HYDROCARBONS REMOVAL FROM BILGE WATER BY ADSORPTION ONTO ACTIVATED BIOCHAR FROM POSIDONIA OCEANICA

The normal operations carried out on the boats during navigation generate waste waters such as oily bilge water. The latter is the aqueous mixture of potential pollutants of different origins and types: oily fluids, lubricants and greases, cleaning fluids and other wastes that accumulate in the lower part of the vessel [1,2]. The current legislation provides that they can be discharge directly into the sea if the concentrations of some components are below the expected limits. In particular, with regard to oil / hydrocarbons contamination, the current regulatory limit is 15 mg L-1 of total hydrocarbons. The present work starts from a public/private partnership funded by a grant of the Ministry of Economic Development (MiSE). Among the aims of the project, novel methods shall be tested for the reduction of hydrocarbons concentration at values below 5 mg L-1. Moreover, instrumental techniques able to quickly measure the required low hydrocarbons concentration were tested. Among the different steps of bilge water treatment in pilot plant (coagulation, flotation, centrifugation, adsorption etc.), the latter requires the use of adsorbent materials able to reduce the oily concentration below the legal limits. Here we have hosen, optimized and tested materials obtained from bio-oil production waste, a biochar obtained by pyrolysis of Posidonia oceanica, a marine plant widespread in the Mediterranean sea. means of acid or alkali treatments. Moreover, a commercial activated carbon (Filtrasorb 400) has been used for comparison purpose. Synthetic bilge waters were prepared following the reference standards [3] for the preparation of test fluids (used to test the bilge separator plant), containing DMA (distillate marine fuel) and SLS (sodium lauryl sulfate). Batch adsorption isotherms were carried out without ionic medium and at different ionic strengths in NaCl in order to evaluate the effect of salinity on the adsorption ability of dsorbent materials. The same adsorbents were tested by column experiments. In particular, a bench pilot system was built (Figure 1.) and breakthrough curves were obtained changing amount of adsorbent material in column, flow rate, initial DMA and surfactant concentrations. Several instrumental techniques (turbidimetry, TOC, HPLC-QQQ and HPLC-FLD) have been used to measure surfactant and hydrocarbon concentrations in experimental samples. The batch experimental data were fitted with the most used isotherm models (Langmuir, Freundlich, Sips) and important considerations were made on the breakthrough curves of column experiments

Long-Term Stability of TiS2–Alkylamine Hybrid Materials

Layered TiS2 intercalated with linear alkylamines has recently attracted significant interest as a model compound for flexible n-type thermoelectric applications, showing remarkably high power factors at room temperature. The thermal and, particularly, environmental stability of such materials is, however, a still an open challenge. In this paper, we show that amine-intercalated TiS2 prepared by a simple mechanochemical process is prone to chemical decomposition through sulfur exsolution, and that the presence of molecular oxygen is likely to mediate the decomposition reaction. Through computational analysis of the possible reaction pathways, we propose that Ti-N adducts are formed as a consequence of amine groups substituting for S vacancies on the internal surfaces of the S-Ti-S layers. These findings provide insights for possible future applications of similar hybrid compounds as devices operating in ambient conditions, and suggest isolating them from atmospheric oxygen

Dopant-matrix interaction in solid oxide electrolytes and electrodes

Materials for solid oxide fuel cells (SOFC) are extensively investigated aiming at achieving better performances and device durability in view of the hopefully next implementation of hydrogen technology for the production of energy. This contribution deals with the structural aspects of the interaction of dopants with the solid matrix, either for electrodes or electrolytes. The report concerns materials that are likely fit for implementation, such as ceria-based electrolytes and mixed-oxide electrodes. However, in view of the importance of achieving a deeper insight in the mechanism of solid-state O2- conduction, results about Bi2O3 compounds are also reported. Finally, the host matrix-dopant interaction in proton-conducting electrolytes for intermediate temperature SOFC\u2019s is discussed

Solid-state compatibility of Ca:LaNbO4 with perovskite cathodes: Evidences from X-ray microspectroscopy

The solid-state compatibility between calcium-doped lanthanum niobate and three perovskite cathode materials was investigated using two X-ray microbeam techniques, micro X-ray fluorescence and micro X-ray absorption spectroscopy. The cathode powders (lanthanum strontium ferrite, either cobalt or copper-doped, and lanthanum strontium cobaltite) in contact with the dense electrolyte pellet were annealed at 1150°C for 12–144 h to simulate the effect of thermal stresses due to fabrication and long-term operation. As a result, several interdiffusion phenomena were then observed on the bilayer cross-sections: in particular, the chemical state and coordination environment of calcium, iron, niobium and lanthanum were probed with space-resolved X-ray absorption spectroscopy. The ab initio modeling of the near-edge X-ray absorption spectra reveal that the cation interdiffusion is facilitated by the structural flexibility of the perovskite structure, which is able to accommodate a variety of foreign cations in different oxidation states. Limited stability at high-temperatures was found for all candidate perovskite compositions in contact with lanthanum niobate

Toward a new hybrid proton conductor: lanthanum niobate layered perovskites as a source of tailorable surfaces

The modification of metal oxide surfaces with organic moieties has been widely studied as a method of preparing organic-inorganic hybrid materials for various applications. Among inorganic oxides, the ion-exchangeable layered perovskites [1], materials composed by perovskite-like slabs and intercalated cations, stimulated authors\u2019 interest in reason of some encouraging electronic and reactive properties. In particular it is well known that the interlayer surface of such materials in their protonated form can be easily functionalized with organic groups (such as alcohols [2-3] or organophosphonic acids [4]) thus allowing the production of stable hybrid materials with new electronic and reactive features. As a first step to design a new inorganic-organic hybrid proton conductor, a comprehensive theoretical investigation of the MLaNb2O7 (M=H, Li, Na, K, Rb and Cs) series of ion-exchangeable layered perovskite is presented. In particular, their structural and electronic properties have been investigated by periodic calculations in the framework of DFT. A general very good agreement with the available experimental data has been found. The protonated compound (HLaNb2O7) has been then functionalized with imidazole trying two different settings: in the first arrangement the molecule is adsorbed on the layered oxide exposing the interlayer surface, in the second the organic moiety is just put between two perovskites slabs. This latter model, including the effect of the confinement, allowed to better reproduce the experimental structural XRD data and 13C-NMR measurements of the hybrid system. [1] Schaak, R. E. and Mallouk T. E., Chem. Mat. 2002, 14, 1455-1471. [2] Takahashi S. et al., Inorg. Chem. 1995, 34, 5065-5069. [3] Suzuki H. et al., Chem. Mater. 2003, 15, 636-641. [4] Shimada, A. et al., Chem. Mat. 2009, 21, 4155-4162

Solid-Solid Interfaces in Protonic Ceramic Devices: A Critical Review

The literature concerning protonic ceramic devices is critically reviewed focusing the reader's attention on the structure, composition, and phenomena taking place at solid-solid interfaces. These interfaces play a crucial role in the overall device performance, and the relevance of understanding the phenomena taking place at the interfaces for the further improvement of electrochemical protonic ceramic devices is therefore stressed. The grain boundaries and heterostructures in electrolytic membranes, the electrode-electrolyte contacts, and the interfaces within composite anode and cathode materials are all considered, with specific concern to advanced techniques of characterization and to computational modeling by ab initio approaches. An outlook about future developments and improvements highlights the necessity of a deeper insight into the advanced analysis of what happens at the solid-solid interfaces and of in situ/operando investigations that are presently sporadic in the literature on protonic ceramic devices

The local structure of SOFC materials investigated by X-Ray absorption spectroscopy

This chapter is devoted to the analysis of the local atomic structure of solid oxide fuel cell (SOFC) electrolyte and electrode materials. Among the experimental techniques able to provide information about the local structure of materials, the X-ray absorption spectroscopy has the peculiarity of element selectivity, allowing to investigate the chemical environment of specific atoms embedded in a matrix. Solid oxide electrolytes allow the conduction of ionic charge carriers between the electrodes of a SOFC device; the mechanism of ion conduction depends on the type of carrier, and it is finely tuned-or even only possible-if the solid matrix is suitably tailored by insertion of doping species that modify the local structure and the dynamics of the lattice. The oxygen reduction and fuel oxidation processes are catalyzed at the respective electrodes; moreover, the cathode and anode layers must: (1) allow an efficient exchange of reactants with the environment, (2) convey the ionic species to/from the electrolyte and (3) ensure the conduction of the electrons involved in the reduction and oxidation processes. The chemical and physical stability of the interface with the electrolyte layer is another essential issue of electrode materials. The chapter begins with a section describing the basic theory underlying the X-ray absorption spectroscopy and the experimental set-ups used in fuel cell applications. The second section reports on case studies and perspectives of future development of fuel cell materials under the keynote of local structure

Supramolecular Eutecto Gels: Fully Natural Soft Materials

The obtainment of materials featured by high environmental compatibility is one of the main goals of modern research. On this subject, we herein report the first example of supramolecular gel in deep eutectic solvents. In particular, we prepared gels of the L-amino acids isoleucine and tryptophan in choline chloride/phenylacetic acid 1:2. All gel components are readily available and nontoxic. Gels have been fully characterized by standard gelation tests, rheology, X-ray diffraction, morphology and gelation kinetics. Data collected show that gels properties depend on the gelator nature. In particular, gel phases exhibit strong colloidal forces and, this high mechanical resistance, together with their environmental friendly nature, make them promising candidates for applications in all those fields requiring good performance and low environmental impact

X-ray Spectroscopy of (Ba,Sr,La)(Fe,Zn,Y)O3-δIdentifies Structural and Electronic Features Favoring Proton Uptake

Mixed protonic-electronic conducting oxides are key functional materials for protonic ceramic fuel cells. Here, (Ba,Sr,La)(Fe,Zn,Y)O3-δ perovskites are comprehensively investigated by X-ray spectroscopy (in oxidized and reduced states). Extended X-ray absorption fine structure shows that Zn,Y doping strongly increases the tendency for Fe-O-Fe buckling. X-ray absorption near-edge spectroscopy at the Fe K-edge and X-ray Raman scattering at the O K edge demonstrate that both iron and oxygen states are involved when the samples are oxidized, and for the Zn,Y doped materials, the hole transfer from iron to oxygen is less pronounced. This can be correlated with the observation that these materials show the highest proton uptake