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Resultados 3531-3540 de 4,935
The combination of Luffa cylindrical fibers and metal oxides offers a highly performing hybrid fiber material in water decontamination Texto completo
2019
Kesraoui, Aida | Bouzaabia, Sarra | Seffen, Mongi
The present investigation aims to prepare a hybrid material from Luffa cylindrica and metal oxides (ZnO, Al₂O₃) by precipitation for different percentages of zinc and aluminum (1, 2, and 4%) with a determined amount of biomass (a diameter of 250 μm). Physicochemical characterization of “Luffa cylindrica” and “Luffa cylindrica-metal oxides” was carried out by Boehm titration, pHPZC determination, scanning electron microscopy (SEM), and FTIR spectroscopic analysis. The process was optimized according to the adsorbed amount of methylene blue: MB (cationic dye) and methyl orange: MO (anionic dye) onto Luffa cylindrica and hybrid materials prepared. The results demonstrated the efficiency of the designed hybrid materials in removing MB and MO, accelerating the biosorption process and improving the performance of Luffa cylindrica fibers. The highest quantities adsorbed of dyes were obtained by the hybrid material prepared using 4% ZnO. Finally, the Brouers-Sotolongo mathematical modeling of kinetics was used in order to describe the pollutants retention process.
Mostrar más [+] Menos [-]Enhancement of phytoextraction by Taiwanese chenopod and Napier grass by soapnut saponin and EDDS additions Texto completo
2019
Ko, Chun-Han | Yang, Bing-Yuan | Chang, Fang-Chih
Employment of biosurfactants and biodegradable chelants could further promote sustainability of soil and groundwater remediation tasks. Biosurfactant (soapnut saponin) and biodegrading chelants (ethylenediamine-N,N′-disuccinic acid (EDDS)) were employed to enhance the phytoextraction by native Taiwanese chenopod (Chenopodium formosanum Koidz.), Napier grass (Pennisetum purpureum) cultivar Taishi No. 4, and soapwort (Saponaria officinalis). Ethylene diamine tetraacetic acid (EDTA) was also employed as the control. Contaminated soils as silty clay loam texture was collected from a defunct rice paddy, containing chromium (Cr), cadium (Cd), and copper (Cu). Addition of both soapnut saponin and EDDS proportionally increased bioaccumulation factors (BCFs) of aboveground biomass for all three plants. Taiwanese chenopod demonstrated the best BCF values among three plants, with BCF increased from 0.76 to 2.6 and 1.3 for Cu under the presence of the highest dosages of EDDS and saponin. Plant aboveground biomass did exhibit negative correlation toward biomass metal concentrations. Presence of saponin did exhibit the least negative slopes among the correlations of all three additives for three plants. Taiwanese chenopod did exhibit the least negative slopes among the correlations of all three additives for three plants. Above observations suggested that saponin may have some protection for plants, especially for Napier grass. Taiwanese chenopod could possess more tolerance toward heavy metals than Napier grass does.
Mostrar más [+] Menos [-]Daily exposure to toxic metals through urban road dust from industrial, commercial, heavy traffic, and residential areas in Petaling Jaya, Malaysia: a health risk assessment Texto completo
2019
Shabanda, Ibrahim Sani | Koki, Isa Baba | Low, Kah Hin | Zain, Sharifuddin Md | Khor, Sook Mei | Abu Bakar, Nor Kartini
Human health is threatened by significant emissions of heavy metals into the urban environment due to various activities. Various studies describing health risk analyses on soil and dust have been conducted previously. However, there are limited studies that have been carried out regarding the potential health risk assessment of heavy metals in urban road dust of < 63-μm diameter, via incidental ingestion, dermal contact, and inhalation exposure routes by children and adults in developing countries. Therefore, this study evaluated the health risks of heavy metal exposure via ingestion, dermal contact, and inhalation of urban dust particles in Petaling Jaya, Malaysia. Heavy metals such as lead (Pb), chromium (Cr), zinc (Zn), copper (Cu), and manganese (Mn) were measured using dust samples obtained from industrial, high-traffic, commercial, and residential areas by using inductively coupled plasma mass spectrometry (ICP-MS). The principal component and hierarchical cluster analysis showed the dominance of these metal concentrations at sites associated with anthropogenic activities. This was suggestive of industrial, traffic emissions, atmospheric depositions, and wind as the significant contributors towards urban dust contamination in the study sites. Further exploratory analysis underlined Cr, Pb, Cu, and Zn as the most representative metals in the dust samples. In accommodating the uncertainties associated with health risk calculations and simulating the reasonable maximum exposure of these metals, the related health risks were estimated at the 75th and 95th percentiles. Furthermore, assessing the exposure to carcinogenic and non-carcinogenic metals in the dust revealed that ingestion was the primary route of consumption. Children who ingested dust particles in Petaling Jaya could be more vulnerable to carcinogenic and non-carcinogenic risks, but the exposure for both children and adults showed no potential health effects. Therefore, this study serves as an important premise for a review and reformation of the existing environmental quality standards for human health safety.
Mostrar más [+] Menos [-]Does energy consumption, financial development, and investment contribute to ecological footprints in BRI regions? Texto completo
2019
Khan, Anwar | Chenggang, Yang | Hussain, Jamal | Bano, Sadia
This study applies augmented mean group (AMG) along with common correlated effect mean group (CCEMG) estimator and panel heterogeneous causality to examine the interrelationship between GDP, energy consumption, financial development, foreign investment, and ecological footprints for five Belt and Road initiative (BRI) regions and in aggregated panel of BRI over the time 1990–2016. Using a multivariate framework, this study examines four alternative and conceivable hypotheses, including Pollution haven hypothesis, environmental Kuznets curve hypothesis, energy push emission hypothesis, and finance push emission hypothesis. The empirical results supported all four hypotheses for the panel of BRI and partially supported the existence of these hypotheses across the regions. Moreover, a variety of causal nexuses has been discussed in the study. Based on these results, the current research has proposed policy implications to combat the ecological footprints of BRI countries and across the regions.
Mostrar más [+] Menos [-]Are soils beneath coniferous tree stands more acidic than soils beneath deciduous tree stands? Texto completo
2019
Burgess-Conforti, Jason R. | Moore, Philip A. Jr | Owens, Phillip R. | Miller, David M. | Ashworth, Amanda J. | Hays, Phillip D. | Evans-White, Michelle A. | Anderson, Kelsey R.
In 2008, the Mulberry River, a National Wild and Scenic River, was listed as impaired due to low pH (below pH 6.0). Over the last 50 years, the volume of conifers in the Ozark region has increased 115% since 1978 which may result in the acidification of nearby aquatic ecosystems. The objective of this study was to determine if differences exist in soil and litter chemical properties between deciduous and coniferous tree stands. Aboveground litter (n = 200) and soil (n = 400) at 0- to 5- and 5- to 15-cm depths were collected at paired deciduous and coniferous stands at 10 locations within the Mulberry River watershed and analyzed for a suite of chemical parameters. There were no differences (P > 0.05) in several measures of soil acidity between deciduous and coniferous stands. Litter collected from the coniferous stands was more acidic than deciduous litter (4.4 vs 4.7; P < 0.05). Cation exchange capacity, exchangeable Ca and Mg, and water-soluble P and Mg contents differed (P < 0.05) by stand and depth. Cation exchange capacity and exchangeable Ca and Mg were greatest in the 0- to 5-cm depth interval of the coniferous stands. Water-soluble P and Mg contents were greatest within the 0- to 5-cm depth interval which did not differ (P > 0.05) between stand but were greater than the 5- to 15-cm depth interval. Although limited to the top 15-cm of soil, the similarity in soil acidity between stands suggests that conifer growth may not be a substantial source of acidity to the Mulberry River.
Mostrar más [+] Menos [-]Superior “green” electrode materials for secondary batteries: through the footprint family indicators to analyze their environmental friendliness Texto completo
2019
Wu, Haohui | Gong, Yuan | Yu, Yajuan | Huang, Kai | Wang, Lei
As secondary batteries are becoming the popular production of industry, especial for lithium ion batteries (LIBs), the degree of environmental friendliness will gather increasing attention to their products of the whole life cycle. The research combines the life cycle assessment (LCA) and footprint family definition to establish a framework to calculate the footprint family of secondary battery materials. Through the method, we calculated the values of carbon footprint, water footprint, and ecological footprint about this eight kinds of secondary cathode battery materials with Ni-MH, Li₁.₂Ni₀.₂Mn₀.₆O₂/C, LiNi₁/₃Co₁/₃Mn₁/₃O₂/C, LiNi₀.₈Co₀.₂O₂/C, LiFePO₄/C, LiFe₀.₉₈Mn₀.₀₂PO₄/C, FeF₃(H₂O)₃/C, and NaFePO₄/C. When comparing and analyzing their values in each footprint, it can summarize the evaluation method for some secondary batteries by footprint indicators and construct the evaluation system. Through the comprehensive evaluation of footprint family system, the NaFePO₄/C battery gets the best performance of three main footprints when combining 1 kg of cathode materials, while Ni-MH is opposite. Hence, among these eight batteries environmental impacts evaluation, the NaFePO₄/C battery is regarded as the superior “green” battery, albeit the current application is restricted because of the synthesis limitation on large scale and energy density of storage. In LIBs comparison, the FeF₃(H₂O)₃ material shows its characteristics of environmental friendliness, which is expected to be a greener battery material of LIB. In conventional LIBs, the iron-containing cathode materials show lower environmental burden than ternary cathode materials. We can reduce environmental impacts through developing new advanced materials and reducing the content of high sensitivity element in raw materials.
Mostrar más [+] Menos [-]Spermidine application reduces fluoride uptake and ameliorates physiological injuries in a susceptible rice cultivar by activating diverse regulators of the defense machinery Texto completo
2019
Banerjee, Aditya | Singh, Ankur | Roychoudhury, Aryadeep
The manuscript illustrates the ameliorative effects of exogenously applied higher polyamine (PA), spermidine (Spd) in the susceptible indica rice cultivar IR-64 subjected to prolonged fluoride stress. The Spd treatment drastically reduced fluoride bioaccumulation by restricting entry of the anions through chloride channels and enabled better maintenance of the proton gradient via accumulation of P-H⁺/ATPase, thereby improving the root and shoot lengths, fresh and dry weights, RWC, chlorophyll content and activities of pyruvate dehydrogenase (PyrDH), α-amylase, and nitrate reductase (NR) in the Spd-treated, stressed plants. Expression of RuBisCo, PyrDH, α-amylase, and NR was stimulated. Spd supplementation reduced the molecular damage indices like malondialdehyde, lipoxygenase, protease activity, electrolyte leakage, protein carbonylation, H₂O₂, and methylglyoxal (detoxified by glyoxalase II). Mitigation of oxidative damage was facilitated by the accumulation and utilization of proline, glycine-betaine, total amino acids, higher PAs, anthocyanin, flavonoids, β-carotene, xanthophyll, and phenolics as verified from the expression of genes like P5CS, BADH1, SAMDC, SPDS, SPMS, DAO, PAO, and PAL. Spd treatment activated the ascorbate-glutathione cycle in the stressed seedlings. Expression and activities of enzymatic antioxidants showed that GPOX, APX, GPX, and GST were the chief ROS scavengers. Exogenous Spd promoted ABA accumulation by upregulating NCED3 and suppressing ABA8ox1 expression. ABA-dependent osmotic stress-responsive genes like Osem, WRKY71, and TRAB1 as well as ABA-independent transcription factor encoding gene DREB2A were induced by Spd. Thus, Spd treatment ameliorated fluoride-mediated injuries in IR-64 by restricting fluoride uptake, refining the defense machinery and activating the ABA-dependent as well as ABA-independent stress-responsive genes.
Mostrar más [+] Menos [-]Biodegradation aspects of ibuprofen and identification of ibuprofen-degrading microbiota in an immobilized cell bioreactor Texto completo
2019
An enrichment process was employed by applying high ibuprofen concentration in an immobilized cell bioreactor in order to favor the ibuprofen-degrading community present in activated sludge. Experimental data showed the ability of the immobilized cell bioreactor to achieve high ibuprofen removal efficiencies (98.4 ± 0.3%), the tendency of the enriched biomass to acidify the treated liquor, and the inhibition of the nitrification process. Illumina sequencing revealed a massive increase in the relative abundance of Alphaproteobacteria and Gammaproteobacteria (from 29.1 to 80.8%) and a dramatic decrease in the proportion of Bacteroidetes, Planctomycetes, and Verrucomicrobia (from 42.7 to 2.1%) when pure ibuprofen served as the sole carbonaceous feeding substrate. This shift in the feeding conditions resulted in the predominance of Novosphingobium and Rhodanobacter (25.5 ± 10.8% and 25.2 ± 3.0%, respectively) and demonstrated a specialized ibuprofen-degrading bacterial community in activated sludge, which possessed the selective advantage to cope with its degradation. To the best of our knowledge, this bioreactor system was capable of effectively treating the highest ibuprofen concentration applied in wastewater treatment plants.
Mostrar más [+] Menos [-]Adsorption of a textile dye onto piaçava fibers: kinetic, equilibrium, thermodynamics, and application in simulated effluents Texto completo
2019
Marques, Bianca Silva | Frantz, Tuanny Santos | Sant’Anna Cadaval Junior, Tito Roberto | de Almeida Pinto, Luiz Antonio | Dotto, Guilherme Luiz
This research was conducted to evaluate the methylene blue dye adsorption by piaçava fibers. The effects of adsorbent amount, pH, kinetics, equilibrium, and thermodynamics were analyzed, as well as the adsorbent performance in the treatment of synthetic textile effluents. The adsorbent characterization was also performed. Experimental kinetic data were fitted with pseudo-first-order, pseudo-second-order, and Elovich models. The equilibrium tests were done at 298, 308, and 318 K, and the models of Freundlich, Langmuir, Redlich–Peterson, and Sips were used. The adsorption was favored using 0.025 g of adsorbent, pH 10, and 318 K. The Elovich model provided better fit to kinetic data. The equilibrium experimental points were well represented by the Sips model. The maximum experimental adsorption capacity of methylene blue dye was 427.3 mg g⁻¹. It was verified a spontaneous, favorable, and endothermic adsorption. Piaçava fiber was a promising low-cost material to be used for color removal in effluents containing methylene blue.
Mostrar más [+] Menos [-]Effects of perinatal dioxin exposure on development of children: a 3-year follow-up study of China cohort Texto completo
2019
The purpose of this study was to investigate the longitudinal effects of perinatal exposure to dioxin on physical growth in a 3-year follow-up study. In 2015, 27 mother–infant pairs living in an electronic waste (e-waste) dismantling region and 35 pairs living in a control region were enrolled in the present study. Breast milk samples were collected at 4 weeks after birth. Physical growth, including weight, height, and head and chest circumferences, was measured at 6 months and 3 years of age. Dioxin levels in the breast milk were measured by gas chromatography/high-resolution mass spectrometry. Levels of 2,3,7,8-tetrachlorodibenzo-p-dioxin and toxic equivalency values in maternal breast milk of polychlorinated dibenzodioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and PCDDs/PCDFs were significantly higher in women residing in the e-waste dismantling region. In 3-year-old boys, inverse associations were found between height and PCDDs-TEQ. In girls, positive associations were found between height and 2,3,7,8-TetraCDD, PCDDs-TEQ, and PCDDs/PCDFs-TEQ, and for weight and PCDDs-TEQ and PCDDs/PCDFs-TEQ at 3 years of age. In this study, sex-specific differences were observed in children, in whom dioxin exposure decreased growth in boys but increased growth in girls during the first 3 years of life.
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