Coal fly ash (FA) supported Pd-Ag bimetallic nanoparticles (FA-Pd-Ag) was prepared by reducing Pd(II) and Ag(I) salts together onto the dispersed solid support in aqueous medium. Electron microscope analysis (FE-SEM,...

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A continuous flow photocatalytic reactor was developed by combining the reaction kinetics and mass balance concept. The concept of cascade aerator was also considered in designing it as a stepped reactor. The reactor was used to investigate the photocatalytic degradation of methylene blue in aqueous solution by Ag + doped TiO 2 (2 g/L) under UV irradiation by 15 W UV lamps (254 nm). Methylene blue solution (20 ppm) was found to be decolorized by > 99, 97, 85 and 57 % under flow rates of 1, 1.5, 2 and 3 L/h, respectively after 120 minutes. The corresponding mineralization was > 80, 78, 75 and 54 %, respectively. At higher flow rates (Re number 208.2 and 415.5) > 99 % decolourization was achieved by recycling the solution 5 and 7 times with fresh doses of photocatalyst. At steady state, maintained by repeating the addition of photocatalyst at fixed time intervals, the dye solution could be decolourized continuously by > 99, 97 and 76 % at flow rates of 1, 2 and 3 L/h, respectively while the mineralization was > 82, 79 and 62 %, respectively. The reactor was also effectively used to mineralize textile wastewater collected from a textile mill in Kolkata. The mineralization was greater than 75, 73 and 64 % at flow rates of 1, 2 and 3 L/h, respectively after 120 minutes. The efficiency of the reactor depended upon the residence time of the contaminant in the reactor. At steady state, the design data simulated well with the corresponding experimental data.

We demonstrate a bio‐inspired multi‐component assembly method to design oriented composite structures for application as visible‐light sensitive plasmon‐induced photocatalysts. Similar to the role of polypeptides in the formation of intricately designed structures of biominerals, we utilize spermine to simultaneously mineralize and assemble the photocatalytic system consisting of ZnO, Ag nanoparticles and reduced graphene oxide under mild reaction conditions. With an appropriately assembled interfacial structure and composition, the resulted material exhibits efficient catalytic activity under visible‐light irradiation. The activity of this ternary system is higher by more than one order compared with that for the binary and the ternary systems prepared via alternative methods. These results with detailed analyses reveal the importance of the interfacial assembly in creating synergistic interactions among the components. Furthermore, this interaction allows the photocatalyst to remain active and stable in the reaction addressing the issues pertaining to the charge recombination and photo‐corrosion known in plasmon‐induced ZnO‐based catalytic systems.