Catalytic reduction of bromate by Co-embedded N-doped carbon as a magnetic Non-Noble metal hydrogenation catalyst

Novel Vanadia/meso-Co3O4 catalysts for the conversion of benzene-toluene-xylene to environmental friendly components via catalytic oxidation

Three - dimensional meso-porous Co₃O₄ was prepared by nanocasting pathway based on the use of mesoporous silica (KIT-6) as hard template with different Cobalt concentrations (0.5-2.5 mol ratio based on mesoporous silica KIT-6). The prepared samples was used as supports for preparing V₂O₅/Co₃O₄ (1, 6 wt% of V₂O₅) catalysts. The prepared samples were characterized by different techniques. The catalytic activity of the prepared samples were evaluated in the complete oxidation reaction of toluene, benzene, and/or p-xylene; (as model reactants of volatile organic compounds) in terms of CO₂. The catalytic reaction was carried out in a fixed-bed micro-reactor operated under atmospheric pressure and within the reaction temperature range of 200-400 °C. The data confirmed that the three dimensional-mesoporous Co₃O₄ (1.0 mole ratio) replicated sample possessed improved different parameters compared to those of the Co₃O₄ sample with other mole ratios. The data reflected the yield of Co2 is decreased upon the increase in reaction temperature to 400°C. 1 wt.% V₂O₅/m-Co₃O₄ catalyst shows a reverse direction, the CO₂ yield slowly increased in the range 150-250 °C, then jumped at 300 °C until maximum yield (100%) is observed at 400 °C. 1 wt.% V₂O₅/m-Co₃O₄ catalyst was found to be the active and selective promised catalyst for the complete oxidation of either individual aromatic volatile organic compounds (benzene, toluene, and/or xylene) and/or their mixtures to 100% CO₂.

Ultrasound process-enhanced removal of the toxic disinfection by-product bromate from water by aluminum: A comparative study

As bromate removal and reduction can be also achieved using metals, aluminum (Al) appears as the most promising one for reduction of bromate because Al is abundant element and exhibits a high reduction power. Reactions between bromate and Al shall be even enhanced through ultrasound (US) process because US can facilitate mass transfer on liquid/solid interfaces and clean surfaces via generating microscale turbulence to facilitate reactions. Therefore, the aim of this study is for the first time to investigate the effect of US on bromate removal by Al metal. Specifically, Al particle would be treated by HCl to afford HCl-treated Al (HCTAL), which is capable of removing bromate and even reducing it to bromide. Such a mechanism is also validated by density function theory calculation through determining adsorption energy as -152.8 kJ/mole, and oxygen atoms of bromate would be extracted and reacted with Al atoms, releasing bromide ion. US not only facilitated bromate removal by further increasing removal capacity under the acidic condition but also suppressed the inhibitive effect from basicity at relatively high pH. The spent HCTAL could still remove bromate and convert it to bromide after regeneration. These features indicate that US considerably enhances bromate removal by Al. PRACTITIONER POINTS: Bromate removed by Al is elucidated by DFT calculation with E_absorption  = -152.8 kJ/mole. Oxygen atoms of bromate are extracted and reacted with Al atoms, releasing bromide ion. A higher power of ultrasound would substantially enhance bromate removal efficiency. Ultrasound also suppresses the inhibitive effect from basicity at relatively high pH. With ultrasound, the interference of co-existing anions on bromate removal is lessened.

The Use of H2 in Catalytic Bromate Reduction by Nanoscale Heterogeneous Catalysts

The formation of bromate (BrO₃^-)in groundwater treatment is still a severe environmental problem. Catalytic hydrogenation by nanoscale heterogeneous catalysts with gaseous H₂ or solid-state H₂ has emerged as a promising approach, which relies on reducing BrO₃^- to innocuous Br^- via the process of direct electron transfer or reduction with atomic hydrogen. Several nanocatalysts have demonstrated high efficiency with a 100% effective BrO₃^- reduction with greater than 95% of Br^- generation in the batch and continuous reactors. However, this technology has not been widely adopted in water treatment systems. Indeed, this research article summarizes the advantages and disadvantages of these technologies by highlighting the factors of nanomaterials reduction efficiency, long-term durability, and stability, as well as addressing the essential challenges limiting the implementation of the use of H₂ for BrO₃^- reduction. In this work, we provide an economic evaluation of catalytic BrO₃^- removal, safe hydrogen supply, storage, and transportation.