خيارات البحث
النتائج 3481 - 3490 من 4,924
An empirical evaluation about the effects of environmental expenditures on environmental quality in coordinated market economies
2019
Basoglu, Aykut | Uzar, Umut
Acceleration of environmental degradation in recent years highlights the environmental quality as an indication of welfare and increases the number of studies conducted within this framework. Also, economic decision-making units have been doing various spending in order to maintain/increase environmental quality. In this context, the aim of this study is to examine the effect of environmental expenditures made by public sector on ecological deficit as a representative of the environmental quality for 9 coordinated market economies in Europe from 1995 to 2014. According to the findings acquired in the research, a cointegration relationship has been found between variables. It has been detected within the frame of panel ARDL analysis that total public expenditures increase the ecological deficit while environmental expenditures decrease it. In other words, scale effect of public expenditures affects the environmental quality negatively but its composition effect which will take place in favour of environmental expenditures has a positive effect. Thus, instead of the size of public expenditures, focusing on how the content of public expenditures of policy makers is formed in a way highlighting the environmental expenditures can boost welfare over environmental quality.
اظهر المزيد [+] اقل [-]Degradation of Nystatin in aqueous medium by coupling UV-C irradiation, H2O2 photolysis, and photo-Fenton processes
2019
Boucenna, Amira | Oturan, Nihal | Chabani, Malika | Bouafia-Chergui, Souad | Oturan, Mehmet A.
Oxidative degradation and mineralization of the antifungal drug Nystatin (NYS) was investigated using photochemical advanced oxidation processes UV-C irradiation (280–100 nm), H₂O₂ photolysis (UV/H₂O₂), and photo-Fenton (UV/H₂O₂/Fe³⁺). The effect of operating parameters such as [H₂O₂], [Fe³⁺], and [NYS] initial concentrations on degradation efficiency and mineralization ability of different processes was comparatively examined in order to optimize the processes. Photo-Fenton was found to be the most efficient process attaining complete degradation of 0.02 mM (19.2 mg L⁻¹) NYS at 2 min and a quasi-complete mineralization (97%) of its solution at 5 h treatment while UV/H₂O₂ and UV-C systems require significantly more time for complete degradation and lower mineralization degrees. The degradation and mineralization kinetics were affected by H₂O₂ and Fe³⁺ initial concentration, the optimum dosages being 4 mM and 0.4 mM, respectively. Consumption of H₂O₂ during photo-Fenton treatment is very fast during the first 30 min leading to the appearance of two stages in the mineralization. The evolution of toxicity of treated solutions was assessed and confirmed the effectiveness of photo-Fenton process for the detoxification of NYS solution at the end of treatment. Application to real wastewater from pharmaceutical industry containing the target molecule NYS showed the effectiveness of photo-Fenton process since it achieved 92% TOC removal rate at 6-h treatment time.
اظهر المزيد [+] اقل [-]Alkali promoted the adsorption of toluene by adjusting the surface properties of lignin-derived carbon fibers
2019
Song, Min | Yu, Lei | Song, Bing | Meng, Fanyue | Tang, Xinhong
The lignin-based carbon fibers were prepared by electrospinning followed by stabilization, carbonization, and activation (i.e., steam activation, one-step KOH activation, and metal activation). The effect of carbonization temperature on prepared carbon fibers (CFs) was investigated. As a result, 800 °C is the most suitable carbonization temperature because the prepared carbon fibers possess greater specific surface area and pore volume. With the help of various characterization methods, the structural characteristics of the activated carbon fibers (ACFs) prepared by the three activation methods and the adsorption performance of toluene were compared. It was observed that the activated carbon fibers prepared by KOH one-step activation method (ACFK) exhibited higher specific surface area (1147.16 m²/g) and greater toluene adsorption (463 mg/g). Particularly, abundant microporous structures and surface functional groups play a vital role in the adsorption process. Further, the adsorption performance of toluene onto ACFK was further investigated in a gas-phase dynamic adsorption system and the results showed that ACFK has great potential application in adsorption of volatile organic compounds.
اظهر المزيد [+] اقل [-]Photo-assisted SCR removal of NO by upconversion CeO2/Pr3+/attapulgite nanocatalyst
2019
Li, Xiazhang | Zhang, Haiguang | Lü, Huihong | Zuo, Shixiang | Zhang, Yuying | Yao, Chao
The emission of nitrogen oxides has caused severe harm to the ecosystem; thus, the development of low-cost and high-efficiency denitrification catalysts and new methods are of great significance. In this work, a co-precipitation method was employed to prepare Pr-doped CeO₂/attapulgite (CeO₂/Pr³⁺/ATP) nanocomposites. X-ray diffraction (XRD), photoluminance spectroscopy (PL), ultraviolet-visible diffuse reflectance (UV-Vis), Fourier transform infrared (FT-IR), and high-resolution transmission electron microscopy (HRTEM) were utilized to characterize the products. Results showed that the CeO₂/Pr³⁺ nanoparticles were uniformly coated on the surface of ATP and demonstrated outstanding upconversion effect which converted the visible light to ultraviolet light. The upconversion luminescence of CeO₂/Pr³⁺/ATP was strongest when the molar doping amount of Pr was 1 mol%, and the photo-SCR denitrification achieved the highest of 90% conversion and 95% selectivity when the loading amount of CeO₂/Pr³⁺ was 40 wt%. The ATP and CeO₂/Pr³⁺ constructed an indirect Z-type heterojunction structure mediated by oxygen vacancy which benefited the separation of charge carriers and enhanced the reduction-oxidation potentials, both are responsible for the remarkable denitrification performance.
اظهر المزيد [+] اقل [-]Treatment of synthetic wastewater and cheese whey by the anaerobic dynamic membrane bioreactor
2019
Paçal, Müge | Semerci, Neslihan | Çallı, Barış
The aim of this study was to develop a laboratory-scale anaerobic dynamic membrane bioreactor (AnDMBR) for the treatment of high-strength synthetic and real cheese whey wastewater. We determined the appropriate pore size for a convenient type of support material (nylon mesh) to optimize cake layer formation. The performance of the AnDMBRs was measured in terms of chemical oxygen demand (COD) and solids removal efficiencies. During high-strength synthetic wastewater treatment, the 70-μm pore size AnDMBR achieved COD removal efficiencies of 78% and 96% with COD loading rates of 4.03 and 2.34 kg m⁻³ day⁻¹, respectively, while the 10-μm pore size AnDMBR achieved 66% and 92% COD removal efficiencies at COD loading rates of 5.02 and 3.16 kg m⁻³ day⁻¹. The 10 μm pore size AnDMBR was operated in two periods: first period and second period (before and after physical cleaning) during high-strength synthetic wastewater treatment. The 10-μm pore size AnDMBR removed 83% and 88% of suspended solids during period 1 and period 2, respectively. Furthermore, using a pore size of 10 μm retained 72% of solids (973 mg L⁻¹) in the reactor outlet. The 10-μm pore size AnDMBR performed better than the 70-μm pore size AnDMBR in terms of cake layer formation. The 10-μm pore size AnDMBR was used to treat real cheese whey wastewater, resulting in COD removal efficiencies ranging from 59% (4.32 kg m⁻³ day⁻¹) to 97% (5.22 kg m⁻³ day⁻¹). In addition, 85% of suspended solids were removed from real cheese whey wastewater after treatment. The results show that dynamic membrane technology using a pore size of 10 μm can be used to treat real industrial wastewater.
اظهر المزيد [+] اقل [-]Changes in microbial communities during the removal of natural and synthetic glucocorticoids in three types of river-based aquifer media
2019
Li, Xinyu | Ma, Mengsi | Rene, Eldon R. | Ma, Weifang | Zhang, Panyue
Glucocorticoids in sewage treatment plant effluent discharged into rivers could influence microbial community structure in river-based aquifer media and affect groundwater quality. The effect of representative natural and synthetic glucocorticoids, namely, hydrocortisone (CRL) and dexamethasone (DEX), on the microbial communities in three types of river-based aquifer media was evaluated. The aquifer media was taken from the Beijing Chaobai River (BJ), Hebei Hutuo River (HB), and Tianjin Duliujian River (TJ) and they exhibited different physicochemical and biological properties. The attenuation rates of CRL were 0.175, 0.119, and 0.096 day⁻¹ and for DEX were 0.222, 0.151, and 0.113 day⁻¹ in the media from BJ, HB, and TJ, respectively. All the attenuation rates followed first-order kinetics. The biodiversity decreased significantly with CRL and DEX amendment. The microbial community composition differed in relation to the type of aquifer media and glucocorticoids, especially for BJ at the phylum level. In BJ, the major bacterial genus was Bacillus and in HB it was Rhodobacter. However, in TJ, three bacterial genera (Methylophilus, Methylobacillus, and Methylotenera) and Candidatus_Nitrososphaera were predominant in the microflora. All these genera were able to degrade both CRL and DEX. Distance-based redundancy analysis revealed that total organic carbon (TOC), the type of glucocorticoid, and the pH were the main factors explaining the variations in microbial community composition.
اظهر المزيد [+] اقل [-]The TiO2 (B) nano-belts with excellent performance prepared via alkaline stirring hydrothermal method and its application to remove 17α-ethynylestradiol
2019
Luo, Lijun | Xia, Lihong | Tan, Wei | Li, Junhong | Barrow, Colin J. | Yang, Wenrong | Wang, Hongbin | Shu, Li
In this work, TiO₂ (B) nano-belts were synthesized by hydrothermal method under stirring, and static conditions and preparation conditions were optimized. The prepared materials were characterized by scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), photoluminescence spectroscopy (PL), and N₂ adsorption/desorption measurement. The photocatalytic performance was evaluated by removing synthetic estrogen 17α-ethynylestradiol (EE2), which is the most potent endocrine-disrupting chemical. The results show that the TiO₂ nano-belt possesses pure metastable monoclinic TiO₂ (B) and has uniform nano-belt shape with 80~120-nm diameters and 62.904 m² g⁻¹ of specific surface area. Under the best optimal preparation conditions (0.5 g P25, 20 mL 10 mol L⁻¹ NaOH, hydrothermal temperature 180 °C for 18 h under stirring, 400 °C calcination for 2 h), the TiO₂ (B) has better catalytic activity with 100.00% removal rate towards 3 mg L⁻¹ EE2 in 120 min. The removal rates of EE2 over catalyst which was prepared under static condition and P25 are 74.66% and 70.71%, respectively. The photocatalytic degradation rate constant of TiO₂ (B) prepared under stirring condition (0.0379 min⁻¹) is 4.51 times and 8.42 times than those of TiO₂ prepared under static condition (0.0084 min⁻¹) and P25 (0.0045 min⁻¹). The excellent photocatalytic activity is mainly ascribed to longer one-dimensional nano-belt structure and effective suppression of photo-produced electron-hole.
اظهر المزيد [+] اقل [-]Protective effect of cinnamon against acetaminophen-mediated cellular damage and apoptosis in renal tissue
2019
Abdeen, Ahmed | Abdelkader, Afaf | Abdo, Mohamed | Wareth, Gamal | Aboubakr, Mohamed | Aleya, Lotfi | Abdel-Daim, Mohamed
Acetaminophen, APAP, is a common over-the-counter drug with antipyretic-analgesic action. When APAP is used in large doses, it causes hepatotoxicity and nephrotoxicity but safe at therapeutic doses. Cinnamon (Cinnamomum zeylanicum) is extensively used in folk medicine due to its high content of natural antioxidants. The current investigation was planned to study the possible ameliorative effect of cinnamon toward induced APAP-apoptosis and cellular damage in renal cells. Four groups (nine rats each) were used; negative control group administrated distilled water for 15 days; positive control APAP group administrated a single dose of APAP (1 g/kg) orally on the last day; APAP+Cin L (200 mg/kg) and APAP+Cin H (400 mg/kg) aqueous extract of cinnamon orally once a day for 15 days. An hour after the last dose of cinnamon, all rats in the third and fourth group were administrated a single dose of APAP (1 g/kg) orally. GC/MS analysis was performed to identify the plant used in the study. APAP markedly increased serum levels of creatinine, BUN, and glucose and decreased levels of albumin and total protein. In addition, APAP could also exert severe alteration in the kidney histopathology along with upregulation of caspase-3 and PCNA. However, pre-treatment with cinnamon ameliorated the APAP-induced cellular alterations and apoptosis, possibly through its high content of antioxidants.
اظهر المزيد [+] اقل [-]Effect of sand dust accumulation on photovoltaic performance in the Saharan environment: southern Algeria (Adrar)
2019
Mostefaoui, Mohammed | Ziane, Abderrezzaq | Bouraiou, Ahmed | Khelifi, Seyfallah
Many climatic conditions have a negative impact on production of photovoltaic (PV) systems, and sand dust could be one of the main reasons of degradation of PV panels. The objective of this study is to investigate the reduction in the electrical performance caused by sandstorm and the accumulation of sand dust on the photovoltaic module surface installed in the Saharan area of south Algeria (Adrar). For this purpose, four PV modules (ISO-100/24) were selected and their current–voltage characteristics were measured to evaluate the sand dust effect on their performances. Our results show that sandstorm and dust accumulation on the surface of the module reduce the performance in terms of energy and power, due to a decrease of the transmittance. Obtained outcomes show that in sandstorm periods, the particle deposition density is much higher. This study reveals that leaving PV module without any cleaning in the Saharan environmental conditions significantly reduces PV power output, in addition to the presence of the shading mismatch effects in case of partial cleaning.
اظهر المزيد [+] اقل [-]Seasonal variation of the organic and inorganic composition of sugarcane vinasse: main implications for its environmental uses
2019
de Godoi, Leandro Augusto Gouvêa | Camiloti, Priscila Rosseto | Bernardes, Alan Nascimento | Sanchez, Bruna Larissa Sandy | Torres, Ana Paula Rodrigues | da Conceição Gomes, Absai | Botta, Lívia Silva
Sugarcane vinasse is the main waste stream of the Brazilian agroindustry. The typical composition of sugarcane vinasse gives it a high polluting potential that implies the necessity to define sustainable strategies for managing this waste. Knowledge of the inorganic and organic composition of vinasse and its seasonal variation is extremely important to conduct scientific research to define alternative managements for vinasse disposal other than fertigation. This study evaluated the variability of vinasse composition throughout the same harvesting season and among three harvesting seasons of one Brazilian annexed biorefinery (2015–2017). The contents of chemical oxygen demand (COD), biochemical oxygen demand (BOD₅), total solids (TS), suspended solids (SS), salinity (K⁺, Na⁺, Ca²⁺, Mg²⁺, Cl⁻, F⁻), nutrients (N, P, S), trace metals (Al³⁺, As²⁺, Ba²⁺, Cd²⁺, Cr³⁺, Co²⁺, Cu²⁺, Fe²⁺, Pb²⁺, Mn²⁺, Hg²⁺, Mo²⁺, Ni²⁺, Se²⁺, Zn²⁺), and specific soluble organic compounds (sugars, alcohols, and organic acids), as well as pH and conductivity, were monitored in 13 samples. The results indicated that sugarcane vinasse is a suitable feedstock for biological treatments, such as anaerobic digestion processes for energy recovery, as well as substrate for biomass (e.g., microalgae, energy crops, lignocellulosic biomass) growth. The application of a previous treatment makes vinasse a more environmentally friendly natural fertilizer for land fertigation.
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