In this work, metal-doped titanium dioxide (TiO2) was synthesised with the aim of improving photocatalytic degradation and antimicrobial activities; TiO2 was doped with copper (Cu) ranging from 0.1 to 1.0 wt%. The physical and chemical properties of the Cu-doped TiO2 nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), the Brunauer–Emmett–Teller method (BET) and diffuse reflection spectroscopy (DRS). The results revealed that the anatase phase of TiO2 was maintained well in all the Cu-doped TiO2 samples. No significant difference in the particle sizes or the specific surface areas was caused by increasing Cu doping. However, the band gap decreased continuously from 3.20 eV for undoped TiO2 to 3.12 eV for 1.0 wt.% Cu-doped TiO2. In addition, the 0.1 wt.% Cu-doped TiO2 displayed a much greater photocatalytic degradation of methylene blue (MB) and excellent antibacterial ability for Escherichia coli (E. coli) compared to undoped TiO2. On the other hand, the high Cu doping levels had negative impacts on the surface charge of nanoparticles and charge transfer for OH• generation, resulting in decreasing MB degradation and E. coli photokilling for 1.0 wt.% Cu-doped TiO2.
In this present work, the photocatalytic degradation of salbutamol [2-(tert-butylamino)-1-(4-hydroxyl-3-hydroxymethylphenyl)ethanol] under visible irradiation using Mn-doped TiO2. The Mn-doped TiO2 nanoparticles were synthesized by sol-gel method with the ratio of 0.1%, 0.2% and 0.3%. The significant characteristics including rutile/anatase phase ratio, specific surface area and band gap energy was due to the amount of Mn doping; the narrowest band gap energy of 2.80 eV was observed in the 0.2% Mn-doped TiO2 with the specific surface area of 89.36 m2/g and 10.87/ 89.13 of rutile/anatase phase. The investigation involved salbutamol photocatalytic degradation, kinetic study and identification of intermediate compounds. The results indicated that the 0.2% Mn-doped TiO2 obtained the best salbutamol removal of 95% under irradiation time of 180 min. The salbutamol was slowly degraded to the intermediate compounds in the first 60 min (k = 0.0088 1/min) and they was dramatically mineralized to small hydrocarbon fragments and carbon dioxide in the later irradiation times (k = 0.0179 1/min). According to the HPLC-MS results, the possible degradation pathways of salbutamol were proposed; 2-(tert-butylamino)-1-(3,4-dihydroxyphenyl)ethanone, 2-(tert-butylamino)-ethanol and 2-(tert-butylamino)-1-(4-hydroxyl-3-hydroxymethylphenyl)ethanone were initially formed and then transformed to 2-(methylamino)-1-(3,4-dihydroxyphenyl)ethanone, 2-(tert-butylamino)-acetic acid, hydroqunone and 1-(4-hydroxylphenyl)ethanol. The mineralization of all intermediate compounds was verified by 90% of COD reduction and the effluent contained relatively low COD concentration of 7.8 mg/L.
In the present work, the photocatalytic degradation of salbutamol [2-(tert-butylamino)-1-(4-hydroxyl-3-hydroxymethylphenyl)ethanol] under visible irradiation using Mn-doped TiO2 is investigated. The Mn-doped TiO2 nanoparticles were synthesized by the sol–gel method with ratios of 0.1, 0.2, and 0.3%. Significant characteristics, including the rutile/anatase phases ratio, specific surface area, and band gap energy, were due to the amount of Mn doping; the narrowest band gap energy of 2.80 eV was observed in 0.2% Mn-doped TiO2 with specific surface areas of 89.36 m2/g and 10.87/89.13 of rutile/anatase phases. The investigation involved salbutamol photocatalytic degradation, a kinetic study, and the identification of intermediate compounds. The results indicated that 0.2% Mn-doped TiO2 obtained the best salbutamol removal of 95% under an irradiation time of 180 min. Salbutamol slowly degraded to the intermediate compounds in the first 60 min (k = 0.0088 1/min), and these intermediate compounds were dramatically mineralized to small hydrocarbon fragments and carbon dioxide in the later irradiation times (k = 0.0179 1/min). According to the high-performance liquid chromatography–mass spectrometry (HPLC-MS) results, possible degradation pathways of salbutamol were proposed: 2-(tert-butylamino)-1-(3,4-dihydroxyphenyl)ethanone, 2-(tert-butylamino)-ethanol, and 2-(tert-butylamino)-1-(4-hydroxyl-3-hydroxymethylphenyl)ethanone were initially formed and then transformed to 2-(methylamino)-1-(3,4-dihydroxyphenyl)ethanone, 2-(tert-butylamino)-acetic acid, hydroquinone, and 1-(4-hydroxylphenyl)ethanol, respectively. The mineralization of all intermediate compounds was verified by 90% chemical oxygen demand (COD) reduction, and the effluent contained a relatively low COD concentration of 7.8 mg/L.
A sol–gel method was used to synthesize TiO2 nanoparticles doped with varying amounts of Mn. The physico-chemical properties of the synthesized nanoparticles were characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and diffuse reflection spectroscopy (DRS). The XRD results indicated that the anatase phase was the major phase of TiO2, while a minor rutile phase was observed in the Mn-doped TiO2 0.2 wt.% and 0.3 wt.% samples. The TEM analysis showed that the Mn atoms existed in different oxidation states, including Mn[Formula: see text], Mn[Formula: see text], Mn[Formula: see text] and Mn[Formula: see text], and that the nanoparticles had a spherical-like morphology with a size ranging from 10[Formula: see text]nm. The narrowest band gap of 2.80[Formula: see text]eV was observed in the Mn-doped TiO2 0.2 wt.% sample. The photocatalytic activity of the synthesized nanoparticles was evaluated for methylene blue (MB) photodegradation and Escherichia coli (E. coli) photokilling under visible light irradiation. The MB degradation efficiency was found to be the highest in the Mn-doped TiO2 0.2 wt.% sample, with a removal efficiency of 96% and a degradation rate constant of 0.08 1/min. The degradation efficiency decreased in the following order: Mn-doped TiO2 0.1 wt.%, 0.3 wt.% and undoped TiO2. Similarly, complete E. coli photokilling was achieved only in the Mn-doped TiO2 0.2 wt.% sample, while some residual E. coli was observed in the other doping nanoparticles and undoped TiO2. In summary, the results suggest that Mn doping significantly improved the photocatalytic activity of TiO2 nanoparticles, and the Mn-doped TiO2 0.2 wt.% sample exhibited the highest efficiency in both MB photodegradation and E. coli photokilling under visible light irradiation.
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