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The objective of this work was to characterize the produced activated carbons based on Phoenix dactylifera rachis (date palm rachis: RP) using steam with different burn-off values (45, 55, and 65%), and then use those carbons to eliminate BEZAKTIV Red S-MAX (RS), a commercial textile dye. The characterization of the carbons was carried out by analyzing N2 adsorption–desorption, SEM, FTIR, TGA/SM, Boehm titration, and pHPZC. The specific surface area S2D-NLDFT was 500, 646, and 507 m2/g for the activated carbons PRAC45, PRAC55, and PRAC65, respectively. The Box–Behnken design (BBD) of experiments was applied to determine the influence of burn-off (A), initial concentration (B), and pH of the solution (C) for the RS dye elimination from the aqueous system. The significant interactions between the factors were AB and BC with p-value < 0.05. The RS dye adsorption experiments were examined by applying the kinetic and isotherm models and by studying temperature and pH effect. It was found that the RS adsorption followed the pseudo-second-order (R2 > 0.99) and the removal data were well fitted to the Langmuir isotherm model. The Langmuir maximum adsorption capacity Qm of RS dye was 198 mg/g for PRAC55. The regeneration of the carbons using thermal treatment was tested, and it revealed that the specific surface area S2D-NLDFT and the RS adsorption capacity Qm increased after the regeneration to 965 m2/g and 56.3 mg/g, respectively, for PRAC55. The Phoenix dactylifera rachis adsorbents could eliminate industrial wastewater (IW) which contains BEZAKTIV dyes with an adsorption rate superior to 55%. [ABSTRACT FROM AUTHOR]

Activated carbons (JSAC45 and JSAC55) were fabricated via both processes of pyrolysis and gasification using steam with burn-off of 45 and 55%. These materials derived from Ziziphus jujube were characterized by the adsorption–desorption of N2, thermogravimetric analyzer coupled with mass spectrophotometer (TGA/MS), electron microscope (SEM), Fourier transform infrared spectroscope (FTIR), Boehm titration, and pHPZC. The specific surface area (SBET) of activated carbons was 953 m2/g for both materials with the predominance of basic character ( pH PZC ≅ 10) . Then, the prepared carbons were used to adsorb BEZAKTIV Red S-Max (RS). The effect of initial RS concentration (10–100 mg/L), contact time (0–1440 min), pH (2–10), and temperature (25–45 °C) on adsorption capacity of JSAC45 and JSAC55 were examined; and it was revealed that RS dye was well adsorbed at pH = 10. The equilibrium adsorption data suggested that the Langmuir model fitted well the RS dye adsorption, and the pseudo-second-order model best fitted the adsorption kinetic data. The maximum of adsorption capacity of RS onto JSAC55 was 113.3 mg/g. Thermodynamics studies of JSAC45 and JSAC55 indicated that the adsorption process was endothermic, spontaneous, and feasible. The activated carbons were reused after applying the thermal regeneration process. The Ziziphus jujube adsorbents could adsorb industrial wastewater (IW) with an elimination rate of about 40% for both adsorbents. These results confirm that the Ziziphus jujube stones may be considered as an inexpensive and promising precursor for commercial activated carbons production. [ABSTRACT FROM AUTHOR]

This study investigated pyrolysis and activation of palm rachis and jujube stones at 1073 K to determine the yield of the detailed composition of the released gases, tar, condensable and solid material after each step of the process. The biomasses and their derived materials were characterized using approximate and ultimate analysis and calorimetry analysis in order to carry out the matter and the energy balance of both examined processes. Empirical assumptions were used to mine the collected data. Furthermore, wood was also used in this study for comparison purpose. The carbon weight percentage (%C) was 46.1, 49.3 and 49.2% for palm rachis, jujube stones and wood, respectively. This last parameter becomes 67.3, 91.7 and 87.0% for the same burn-off value (55%) for the activated carbons produced from the cited biomasses, respectively. The global matter balance of the solid materials recovered from the processes was 15.9, 11.6 and 12.5% for activated carbon (at 55% of burn-off) prepared from palm rachis, jujube stones and wood, respectively. The global energy balance was positive for all examined samples with the recovery of close to 70% of the energy initially contained in virgin biomass as combustible gases form. Finally, it was found that rachis palm and jujube stones are efficient as precursor for thermochemical conversion. [ABSTRACT FROM AUTHOR]

Exhibiting a very high surface area, a good electrical conductivity and a high density of active sites, nitrogen-doped graphenic materials are considered as promising catalysts for the oxygen reduction reaction (ORR). Seldom studied in acidic media, N-doped graphenic foams were tested here as the cathode catalysts of a polymer electrolyte membrane fuel cell (PEMFC). The materials were prepared via a solvothermal-based process, by reacting either cyclohexanol and ethanolamine or 1-(2-hydroxyethylethyl) piperidine with metallic sodium, under high pressure and temperature. Membrane electrode assemblies were prepared with a Pt/C anode, 212 Nafion membrane, and an 8 mm disk cathode based on the graphenic materials. The performance exhibited by the PEMFC was evaluated using chronopotentiometry and impedance spectroscopy, depending on the synthesis conditions. The kinetic parameters of the ORR were estimated by interpretation of the experimental data: the high Tafel slope found might express the partial control of oxygen diffusion through the graphenic microporous structure. Relationships between the electrochemical behavior of the materials and their structural properties are discussed. Moderately crystallized materials with a low oxygen content showed the highest catalytic properties, with a current density larger than 30 mA cm−2 and a maximum power density at 2.3 mW cm−2. [ABSTRACT FROM AUTHOR]

Highly-efficient solid oxide fuel cell (SOFC) systems are gaining increased attention for future energy conversion applications. Many planar SOFC stack designs utilise ferritic stainless steel (FSS) interconnect components. During operation, surface corrosion of FSS interconnects degrades stack operation by increasing electrical resistance and introducing other deleterious material interactions. To minimise these effects, various surface modifications and coatings are currently under investigation. Two of these methods under development for this application are: metal organic chemical vapour deposition (MO-CVD); and, large area filtered arc deposition (LAFAD). SOFC interconnect-relevant corrosion behaviour of an MO-CVD coating on Crofer 22 APU, AL453, Fe30Cr and Haynes230, and complex, amorphous LAFAD AlCrCoMnTiYO coatings on FSS 430 were investigated. Both of these surface modifications and coatings exhibit significantly improved corrosion protection as compared with uncoated FSS samples. [ABSTRACT FROM AUTHOR]