Highly Effective B@g‐C3N4/Polyaniline Nanoblend for Photoelectrocatalytic Reduction of CO2 to Methanol

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Highly Effective B@g-C3N4/Polyaniline Nanoblend for Photoelectrocatalytic Reduction of CO2 to Methanol

Photoelectrocatalytic (PEC) reduction can convert CO2 and water to hydrocarbons and other value-added products. Herein, a B@g-C3N4/polyanaline nanostructured photoelectrocatalyst was synthesized, characterized, and used for PEC CO2 reduction. Its enhanced photocurrent density when exposed to light in the presence of CO2 suggests potential applications in the PEC reduction of CO2 to methanol.


Abstract

Photoelectrocatalytic (PEC) conversion of CO2 has been extensively investigated as it uses solar energy to combine CO2 and water to produce hydrocarbons. In the present work, B@graphitic carbon nitride (g-C3N4)/polyaniline (PANI) nanoblend was synthesized by in situ polymerization of aniline in the presence of B@g-C3N4 for PEC CO2 reduction. The catalyst was characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy, X-ray diffraction, UV-Vis absorption spectroscopy, photoluminescence, X-ray photoelectron spectroscopy (XPS), and Mott-Schottky analysis. The PEC activity was evaluated by linear sweep voltammetry (LSV) and chronoamperometry. XRD revealed the formation of g-C3N4, while B doping was confirmed by XPS. The presence of PANI was visualized by FESEM. A remarkable cathodic current associated with CO2 reduction was observed during LSV from an onset potential of –0.01 V vs. normal hydrogen electrode (NHE), which is more positive than that of B@g-C3N4 (–0.82 V vs. NHE), and the positive shift is attributed to the slow charge recombination kinetics of B@g-C3N4/PANI as evidenced by PL results. The mechanism of PEC CO2 reduction was investigated and discussed on the basis of the Mott-Schottky results. In conclusion, B@g-C3N4/PANI opens a new avenue to develop photoelectrocatalysts for PEC CO2 reduction to methanol.

Optimizing the Disinfection Inactivation Efficiency in Wastewater Treatment: A Computational Fluid Dynamics Investigation of a Full‐Scale Ozonation Contactor

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Optimizing the Disinfection Inactivation Efficiency in Wastewater Treatment: A Computational Fluid Dynamics Investigation of a Full-Scale Ozonation Contactor

The disinfection efficiency of a full-scale ozonation contactor using a three-dimensional multiphase computational fluid dynamics model is investigated in order to improve the treatment performance for total coliforms and reduce energy costs. The proposed upgrading measures include design rehabilitation, ozone transfer improvements, inactivation kinetics improvements, and cost-benefit analysis.


Abstract

The inactivation kinetics of total coliforms to increase the pathogenic removal efficiency in a full-scale ozonation contactor in a wastewater treatment plant in Algeria is investigated. An enhanced ozone contactor design is proposed and 3D multiphase computational fluid dynamics simulations were conducted to optimize the operating parameters, including flow rates, ozone concentrations considering the treatment performance, and total operating cost. The existing design has several limitations, including poor mass-transfer efficiency and uneven distribution of dissolved ozone. To address these issues, the optimized design includes new injection-point settings and an increased number of diffusers. The optimized design achieved a significant improvement in mass transfer efficiency. The ozone treatment effectively reduced the total coliform counts in the wastewater samples compared to the existing design. The Chick-Watson model predicted inactivation kinetics, with a reduction of up to 99.997 %. The practical implications of this research can significantly improve the inactivation kinetics of ozone treatments.