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 Eabsorption = -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.

Nanoneedle-Assembled Copper/Cobalt sulfides on nickel foam as an enhanced 3D hierarchical catalyst to activate monopersulfate for Rhodamine b degradation.

While metal oxides are conventionally proposed for activating monopersulfate (MPS) to degrade refractory contaminants, metal sulfides have recently gained increased attention for MPS activation because these sulfides exhibit more reactive redox characteristics to enhance the catalytic activation of MPS. The present study attempts to develop a novel material comprised of metal sulfides with 3D hierarchical nanostructures to activate MPS. Specifically, a 3D hierarchically structured catalyst was fabricated by growing CuCo-layered double hydroxide (LDH) on nickel foam (NF), followed by direct sulfurization, affording Cu/CoS@NF (CCSNF). CCSNF could exhibit a unique morphology of floral bunches comprised of nano-needles, residing on the NF surfaces. Compared with its precursor, CuCo-LDH@NF, oxide analogue, and CuCo2O4@NF, CCSNF possessed superior physical and chemical properties, including larger surface area and pore volume, higher current density, and lower charge transfer resistance. These features render CCSNF a much more effective catalyst than CuCo-LDH@NF and CuCo2O4@NF for activating MPS to degrade Rhodamine B (RB). In particular, RB degradation by CCSNF-activated MPS required an activation energy only 26.8 kJ/mol, which is much lower than the reported values. The activation mechanism and degradation pathway of RB degradation by CCSNF-activated MPS were investigated and validated through experimental evidences and density function theory calculations.