Stability and toxicity of selected chlorinated benzophenone-type UV filters in waters

Stability and toxicity of selected chlorinated benzophenone-type UV filters in water

Stability and Toxicity of Selected Chlorinated Benzophenone-type UV Filters in Waters

In our study, the transformation of two most widely used UV filters, benzophenone-3 (BP3) and benzophenone-4 (BP4), in chlorinated water with disinfection reagents sodium hypochlorite (NaClO) and trichloroisocyanuric acid (TCCA) was studied. Based on the HPLC/MS and UV-Vis analysis the formation of two different chlorinated products (5-chloro-2-hydroxy-4-methoxybenzophenone and 3,5-dichloro-2-hydroxy-4-methoxybenzophenone) was established. Identity of chlorinated products was confirmed by means of comparison of retention times with independently synthesized standards. Photostability study showed that dichloro-derivative in water is less stable then parent compounds, which is not the case for monochloro-derivatives. Toxicity of chlorinated compounds tested by Vibrio fischeri was found to be in the same range as that of the starting compounds. Preliminary testing of real water samples from swimming pools and sea swimming areas confirmed the presence of BP3 and its 3,5-dichloro derivative

Supplementary data for the article: Grbović, G.; Malev, O.; Dolenc, D.; Klobučar, R. S.; Cvetković, Z.; Cvetković, B.; Jovančicévić, B.; Trebše, P. Synthesis, Characterisation and Aquatic Ecotoxicity of the UV Filter Hexyl 2-(4-Diethylamino-2-Hydroxybenzoyl)Benzoate (DHHB) and Its Chlorinated by-Products. Environmental Chemistry 2016, 13 (1), 119–126. https://doi.org/10.1071/EN15013

Supplementary material for: [https://doi.org/10.1071/EN15013]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/2020

Stability and Toxicity of Selected Chlorinated Benzophenone-type UV Filters in Waters

In our study, the transformation of two most widely used UV filters, benzophenone-3 (BP3) and benzophenone-4 (BP4), in chlorinated water with disinfection reagents sodium hypochlorite (NaClO) and trichloroisocyanuric acid (TCCA) was studied. Based on the HPLC/MS and UV-Vis analysis the formation of two different chlorinated products (5-chloro-2-hydroxy-4-methoxybenzophenone and 3,5-dichloro-2-hydroxy-4-methoxybenzophenone) was established. Identity of chlorinated products was confirmed by means of comparison of retention times with independently synthesized standards. Photostability study showed that dichloro-derivative in water is less stable then parent compounds, which is not the case for monochloro-derivatives. Toxicity of chlorinated compounds tested by Vibrio fischeri was found to be in the same range as that of the starting compounds. Preliminary testing of real water samples from swimming pools and sea swimming areas confirmed the presence of BP3 and its 3,5-dichloro derivative

Supplementary data for the article: Grbović, G.; Malev, O.; Dolenc, D.; Klobučar, R. S.; Cvetković, Z.; Cvetković, B.; Jovančicévić, B.; Trebše, P. Synthesis, Characterisation and Aquatic Ecotoxicity of the UV Filter Hexyl 2-(4-Diethylamino-2-Hydroxybenzoyl)Benzoate (DHHB) and Its Chlorinated by-Products. Environmental Chemistry 2016, 13 (1), 119–126. https://doi.org/10.1071/EN15013

Supplementary material for: [https://doi.org/10.1071/EN15013]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/2020

Online gas composition estimation in solid oxide fuel cell systems with anode off-gas recycle configuration

Degradation and poisoning of solid oxide fuel cell (SOFC) stacks are continuously shortening the lifespan of SOFC systems. Poisoning mechanisms, such as carbon deposition, form a coating layer, hence rapidly decreasing the efficiency of the fuel cells. Gas composition of inlet gases is known to have great impact on the rate of coke formation. Therefore, monitoring of these variables can be of great benefit for overall management of SOFCs. Although measuring the gas composition of the gas stream is feasible, it is too costly for commercial applications. This paper proposes three distinct approaches for the design of gas composition estimators of an SOFC system in anode off-gas recycle configuration which are (i.) accurate, and (ii.) easy to implement on a programmable logic controller. Firstly, a classical approach is briefly revisited and problems related to implementation complexity are discussed. Secondly, the model is simplified and adapted for easy implementation. Further, an alternative data-driven approach for gas composition estimation is developed. Finally, a hybrid estimator employing experimental data and 1st-principles is proposed. Despite the structural simplicity of the estimators, the experimental validation shows a high precision for all of the approaches. Experimental validation is performed on a 10 kW SOFC system

Removal of flotation collector O-isopropyl-N-ethylthionocarbamate from wastewater

Flotation collector O-isopropyl N-ethylthionocarbamate (IPETC) is widely used for separation of sulfide ores. Its removal from water by several oxidation processes was studied. Photocatalytic oxidation with air in the presence of iron salts, utilizing solar irradiation or artificial UV-A light is very efficient. Oxidation leads through the formation of O-isopropyl N-ethylcarbamate and several other reaction intermediates to total decomposition of organic compound in the final stage in 1 day. Similar results were obtained with a Fenton type oxidation with hydrogen peroxide and iron salts. Treatment with sodium hypochlorite yields mainly O-isopropyl N-ethylcarbamate. The formation of this compound in wastewaters can be of concern, since simple alkyl carbamates are cancer suspect agents

Soft Sensor Design for Estimation of SOFC Stack Temperatures and Oxygen-to-Carbon Ratio

The life span of a solid oxide fuel cell (SOFC) stack depends on several factors, such as internal stack temperature and temperature gradients as well as the fuel gas oxygen-to-carbon (O/C) ratio. An excessive stack temperature generally accelerates the degradation, while large temperature gradients across the stack cause thermal stress, which leads to delamination. Too low O/C ratio inflicts carbon deposition, which quickly leads to stack breakage. Therefore, monitoring of these variables is of vital importance. Although direct sensing of temperatures within the stack as well as fuel gas composition in fuel stream is feasible, it is not desirable due to increased equipment cost. In this paper a data-driven design of soft sensors for minimal and maximal stack temperatures as well as the O/C ratio is presented. Dynamic and static models for stack temperature are identified from data and their performance is compared. The dynamic model is derived by means of the subspace identification, which results in a causal state-space model. The non-causal static model assumes that a combination of process variables at the stack inlet and outlet describe its internal condition. The estimator of O/C ratio is based on static relationships. The soft sensors are designed in such a way that adding extra inputs to the model yields no further increase in accuracy of the estimates. The empirical data required for modelling were obtained from a SOFC power generating unit. The results show that the reconstruction of all the relevant variables can be accomplished by simple linear regression models

High Recovery Chromatographic Purification of mRNA at Room Temperature and Neutral pH

Messenger RNA (mRNA) is becoming an increasingly important therapeutic modality due to its potential for fast development and platform production. New emerging RNA modalities, such as circular RNA, drive the need for the development of non-affinity purification approaches. Recently, the highly efficient chromatographic purification of mRNA was demonstrated with multimodal monolithic chromatography media (CIM® PrimaS), where efficient mRNA elution was achieved with an ascending pH gradient approach at pH 10.5. Here, we report that a newly developed chromatographic material enables the elution of mRNA at neutral pH and room temperature. This material demonstrates weak anion-exchanging properties and an isoelectric point of 5.3. It enables the baseline separation of mRNA (at least up to 10,000 nucleotides (nt) in size) from parental plasmid DNA (regardless of isoform composition) with both a NaCl gradient and ascending pH gradient approach, while mRNA elution is achieved in a pH range of 5–7. In addition, the basic structure of the novel material is a chromatographic monolith, enabling convection-assisted mass transfer of large RNA molecules to and from the active surface. This facilitates the elution of mRNA in 3–7 column volumes with more than 80% elution recovery and uncompromised integrity. This is demonstrated by the purification of a model mRNA (size 995 nt) from an in vitro transcription reaction mixture. The purified mRNA is stable for at least 34 days, stored in purified H2O at room temperature

Synthesis, characterisation and aquatic ecotoxicity of the UV filter hexyl 2-(4-diethylamino-2-hydroxybenzoyl)benzoate (DHHB) and its chlorinated by-products

Environmental context Various UV-filtering chemicals are added to sunscreens in order to protect humans from the harmful effects of the sun. As a consequence of disinfection processes in swimming pools, sunscreen components may be chlorinated and change their structure and properties, leading to derivatives with higher toxicity. The safety of sunscreen components as well as that of their transformation products during their use requires further study. Abstract In this work is presented a synthesis pathway for the UV filter hexyl 2-(4-diethylamino-2-hydroxybenzoyl)benzoate (DHHB) and its chlorinated by-products in order to investigate the transformation behaviour and toxicity changes of DHHB during chlorination disinfection treatment. Acute toxicity was measured using standardised tests with aquatic model organisms. The potency of DHHB was compared with other benzophenone-like UV filters tested in the same experimental set-up. The toxicity of chlorinated compounds tested with photobacteria was found to be in a similar range to that of the starting compound. Microalgae were more sensitive to DHHB than to its chlorinated by-products, whereas daphnids were affected more by DHHB's chlorinated products. The comparative toxicity data showed DHHB and even more its chlorinated by-products as more highly biologically potent to daphnids than other tested UV filters. The toxic potential of benzophenone-like UV filters should be interpreted together with data on their chemical properties, chlorination effects and affected organisms.Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3632