are generated and can be converted into electricity and thermal energy by combustion or gasification. The legislations of many European countries such as Italy concerning renewable energy and energy efficiency along the taxation schemes have raised the incentives for small scale cogeneration plants. Consequently, there is a clear economic interest of the companies in this sector and there is also a scientific interest towards demonstration of their energetic efficiency, environmental performance and reliability. Among the suggested technologies for the biomass conversion into energy, downdraft gasification (using air as gasification agent), coupled with internal combustion engines, has the advantage of high electric efficiency (~ 25%) and low tar generation, making easier the gas cleaning process necessary for its use into engines. In the present work, the results of a measurement campaign performed on a commercial scale 350 kWth downdraft woodchips gasification plant, coupled with an SI internal combustion engine (ICE), are presented and discussed. The main goals of this first experimental campaign have been to verify the stability of gasifier and engine operation, operability of the plant and to determine its energy efficiency. The campaign verified a stable operation of the gasifier and the plant produced a syngas with a composition suitable for a gas engine. The energy balance resulted in a potential overall wood fuel to electricity efficiency of about 23 %.

With the awareness of the need for optimal and sustainable use of natural resources, hydrothermal treatment of biomass and biomass waste for energy and resource recovery has received increasing attention. The hydrothermal carbonization (HTC) of a biomass is achieved using water as the reaction medium and applying mild temperatures (180–250 ° C) under saturated pressure (autogenous or provided by a gas) for several hours. The thermochemical process applied to biomass includes simultaneous reactions of hydrolysis, dehydration, decarboxylation, condensation, polymerization and aromatization of the original precursor. The main resulting products are a carbon-rich solid, known as hydrochar, and a water phase containing soluble organic compounds. In this work, an experimental study on HTC process of orange peels to assess the yield of levulinic acid in water phase during the acid-catalyzed hydrolysis is reported. The results are promising, and comparable with other lignocellulosic biomass sources.

Since the CO2 separation is the first and most energy intensive step of carbon capture and storage (CCS) technology, many research have targeted at improving the current technologies or developing new approaches of CO2 separation and capture. In this study, lithium orthosilicate-based pellets were developed and characterized as potential regenarable high-temperature CO2 sorbents. A mechanical method was used for pelletization of the powdered materials, namely K2CO3-doped lithium silicate (Li4SiO4). For increasing the performance of the pellets over multiple cycles an activation strategy was applied: the powdered sorbents were pelletized with a binder for enhancing their porosity by applying a thermal activation before adsorption process. Different amounts of binders (layered graphite and carbon nanotubes) were added to powered doped-sorbent in order to identify the optimal amount to ensure an adequate porosity into the pellets. The CO2 sorption properties of the obtained pellets were investigated by using a thermal gravimetric analyzer (TGA) in a controlled gas flow environment at low CO2 partial pressure (0.04 atm). Compared to the pure K2CO3-doped lithium silicate pellets, the sorbents prepared using layered graphite showed greater CO2 capture capabilities, which were ascribed to the higher porosity developed as a result of the activation. At 580 °C and a CO2 partial pressure of 0.04 atm, the uptake of CO2 in pellets prepared with 20 % of graphite reached about 200 mg CO2/g sorbent within 120 minutes corresponding to a Li4SiO4-conversion of 72.1 %. During multiple sorption/desorption cycles, a decay of the sorption capacity of the pellets was observed due to a partial sintering of the materials.

Polyhydroxyalkanoates (PHAs) are a family of biopolyesters produced by many bacteria as intracellular storage carbon and energy source. Poly-ß-hydroxybutyrate (PHB) is probably the most common type of PHA. It is biodegradable and renewable, with relevant thermoplastic properties along with adjustable thermal and mechanical properties. The thermoplastic properties of PHB and its biodegradability make it a potential alternative to petroleum-based plastics. Several microorganisms growing in the dark and/or in the light produce PHB. The polymer is mainly accumulated in the cytoplasm of cells when microorganisms are growing under conditions of stress. If purple non-sulfur photosynthetic bacteria (PNSB) are grown under nitrogen starvation conditions, a photoevolution of molecular hydrogen occurs as well. The PHB amount increases when carbon and energy sources are in excess, but the growth is limited, for example, by the lack of a nitrogen, phosphorous or sulfur source. This work deals the possibility of producing PHAs by photosynthetic microorganisms belonging to cyanobacteria and PNSB. Different culture broths, with and without organic carbon sources, were investigated to maximize PHA production by photosynthetic microorganisms. An unbalanced agro-industrial wastewater has been also investigated in the present study. It concerns the olive mill wastewater (OMW) containing significant reusable carbon fractions suitable for an eco-efficient valorization by feeding photosynthetic processes. The maximum PHA concentration in a cyanobacterium dry- biomass was 317 mg/L, when growing cells in a medium with a low content of acetic acid (LAC). In PNSB dry- biomass the maximum PHB content was 215 mg/L, when growing PNSB in a synthetic medium. A simultaneous H2 co-production (1,295 mL/L of culture) was cumulated as well, at the end of the process.

In this work, blends of poly(3-hydroxybutyrate) (PHB), the most widespread member of the polyhydroxyalkanoates (PHAs), with wood fibres were investigated to assess the feasibility of producing biodegradable materials suitable for applications in packaging and agricultural environment. Due to its high crystallinity, PHB is stiff and brittle resulting in very poor mechanical properties with low extension at break, which limits its range of application. PHB was compounded successfully with wood fibres up to 30 % by weight in presence of polyethylene glycol (PEG) by extrusion. The composites were characterized by differential scanning calorimetry (DSC) and by scanning electron microscopy (SEM). Their mechanical properties were tested by dynamic mechanical thermal analysis (DMTA) and tensile tests. Preliminary tests in soil were carried out on the samples with wood fibres in order to investigate their biodegradation behavior, and further tests were performed in compost. Polyethylene glycol resulted effective as lubricating agent for the production of composites based on PHB and fibres. The good preliminary biodegradability results in soil showed that the blends PHB/wood fibres appear suitable for the production of natural fibre-reinforced thermoplastic items degradable in agricultural environment.

In this study, high-temperature CO2 capture by solid sorbent based on lithium orthosilicate (Li4SiO4) was investigated in the presence of gas contaminants, such as NO and SO2. Simulated flue gas containingCO2 (4 vol%), SO2 (up to 2,000 ppm), and NO (up to 1,000 ppm) was used during the CO2 capture process. The CO2 sorption properties of the sorbent were investigated at high temperature (580 °C) by a thermal gravimetric analyzer (TGA). The tested sorbent showed high CO2 sorption capacity (210 mg CO2/g sorbent) along with high absorption rates, and lower regeneration temperature than other solids such as calcium oxide. The results also showed that the solid sorbent is inert with respect to NO. Instead, the presence of SO2 resulted in a negatively effect on the sorption capacity of the sorbent, due to an irreversible reaction with the adsorbent. Thus, industrial application would require desulfurization of flue gas prior to contacting the sorbent.

The use of plastics packaging is widespread. For this reason, there is a growing interest in develop of novel materials by blends of synthetic and natural polymers which can help to reduce the environmental impact of plastics. Hydrolyzed collagen (HC) from leather industry is an inexpensive natural biopolymer and it is a promising material for blending with synthetic polymers (e.g., polyethylene) to produce different types of item (it is no food competition, low cost, and biodegradable-compostable). Due to the wide di?erence in polarity, the natural polymer does not disperse easily in nonpolar thermoplastics, therefore the structural di?erencesbetween polyethylene and collagen hydrolizate make them incompatible. Thus, in this work compatibilizingagents as maleic anhydride functionalized ethylene elastomers have been used. The content of HC in polyethylene matrix varied between 10 and 50 wt%. Transparent, cohesive and flexible films, having an average thickness of 60 µm, were obtained by using the film blowing technique. Film blowing is a shaping technique used extensively to produce most plastics films and bags for packaging applications. The extruded films were characterized through mechanical testing, scanning electron microscopy, and thermal analysis. The films containing up to 20 % of collagen hydrolizate, in the presence of compatibilizing agents, are characterized by satisfactory thermal-mechanical properties. Thus HC/PE blends appear as promising candidate for the production of innovative material suitable for production of thermoplastic items for applications in packaging and agricultural segments.

Actually, several applications of small (=1 MWe) CHP (Combined Heat and Power) plants fuelled with solid wood can be found in Europe. Innovative technologies are facing the market, giving new perspectives for wood utilisation in district heating and/or in industrial-commercial activities. However, while the energy saving and the environmental benefits of CHP plants are undoubted, technological and no technological barriers still obstacle their large diffusion. The present study reports a comparative evaluation of the different available technologies in terms of thermal and electric efficiencies and their possible applications. Taking into consideration the electric-thermal performances of each configuration and the actual economic incentives guaranteed by the Italian government, a preliminary estimation of economic convenience of each plant is given.

As an alternative to the traditional process based on the use of sulfides, an unhairing process in drum by hydrogen peroxide, named DEPOXO, was developed for the production of high-quality bovine upper leather. A preliminary investigation at laboratory scale has allowed to set out the optimal process conditions, in terms of H2O2 dosage (9 %) and pH (12.5), in order to achieve an effective unhairing and a compatible swelling of hides. The following pilot-scaled runs have assessed the industrial feasibility of the process that allows the production of a versatile base for different final applications of the leather (either chrome or vegetable tanned), and appear practical to implement. The crust leather obtained by the oxidative unhairing process showed good physical-mechanical and technical properties comparable with those obtained by the traditional one, and the leather was technically assessed as satisfactory and suitable according to the market request. The actual reduction of the environmental impact of the novel process, in relation with the traditional one, was evaluated performing a Life Cycle Assesment (LCA) using SimaPro 7.3, one of the most used software for LCA analysis. The results of the life cycle impact assessment underline that damages on main impact categories are greatly reduced through the adoption or the oxidative unhairing. Therefore, the DEPOXO process appears a feasible process, either from the environmental or from the technical point of view, to produce high quality bovine upper leather.

The Life Cycle Assessment (LCA) is an ISO standardized and widely used methodology for environmental assessment of products, processes and services, by identifying, quantifying and evaluating all the resources consumed and all the emissions and wastes released. The LCA methodology enables adequate comparison between different remediation options and can be used as a decision-making tool for the authorities. In this study, LCA was used to compare, in terms of their associated environmental burdens, two scenarios for managing the contaminated dredged sediments of the seabed of the Livorno Port area. The compared options were: (i) confined longshore disposal, i.e. placement of dredged material in a confined disposal facility; (ii) phytoremediation treatment, by an association of salt-tolerant shrub and grass species, aimed at turning the polluted sediment an agronomic substrate (techno-soil). The results of the life cycle impact assessment underline that the potential impacts of the two compared options involve different environmental problems. Indeed, for phytoremediation the most significant impacts are related to energy and resources consumption, while for the confined disposal is related to loads in the marine ecotoxicity categories. Therefore, phytoremediation can be considered a promising alternative solution for the management and valorization of contaminated dredged sediments.

In this study, lithium orthosilicate-based pellets were developed and characterized as potential regenarable high-temperature CO2 sorbents. A mechanical method was used for pelletization of the powdered materials, namely K2CO3-doped lithium silicate (Li4SiO4) with cellulose fibres. Different amounts of cellulose fibres (20, 30 and 40 wt%) were added to powered doped-sorbent in order to identify the optimal amount to ensure an adequate porosity to the produced pellets. The CO2 sorption properties of the produced pellets were investigated at high temperature (500 - 600 °C) by using a thermal gravimetric analyzer (TGA) at low CO2 partial pressure with repeated calcination/carbonation cycles. Compared to the pure K2CO3-doped lithium silicate pellets, the sorbents prepared using cellulose fibres showed greater CO2 capture capabilities, which were ascribed to the higher porosity developed as a result of thermal degradation of cellulose. At 580 °C and a CO2 partial pressure of 0.04 atm, the uptake of CO2 in pellets prepared with 20 % of cellulose fibres reached about 20 wt% within 120 min corresponding to a Li4SiO4-conversion of 57 %. During multiple sorption/desorption cycles, a decay of the sorption capacity of the pellets was observed due to a partial sintering of the materials. This suggested that an appropriate binder should be added in order to improve the cyclic stability and the strength of the produced pellets.

In this paper, a one-dimensional unsteady state mathematical model for the simulation of a small scale fixed-bed updraft gasifier is presented. The model is based on a set of differential equations which couples heat and mass transport in the solid and gas phases with sewage sludge drying and devolatilization, char gasification and combustion of both char and gaseous species. The model was used to simulate the behavior of sewage sludge with 20 % moisture in an updraft fixed-bed gasifier (2 m height, 0.165 m i.d.) of a pilot-scale plant operating at atmospheric pressure. Good agreement was achieved between predictions and experimental measurements for the dynamic axial temperature profiles and the steady state composition of the producer gas.

Solid sorbents based on lithium orthosilicate (Li4SiO4) have shown promise for CO2 capture at high temperature. Improved sorption properties can be obtained by appropriate doping. In this study, different promoted Li4SiO4-based sorbents were prepared by addition of potassium carbonate and binary/ternary alkali (Li, K and Na) carbonate eutectic mixtures. The CO2 sorption properties of the sorbents were investigated by thermal gravimetric analysis (TGA) at different temperatures in the range between 500 and 600 °C and at low CO2 partial pressure (0.04 atm). The results showed that all the promoters used noticeably improved the CO2 sorption capacity in comparison to no-promoted Li4SiO4. At the optimum sorption temperature of 580 °C, Li4SiO4 with addition of 30 wt% of K2CO3 showed the best CO2 adsorption proprieties with sorption capacities of 230 mg CO2/g sorbent corresponding to a conversion of about 80 %. Besides this sample maintained its original capacity during multiple CO2 sorption/desorption cycles.