Efficient Photodegradation of Organic Pollutants By Using a Bi 2 CuO 4 /BiPO 4 Heterojunction Photocatalyst

Imidazolium and Pyridinium-Based Ionic Porous Organic Polymers: Advances in Transformative Solutions for Oxoanion Sequestration and Non-Redox CO2 Fixation

The rapid pace of industrialization has led to a multitude of detrimental environmental consequences, including water pollution and global warming. Consequently, there is an urgent need to devise appropriate materials to address these challenges. Ionic porous organic polymers (iPOPs) have emerged as promising materials for oxoanion sequestration and non-redox CO2 fixation. Notably, iPOPs offer hydrothermal stability, structural tunability, a charged framework, and readily available nucleophilic counteranions. This review explores the significance of pores and charged functionalities alongside design strategies outlined in existing literature, mainly focusing on the incorporation of pyridinium and imidazolium units into nitrogen-rich iPOPs for oxoanion sequestration and non-redox CO2 fixation. The present review also addresses the current challenges and future prospects, delineating the design and development of innovative iPOPs for water treatment and heterogeneous catalysis.

BiPO4-coated carbon microtube electrodes: preparation and characterization of their properties and electrocatalytic degradation of methylene blue

Bismuth phosphate (BiPO₄), a very attractive candidate for organics electrodegradation, harbors tremendous potential on removing contaminants from water. Here, four carbon microtube electrodes were prepared from corncob, each coated with BiPO₄ by a different method to study the electrodegradation of methylene blue (MB). A thorough insight into the composite features of four electrodes was characterized. Better reversibility and electrocatalytic activity of the fourth electrode (BCC4) prepared by digital signal generator was presented with a current density of 5.71 mA cm^-2 at a potential of 1.6 V vs Ag/AgCl. The electrochemical impedances and actual lifetime of BCC4 were 125 Ω and 833 h, respectively. The effectiveness of each kind of BiPO₄/carbon electrode was preliminarily evaluated by analyzing the actual conversion rate of the MB concentration, which confirms MB electrodegradation by the BiPO₄/carbon electrode was mainly dominated by the hydroxyl radical oxidation. The mass transfer rate was increased by carbon microtube; thereby, electrocatalysis of BiPO₄/carbon electrode increased as revealed by an increase in the MB degradation rate. The rate constants k obtained for the degradation of MB by BiPO₄/carbon electrode at 20 ℃ was 0.0046 mM^-1 s^-1, which was 11 times than that of BiPO₄. The diffusion layer was decreased by carbon microtube, resulting in MB electrodegradation rate increased. The BiPO₄ coated on the surface of the carbon microtube electrodes strengthened their electrocatalytic performance, which shed new light on effective selection of suitable carbon electrode for degradation of organics. Therefore, BiPO₄/carbon electrode could be potentially applied in the electrodegradation of organic pollutants.

Photocatalyst-coated carbon microtube electrodes: Preparation and characterization of their properties and photocatalytic degradation of methylene blue

Photocatalysis is a potential technology for removing pollutants from water. As the recombination of the photogenerated electron-hole pairs can hinder the photocatalytic efficiency in the treatment of wastewater, the surface of the carrier is usually coated with a semiconductor. In this study, carbon microtube electrode prepared from corncob was coated with either titanium oxide (TiO₂) or bismuth phosphate (BiPO₄) and then used as a photocatalyst (C-TiO₂ or C-BiPO₄) to investigate the photodegradation of methylene blue (MB). The two photocatalysts, C-TiO₂ and C-BiPO₄, were characterized by phase determination, microstructure observation, water contact angle measurement, and base site analysis. The influences of reaction time, stability, MB concentration, initial pH, and OH radicals quenching on the degradation of MB were also evaluated. The degradation of MB by C-TiO₂ and C-BiPO₄ was mainly dominated by OH radical oxidation. The carbon microtube increased both the mass transfer rate and the photogenerated electron-hole pairs separation rate, thereby increasing the photocatalysis of both C-TiO₂ and C-BiPO₄ as revealed by an increase in the rate of MB degradation. The rate constants obtained for the degradation of MB by C-TiO₂ and C-BiPO₄ at 20 °C were 9.739 × 10^-7 mM min^-1 and 1.111 × 10^-7 mM min^-1, respectively. The coating of TiO₂ and BiPO₄ on the surface of the carbon microtube electrode enhanced their photocatalytic performance, and therefore, C-TiO₂ and C-BiPO₄ could be developed into a novel material to be used in the photodegradation of dye pollutants.