Fares AlMomani

Solar Thermochemical Hydrogen Production via Terbium Oxide Based Redox Reactions

The computational thermodynamic modeling of the terbium oxide based two-step solar thermochemical water splitting (Tb-WS) cycle is reported. The 1st step of the Tb-WS cycle involves thermal reduction of TbO2 into Tb and O2, whereas the 2nd step corresponds to the production of H2 through Tb oxidation by water splitting reaction. Equilibrium compositions associated with the thermal reduction and water splitting steps were determined via HSC simulations. Influence of oxygen partial pressure in the inert gas on thermal reduction of TbO2 and effect of water splitting temperature () on Gibbs free energy related to the H2 production step were examined in detail. The cycle () and solar-to-fuel energy conversion () efficiency of the Tb-WS cycle were determined by performing the second-law thermodynamic analysis. Results obtained indicate that and increase with the decrease in oxygen partial pressure in the inert flushing gas and thermal reduction temperature (). It was also realized that the recuperation of the heat released by the water splitting reactor and quench unit further enhances the solar reactor efficiency. At K, by applying 60% heat recuperation, maximum of 39.0% and of 47.1% for the Tb-WS cycle can be attained.

Solar hydrogen production via erbium oxide based thermochemical water splitting cycle

The erbium oxide based water splitting (Eb-WS) cycle was thermodynamically studied by using the HSC Chemistry software and databases. The first step of the Eb-WS cycle involves thermal reduction of Er2O3, whereas the second step corresponds to the production of H2 via water splitting reaction. Equilibrium compositions associated with the thermal reduction and water splitting steps were determined by performing HSC simulations. Influence of partial pressure of oxygen ( PO2) in the inert purge gas on thermal reduction temperature ( TH) and equilibrium compositions associated with the solar thermal dissociation of Er2O3 was identified. Furthermore, energy and exergy analysis of the Eb-WS cycle was carried out to estimate the cycle ( ηcycle) and solar-to-fuel conversion efficiency ( ηsolar−to−fuel). Simulation results indicate that the ηcycle and ηsolar−to−fuel of Eb-WS cycle increase with the decrease in TH. Also, the ηcycle and ηsolar−to−fuel can be increased further via the recuperation of the heat release...

PdZn nanoparticle electrocatalysts synthesized by solution combustion for methanol oxidation reaction in an alkaline medium

Herein, we report the synthesis of PdZn nanoparticle (NP) electrocatalysts for the methanol oxidation reaction (MOR). The PdZn NPs were synthesized by solution combustion synthesis in the presence of Pd(NO3)2·xH2O, Zn(NO3)2·6H2O and glycine in H2O, where glycine acted as a fuel. In this synthesis, the glycine amount was varied with a fixed stoichiometric ratio of Pd- and Zn-precursors at 1 : 1 to obtain two electrocatalysts (PdZn/C) of fuel-high (glycine to metal nitrate ratio = 1.75), PdZn/C (1.75) and fuel-low (glycine to metal nitrate ratio = 0.5), PdZn/C (0.5). The NPs were characterized by X-ray diffractometry, transmission electron microscopy and scanning electron microscopy for the crystallite size, morphology and elemental composition of the electrocatalysts. High-angle annular dark-field-scanning transmission electron microscopy coupled to energy dispersive X-ray spectroscopy was used to obtain the elemental distribution maps of the aggregated NPs, which confirmed the NPs with Pd and Zn in the alloyed state. X-ray photoelectron spectroscopy was performed to analyze the electronic structures of the elements in the samples. The NPs were then applied in the electrocatalysis for MOR in an alkaline medium. We found that PdZn/C showed an improved electrocatalytic activity by a factor of ∼1.4–1.9 in comparison with Pd/C synthesized using the same method. The MOR on PdZn/C (1.75) began at an earlier onset potential and higher current density than for Pd/C and PdZn/C (0.5). Stability tests were performed by chronoamperometry on PdZn/C and Pd/C, and the results showed a higher stability of PdZn/C (1.75) compared to PdZn/C (0.5) and Pd/C. The fuel amount affected the NP sizes, reaction yield and electrocatalytic properties.

Solar Energy Storage via Thermochemical Metal Oxide/Metal Sulfate Water Splitting Cycle

Full thickness rotator cuff tears (RCT) and the associated muscle degeneration that results due to this injury presents a significant clinical burden. The prevention or recovery from this degeneration requires the synchronized behavior of many cells that participate in regeneration. Strategies that tune the inflammatory cascade that is initiated after injury serves as a powerful way to influence tissue repair. Here, we use the local, sustained delivery of the immunomodulatory small molecule FTY720 to examine whether the recruitment of pro-regenerative myeloid cells affects the healing outcome. We find that PLGA microparticles have an atrophic effect on the muscle that is ameliorated with the release of FTY720. However, the inability of FTY720 delivery to induce pro-regenerative monocyte and macrophage recruitment and our findings demonstrating enrichment of CD4+ T cells suggest that effects of this small molecule are context dependent and that the underlying mechanisms behind this RCT associated muscle degeneration require further studies.This paper reports the effect of Ar molar flow-rate on thermodynamic efficiency analysis of zinc oxide-zinc sulfate (ZnS-ZnO) water splitting cycle useful for solar H 2 production. The thermodynamic efficiency analysis is conducted using the HSC Chemistry 7.1 software and its thermodynamic database. Influence of Ar molar flow-rate on total solar energy input essential for the continuous operation of the cycle is explored. Furthermore, the solar-to-fuel energy conversion efficiency for the ZnS-ZnO water splitting cycle is determined.

Field study comparing the effect of hydraulic mixing on septic tank performance and sludge accumulation

ABSTRACT This study investigates the effect of hydraulic mixing on anaerobic digestion and sludge accumulation in a septic tank. The performance of a septic tank equipped with a hydraulic mixer was compared with that of a similar standard septic tank over a period of 10 months. The study was conducted in two phases: Phase-I – from May to November 2013 (6 months); Phase-II – from January to May 2014 (4 months). Hydraulic mixing effectively reduced the effluent biological oxygen demand (BOD) and total suspended solids, and reduced the sludge accumulation rate in the septic tank. The BOD removal efficiencies during Phase-II were 65% and 75% in the standard septic tank and a septic tank equipped with hydraulic mixer (Smart Digester™), respectively. The effect of hydraulic mixing reduced the rate of sludge accumulation from 0.64 cm/day to 0.27 cm/day, and increased the pump-out interval by a factor of 3.