Vertical 3D Printed Pd/TiO_(2) Arrays for High Efficiency Photo-assisted Catalytic Water Treatment

Catalytic degradation of organic contaminants is at the frontier of water treatment due to its selectivity,energy savings,and ability to convert harmful contaminants into harmless or even valuable chemical products for recycling.However,achieving sufficiently high performance in the catalytic removal of organic contaminants for practical application is still extremely challenging.Herein,we report a Pd-decorated TiO_(2)(Pd/TiO_(2))hierarchical vertical array for fast and efficient catalytic water treatment.Such a forest-like Pd/TiO_(2) vertical array demonstrates the following distinct advantages over conventional planar or bulk catalytic systems:1)abundant anchoring sites for nanocrystals loading;2)high sunlight absorption;3)efficient mass transfer channels for the reactants and products.As a proof of concept,the Pd/TiO_(2) array demonstrated rapid and efficient photo-assisted catalytic reduction of high concentrations of 4-nitrophenol wastewater(2 g/L,ca.14.38 mmol/L)and its feasibility for continuous flow wastewater treatment.The turnover frequency(TOF)value of the Pd/TiO_(2) array was up to 8.00 min^(-1),which was approximately 4.2 times that of planar Pd/TiO_(2) film with the same area(1.91 min^(-1)).Our strategy of incorporating nanocatalysts with a hierarchical vertical array provides a promising approach to boosting the catalytic performance of catalysts for different chemical reactions.

Catalytic activities of ultra-small β-FeOOH nanorods in ozonation of 4-chlorophenol

We report the catalytic properties of ultra-small β-FeOOH nanorods in ozonation of4-chlorophenol（4-CP）. XRD, TEM, EDS, SAED, FTIR and BET were used to characterize the prepared material. Interaction between O3 and β-FeOOH was evident from the FTIR spectra.The removal efficiency of 4-CP was significantly enhanced in the presence of β-FeOOH compared to ozone alone. Removal efficiency of 99% and 67% was achieved after 40 min in the presence of combined ozone and catalyst and ozone only, respectively. Increasing catalyst load increased COD removal efficiency. Maximum COD removal of 97% was achieved using a catalyst load of 0.1 g/100 m L of 4-CP solution. Initial 4-CP concentration was not found to be rate limiting below 2 × 10^-3mol/L. The catalytic properties of the material during ozonation process were found to be pronounced at lower initial p H of 3.5.Two stage first order kinetics was applied to describe the kinetic behavior of the nanorods at low p H. The first stage of catalytic ozonation was attributed to the heterogeneous surface breakdown of O3 by β-FeOOH, while the second stage was attributed to homogeneous catalysis initiated by reductive dissolution of β-FeOOH at low p H.

Low-temperature conversion of ammonia to nitrogen in water with ozone over composite metal oxide catalyst

As one of the most important water pollutants, ammonia nitrogen emissions have increased year by year, which has attracted people＇s attention. Catalytic ozonation technology, which involves production of ·OH radical with strong oxidation ability, is widely used in the treatment of organic-containing wastewater. In this work, MgO-Co3O4 composite metal oxide catalysts prepared with different fabrication conditions have been systematically evaluated and compared in the catalytic ozonation of ammonia（50 mg/L） in water. In terms of high catalytic activity in ammonia decomposition and high selectivity for gaseous nitrogen, the catalyst with MgO-Co3O4 molar ratio 8：2, calcined at 500°C for 3 hr, was the best one among the catalysts we tested, with an ammonia nitrogen removal rate of 85.2% and gaseous nitrogen selectivity of44.8%. In addition, the reaction mechanism of ozonation oxidative decomposition of ammonia nitrogen in water with the metal oxide catalysts was discussed. Moreover, the effect of coexisting anions on the degradation of ammonia was studied, finding that SO2-4 and HCO-3 could inhibit the catalytic activity while CO2-3 and Br-could promote it. The presence of coexisting cations had very little effect on the catalytic ozonation of ammonia nitrogen. After five successive reuses, the catalyst remained stable in the catalytic ozonation of ammonia.