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Resultados 5701-5710 de 6,489
Study on the adsorption behavior of cadmium, copper, and lead ions on the crosslinked polyethylenimine dithiocarbamate material Texto completo
2020
Hu, Shaozhong | Zhou, Yue | Zhou, Lihong | Huang, Yi | Zeng, Qingle
In order to obtain a highly efficient solid-state heavy metal ion absorbing material, the crosslinked polyethylenimine dithiocarbamate was prepared via condensation of polyethyleneimine (PEI) with abundant amino groups and glutaraldehyde to form the crosslinked polymer, reduction of the resulting C=N double bonds to a much stable C–N single bonds, and then grafted with carbon disulfide. The material was evaluated in adsorbing cadmium (II), copper (II), and lead (II) ions. The adsorption behavior of cadmium, copper, and lead ions on the absorbent material was studied. Experiment results show that the adsorption rate is rapid for heavy metal ions, and the adsorption amount tends to constant after 40 min. Its absorption capabilities for cadmium (II), copper (II), and lead (II) ions reach up to 205.99, 215.02, and 451.79 mg/g, respectively. Furthermore, the absorbing material has good desorption and regeneration performance. The adsorption kinetics model well accords with the pseudo-second order kinetic equation. And the process of the adsorption is linear with the Langmuir adsorption model, and thus the adsorption process is monolayer adsorption.
Mostrar más [+] Menos [-]Biology, ecology and management of Raphanus raphanistrum L.: a noxious agricultural and environmental weed Texto completo
2020
Kebaso, Lynda | Frimpong, David | Iqbal, Nadeem | Bajwa, Ali Ahsan | Namubiru, Halima | Ali, Hafiz Haider | Ramiz, Zarka | Hashim, Saima | Manalil, Sudheesh | Chauhan, Bhagirath Singh
Weeds are a major constraint to crop production and a barrier to human efforts to meet the ever-rising global demand for food, fibre and fuel. Managing weeds solely with herbicides is unsustainable due to the rapid evolution of herbicide-resistant weeds. Precise knowledge of the ecology and biology of weeds is of utmost importance to determine the most appropriate nonchemical management techniques. Raphanus raphanistrum L. is an extremely invasive and noxious weed due to its prolific seed production, allelopathic potential, multiple herbicide resistance and biological potential. R. raphanistrum causes high crop yield losses and thus has become one of the most troublesome agricultural and environmental weeds. R. raphanistrum could exchange pollen with herbicide-tolerant canola and could become an environmental threat. This weed has evolved resistance to many herbicides, and relying exclusively on herbicide-based management could lead to severe crop loss and uneconomical cropping. Although reviews are available on the ecology and biology of R. raphanistrum, significant changes in tillage, weed management and agronomic practices have been occurring worldwide. Therefore, it is timely to review the status of noxious weeds in different agro-ecological zones and management scenarios. This review focuses on the response of R. raphanistrum to different cultural, mechanical, biological, chemical and integrated management strategies practiced in various agro-ecosystems, and its biological potential to thrive under different weed management tactics. In addition, this review facilitates a better understanding of R. raphanistrum and describes how weed management outcomes could be improved through exploiting the biology and ecology of the weed.
Mostrar más [+] Menos [-]Nano-SiO2 combined with a surfactant enhanced phenanthrene phytoremediation by Erigeron annuus (L.) Pers Texto completo
2020
Zuo, Runzhang | Liu, Huigang | Xi, Ying | Gu, Yan | Ren, Dong | Yuan, Xi | Huang, Yingping
The objective of this experiment was to evaluate the effects of Triton X-100 (1000 mg kg⁻¹) and nano-SiO₂ (500 mg kg⁻¹) on Erigeron annuus (L.) Pers. grown in phenanthrene spiked soil (150 mg kg⁻¹) for 60 days. Results show that untreated groups, groups treated with both Triton X-100 and nano-SiO₂, exhibited better phenanthrene degradation rates and improved root biomasses, chlorophyll contents, and soil enzyme activities. This study demonstrates that Triton X-100 combined with nano-SiO₂ protects plants, alleviating the stress of polycyclic aromatic hydrocarbons (PAHs), and can provide a means for improving phytoremediation of PAH contaminated soils.
Mostrar más [+] Menos [-]Enhancing Salix viminalis L.–mediated phytoremediation of polycyclic aromatic hydrocarbon–contaminated soil by inoculation with Crucibulum laeve (white-rot fungus) Texto completo
2020
Ma, Xiaodong | Li, Xia | Liu, Junxiang | Cheng, Yunhe | Zhai, Feifei | Sun, Zhenyuan | Han, Lei
Although plant-white-rot fungi (WRF) remediation is considered efficient in improving polycyclic aromatic hydrocarbon (PAH)–contaminated soil, the prospects for using it remain poorly known. Therefore, we evaluated whether the WRF Crucibulum laeve could improve the phytoremediation of PAH-contaminated soil by Salix viminalis L. A 60-day pot experiment was conducted to investigate the effects of C. laeve inoculation (using two inoculation treatments and a non-inoculated control) on the phytoremediation potential, growth, and antioxidant metabolism of S. viminalis cultivated in PAH-contaminated soil. The S. viminalis-C. laeve association synergistically caused the highest PAH removal rate. Under the S. viminalis-C. laeve treatment, 80% of the biological concentration and translocation factors for all tissues of S. viminalis were > 1, whereas only 20% of these factors were > 1 when S. viminalis was used alone. C. laeve inoculation remarkably enhanced phytoremediation by promoting S. viminalis–based phytoextraction of PAHs from soils. Furthermore, although C. laeve inoculation altered the antioxidant metabolism of S. viminalis by inducing oxidative stress, thereby inhibiting plant growth, the plant’s hardiness enabled it to survive and grow normally for 60 days after treatment. Therefore, phytoremediation using S. viminalis inoculated with C. laeve can be considered a feasible approach for the phytoremediation of PAH-contaminated soil.
Mostrar más [+] Menos [-]Zebrafish toxicity assessment of the photocatalysis-biodegradation of diclofenac using composites of TiO2 and activated carbon from Argania spinosa tree nutshells and Pseudomonas aeruginosa Texto completo
2020
Daou, Claude | Hamade, Aline | El Mouchtari, El Mountassir | Rafqah, Salah | Piram, Anne | Wong-Wah-Chung, Pascal | Najjar, Fadia
The occurrence and persistence of pharmaceutical products (PPs) in the environment have recently been well-documented and are a major concern for public health. Their incidence in aquatic ecosystems is the result of their direct release without any prior treatment or insufficient wastewater treatment. Therefore, an efficient and safe posttreatment process for removing PPs must be developed. In this study, we focused on the ability of photocatalysis or combined photocatalysis and biodegradation to effectively and safely remove diclofenac (DCF) and its by-products from water. The heterogeneous photocatalysis system was based on bio-sourced activated carbon obtained from Argania spinosa tree nutshells and Degussa P25 titanium dioxide (ACP-TiO₂), and biodegradation involved Pseudomonas aeruginosa. Toxicity tests were conducted with zebrafish embryos to evaluate the applicability of the treatment processes. The results showed that photocatalytic treatment with 0.1 mg/L of ACP-TiO₂ 9% for 7.5 h is sufficient to eliminate DCF (50 mg L⁻¹) and its by-products from water. Low levels of malformation (< 20%) were detected in zebrafish embryos treated with photocatalyzed DCF solutions at 1, 5, and 7 mg L⁻¹ after 4 days of exposure. After 3 h of incubation, P. aeruginosa was found to reduce the toxicity of DCF (10 mg L⁻¹) photocatalyzed for 2 and 4 h. Additional studies should be conducted to elucidate the biodegradation mechanism.
Mostrar más [+] Menos [-]Enhanced adsorption of antimonate by ball-milled microscale zero valent iron/pyrite composite: adsorption properties and mechanism insight Texto completo
2020
He, Xingyu | Min, Xiaobo | Peng, Tianyu | Ke, Yong | Zhao, Feiping | Sillanpää, Mika | Wang, Yunyan
Ball-milling is considered as an economical and simple technology to produce novel engineered materials. The ball-milled microscale zero valent iron/pyrite composite (BM-ZVI/FeS₂) had been synthesized through ball-milling technology and applied for highly efficient sequestration of antimonate (Sb(V)) in aqueous solution. BM-ZVI/FeS₂ exhibited good Sb(V) removal efficiency (≥ 99.18%) at initial concentration less than 100 mg Sb(V)/L. Compared to ball-milled zero valent iron (ZVI) and pyrite (FeS₂), BM-ZVI/FeS₂ exhibited extremely higher removal efficiency due to the good synergistic adsorption effect. BM-ZVI/FeS₂ showed efficient removal performance at broad pH (2.6–10.6). Moreover, the coexisting anions had negligible inhibition influence on the Sb(V) removal. The antimony mine wastewater can be efficiently remediated by BM-ZVI/FeS₂, and the residual Sb(V) concentrations (< 0.96 μg/L) can meet the mandatory discharge limit in drinking water (5 μg Sb/L). Experimental and model results demonstrated that endothermic reaction and chemisorption were involved in Sb(V) removal by BM-ZVI/FeS₂. The XRD and XPS analyses confirmed that the complete corrosion of ZVI occurred on BM-ZVI/FeS₂ after Sb(V) adsorption, resulting in the enhanced Sb(V) sequestration. Mechanism analyses showed that the excellent removal performance of BM-ZVI/FeS₂ was ascribed to the high coverage of iron (hydr)oxide oxidized from ZVI. Because of the advantages of economical cost, high Sb(V) removal capacity and easy availability, BM-ZVI/FeS₂ offers a promising adsorbent for Sb(V) remediation.
Mostrar más [+] Menos [-]Krill oil alleviates oxidative stress, iron accumulation and fibrosis in the liver and spleen of iron-overload rats Texto completo
2020
Helal, Manar G. | El-Kashef, Dalia H.
Krill oil (KO) is a recent supplement which is rich in eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). These fatty acids are found in both krill oil and fish oil. In krill oil, they esterified to phospholipids, but in fish oil, they are esterified to triacylglycerols. The target of this study was to investigate whether KO could help against iron overload–induced toxicity in liver and spleen. Rats were randomly assigned into 3 categories: control rats, rats received iron in a drinking water for 8 weeks followed by either vehicle or KO (40 mg/kg) treatment for an extra 8 weeks. Extent of hepatic and splenic injury was assessed via biochemical, histopathological and immunohistochemical evaluations. KO effectively improved the microscopic features of liver and spleen. Moreover, it decreased the increased levels of serum transaminases, ALP, LDH, iron, and ferritin and increased albumin serum level as well. In addition, it restored the balance between oxidants and antioxidants in the hepatic and splenic tissues. Furthermore, it decreased HO-1 levels, upregulated the production of Nrf2, and limited the expression of MMP9. These findings altogether suggest that KO might be a new candidate for treatment of iron overload-induced toxicity. Graphical abstract Graphical abstract
Mostrar más [+] Menos [-]Does asymmetric persistence in convergence of the air quality index (AQI) exist in China? Texto completo
2020
Zhang, Xue-Tao | Liu, Xi-Hua | Su, Chi-Wei | Umar, Muhammad
In recent years, China’s air pollution has caused significant concern in the academia. China is the hub of business and financial activities, with the most populous cities. It is important to determine the convergence and asymmetric persistence of air quality index (AQI hereafter) in China to achieve sustainable development goals, especially the ones related to the environment. This paper uses the Fourier quantile unit root test to check for inter-regional convergence of monthly AQI for 74 cities across China from January 2013 to July 2019. For a comparative baseline analysis, five conventional univariate and quantile unit root tests are also conducted. The empirical outcomes show that the Fourier quantile unit test exhibits a significant advantage in detecting smooth breaks and evaluating the asymmetric behavior and mean-reverting properties of AQI. Moreover, the monthly AQI in 70 out of 74 C0hinese cities are stationary processes. These findings not only focus on the appropriate use of relevant modeling techniques of smooth breaks and asymmetries in the AQI series of the 74 Chinese cities but also provide crucial environmental sustainability and economic implications for AQI regulation policies.
Mostrar más [+] Menos [-]Markers of polychlorinated biphenyl (PCB) degradation in highly contaminated soil of Central Russia Texto completo
2020
Malina, Natalia | Mazlova, Elena A. | Kulikova, Olga
The highly polychlorinated biphenyl (PCB)–contaminated historical soil is located in the Serpukhov region (Central Russia). This study evaluates the processes of PCB degradation in the soil under natural conditions. Compositions of industrial mixtures (Sovol, Sovtol, and trichlorodiphenyl) were compared with PCB-contaminated soil from different depths. An increased number of dichlorobiphenyls (6 congeners) were determined in the deeper soil horizons (40–60 cm) in comparison with the surface layer (1 congener). Non-associated with industrial mixture congener, PCB 11 was determined in some soil layers with concentrations reaching 3.6 mg/kg. PCB 11 can be considered as a potential marker of activated degradation processes in highly contaminated soils with industrial mixtures. Aegopodium podagraria reduced total PCB concentrations in the contaminated soil to 25% during pot experiments. Prospective precursors of PCB 11 were significantly depleted (62–88%) after phytoremediation, but this did not increase PCB 11 concentration in the soil.
Mostrar más [+] Menos [-]Nexus between sustainable entrepreneurship and environmental pollution: evidence from developing economy Texto completo
2020
Iqbal, Nadeem | Khan, Arman | Gill, Abdul Saboor | Abbas, Qaiser
Today, society is seeking solutions to achieve sustainable development, through association between entrepreneurship, innovation and sustainable development has become a topic of great apprehension. In this perspective, this article aims to link environmental responsive entrepreneurship with sustainable development through empirical evidences from developing country. Therefore, the purpose of this study is to validate the environmental Kuznets curve hypothesis to confirm the achievement of sustainable development goals in Pakistan. We use the combined mean estimator of the autoregressive distribution lag model and GMM model to determine the long-term relationship between the variables and analyze the environmental Kuznets curve hypothesis. We found U-shaped environmental Kuznets curves in Pakistan. Further results show long-term relationship using the PMG-ARDL estimator. Our findings indicate the presence of EKC, U-shaped EKC. This means that at a certain level of economic growth, a 1% increase in per capita income can lead to reductions in environmental pollution by 2.88%, 4.54%, and 2.48%. Therefore, governments and policy makers should strengthen policies to reduce environmental pollution and, more importantly, formulate green financing policies to encourage aspiring environmental entrepreneurs to establish environmentally driven enterprises, promote the use of environmental products to reduce environmental problems, and achieve sustainable development in Pakistan.
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