Emerging trends in research and development on earth abundant materials for ammonia degradation coupled with H2 generation.

Ammonia, as an essential and economical fuel, is a key intermediate for the production of innumerable nitrogen-based compounds. Such compounds have found vast applications in the agricultural world, biological world (amino acids, proteins, and DNA), and various other chemical transformations. However, unlike other compounds, the decomposition of ammonia is widely recognized as an important step towards a safe and sustainable environment. Ammonia has been popularly recommended as a viable candidate for chemical storage because of its high hydrogen content. Although ruthenium (Ru) is considered an excellent catalyst for ammonia oxidation; however, its high cost and low abundance demand the utilization of cheaper, robust, and earth abundant catalyst. The present review article underlines the various ammonia decomposition methods with emphasis on the use of non-noble metals, such as iron, nickel, cobalt, molybdenum, and several other carbides as well as nitride species. In this review, we have highlighted various advances in ammonia decomposition catalysts. The major challenges that persist in designing such catalysts and the future developments in the production of efficient materials for ammonia decomposition are also discussed.

In this dynamic area, ammonia degradation to hydrogen fuel provides a valuable contribution in the carbon neutral economy. Ammonia has been used extensively in several industries and is considered an ideal candidate for hydrogen generation and storage due to its high hydrogen content. Consequently, the ammonia decomposition to yield green hydrogen has become a hot topic in research. Although numerous studies on ammonia decomposition have been conducted over the last few decades, still very few review articles on the most recent advances in this field of catalysis have been published. Through this review, systematic information on the types of decomposition catalysts including both noble (Ru) and non-noble earth abundant metals such as iron, nickel, cobalt, molybdenum, their carbides and nitrides, catalytic routes, as well as the reactivity and mechanism can be comprehended. The literature on newly discovered catalysts, specifically from the last five years, is well documented and explained in this review article. Furthermore, the effect of catalyst supports, their reaction kinetics and mechanistic insights have also been discussed. The challenges and opportunities associated with the decomposition catalysts are comprehensively explicated in the end.

Ammonia decomposition reaction (ADR) is a viable method for hydrogen storage in the form of chemical bonds.Catalysts composed of noble, non-noble metals, amides, imides, carbides, nitrides, and their combinations have been widely explored towards the ADR.Challenges and opportunities in the ammonia oxidation are pointed out.

STUDIES ON RADIATION SHIELDING PROPERTIES OF NEWLY DEVELOPED HIGH-DENSITY CONCRETE FOR ADVANCED RADIOTHERAPY FACILITIES.

The linear attenuation coefficients and tenth-value layers are determined experimentally for the newly developed Cement-based high-density Concrete and Fly-Ash-based Geopolymer high-density Concrete using Red-Mud-based synthetic aggregate made up from industrial waste. Linear attenuation coefficients were determined in narrow and broad beam conditions for five megavoltage X-ray photon beam energies, i.e. 6, 10, 15 MV, and 6 and 10 MV-FFF generated by Varian TrueBeam medical linear accelerator. These materials are found to be more effective in radiation shielding when compared with ordinary concrete and hematite ore-based high-density concrete making it a useful construction material for radiotherapy accelerator vaults. Similar values of linear attenuation coefficients are observed for all the above-mentioned X-ray beam energies when cement is replaced with fly-ash in ordinary concrete, hematite-based high-density concrete and red-mud-based high-density concrete, making it a good eco-friendly alternative of cement and useful for the construction of radiotherapy vaults.

Utilization of concentrate of membrane filtration of bleach plant effluent in brick production.

Utilization potential of membrane filtration retentate (concentrate) of bleach plant effluent from paper industry, in bricks production, was investigated in the present study. Bricks were prepared by using retentate of membrane filtration in place of water. The physical properties measured for bricks were dimensions, density, moisture content, compressive strength, water absorption and porosity. Chemical analysis of the bricks was performed for water leachability and acid leachability, using ASTM Standard methods D 3987-06 and D 5233-92 respectively. The leachate samples were analyzed for Al, Cu, Fe, Co, Cr, Pb, Ni and Zn using AAS (atomic absorption spectrophotometer). Adsorbable organic halides (AOX) of leachate were analyzed by using AOX analyzer model ECS 1200 using column method. It was observed that the physical and chemical properties of bricks especially fire clay bricks were not adversely affected by the use of wastewater. Therefore, the organic matter of the retentate of membrane filtration creates no problems for this application.