Photocatalytic Degradation Of Naphthalene Research Articles

Metal ion endogenous cycles of CoFe2O4-x induced boosted photocatalytic/PMS degradation toward polycyclic aromatic hydrocarbons.

The rational design of photocatalytic nanomaterials with unique structures is critical for remediating environmental problems and thus reducing ecological risks. In this work, we employed H2 temperature-programmed reduction to modify MFe2O4 (M = Co, Cu, and Zn) photocatalysts for obtaining additional oxygen vacancies. After activation of PMS, naphthalene and phenanthrene degradation rates in the soil phase were increased by 3.24-fold and 1.39-fold, respectively, and 1.38-fold for naphthalene in the aqueous phase by H-CoFe2O4-x. The extraordinary photocatalytic activity is attributed to the oxygen vacancies on the H-CoFe2O4-x surface, which promote electron transfer and thus enhance the redox cycle from Co(III)/Fe(III) to Co(II)/Fe(II). In addition, oxygen vacancies are used as electron traps to hinder the recombination of photogenerated carriers and accelerate the generation of hydroxyl and superoxide radicals. Quenching tests showed that the addition of p-benzoquinone resulted in the greatest decrease in the degradation rate of naphthalene (inhibition of about 85.5%), demonstrating that O2˙- radicals are the main active species in the photocatalytic degradation of naphthalene. H-CoFe2O4-x showed improved degradation performance in synergy with PMS (82.0%, kapp = 0.00714 min-1) while maintaining excellent stability and reusability. Hence, this work provides a promising approach for the design of efficient photocatalysts to degrade persistent organic pollutants in soil and aqueous environments.

Photocatalytic Degradation of Naphthalene in Aqueous Dispersion of Nanoparticles: Effect of Different Parameters

Photocatalytic Degradation of Naphthalene in Aqueous Dispersion of Nanoparticles: Effect of Different Parameters

Thermal decomposition synthesis of Zn-HAP (extracted from fish scale) nanopowder and its photocatalytic and antibacterial activities under visible light

The present study, for the first time, reports synthesizes Zn-Hydroxyapatite (Zn-HAP) nanopowder through a novel thermal decomposition method. Zn-HAP was characterized using FE-SEM, EDX, XRD, BET, DRS, PL, and FT-IR spectroscopy techniques. FT-IR spectroscopy confirmed that the main characteristic peaks of HAP are preserved in Zn-HAP with little variations in peak positions. The XRD pattern also confirmed the intensity of peaks of Zn-HAP is slightly lowered due to zinc substitution, while the diffraction peak positions are not shifted. DRS data showed two band gaps energies of 2.9 eV and 3.5 eV. PL emission spectra represented that doping of Zn2+ ions into the crystal structure of HAP facilitates the separation of charge carriers, therefore suppress electron-hole recombination. It is also found that Zn-HAP can be used for adsorption and photocatalytic degradation of naphthalene under visible light (R% = 68.5%). The results of EIS and photocurrent generation measurements demonstrated that the Zn-HAP has faster transfer of the photogenerated electron–holes pairs and higher separation efficiency comparing with pure HAP. The antibacterial activity was examined on gram-positive (Streptococcus aureus and Bacillus subtilis) and gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa and Klebsiella pneumonia). The results show that HAP nanopowder does not exhibit antibacterial activity at the concentrations studied, while Zn-HAP displays antibacterial properties for both gram-positive and gram-negative bacteria. Moreover, inactivation of E. coli by various scavengers suggested that OH.,O2−. and hole are the major species involved in bacterial disinfection. Overall, the results revealed that prepared Zn-HAP is a good and inexpensive nanomaterial to remove bacteria and organic dyes from drinking water resources.

Investigation of Naphthalene Removal from Aqueous Solutions in an Integrated Slurry Photocatalytic Membrane Reactor: Effect of Operating Parameters, Identification of Intermediates, and Response Surface Approach

A laboratory scale indigenous integrated slurry photocatalytic membrane reactor (PMR), coupling TiO2/UV-C photocatalysis and ultrafiltration (UF) membrane process was evaluated for the removal of naphthalene (NAP)—one of the low molecular weight polycyclic aromatic hydrocarbons (PAHs), frequently detected in municipal and industrial wastewaters. The different operational parameters such as initial NAP concentration (5–25 mg/L), catalyst dosage (0.1–0.9 g/L), and feed solution pH (3–9) were investigated for NAP and total organic carbon (TOC) removal. The experimental results obtained from the batch study of the integrated process showed 92.8% and 90.2% of NAP and TOC removals while the individual processes; UV-TiO2 (76.8% NAP and 56.4% TOC removals) and UF membrane separation process (49.1% NAP removal) exhibited low removal rates for the same experimental conditions. The NAP and TOC removals obtained during continuous flow studies were 93.1% and 91.4% at 180 min and thereafter remained constant up to 560 min of reactor running time. This study also includes the identification of intermediates that are formed after 30 min of operation of PMR. The photocatalytic degradation of NAP followed pseudo-first-order kinetics and the obtained experimental data were analyzed with response surface methodology (RSM) using design expert software.

Modelling and Optimization of Photocatalytic Degradation of Naphthalene Using ZnO-ZnFe2O4 Composite

ZnO-ZnFe2O4 composite was applied for photocatalytic degradation of naphthalene in fresh and saline waters under visible light irradiation. The effects of initial concentration of naphthalene, ZnO-ZnFe2O4 dosage and salinity on photocatalytic degradation of naphthalene were investigated using the central composite design. Statistically significant model quadratic equation was developed for photocatalytic degradation of naphthalene using ZnO-ZnFe2O4 composite. The most significant parameter in the photocatalytic degradation is the ZnO-ZnFe2O4 dosage followed by the initial concentration of naphthalene and then salinity. The highest photocatalytic degradation of naphthalene was achieved at salinity of zero (that is in fresh water). The predicted optimum conditions for photocatalytic degradation of naphthalene using the ZnO-ZnFe2O4 composite are: initial naphthalene concentration of 16.8 mg/l, ZnO-ZnFe2O4 dosage of 0.50 g/l, and salinity of 0 ppt. The model quadratic equation was validated by performing experiments under the predicted optimum values. The experimental and the predicted values of naphthalene degradation under the predicted optimum values are 99.04 % and 98.8 %. Hence, the developed quadratic model is reliable for predicting photocatalytic degradation of naphthalene using ZnO-ZnFe2O4 composite.

Photocatalytic Degradation of Naphthalene by Electrospun Mesoporous Carbon-Doped Anatase TiO2 Nanofiber Mats

We have fabricated partially aligned free-standing mesoporous pure anatase TiO2 nanofiber mats (TiO2-NF) for photocatalysis by electrospinning on a rotating drum collector using a blend of titanium isopropoxide (Ti(OiPr)4), with a carrier polymer, polyvinylpyrrolidone (PVP) in acetic acid and ethanol. Calcination removes PVP and generates mesoporous TiO2-NF with fiber diameters in the range of 25–75 nm by optimizing the electrospinning parameters such as electric field strength, polymer concentration, and flow rate of solution, etc. The band gap energy of TiO2 nanofibers from the UV–vis absorption spectra is found to increase with an increase in the calcination temperature, thus allowing band gap engineering for different applications. The surface morphology, phase composition, crystallinity, surface area, and porosity of the TiO2-NF are also investigated. We demonstrate the efficient and reusable photocatalytic action of the partially aligned pure electrospun TiO2-NF and residual carbon containing TiO2-N...

Preparation and Application of Mesoporous Nanotitania Photocatalysts Using Different Templates and pH Media

Mesoporous nanotitania photocatalysts were prepared by sol-gel method in acidic or basic media. Three types of surfactants, namely, cetyltrimethylammonium bromide, sodium dodecylbenzenesulfonate, and nonylphenol ethoxylate, were used as templating agents. The effects of surfactant type and pH on the morphology, particle size, surface area, pore-size distribution, UV-Vis absorbance, and TiO2phase transformation were traced by SEM, TEM, BET, and XRD. In absence of surfactants, XRD revealed 54.5% anatase at pH 3-4 and 97.0% at pH 7–9. In presence of surfactant, phase transformation of anatase has been significantly inhibited such that anatase amounts to 82–100% in acidic media. In basic media, the brookite phase appeared in low concentrations (8–15%) while rutile totally disappeared. The photocatalytic performance of the synthesized catalysts was tested via naphthalene degradation, which exhibited high activity in visible irradiation (>400 nm). The data obtained indicate that the surface area and pore volume of the current catalysts are the most effective factors for photocatalytic performance. Nevertheless, at the low pH (acidic) range, the CTAB templated catalyst gave the highest surface area (86.7 cm3/g), which is mainly assigned to acquiring the highest photocatalytic degradation of naphthalene (97% after 4 h irradiation time).

Optimization of photocatalytic degradation of naphthalene using nano-TiO2/UV system: statistical analysis by a response surface methodology

AbstractIn this study, the response surface methodology (RSM) was applied for modeling and optimization of photocatalytic degradation of naphthalene using TiO2 nanoparticles in a batch slurry system. The effect of four independent parameters such as agitation speed (X1), air flow rate (X2), catalyst loading (X3), UV light intensity (X4), and their interactions was investigated. A quadratic model was qualified to predict the degradation percent of naphthalene in different conditions, consequently. The significance of independent variables and their interactions were evaluated by the analysis of variance (ANOVA). Evaluation of the p-value approved that the effect of interactions is not very significant and so interaction terms were removed from the initial model. In order to achieve the maximum degradation percent, the optimum conditions were obtained by mathematical and statistical methods. The results showed that the maximum degradation efficiency can be achieved at the optimum conditions: X1 = 150 rpm, X...

Photocatalytic degradation of naphthalene in aqueous TiO 2 dispersions: Effect of nonionic surfactants

The decomposition of naphthalene in the presence of TiO 2 dispersions irradiated with simulated solar light has been investigated in water and in aqueous Brij 35 solutions, used to wash soil samples containing the adsorbed pollutant. The monitoring of the reaction system performed during the treatment showed the formation of various aromatic intermediates, in turn degraded, which were identified using suitable analytical techniques. Fast and complete mineralization of naphthalene to CO 2 was achieved when working in the absence of additives, whereas a neat inhibition of the degradation was observed in the presence of amphiphiles and other organic components coming from soil. Experimental conditions under which surfactant-containing washes can be treated were investigated and defined.

Photocatalytic degradation of naphthalene and anthracene: GC-MS analysis of the degradation pathway

The mechanism of the photocatalytic transformation of naphthalene and anthracene has been studied qualitatively in aqueous suspensions of titanium dioxide under UV-irradiation. The degradation products were identified by GC-MS technique. 15 different intermediates have been identified during the photocatalytic degradation of naphthalene. A detailed reaction mechanism is proposed to explain their formation. For the photocatalytic degradation of anthracene phthalic acid and 9, 10-anthraquinone have been found as relatively stable intermediates. Their photocatalytic degradation has been followed in separate experiments to achieve further clarification of the reaction pathway.