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Результаты 2331-2340 из 4,935
Understanding corporate surplus food donation in China: testing the roles of environmental concern, altruism, past experience, and perceived risk Полный текст
2019
Liao, Chuanhui | Hong, Jin | Zhao, Dingtao
This paper investigates the motives behind corporate giving and determines whether perceived risk plays a major role in corporate surplus food donation intention. A conceptual model is developed from the perspectives of perceived risk, economic concern, past behavior, and moral motives. A questionnaire survey is conducted among food manufacturers and retailers in the Sichuan Province in China. A total of 143 valid observations are used to conduct structural equation modeling analysis. The results show that corporate reputation, legislation, and business risks are the main sub dimensions of risks that corporations perceive. Perceived risk, past behavior, environmental concern, and altruism affect corporate donation intention significantly. Implications of the findings for promoting surplus food donation are also discussed.
Показать больше [+] Меньше [-]Progress in ultrasonic oil-contaminated sand cleaning: a fundamental review Полный текст
2019
Mat-Shayuti, Muhammad Shafiq | Tuan Ya, Tuan Mohammad Yusoff Shah | Abdullah, Mohamad Zaki | Megat Khamaruddin, Putri Nadzrul Faizura | Othman, Nur Hidayati
Steady efforts in using ultrasonic energy to treat oil-contaminated sand started in the early 2000s until today, although pilot studies on the area can be traced to even earlier dates. Owing to the unique characteristics of the acoustic means, the separation of oil from sand has been showing good results in laboratories. This review provides the compilation of researches and insights into the mechanism of separation thus far. Related topics in the areas of oil-contaminated sand characterizations, fundamental ultrasonic cleaning, and cavitation effects are also addressed. Nevertheless, many of the documented works are only at laboratory or pilot-scale level, and the comprehensive interaction between ultrasonic parameters towards cleaning efficiencies may not have been fully unveiled. Gaps and opportunities are also presented at the end of this article.
Показать больше [+] Меньше [-]Effects of residual ozone on the performance of microorganisms treating petrochemical wastewater Полный текст
2019
Fu, Liya | Wu, Changyong | Zhou, Baoying | Zuo, Jiane | Song, Guangqing
This study investigated the effects of residual ozone on the performance of microorganisms treating petrochemical wastewater using batch experiments with low and high ozone dosages (5.0 mg/L and 50.0 mg/L, respectively). The results indicated that the low residual ozone concentration significantly increased COD removal by 24.21% in the biological process compared to control group with no ozone residual, while the high residual ozone concentration showed the opposite effect. In the reactor with low residual ozone concentration (0.45 mg/L), the amount of loosely bound (LB)-extracellular polymeric substances (EPS) in the activated sludge decreased by 23.23%, while the amount of tightly bound (TB)-EPS increased by 129.16% compared to the none-ozone residual reactor. In addition, the low residual ozone was found to improve the bioactivity of activated sludge by 139.73% in the first 30 min of the biological process. In the reactor with high residual ozone concentration (0.91 mg/L), both LB- and TB-EPS of the activated sludge increased, while bioactivity decreased. This implies that low residual ozone in a bio-reactor can enhance microbial activity by increasing contact between the pollutants and cells by removing LB-EPS covering the outer layer of the sludge. The microorganisms in the sludge samples could be classified into three groups representing those that are susceptible to ozone, tolerant to low dose of residual ozone, and resistant to high dose of residual ozone. The resistant bacteria Gemmatimonadaceae uncultured became predominant, with a relative abundance of 11.37%, under low residual ozone conditions, while it decreased at high ozone concentrations. The results showed that a certain amount of residual ozone could stimulate the activity of microorganisms by altering the EPS fraction and structure of the microbial community, and thus it is important for the removal of refractory organics from wastewater in the ozone-biological process.
Показать больше [+] Меньше [-]Chitosan-iron oxide hybrid composite: mechanism of hexavalent chromium removal by central composite design and theoretical calculations Полный текст
2019
Chagas, Pricila Maria Batista | Caetano, Aline Aparecida | Rossi, Marco Aurélio | Gonçalves, Mateus Aquino | de Castro Ramalho, Teodorico | Corrêa, Angelita Duarte | do Rosário Guimarães, Iara
In this study, the synthesis of iron oxide stabilized by chitosan was carried out for the application and optimization in the removal process of aqueous Cr(VI) by central composite design (CCD). The calculation of these effects allowed to know, quantitatively, the variables and the interaction between them that could affect the Cr(VI) removal process. It was also verified that the most favorable conditions for chromium removal were the following: pH 5.0, Cr(VI) concentration of 130 mg L⁻¹, adsorbent mass of 5 mg, and Fe(II) content of 45% (w/w) in the CT-Fe beads. The adsorption kinetics performed under these conditions showed that the chitosan/iron hybrid composite is an adsorbent material with high chromium removal capacity (46.12 mg g⁻¹). It was found that all variables were statistically significant. However, it was observed that the variable that most affected Cr(VI) removal was the pH of the solution, followed by the concentration of chromium ions in solution and the interaction between them. Therefore, the studied experimental conditions are efficient in chromium adsorption, besides the operational simplicity coming from statistical design. Theoretical calculations showed that the most stable chitosan was that with Fe(II) in the structure, that is, in the reaction mechanism, there is no competition of Fe(II) with Cr(III, VI) in the available sites of chitosan. Thus, the theoretical calculations show that the proposed Cr(VI) removal is effective.
Показать больше [+] Меньше [-]Phosphorous-doped TiO2 nanoparticles: synthesis, characterization, and visible photocatalytic evaluation on sulfamethazine degradation Полный текст
2019
Mendiola-Alvarez, Sandra Yadira | Hernández-Ramírez, Ma Aracely | Guzmán-Mar, Jorge Luis | Garza-Tovar, Lorena Leticia | Hinojosa-Reyes, Laura
Mesoporous phosphorous-doped TiO₂ (TP) with different wt% of P (0.5, 1.0, and 1.5) was synthetized by microwave-assisted sol–gel method. The obtained materials were characterized by XRD with cell parameters refinement approach, Raman, BET-specific surface area analysis, SEM, ICP-OES, UV–Vis with diffuse reflectance, photoluminescence, FTIR, and XPS. The photocatalytic activity under visible light was evaluated on the degradation of sulfamethazine (SMTZ) at pH 8. The characterization of the phosphorous materials (TP) showed that incorporation of P in the lattice of TiO₂ stabilizes the anatase crystalline phase, even increasing the annealing temperature. The mesoporous P-doped materials showed higher surface area and lower average crystallite size, band gap, and particle size; besides, more intense bands attributed to O–H bond were observed by FTIR analysis compared with bare TiO₂. The P was substitutionally incorporated in the TiO₂ lattice network as P⁵⁺ replacing Ti⁴⁺ to form Ti–O–P bonds and additionally present as PO₄³⁻ on the TiO₂ surface. All these characteristics explain the observed superior photocatalytic activity on degradation (100%) and mineralization (32%) of SMTZ under visible radiation by TP catalysts, especially for P-doped TiO₂ 1.0 wt% calcined at 450 °C (TP1.0-450). Ammonium, nitrate, and sulfate ions released during the photocatalytic degradation were quantified by ion chromatography; the nitrogen and sulfur mass balance evidenced the partial mineralization of this recalcitrant molecule.
Показать больше [+] Меньше [-]CFD modeling of a UV-A LED baffled flat-plate photoreactor for environment applications: a mining wastewater case Полный текст
2019
Devia-Orjuela, John Steven | Betancourt-Buitrago, Luis Andrés | Machuca-Martinez, Fiderman
The use of ultraviolet light in photoreactors for wastewater treatment has become popular as an alternative of known chemical oxidative substances. UV LED light represents cheaper, robust, and versatile alternative to traditional UV lamps. In this study, it was designed and evaluated a photoreactor with an approach of chemical fluid dynamics (CFD) and experimental validation. The evaluation consisted of (1) CFD velocity profile analysis, (2) characterization of the average light distribution with potassium ferrioxalate actinometry, (3) degradation of a typical recalcitrant metallic cyanocomplex Fe(CN)₆³⁻, and (4) scavenger effect analysis in the photodegradation using potassium persulfate. Actinometrical essay concluded that the system was able to receive 1.93 μE/s. The reactor operated under turbulent regime and best result for Fe(CN)₆³⁻ degradation was obtained at 4 h of operation, using 5-W UV-A LEDs, with pH ~ 7 and 10 mM de S₂O₈²⁻. Baffled photoreactor demonstrated to be useful for this type of illumination and wastewater treatment.
Показать больше [+] Меньше [-]Improving Biohydrogen Evolution from Glucose with Magnetic Activated Carbon Полный текст
2019
Magnetic activated carbon (MAC) was fabricated to improve biohydrogen (bio-H₂) production. The MAC exhibited higher biocatalytic capability and better microbial immobilization than activated carbon (AC) during the bio-H₂ process. Glucose supplemented with 200 mg/L MAC obtained the highest H₂ yield of 214 mL/g glucose, much higher than that (130 mL/g glucose) of the control group without MAC. Suitable dosage such as 300 mg/L AC or 200 mg/L MAC promoted volatile fatty acid (VFA) formation and H₂ generation. Besides, the metabolites showed that AC or MAC did not change the bio-H₂ evolution pathway. Some possible biochemical mechanisms were as follows: MAC served as a microbial carrier to promote cell colonization and electron transfer rate, and it released Fe³⁺ to enhance glucose acidogenesis and Fe²⁺ to increase microbial concentration and activity in the bio-H₂ evolution. Graphical Abstract Magnetic activated carbon (MAC) was fabricated and subsequently used in bio-H₂ process through glucose-fed anaerobic mixed bacteria at 37 °C. The MAC acted as a carrier of anaerobes to promote cell growth and electron transfer rate, and released Fe³⁺ to increase glucose acidogenesis and Fe²⁺ to improve microbial concentration and activity in the bio-H₂ evolution process.
Показать больше [+] Меньше [-]Impact of air pollution on hospital admissions with a focus on respiratory diseases: a time-series multi-city analysis Полный текст
2019
Slama, Alessandro | Śliwczyński, Andrzej | Woźnica, Jolanta | Zdrolik, Maciej | Wiśnicki, Bartłomiej | Kubajek, Jakub | Turżańska-Wieczorek, Olga | Gozdowski, Dariusz | Wierzba, Waldemar | Franek, Edward
Together with the growing availability of data from electronic records from healthcare providers and healthcare systems, an assessment of associations between different environmental parameters (e.g., pollution levels and meteorological data) and hospitalizations, morbidity, and mortality has become possible. This study aimed to assess the association of air pollution and hospitalizations using a large database comprising almost all hospitalizations in Poland. This time-series analysis has been conducted in five cities in Poland (Warsaw, Białystok, Bielsko-Biała, Kraków, Gdańsk) over a period of almost 4 years (2014–2017, 1255 days), covering more than 20 million of hospitalizations. The hospitalizations have been extracted from the National Health Fund registries as daily summaries. Correlation analysis and distributed lag nonlinear models have been used to investigate for statistically relevant associations of air pollutants on hospitalizations, trying by various methods to minimize potential bias from atmospheric parameters, days of the week, bank holidays, etc. A statistically significant increase of respiratory disease hospitalizations has been detected after peaks of particulate matter concentrations (particularly PM₂.₅, between 0.9 and 4.5% increase per 10 units of pollutant increase, and PM₁₀, between 0.9 and 3.5% per 10 units of pollutant increase), with a typical time lag between the pollutant peak and the event of 2 to 6 days. For other pollution parameters and other types of hospitalizations (e.g., cardiovascular events, eye and skin diseases, etc.), a weaker and ununiform correlations were recorded. Ambient air pollution exposure increases are associated with a short-term increase of hospitalizations due to respiratory tract diseases. The most prominent effect was recorded with the correlation of PM₂.₅ and PM₁₀. There is only weak evidence indicating that such short-term associations exist between peaks of air pollution concentrations and increased hospitalizations for other (e.g., cardiovascular) diseases. The obtained information could be used to better predict hospitalization patterns and costs for the healthcare system and perhaps trigger additional vigilance on particulate matter pollution in the cities.
Показать больше [+] Меньше [-]Aqueous Film-Forming Foams (AFFFs) Are Very Toxic to Aquatic Microcrustaceans Полный текст
2019
da Silva, Silvana Carmo | Pusceddu, Fabio Hermes | dos Santos Barbosa Ortega, Andressa | de Souza Abessa, Denis Moledo | Pereira, Camilo Dias Seabra | Maranho, Luciane Alves
The use of aqueous film-forming foams (AFFFs) have been related to environmental contamination due to handling, storage, and use in the firefighting against class B fire. Studies have associated the use of AFFFs with toxic effects from its perfluorinated compounds (PFCs) to the aquatic ecosystem, which led the Stockholm Convention to restrict their use. In Brazil, despite the large-scale use, there is no data on employment or annual commercialization of these products. This study evaluated the toxicity of seven brands of AFFFs used in the firefighting of the petrochemical’s terminal of fuel storage in Port of Santos (Santos, São Paulo, Brazil) which occurred in 2015, in which more than 61,000 L of AFFFs drained into the adjacent aquatic ecosystems. The toxicity evaluation was performed by means of the acute bioassay using the freshwater microcrustacean Daphnia similis. The AFFF brands tested were considered toxic to D. similis, including at much lower dilutions than those recommended by the manufacturers. The brand that showed the lowest toxicity was Kidde Sintex® 3% × 6%, followed by Kidde Sintex® 1% × 3%, Argus Prime®, Cold Fire®, Ageofoam®, and Liovac®, and the one with the highest toxicity was F-500 fire®. These results provide valuable information for the development of public policies aimed at managing the AFFF discharge in freshwater ecosystems.
Показать больше [+] Меньше [-]Effect of Residual NAPLs on the Transport of Bisphenol A and Bisphenol S in Saturated Porous Media Полный текст
2019
Shi, Yanfeng | Gao, Bin | Sun, Yuanyuan | Sun, Kaixuan | Xu, Hongxia | Wu, Jichun
Endocrine disrupter, like bisphenol A (BPA) and bisphenol S (BPS), is frequently detected in the subsurface environment, imposing threats to the groundwater quality and public health. However, current understanding of environmental fate and transport of BPA/BPS is still not clear, especially with respect to those in the subsurface media with trapped non-aqueous phase liquids (NAPLs). In this study, the effect of residual NAPLs on the retention and transport of BPA/BPS in the saturated sand and soil media was investigated using column experiments. The results showed that residual NAPLs (i.e., xylene and perchloroethylene (PCE)) inhibited the transport of BPA in the sand columns, and the inhibit effect of xylene was greater than that of PCE. While the presence of NAPLs showed little influence on the transport of BPS in the sand columns, in soil A (sandy soil), the residual NAPLs had similar effect on the retention and transport of BPA and BPS. Both BPA and BPS showed higher retention in the soil B columns than in the sand and soil A columns due to soil B’s higher organic matter contents, which can strongly sorb BPA/BPS. The presence of residual NAPLs reduced the retention of BPA/BPS in the soil B columns because the NAPLs blocked the sorption sites of the soil organic matter for BPA/BPS. This study demonstrates the importance of residual NAPLs, types of media, properties of contaminants, and their interactions to the fate and transport of BPA/BPS in saturated porous media.
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