Changes in ecotoxicity of naphthalene and alkylated naphthalenes during photodegradation in water

Kang, Hyun-Joong,Jung, Yerin,Kwon, Jung-Hwan Pergamon Press 2019 Chemosphere Vol. No.

<P><B>Abstract</B></P> <P>Crude oil released into the environment contains many polycyclic aromatic hydrocarbons (PAHs). Alkylated PAHs are more abundant than unsubstituted PAHs and their toxicity is also of serious concern. Among the various physical, chemical, and biological weathering processes of crude oils, photodegradation is one of the most important for determining the environmental fate of oil residues. In this study, the photodegradation rate constants of naphthalene and alkylated naphthalenes were determined under simulated laboratory conditions at different temperature. Changes in the luminescence inhibition of <I>Aliivibrio fischeri</I>, as an indicator of the baseline toxicity, were observed in photodegradation mixtures. The major transformation products were also identified by gas chromatography–mass spectrometry. The photodegradation of naphthalene and the eight alkylated naphthalenes was described well by pseudo-first-order kinetics regardless of experimental temperature. The measured toxicity of the reaction mixtures obtained by photodegradative weathering slightly increased initially and then decreased with further weathering. In all cases, the observed toxicity was greater than accounted for by the parent compounds, indicating that the photodegradation products also contributed significantly to the overall toxicity of the mixtures. The identified photodegradation products were mostly oxygenated compounds such as alcohols, aldehydes, ketones, and quinones, which warrant further investigation.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Toxicity changes of Naph and alkyl-Naph by photodegradation were studied. </LI> <LI> The observed photodegradation was well-explained by pseudo-first-order kinetics. </LI> <LI> The observed toxicity of Naph and alkyl-Naph was decreased by photodegradation. </LI> <LI> The toxic contribution by photodegradation products was significant. </LI> <LI> The identified photodegradation products were mainly oxygenated forms. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Prevention of Transition Metal Dichalcogenide Photodegradation by Encapsulation with h-BN Layers

Ahn, Seongjoon,Kim, Gwangwoo,Nayak, Pramoda K.,Yoon, Seong In,Lim, Hyunseob,Shin, Hyun-Joon,Shin, Hyeon Suk American Chemical Society 2016 ACS NANO Vol.10 No.9

<P>Transition metal dichalcogenides (TMDs) have recently received increasing attention because of their potential applications in semiconducting and optoelectronic devices exhibiting large optical absorptions in the visible range. However, some studies have reported that the grain boundaries of TMDs can be easily degraded by the presence of oxygen in water and by UV irradiation, ozone, and heating under ambient conditions. We herein demonstrate the photodegradation of WSe2 and MoSe2 by laser exposure (532 nm) and the subsequent prevention of this photodegradation by encapsulation with hexagonal boron nitride (h-BN) layers. The photodegradation was monitored by variation in peak intensities in the Raman and photoluminescence spectra. The rapid photodegradation of WSe2 under air occurred at a laser power of >0.5 mW and was not observed to any extent at <= 0.1 mW. However, in the presence of a water droplet, the photodegradation of WSe2 was accelerated and took place even at 0.1 mW. We examined the encapsulation of WSe2 with h-BN and found that this prevented photodegradation. However, a single layer of h-BN was not sufficient to fully prevent this photodegradation, and so a triple layer of h-BN was employed. We also demonstrated that the photodegradation of MoSe2 was prevented by encapsulation with h-BN layers. On the basis of X-ray photoelectron spectroscopy and scanning photoemission microscopy data, we determined that this degradation was caused by the photoinduced oxidation of TMDs. These results can be used to develop a general strategy for improving the stability of 2D materials in practical applications.</P>

수중 Trichloroethylene의 광촉매 분해특성에 관한 연구

조성혜,남주희,김일규 대한상하수도학회 2011 상하수도학회지 Vol.25 No.4

The photocatalytic degradation of trichloroethylene (TCE) in TiO2 aqueous suspension has been studied. TiO2 photocatalysts are prepared by a sol-gel method. The dominant anatase-structure on TiO2 particles is observed after calcining the TiO2 gel at 500℃ for 1hr. The Langmuir-Hinshelwood model is applicable to describe the photodegradation, which indicates that adsorption of the solute on the surface of TiO2 particles plays an important role in photodegradation. Photocatalysts with various transition metals (Nd, Pd and Pt) loading are tested to evaluate the effect of transition metal impurities on photodegradation. The photodegradation efficiencies with TiO2 including Pt, Pd and Nd are lower than pure TiO2 powder. The effect of pH is investigated and the maximum photodegradation efficiency is obtained at pH 7. In addition, the intermediates such as dichloromethane, chloroform, and trichloroethane are detected during the photodegradation of TCE.

Preparation of titania-containing photocatalysts from metallurgical slag waste and photodegradation of 2,4-dichlorophenol

Hong Liu,S Vigneswaran,Tao Xia,H.K. Shon 한국공업화학회 2011 Journal of Industrial and Engineering Chemistry Vol.17 No.3

A low cost, high performance titania-containing metallurgical slag photocatalysts (TCMSPx, x = H2SO4,HNO3, HCl) were prepared using a hydrothermal method. The prepared TCMSPx were characterized in terms of visual, physical and chemical properties. The photocatalytic activity of the TCMSPx was evaluated via the photodegradation of 2,4-dichlorophenol (2,4-D) in aqueous solution. The results showed that the characteristics and photocatalytic activity of TCMSPx were strongly affected by acidic solutions used during the acidolysis. TCMSPH2SO4 exhibited better characteristics and higher photocatalytic activity than TCMSPHNO3 and TCMSPHCl. OH radicals from TCMSPH2SO4 were produced under UV, visible and solar light irradiation. The degree of photodegradation of 2,4-D by TCMSPH2SO4 was 80.1%, 50.0% and 61.5% under UV, visible and solar light irradiation respectively. In addition, the removal of chlorine functional group on the 2,4-D benzene ring and the production of intermediates during 2,4-D photodegradation were monitored using ion chromatography, UV–vis spectra and high performance liquid chromatography of 2,4-D before and after photodegradation.

Effect of Fe Contents in Fe-AC/TiO2 Composites on Photodegradation Behaviors of Methylene Blue

Won-Chun Oh,Ming-Liang Chen,Feng-Jun Zhangl,장현태 한국세라믹학회 2008 한국세라믹학회지 Vol.45 No.6

Activated carbon/TiO2 (AC/TiO2) composites modified with different concentrations of Fe were prepared. The N2 adsorption data showed that the composites had decreased surface area compared with the pristine activated carbon. This indicated the blocking of the micropores on the surface of AC, which was further supported by observation via SEM. XRD results showed patterns for the composites and an anatase typed titanium dioxide structure with a small part of rutile in a higher Fe concentration (>1.0 mol/L). EDX results showed the presence of C and, O, with Ti peaks on the composites of Fe-AC/TiO2 with relatively lower Ti concentration, which may be due to the higher Fe concentration incorporated into the composites. Subsequently, the photocatalytic effects on methylene blue (MB) were investigated. The improved decomposition of MB showed the combined effects of adsorptions and photodegradation. Especially, the composites modified by Fe revealed enhanced photodegradation behaviors of MB Activated carbon/TiO2 (AC/TiO2) composites modified with different concentrations of Fe were prepared. The N2 adsorption data showed that the composites had decreased surface area compared with the pristine activated carbon. This indicated the blocking of the micropores on the surface of AC, which was further supported by observation via SEM. XRD results showed patterns for the composites and an anatase typed titanium dioxide structure with a small part of rutile in a higher Fe concentration (>1.0 mol/L). EDX results showed the presence of C and, O, with Ti peaks on the composites of Fe-AC/TiO2 with relatively lower Ti concentration, which may be due to the higher Fe concentration incorporated into the composites. Subsequently, the photocatalytic effects on methylene blue (MB) were investigated. The improved decomposition of MB showed the combined effects of adsorptions and photodegradation. Especially, the composites modified by Fe revealed enhanced photodegradation behaviors of MB

Photodegradation of microcystin-LR using graphene-TiO₂/sodium alginate aerogels

Nawaz, Mohsin,Moztahida, Mokrema,Kim, Jiho,Shahzad, Asif,Jang, Jiseon,Miran, Waheed,Lee, Dae Sung Elsevier 2018 Carbohydrate polymers Vol.199 No.-

<P><B>Abstract</B></P> <P>In this study, sustainable graphene oxide-TiO<SUB>2</SUB>/sodium alginate and reduced graphene oxide-TiO<SUB>2</SUB>/sodium alginate aerogels were synthesized and the potential of these aerogels was investigated for microcystin-LR degradation in aqueous solution. Along with the role of alginate in the synthesis of aerogels, effects of different concentrations of photocatalyst, photolysis, pH, and combination of TiO<SUB>2</SUB> (anatase)/Degussa P25 with graphene were investigated in lieu of microcystin-LR photodegradation.The complete degradation of microcystin-LR was attained in case of reduced graphene oxide-TiO<SUB>2</SUB>/sodium alginate aerogel—not in graphene oxide-TiO<SUB>2</SUB>/sodium alginate aerogel case—by the synergistic effect of adsorption and photodegradation. The recyclability study of reduced graphene oxide-TiO<SUB>2</SUB>/sodium alginate aerogel demonstrated high stability and photoactivity and the degradation efficiency was not much hampered during six consecutive cycles of degradation reaction. The possible fragmentation pathways were also proposed based on identified intermediate products. High adsorption and degradation synergy and ease of separation/recycling of reduced graphene oxide-TiO<SUB>2</SUB>/sodium alginate aerogel can make it a suitable option for removing microcystin-LR from water systems.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Sodium alginate helped to synthesize a robust graphene-TiO<SUB>2</SUB> aerogel. </LI> <LI> Graphene-TiO<SUB>2</SUB>/sodium alginate aerogel efficiently degraded microcystin-LR. </LI> <LI> Synthesized aerogel was highly recyclable without producing any secondary pollution. </LI> <LI> In microcystin-LR degradation pathway, significant role of OH radicals was found. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

수중 Dibenzothiophene의 광촉매 분해에 관한 연구

조성혜,여석준,김일규 대한상하수도학회 2011 상하수도학회지 Vol.25 No.4

In this research, the photocatalytic degradation of dibenzothiophene (DBT) in TiO_2 aqueous suspension has been studied. TiO_2 photocatalysts are prepared by a sol-gel method. The dominant anatase-structure on TiO_2 particles is observed after calcining the TiO_2 gel at 500℃ for 1hr. Photocatalysts with various transition metals (Nd, Pd and Pt) loading are tested to evaluate the effect of transition metal impurities on photodegradation. The photodegradation efficiencies with TiO_2 including Pt and Pd are higher than pure TiO_2 powder. Also we investigated the applicability of H_2O_2 to increase the efficiency of the TiO_2 photocatalytic degradation of dibenzothiophene. The degradation efficiency increases with increasing dosage of H_2O_2 in the range of 0.01M to 0.1M . The effect of pH is investigated; we obtained the maximum photodegradation efficiency at pH 5. In addition, the intermediate analysis found dihydroxyl -dibenzothiophene as a reaction intermediate of dibenzothiophene during the photodegradation

Photoprotection for deltamethrin using chitosan‐coated beeswax solid lipid nanoparticles

Nguyen, Hiep Minh,Hwang, In‐,Cheon,Park, Jae‐,Won,Park, Hyun‐,Jin John Wiley Sons, Ltd. 2012 Pest Management Science Vol.68 No.7

<P><B>Abstract</B></P><P><B>BACKGROUND:</B> In the natural environment, photodegradation is one of the most common degradative processes of pesticides. In order to reduce the photodegradation of pesticides, and so increase their killing activity against target pests, chitosan‐coated beeswax solid lipid nanoparticles (CH‐BSLNs) were prepared by a combination of hot homogenization and sonication, with deltamethrin as an active ingredient.</P><P><B>RESULTS:</B> Under optimal conditions, the highest encapsulation efficiency (95%) and a high payload of deltamethrin (approximately 12.5%) were achieved. In direct photolysis, in the case of CH‐BSLNs after UV irradiation for 24 h, 37.3% of deltamethrin remained, as opposed to only 14.6% of the free‐form deltamethrin. In addition, in indirect photolysis, in the case of CH‐BSLNs after UV irradiation for 2 h in 2% acetone solution, approximately 74.5% of deltamethrin remained, as opposed to only 37.6% of the free‐form deltamethrin.</P><P><B>CONCLUSION:</B> CH‐BSLNs showed good protection for deltamethrin against photodegradation. This novel nanocarrier may be useful in crop protection as an economical strategy to enhance the effect of pesticides in the field and protect the environment as well. Copyright © 2012 Society of Chemical Industry</P>

광안정제를 이용한 acetamiprid 액제의 살충효과 증진

김형민(Hyeong-Min Kim),이원기(Weon-Kee Lee),김종관(Jong-Kwan Kim),석창수(Chang-Su Seok),이창혁(Chang-Hyuk Lee),유용만(Yong-Man Yu),황인천(In-Cheon Hwang) 한국농약과학회 2006 농약과학회지 Vol.10 No.3

The study was carried out to select the effective adjuvant as a photostabilizer for acetamiprid 5% SL(soluble concentrate) and to find its optimum content by using chemical and biological methods. Adjuvants used for the study were KS1 and KS2. Photodegradation test, insecticidal efficacies and residual analysis for the study were investigated. Although photodegradation rate of acetamiprid SL was decreased by addition of KS1 and KS2, the difference between KS1 and KS2 was not significant. As KS2 showed better efficacies against the cotton aphid (Aphis gossypii) and higher amount of residue on pepper than KS1, KS2 was selected as a photostabilizer for acetamiprid SL. Acetamiprid SL with KS2 showed lower photodegradation rate, better efficacies against the cotton aphid (Aphis gossypii) and higher amount of residue on pepper as content of KS2 in acetamiprid SL was decreased. Therefore, it was concluded that the optimum content of KS2 was 0.1%. These results have demonstrated that the selected adjuvant could be used to enhance insecticidal activity and reduce spray dose of insecticide by protecting its photodegradation.

Effect of Fe Contents in Fe-AC/Tio₂ Composites on Photodegradation Behaviors of Methylene Blue

Oh, Won-Chun,Chen, Ming-Liang,Zhang, Feng-Jun,Jang, Hyun-Tae The Korean Ceramic Society 2008 한국세라믹학회지 Vol.45 No.6

Activated carbon/$TiO_2$ (AC/$TiO_2$) composites modified with different concentrations of Fe were prepared. The $N_2$ adsorption data showed that the composites had decreased surface area compared with the pristine activated carbon. This indicated the blocking of the micropores on the surface of AC, which was further supported by observation via SEM. XRD results showed patterns for the composites and an anatase typed titanium dioxide structure with a small part of rutile in a higher Fe concentration (> 1.0 mol/L). EDX results showed the presence of C and, O, with Ti peaks on the composites of Fe-AC/$TiO_2$ with relatively lower Ti concentration, which may be due to the higher Fe concentration incorporated into the composites. Subsequently, the photocatalytic effects on methylene blue (MB) were investigated. The improved decomposition of MB showed the combined effects of adsorptions and photodegradation. Especially, the composites modified by Fe revealed enhanced photodegradation behaviors of MB.