Development of catalysts for hydrogen production from hydrogen iodide decomposition in thermo-chemical water-splitting sulfur-iodine cycle: A review

Hydrogen iodide (HI) decomposition is an important part of thermo-chemical water-splitting sulfur-iodine (SI) cycle which can generate large amount of hydrogen without releasing green-house carbon dioxide gas. HI-decomposition is a very slow reaction even at a high temperature of 500°C. The use of catalyst in this reaction increases the reaction rate. So, a highly active and stable catalyst is desired from long time. Development of active and stable non-noble catalysts for HI-decomposition reaction is a significant challenge. Recent developments and trends in catalysis towards the catalyst synthesis, activity, and stability are discussed in this review. The activity, stability, and kinetic studies of different support materials, different monometallic and bimetallic catalysts are summarized here. The effect of preparation methods of catalysts on their activity and stability is also discussed. The high activity of catalysts for HI reaction is related to nanosize particles, metal dispersion, high specific surface area, oxygen vacancies (defects), and alloy formation between two metals. This article also summarized the different material of construction (MoC) used for HI reaction which are essential for building big pilot plants.     

Electrochemical Aspects of Electroosmotic Dewatering of Clay Suspensions

ABSTRACT

An attempt is made to elucidate the electrochemical aspects of the electroosmotic dewatering (EOD) of clays as reported in some recent work, especially that on interrupted DC power electroosmotic dewatering published by Rabie, Mujumdar and Weber (2). These authors showed that the dewatering by EOD stops after the DC power has been on for several minutes or hours; on interruption of their power and on short-circuiting of the electrodes, conditions can be created again for some further dewatering by DC power EOD. This discovery, of Rabie et al. is interpreted as a fuel cell effect and it is shown that it affords clues to several other electrochemical strategies for the possible enhancement of the efficiency of the EOD by DC power.

Further, the open circuit potentials observed by Rabie et al. (2) on the interruption of DC power are given an electrochemical interpretation which leads to quantitative estimates in agreement with the experimental values.     

Economic plantwide control of the ethyl benzene process

Systematic plantwide control system design for economically optimal operation of the ethyl benzene process over a large throughput range is studied. As throughput is increased, constraints progressively become active with the highest number of active constraints at maximum throughput. An economic plantwide control system (CS1) is designed for operation at this most constrained operating point using a novel “top‐down” pairing approach with higher prioritization to the economic objectives over regulatory objectives. This structure is adapted for near optimal low throughput operation with constraints that go inactive taking up additional economic variable control. For comparison, a conventional plantwide control structure (CS2) with the throughput manipulator at a fresh feed and “bottom‐up” pairing for the control objectives is also synthesized. Four overrides are needed in CS2 to handle the hard equipment capacity constraints at maximum throughput. Rigorous dynamic simulations show that CS1 is dynamically and economically significantly superior to CS2. © 2012 American Institute of Chemical Engineers AIChE J, 59: 1996–2014, 2013     

Essential Oils as Natural Food Antimicrobial Agents: A Review

Food-borne illnesses pose a real scourge in the present scenario as the consumerism of packaged food has increased to a great extend. Pathogens entering the packaged foods may survive longer, which needs a check. Antimicrobial agents either alone or in combination are added to the food or packaging materials for this purpose. Exploiting the antimicrobial property, essential oils are considered as a “natural” remedy to this problem other than its flavoring property instead of using synthetic agents. The essential oils are well known for its antibacterial, antiviral, antimycotic, antiparasitic, and antioxidant properties due to the presence of phenolic functional group. Gram-positive organisms are found more susceptible to the action of the essential oils. Essential oils improve the shelf-life of packaged products, control the microbial growth, and unriddle the consumer concerns regarding the use of chemical preservatives. This review is intended to provide an overview of the essential oils and their role as natural antimicrobial agents in the food industry.     

Optical scattering with hyperspectral imaging to classify longissimus dorsi muscle based on beef tenderness using multivariate modeling

The objective of this study was to develop a non-destructive method for classifying cooked-beef tenderness using hyperspectral imaging of optical scattering on fresh beef muscle tissue. A hyperspectral imaging system (λ = 922–1739 nm) was used to collect hyperspectral scattering images of the longissimus dorsi muscle (n = 472). A modified Lorentzian function was used to fit optical scattering profiles at each wavelength. After removing highly correlated parameters extracted from the Lorentzian function, principal component analysis was performed. Four principal component scores were used in a linear discriminant model to classify beef tenderness. In a validation data set (n = 118 samples), the model was able to successfully classify tough and tender samples with 83.3% and 75.0% accuracies, respectively. Presence of fat flecks did not have a significant effect on beef tenderness classification accuracy. The results demonstrate that hyperspectral imaging of optical scattering is a viable technology for beef tenderness classification.     

Studies on slag deposit formation in pulverized coal combustors. 2. Results on the wetting and adhesion of synthetic ash drops on different steel substrates

A simple sticking apparatus has been further developed to study the comparative wetting and adhesion properties of a synthetic coal ash slag on boiler steels. Both the wetting and adhesion behaviour appears to be affected by the physical nature of the oxide layer on the steel surface (i.e., thickness and microporosity). The adhesion force is also found to be a function of the chemical nature of the surface oxide layer on the steel (i.e., whether the layer is predominantly ferrous (FeO) or ferric (Fe₂O₃) oxide). The presence of a sodium salt (either sulfate or carbonate) on the steel surface enhances both the wetting and adhesion properties by dissolution in the molten drop creating a less viscous glass with a lower liquidus temperature at the drop-surface interface. At this time it is difficult to establish whether the bonding between the slag and steel oxide layer is mechanical, chemical, or a combination of both.     

Single-channel microchip for fast screening and detailed identification of nitroaromatic explosives or organophosphate nerve agents

A single-channel chip-based analytical microsystem that allows rapid flow injection measurements of the total content of organic explosive or nerve agent compounds, as well as detailed micellar chromatographic identification of the individual ones, is described. The protocol involves repetitive rapid flow injection (screening) assays--to provide a timely warning and alarm--and switching to the separation (fingerprint identification) mode only when harmful compounds are detected. While micellar electrokinetic chromatography, in the presence of sodium dodecyl sulfate (SDS), is used for separating the neutral nitroaromatic explosive and nerve agent compounds, an operation without SDS leads to high-speed measurements of the "total" explosives or nerve agent content. Switching between the "flow injection" and "separation" modes is accomplished by rapidly exchanging the SDS-free and SDS-containing buffers in the separation channel. Amperometric detection was used for monitoring the separation. Key factors influencing the sample throughput, resolution, and sensitivity have been assessed and optimized. Assays rates of about 360 and 30/h can thus be realized for the "total" screening and "individual" measurements, respectively. Ultimately, such development will lead to the creation of a field-deployable microanalyzer and will enable transporting the forensic laboratory to the sample source.     

Pollution-preventing anionic lithographic inks

Lithographic printing presses use aliphatic and aromatic solvents for cleaning various surfaces, which are coated with the ink. The conventional printing inks also contain volatile solvents. During printing and cleaning operations, volatile organic compounds (VOCs) present in the inks and cleaning solvents are lost to the atmosphere by evaporation and these losses are quantifiable and alarmingly high. A new type of ink based on castor oil, which completely eliminates emissions of VOCs, has been developed. Synthesis of resins and the kinetics of washing of the ink, similar to the recently announced pollution-preventing ink [development of a VOC-free lithographic printing system. TAGA Proc., 324], with water at a slightly elevated pH are studied. A correlation between the mass-transfer coefficient characterizing the washing of ink and the experimental process variables is confirmed. New data are also reported on flake-formation dynamics.