Removal of an Organic Refractory Compound by Photocatalysis in Batch Reactor - Kinetic Studies (original) (raw)
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Current research on the photocatalytic activity of TiO2 mainly focuses on its nano- or micro-particle forms, which are difficult to recycle and apply in real engineering applications. This study aims to apply a small pilot of TiO2 in the ceramic form to remove carbamazepine (CBZ) from an aqueous solution under simulated sunlight. A high removal efficiency up to >99% was shown in a 5 mg L−1 CBZ solution after 6 h of irradiation with a total energy of 150.92 kJ. The kinetic degradation was not affected in an alkaline solution (at pH 7, pH 10, and pH 13) but was faster under acidic conditions (pH 2) in which CBZ existed in the protonated form. The presence of NO3− (10–50 mg L−1) slightly affected the photodegradation of CBZ while humic acid significantly reduced the photocatalytic activity. In addition, the presence of major ions in water also had a negative effect at concentrations between 10 and 50 mg L−1. The MS/MS was used to identify the transformation products of CBZ, and a po...
The light-induced degradation of clofibric acid, carbamazepine, iomeprol and iopromide under simulated solar irradiation has been investigated in aqueous solutions suspended with different TiO 2 materials (P25 and Hombikat UV100). Kinetic studies showed that P25 had a better photocatalytic activity for clofibric acid and carbamazepine than Hombikat UV100. For photocatalytic degradation of iomeprol Hombikat UV100 was more suitable than P25. The results can be explained by the higher adsorption capacity of Hombikat UV100 for iomeprol. The study also focuses on the identification and quantification of possible degradation products. The degradation process was monitored by determination of sum parameters and inorganic ions. In case of clofibric acid various aromatic and aliphatic degradation products have been identified and quantified. A possible multi-step degradation scheme for clofibric acid is proposed. This study proves the high potential of the photocatalytic oxidation process to transform and mineralize environmentally relevant pharmaceuticals and contrast media in water.
Bioresource Technology, 2011
This paper aims to demonstrate that integrating biological process and photocatalytic oxidation in a system operated in recycling mode can be a promising technology to treat pharmaceutical wastewater characterized by simultaneous presence of biodegradable and refractory/inhibitory compounds. A lab-scale system integrating a membrane bioreactor (MBR) and a TiO 2 slurry photoreactor was fed on simulated wastewater containing 10 mg/L of the refractory drug Carbamazepine (CBZ). Majority of chemical oxygen demand (COD) was removed by the MBR, while the photocatalytic oxidation was capable to degrade CBZ. CBZ degradation kinetics and its impacts on the biological process were studied. The adoption of a recycling ratio of 4:1 resulted in removal of up to 95% of CBZ. Effluent COD reduction, sludge yield increase and respirometric tests suggested that the oxidation products were mostly biodegradable and not inhibiting the microbial activity. These results evidenced the advantages of the proposed approach for treating pharmaceutical wastewater and similar industrial effluents.
Journal of Renewable and …, 2010
Photocatalysis process, as an environmental application, is a relatively novel subject with tremendous potential in the near future. A number of studies determine the economic viability of applying various ultraviolet advanced oxidation processes for the purpose of degradation and destroying of various pollutant solutions. The present paper reviews the treatment of hazardous wastewater bearing organic compounds and the effects of various parameters such as pH, initial concentration, mass of catalyst, wavelength, light intensity, electron acceptor, temperature, etc., with the treatment cost for different reactor type. This study investigates the effect of various types of waste-water treatment parameters and the treatment cost for various designs of photocatalytic reactors, using both solar and artificial light, have been proposed for their different types of pollutants.
Applied Catalysis B: Environmental, 2011
The photocatalytic degradation of Carbamazepine (CBZ), 5H-dibenzo[b,f]azepine-5-carboxamide, under near UV-Vis and UV irradiation is studied using P25, synthesized TiO 2 (anatase and rutile), mechanical mixtures and composites of oxidized-multi-walled-carbon-nanotube:anatase, and ZnO suspensions as catalyst, to identify intermediates, and to elucidate its degradation mechanism. Factors affecting the kinetics of the process, such as the type and load of photocatalyst, and the presence of dissolved O 2 or addition of co-oxidants (H 2 O 2), have been compared. Optimal conditions for degradation were obtained using P25 (0.5 g/L), 5 mM of H 2 O 2 or 50% O 2 (v/v), with rate constants ca. 0.3144 min −1 and 0.2005 min −1 , respectively. Complete removal of CBZ was achieved, showing the efficiency of the photocatalytic process. Ten photoproducts of CBZ were assigned by using high-resolution mass spectrometry, the most important of which identified as 10,11-dihydro-CBZ-10,11-epoxide, in accordance with the literature. The reaction mechanism includes previous proposals, and accounts for the pathways giving rise to the identified photoproducts.
Photocatalytic degradation of terbuthylazine: Modelling of a batch recirculating device
Journal of Photochemistry and Photobiology A: Chemistry, 2018
A thin layer photocatalyst using chitosan to immobilize TiO 2 on a glass fiber woven roving material was successfully used for photocatalytic degradation of terbuthylazine, s model s-triazine herbicide. The reaction was conducted in a photocatalytic recirculating reactor with the photocatalyst inserted as a removable module. The experimental reaction system employed in this study was composed of an annular photoreactor with the immobilized TiO 2 /chitosan layer and the radiation source and the second part of the reaction system only used for the aeration or the reaction mixture, both operating in unsteady conditions. The kinetic model is based on a simplified consecutive degradation of terbuthylazine to cyanuric acid through intermediate products. The model of the annular reactor is represented by a hyperbolic partial differential equation solved by method of characteristics; the model of the aeration vessel is given by an ordinary differential equation. The proposed model represents a simple way to describe a complex recirculating reactor system operating in unsteady conditions.
The effect of dosage on the photocatalytic degradation of organic pollutants
Research on Chemical Intermediates, 2007
Heterogeneous photocatalytic degradation of many organic pollutants, such as phenol and phenol derivatives, may be optimised if the catalyst surface saturation and the appearance and accumulation of non-photocatalytically degradable intermediates is avoided. It has been shown that under certain concentration threshold the highest degradation efficiencies are achieved. Over these concentrations, degradation rates become constant owing to the limited catalyst surface. By the dosage of the contaminant, currently in an aqueous solution, the process may be optimised, thus avoiding the formation of inert intermediates which may be more toxic than the parental compound. The effect of dosage on the photocatalytic degradation of phenol and phenol derivatives, such as salicylic acid and 4-aminophenol has been studied. Comparatively notably higher efficiencies have been obtained compared to those of the high initial single dose experiments (non-dosage), for which high initial concentrations of the organics resulted in the catalysts poisoning. Degussa P-25 and its combination with 13% (w/w) activated carbon, namely AC-TiO 2 , have been used as catalysts. Almost complete degradations are achieved at low dosage rates (1-2 pmm/min). At higher dosage rates, different processes such as catalyst poisoning predominate, resulting in lower degradation efficiencies.
Photocatalytic degradation of organic compounds in wastewaters
Technologica Acta, 2019
Due to the toxicity effects and endocrine disrupting properties of many organic compounds, their removal from water and wastewater has gained widespread global attention. This review summarizes photocata-lytic degradation of different organic molecules present in wastewaters. This is an overview of photocatalytic degradation with the goal of presenting the technique as an attractive and viable process unit. This process has great potential for replacing other conventional methods for treatment of wastewaters and can be used at the advanced treatment stage. Photocatalytic degradation techniques should be more used in wastewater treatment because with this technique it is possible to decrease contaminants to certain acceptable discharge limits. However, the technique is still not being utilised on an industrial scale. This is mainly due to focus of researchers to study singular contaminants such as alcohols, carboxylic acid, phenol and its derivate, chlorinated aromatic compounds, colours , active pharmaceutical ingredients, and different type of surface active agents. TiO 2 can be used as a photo-catalyst in water purification to degrade organic pollutants.