Photosensitive chitosan for visible-light water pollutant degradation

Gmurek, Marta; Foszpańczyk, Magdalena; Olak-Kucharczyk, Magdalena; Gryglik, D.; Ledakowicz, S.

doi:10.1016/j.cej.2016.06.125

Cited by 24 publications

(19 citation statements)

References 32 publications

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“…The experiments were carried out at pH 9 in buffer solution and in MQ water without pH control. pH 9 was selected based on our previous study (Gmurek et al 2017 ), where it was found that under those conditions, the photodegradation occurred much faster. The same reaction solution was exposed to the simulated and solar light.…”

Section: Resultsmentioning

confidence: 99%

“…Anyhow, the oxidative ability of 1 O 2 is much lower than the one of HO·. In both cases, the photodegradation process depends on the intensity of light, adsorption of pollutants on catalysts/carrier surface, pH, amount of anions and cations in reaction solution, the reaction temperature, and the surface area of the photocatalyst (Martins and Quinta-Ferreira 2009 ; Chuang and Luo 2015 ; Gmurek et al 2015 , Gmurek et al 2017 ).…”

Section: Introductionmentioning

confidence: 99%

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Comparison of Photocatalytic and Photosensitized Oxidation of Paraben Aqueous Solutions Under Sunlight

Foszpańczyk

Bednarczyk

Drozdek

et al. 2018

Water Air Soil Pollut

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It is well-established that aquatic wildlife is exposed to natural and synthetic endocrine disrupting compounds which are able to interfere with the hormonal system. Although advanced oxidation processes (AOPs) have shown to be effective, their application is limited by a relatively high operational cost. In order to reduce the cost of energy consumed in the AOPs, widely available solar energy instead of UV light may be applied either as photocatalytic oxidation or as photosensitized oxidation. The main goal of the present study was to investigate the sunlight photodegradation of paraben mixture. Two processes, namely the photocatalytic oxidation with modified TiO2 nanoparticles and photosensitized oxidation with photosensitive chitosan beads, were applied. The oxidants were identified as singlet oxygen and hydroxyl radicals for photosensitized and photocatalytic oxidation, respectively. The toxicity, as well as ability to water disinfection of both processes under natural sunlight, has been investigated. Application of sunlight for the processes led to degradation of parabens. The efficiency of both processes was comparable. Despite the fact that singlet oxygen is weaker oxidant than hydroxyl radicals, the photosensitized oxidation seems to be more promising for wastewater purification, due to the possibility of chitosan bead reuse and more effective water disinfection. Graphical Abstractᅟ Electronic supplementary materialThe online version of this article (10.1007/s11270-018-3991-y) contains supplementary material, which is available to authorized users.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Comparison of Photocatalytic and Photosensitized Oxidation of Paraben Aqueous Solutions Under Sunlight

Foszpańczyk

Bednarczyk

Drozdek

et al. 2018

Water Air Soil Pollut

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“…As previously mentioned, the pH of the solution possibly affected the degree of oxidation of the compounds. Most of the examined compounds in the buffer solution occurred in a dissociated form, which promoted the reaction with the singlet oxygen [10]. However, when we compared the pKa values of pHOH (pKa = 9.99), 2-PP (pKa = 10.01), and 3-PP (pKa = 9.5) ( Figure 5C), none of the compounds were predominantly in the dissociated form.…”

Section: Photosensitized Oxidationmentioning

confidence: 99%

“…Moreover, in homogenous systems (where the photosensitizer is dissolved in a water solution), the photosensitizer undergoes photobleaching, resulting in a rapid decrease in yield. Immobilized photosensitizers exhibit the advantages of good activity, stability against photobleaching, and repeated use [10]. Immobilization of a photosensitizer is associated with a decrease in the quantum yield of singlet oxygen [8,9].…”

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confidence: 99%

Heterogeneous Oxidation of Phenolic Compounds with Photosensitizing Catalysts Incorporated into Chitosan

et al. 2019

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The increasing amount of hazardous micropollutants in the aqueous environment has recently become a concern, especially because they are not usually included in environmental monitoring programs. There is also limited knowledge regarding their behavior in the environment and their toxicity. This paper presents results regarding the heterogeneous photosensitized oxidation of 10 phenolic compounds under visible light. All of the selected compounds are classified as pollutants of emerging concern. For the first time, the application of photosensitizing catalysts incorporated into a chitosan carrier was investigated from several points of view, namely, structure characterization, singlet oxygen generation potential, photodegradation ability, biodegradability, and toxicity assessment. It was found that compounds of different origins were degraded with high effectivity. Photoactive chitosan was stable and could be reused for at least 12 cycles without losing its photocatalytic activity. The Hammett constants for all of the degraded compounds were determined. Improved biodegradability after the treatment was achieved for almost all compounds, apart from 4-hydroxybenzoic acid, and only slightly for 2-phenylphenol. The acute toxicity was assessed using bioluminescent Vibrio fischeri bacteria, indicating lower toxicity than the parent compounds.Photosensitized oxidation is undoubtedly one of the most important photochemical methods, since it does not generate any additional pollutants [5]. Moreover, the advantage of photosensitized oxidation is the photooxidation of hard-degradable compounds by singlet oxygen generated in the presence of air and solar radiation [5][6][7], therefore, photosensitized oxidation is classified as a green chemistry process. Moreover, because the heterogeneous process is considered to leave no residue, no sludge is produced from the process. Furthermore, if the immobilized photosensitizer remains unchanged throughout the process, the photocatalyst can easily be reused.Two general mechanisms of photosensitized oxidation for such reactions are well-known as Type I, also called the radical-involving mechanism, and Type II, the singlet oxygen mechanism [8,9]. Our previous research showed that singlet oxygen could be used for water purification. For this kind of area, the immobilization of photosensitizers onto various materials (heterogeneous system) is a desirable approach due to the easy separation from the reaction mixture and the preparation for reuse. Moreover, in homogenous systems (where the photosensitizer is dissolved in a water solution), the photosensitizer undergoes photobleaching, resulting in a rapid decrease in yield. Immobilized photosensitizers exhibit the advantages of good activity, stability against photobleaching, and repeated use [10]. Immobilization of a photosensitizer is associated with a decrease in the quantum yield of singlet oxygen [8,9]. This may be due to limitations in oxygen diffusion into and from the carrier material [9]. These disadvantages can be overcome by reusi...

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“…Such properties make singlet oxygen significantly more electrophilic and more reactive towards unsaturated bonds than the ground state oxygen: it reacts with singlet state electron-rich compounds unsaturated bonds, and typical reactions of singlet oxygen are Schenck reactions and Diels-Alder reactions. (by 1 O2) of benzylparaben and 2, 4-dichlorophenol, the results show that the studied system had good efficacy and could work in wide pH range [131]. Kim et al reported degradation of several pharmaceuticals using tin porphyrin-and C60 aminofullerene-derivatized silica as photosensitizers, where 1 O2 was identified as the primary oxidant, and the performance in real wastewater effluents was still effective [130].…”

Section: Photosensitization Processesmentioning

confidence: 99%

Micropollutant degradation in water by photochemical processes

Yin¹

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Fast growing global population and economy result in an increasing water consumption worldwide. However, the amounts of usable water resources are limited: more than one-third of the accessible renewable fresh water on Earth is being exploited for industrial, agricultural, as well as domestic usage [1]. Locally, especially in water scarce areas, this is often reaching much higher levels, leading to overdraft of water resources [2]. Such facts call for the need to not only exploit new and alternative water resources but also to recycle water streams, to cope with the unfortunate increasing limitations in availability of fresh water sources. Meanwhile, the fast growing population and economy are leading to serious water pollution due to discharge of numerous contaminants into the environment, which in turn possess sever threats to the quality of water resources. Thus, the increasing worldwide demand for water consumption, the limited amount of water resources, and the water pollution make water treatment a vital measure to safeguard the water supply with sufficient quantity and quality that meets the demand of the society. Conventionally, concerns were given to pathogens, nutrients, heavy metals, suspended solids, and bulk organic pollutants (the amount of bulk organic pollutants generally present in concentrations at 0.1-10 g/l in waste water and often denoted with COD or BOD, meaning chemical or biological oxygen demand). Thus in most parts of the world water purification measures have been taken to tackle these problems [3, 4]. In recent decades, many emerging organic pollutants (generally present at rather low concentrations, i.e. ng/L to µg/L level, and therefore also termed as micropollutants). These include pharmaceuticals, antibiotics, herbicides, pesticides, chemicals from personal care products, etc., and have been detected the last two decades extensively in different water bodies worldwide. For instance, many pharmaceuticals were found in various portions of the aquatic system, i.e. in ground water, surface water, as well as in many drinking water sources according to a broad range of studies [5-11]. In a study conducted by Félix-Cañedo et al. in Mexico City, the presence of a group of organic micropollutants (including pharmaceuticals, hormones, herbicides) in several drinking water sources was reported, at concentrations ranging from ng/L to µg/L level [12]. In recent years, a broad range of micropollutants, including Other investigated homogeneous photochemical processes include UV/Cl2, UV/O3, UV/HOCl, UV/ClO2. Application of these techniques for removal of various micropollutants has been studied over last decades. It is reported that UV/Cl2 could achieve relatively good removal of carbamazepine from wastewater, but formation of toxic chlorinated byproducts was an issue [132, 133]. Kong et al. reported efficient degradation of atrazine by UV/Cl2 [134]. Examples of micropollutant removal by UV/O3, UV/HOCl, UV/ClO2, etc., are also abundant in literature [135-138]. 1.3 Research opportunities 1.3.1 Rese...

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Photosensitive chitosan for visible-light water pollutant degradation

Cited by 24 publications

References 32 publications

Comparison of Photocatalytic and Photosensitized Oxidation of Paraben Aqueous Solutions Under Sunlight

Comparison of Photocatalytic and Photosensitized Oxidation of Paraben Aqueous Solutions Under Sunlight

Heterogeneous Oxidation of Phenolic Compounds with Photosensitizing Catalysts Incorporated into Chitosan

Micropollutant degradation in water by photochemical processes

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