Photocatalytic degradation of pentachlorophenol by visible light Ν–F–TiO2 in the presence of oxalate ions: optimization, modeling, and scavenging studies

Abstract

The efficiency of heterogeneous photocatalysis using N-F-TiO2 as photocatalyst to degrade a priority pollutant, pentachlorophenol (PCP), in the presence of oxalates (OA) was investigated in detail. Response surface methodology was used to optimize the effect of three variables (catalyst concentration, OA/PCP ratio, and pH) on the photocatalytic degradation of pentachlorophenol. A quadratic model was established as a functional relationship between three independent variables and the degradation efficiency of PCP. The results of model fitting and statistical analysis demonstrated that the pH played a key role in the degradation of PCP. Within the studied experimental ranges, the optimum conditions for maximum PCP degradation efficiency (97.5 %) were: catalyst concentration 600 mg L(-1), OA/PCP ratio 2, and pH 10. The contribution of HO(·), O2 (·-), and e(-) produced during the photocatalytic treatment was investigated with the addition of scavengers. The photocatalytic degradation was essentially proceeded through an oxidative mechanism at both acid and alkaline pH values by HO(.) and O2 (·-) radicals attack. It was found that O2 (·-) were the major reactive species involved in PCP degradation in pH 4 and HO(·) in pH 10.

Photocatalytic Degradation of Orange G Dye by Using Bismuth Molybdate: Photocatalysis Optimization and Modeling via Definitive Screening Designs

“…The adequacy of the model was tested by the analysis of variance (ANOVA) and all the assumptions were analyzed for the meaningful results. Further violation of regression assumption was checked by several diagnostic methods, which included a graphical illustration of predicted vs. experimental values, to check the normality of the residuals by a normal probability plot of the studentized residuals, to look continually for errors made by studentized residuals vs. predicted plot, to check the outlier by cook distance, and the need of power transformations were checked by the Box-Cox plot [ 44 ].…”

Preparation and Photocatalytic Properties of CdS/F–TiO2 Composites

“…Since Minero et al [13] found in 2000 that the modification of F − could effectively improve the photocatalytic degradation activity of TiO 2 on phenol, fluorine modified TiO 2 has become a research hotspot [14][15][16]. Yu et al [17] showed that the crystallinity of anatase was improved after F − doping and F − could not only inhibit the formation of slate phase but also prevent anatase phase from transforming into rutile.…”

Dynamic Tracking of Highly Toxic Intermediates in Photocatalytic Degradation of Pentachlorophenol by Continuous Flow Chemiluminescence

“…Advanced oxidation processes (AOPs) such as ozonation, , Fenton, , H 2 O 2 /UV, , sonolysis, and photocatalysis have been widely and extensively explored to degrade environmental contaminants such as pentachlorophenol (PCP). − Heterogeneous photocatalysis by TiO 2 is of considerable interest in AOPs due to its low toxicity and strong oxidizing power, − which has been widely concerned as one of the most efficient methods to eliminate chlorophenols from water. ,− However, many reports focused solely on the degradation efficiency and remove conditions of the target compound. It should be worth noting that even after complete removal of PCP, acute toxicity was still observed, ,,,, which might be caused by the generation of toxic PCP byproducts including polychlorinated dibenzodioxins/furans, , tetrachloro-1,4-benzoquinone (TCBQ), − ,, or other toxic intermediates. Therefore, determination of the only pristine PCP concentration may not be sufficient for evaluating an overall efficiency of wastewater treatment.…”