Photocatalytic decomposition of 4-chlorophenol over an efficient N-doped TiO2 under sunlight irradiation

Excellent visible light responsive photocatalytic behavior of N-doped TiO2 toward decontamination of organic pollutants

In this work, N-doped TiO₂ (N-TiO₂) with ample and tunable OVs was successfully synthesized, deriving from facile hydrothermal method and baked in the NH₃ atmosphere. N-doping boosts the amount of surface hydroxyl and superoxide (O₂^-) of TiO₂, demonstrated by XPS and nitroblue tetrazolium (NBT)-O₂^- quantitative reaction. Rich and tunable OVs were confirmed by low temperature electron spin resonance (ESR) results, demonstrating that doping of N into TiO₂ can definitely construct higher OVs than the reference TiO₂. Surface photovoltage spectrum (SPS) test, fluorescence experiments and electrochemical measurements all display that N-TiO₂ photocatalysts with OVs have a higher severance efficiency of photogenerated e-/h⁺ pairs than the pristine TiO₂. Photocatalytic evaluation results exhibit that N-TiO₂ photocatalysts demonstrate better performance than the reference TiO₂ toward decontamination of rhodamine B and tetracycline. TiO₂ treated in ammonia atmosphere for 1 h shows the highest photocatalytic property. The visible light responsive catalytic behavior of TiO₂ treated in ammonia atmosphere for 1 h is much higher than that of commercial TiO₂ (P25) and the pristine TiO₂, separately. The ameliorated visible light behavior of N-TiO₂ photocatalysts is attributable to rich oxygen vacancies produced through introducing N into TiO₂ and the boosted severance of photoactivated e-/h⁺.

Facile synthesis of visible-light-driven Cu2O/BiVO4 composites for the photomineralization of recalcitrant pesticides

In the present study, a facile synthesis of visible-light-driven Cu₂O/BiVO₄ composites, with different Cu₂O co-catalysts, towards to the mineralization of 4-chlorophenol (4-CP) in aqueous media is reported.

The reaction mechanism for highly effective hydrodechlorination of p-chlorophenol over a Pd/CNTs catalyst

Different mass-transfer mechanisms of CNTs and AC for the HDC of p-CP.

Recent advances in non-metal modification of graphitic carbon nitride for photocatalysis: a historic review

This review provides a comprehensive survey and critical comments on the development of photocatalysts with a focus on the metal-free materials.

Degradation of Direct Black 38 dye under visible light and sunlight irradiation by N-doped anatase TIO₂ as photocatalyst

The N-doped TiO(2) photocatalyst was prepared by calcination of a hydrolysis product composed of titanium (IV) isopropoxide with ammonia as the precipitator. X-ray diffraction, surface area, XPS and UV-vis spectra analyses showed a nanosized anatase structure and the appearance of a new absorption band in the visible region caused by nitrogen doping. The degradation of Direct Black 38 dye on the nitrogen-doped TiO(2) photocatalyst was investigated under visible light and sunlight irradiation. The N-doped anatase TiO(2) demonstrated excellent photocatalytic activity under visible light. Under sunlight irradiation, the N-doped sample showed slightly higher activity than that of the non-doped sample.

A survey of photocatalytic materials for environmental remediation

Heterogeneous photocatalysis is an advanced oxidation process which has been the subject of a huge amount of studies related to air cleaning and water purification. All these processes have been carried out mainly by using TiO(2)-based materials as the photocatalysts and ca. 75% of the articles published in the last 3 years is related to them. This review illustrates the efforts in the search of alternative photocatalysts that are not based on TiO(2), with some exceptions concerning particularly innovative modifications as nanoassembled TiO(2) or TiO(2) composites with active carbon, graphite and fullerene. Papers reporting preparation, characterization and testing of binary, ternary and quaternary compounds, have been reviewed. Despite many of these photocatalysts being effective for the photodecomposition of many pollutants, most of them do not allow a complete mineralization of the starting compounds, differently from TiO(2).

Decomposition of 3-chlorophenol on nitrogen modified TiO2 photocatalysts

Photocatalytic activity of nitrogen modified TiO(2) calcined at temperatures of 100-350°C toward 3-chlorophenol (3-CP) degradation was studied. In the experiments the fluorescent UV lamp and the incandescent lamp emitting mainly Vis light were applied. The degradation efficiency was evaluated on a basis of changes of 3-CP, total organic carbon and Cl(-) concentration. A significant improvement of the photoactivity of the N-modified photocatalysts compared to the reference sample was observed. The rate of 3-CP degradation increased with the calcination temperature, and the highest efficiency was achieved for TiO(2) annealed at 350°C. After 5h of UV irradiation in the presence of TiO(2)/N-350 and reference TiO(2) the 3-CP concentration decreased for 77% and 36%, respectively. The 3-CP removal after 24h of Vis irradiation was 30% and 12% for the N-modified and reference samples, respectively. The 3-CP decomposition and mineralization were greatly influenced by pH of the solution, achieving the highest rate at pH 7 for the modified photocatalysts. An increase of the calcination temperature resulted in an increase of the rate of OH formation. The photocatalytic activity of the N-modified TiO(2) remained unchanged during repeated photocatalytic degradation cycles.

Influence of parameters on the heterogeneous photocatalytic degradation of pesticides and phenolic contaminants in wastewater: a short review

In recent years, the application of heterogeneous photocatalytic water purification processes has gained wide attention due to its effectiveness in degrading and mineralizing the recalcitrant organic compounds as well as the possibility of utilizing the solar UV and visible-light spectrum. This paper aims to review and summarize the recent works on the titanium dioxide (TiO(2)) photocatalytic oxidation of pesticides and phenolic compounds, predominant in storm and wastewater effluents. The effects of various operating parameters on the photocatalytic degradation of pesticides and phenols are discussed. Results reported here suggest that the photocatalytic degradation of organic compounds depends on the type and composition of the photocatalyst and, light intensity, initial substrate concentration, amount of catalyst, pH of the reaction medium, ionic components in water, solvent types, oxidizing agents/electron acceptors, catalyst application mode, and calcination temperature in the water environment. A substantial amount of research has focused on the enhancement of TiO(2) photocatalysis by modification with metal, non-metal and ion doping. Recent developments in TiO(2) photocatalysis for the degradation of various pesticides and phenols are also highlighted in this review. It is evident from the literature survey that photocatalysis has good potential to remove a variety of organic pollutants. However, there is still a need to determine the practical utility of this technique on a commercial scale.