细化搜索
结果 21-30 的 5,014
Amino Functionalized Silica Coated Fe3O4 Magnetic Nanoparticles as a Novel Adsorbent for Removal of Pb2+ and Cd2+ 全文
2019
Saadat, A. | Hajiaghababaei, L. | Badiei, A. | Ganjali, M. R. | Mohammadi Ziarani, G.
The present study synthesizes a novel adsorbent by coating Fe3O4 magnetic nanoparticles with amino functionalized mesoporous silica. The FTIR spectrums indicate that silica has been successfully coated on the surface of Fe3O4 and 3-aminopropyl tri methoxysilane compound have been grafted to the surface of silica-coated Fe3O4. The XRD analysis shows the presence of magnetite phase with cubic spinel as a highly crystalline structure, before and after silica coating. The study also investigates the potentials of amino functionalized silica-coated Fe3O4 magnetic nanoparticles for extraction of Pb2+ and Cd2+ cations from aqueous solutions, where it has used flame atomic absorption spectrometry to determine ion concentration in both recovery and sample solutions. The optimum conditions of removal of Pb2+ and Cd2+ ions turn out to be pH= 4-8 with a stirring time of 20 minutes. The minimum amount of 3M nitric acid to strip ions from functionalized magnetic nanoparticles is 10 mL. The experimental data show the adsorption isotherms have been well described by Langmuir isotherm model, with the maximum capacity of the adsorbent being 1000.0 (± 1.4) μg, 454.5 (± 1.6) μg of Pb2+, and Cd2+ per each mg of functionalized magnetic nanoparticles, respectively. Finally, the proposed adsorbent is successfully applied to remove Pb2+ and Cd2+ ions in wastewater samples.
显示更多 [+] 显示较少 [-]Microbeads in Sediment, Dreissenid Mussels, and Anurans in the Littoral Zone of the Upper St. Lawrence River, New York. 全文
2019
Schessl, M. | Johns, C. | Ashpole, S. L.
Global plastic production has exceeded 300 million tons per year (Plastics Europe, 2015). In the marine and freshwater environments, larger plastics abrade and photo-degrade resulting in persistent environmental microplastics that are not effectively removed by existing wastewater treatment plants (WWTPs). The ecological effects of microplastics on the marine environment are poorly understood, with even less attention to freshwater systems. To assess whether microplastics have infiltrated food webs of shallow nearshore ecosystems of the St. Lawrence River, we sampled four sites along the international section of the St. Lawrence River, from Alexandria Bay to Waddington, NY. Twelve sediment samples along with one hundred and forty-nine Dreissenid mussels (Dreissena polymorpha and D. bugensis) were collected from the littoral zone, and forty one road-killed anuran amphibian specimens were collected adjacent to the river. Sediment subsamples at two of four sediment sampling sites contained plastic micro-particles. No microbeads were detected within any of the Dreissenid mussels or anuran digestive tract samples. The Dreissenids were likely too small to ingest microbeads greater than 35 microns. Microplastics congregating in the littoral zone may pose a threat within the food web through potential ingestion, requiring further methodological development.
显示更多 [+] 显示较少 [-]Three-dimensional analytical models for time-dependent coefficients through uniform and varying plane input source in semi-infinite adsorbing porous media. 全文
2019
Yadav, R. R. | Yadav, V.
In the present study, analytical solutions are developed for three-dimensional advection-dispersion equation (ADE) in semi-infinite adsorbing saturated homogeneous porous medium with time dependent dispersion coefficient. It means porosity of the medium is filled with single fluid(water). Dispersion coefficient is considered proportional to seepage velocity while adsorption coefficient inversely proportional to dispersion coefficient. Solutions are derived for both uniform and varying plane input source. The source geometry, including shape and orientation, broadly act major role for the concentration profile through the entire transport procedure. Initially the porous domain is not solute free. It means domain is throughout uniformly polluted. With help of certain transformation advection-dispersion equation is reduced into constant coefficient. The governing advection-dispersion equation, initial and boundary condition is solved by applying Laplace Transform Technique (LTT). The desired closed-form solution for the line source in two-dimensions and point source in one-dimension of uniform and varying nature are also evaluated as particular cases. Effects of parameters and value on the solute transport are demonstrated graphically.
显示更多 [+] 显示较少 [-]Adsorption of heavy metals (Cu, Mn, Fe and Ni) from surface water using Oreochromis niloticus scales 全文
2019
Kwaansa–Ansah, E. E. | Nkrumah, D. | Nti, S. O. | Opoku, F.
Surface water contains a large number of pollutants, particularly human pathogens, organic toxicants and heavy metals. Due to the toxic nature of heavy metals towards marine organisms, its removal from the environment has been a growing issue. The biosorption of heavy metal ions from surface water using fish scales has emerged as an environmentally friendly technique. This study assessed the degree of heavy metals accumulation in the scales of Oreochromis niloticus and determining its efficiency as a bioindicator for Cu, Mn and Fe ions removal in the environment of Wewe and Owabi rivers. This study shows that the levels of Cu, Mn, Fe adsorbed from the Owabi river were 685.70 ± 16.51, 247.06 ± 50.46 and 892.90 ± 96.29 mg/kg, respectively. Moreover, the levels of Cu, Mn and Fe adsorbed from Wewe river were 501.60 ± 77.78, 300.89 ± 54.61 and 413.04 ± 9.92 mg/kg, respectively. Under best optimum adsorption conditions, Cu was the best removed heavy metal ions in both surface water reservoirs. Multivariate analysis showed that Cu and Mn showed association in Owabi river, while Mn and Fe were correlated in Wewe river signifying their similarities to a common anthropogenic activity. The Fourier–transform infrared spectrum revealed the existence of a nitro, amine, and carbonyl groups in the biosorption process. This study highlighted that Oreochromis niloticus scales was an efficient bio–sorbent in removing Cu, Mn and Fe ions from Owabi and Wewe rivers.
显示更多 [+] 显示较少 [-]Evaluating the effectiveness of Tamarindus indica partially activated seed coat biomass in removing of nitrates from aqueous solutions 全文
2019
Srinivasulu, D. | Naidu, GRK | P. K., Pindi
Biomass derived from Tamarindus indica partially activated seed coat was investigated for the removal of nitrate ions from aqueous solutions. Batch experiments were performed to evaluate the parameters like pH, contact time, sorbent dose and initial nitrate concentration. pH of the solution played vital role. The maximum sorption observed at pH=7, sorbent dose 300mg, contact time at 120min, initial nitrate concentration 5mg. Physicochemical properties of the biomass were evaluated using scanning electron microscopy (SEM), energy dispersive X-ray analysis and Fourier Transform infra red (FTIR) spectroscopy. The SEM and FTIR data reveals the suitable surface and the presence of chemical functional groups such as hydroxyl, amide, carbonyl strong acid and primary amine on the biosorbent surface contributes to biosorption. The equilibrium isotherms and kinetics were deliberated. Biosorption equilibrium followed Langmuir isotherm. Pseudo second order kinetics provided better correlation of the experimental data in comparison with pseudo-first-order kinetic model. The study indicated that Tamarindus indica partially activated seed coat biomass found to be a novel biosorbent for the removal of nitrates from aqueous solutions.
显示更多 [+] 显示较少 [-]Experimental and Theoretical Study for Hydrogen Biogas Production from Municipal Solid Waste 全文
2019
Ali, A. H. | Al-Mussawy, H. A. | Ghazal, M. T. | Hamadi, N. J.
This study carried out to investigate the production of hydrogen using the organic fraction of municipal solid waste OFMSW, where the anaerobic digester was depended as a method for disposing and treating OFMSW and producing bio-hydrogen. Bio-hydrogen production had been studied under different parameters including pH, solid content T.S%, temperature and mixing ratios between the thick sludge to OFMSW. The optimal conditions were found at pH, T.S%, temp and mix ratio of 7, 8%, 32oC, and 1:5, respectively where the hydrogen yield was (138.88 mL/gm vs). To found the most important parameters in this process, the ANN model had been applied. The effectiveness of temperature, total solid, mixing ratio and pH comes in the following sequence 100%, 75.8%, 71.9%, and 57.2% respectively, with R2 of 95.7%. Multiple correlation model was used to formulate an equation linked between the hydrogen production and the parameters effected on. Gompertz model was applied to compare between theoretical and experimental outcomes, it also given a mathematical equation with high correlation coefficient R2 of 99.95% where the theoretical bio-hydrogen was (141.76 mL/gm vs) under best conditions. The first order kinetic model was applied to evaluate the dynamics of the degradation process. The obtained negative value of (k = - 0.0886), indicates that, the solid waste biodegradation was fast and progresses in the right direction.
显示更多 [+] 显示较少 [-]Model for the Treatment of Refinery Wastewater and expression of catabolic genes in Fluidized Bed Bioreactor using mixed bacterial consortium 全文
2019
Ajao, A. T. | Mustapha, M. O. | Yakubu, S. E.
This study was undertaken to evaluate a novel aerobic wastewater treatment model for the remediation of refinery effluents and to assess the removal efficiency of Bulkholderia cepacia strain AJI and Corynebacterium kutscheri strain AJ2 to clean oil waste from petrochemical company. Wastewater quality parameters including pH, BOD5, COD, TDS, OIL & GREASE, PHENOL concentration, TPH and THC were monitored at 5, 10 and 15 days of treatment and the removal efficiencies were calculated. Results indicated that the raw oily wastewater effluents used during this study had extremely high levels of all the tested parameters. The mean values of all physicochemical parameters of the wastewater from primary tank at different treatment period were statistically different (P˂0.001) After 15 days of biological treatment, BOD5 ,COD, TDS, Phenol, TPH, Oil & grease level of the refinery wastewater were reduced by 95.60 %, 98.40 % , 66.34 % , 100 %, 97.60 % and 96.20 % respectively. The detection of the catabolic genes in the bacterial isolates recovered from primary tank using polymerase chain reaction revealed that both Bulkholderia cepacia strain AJ1 and Corynebacterium kutsheri strain AJ2 carried alk B and C23O but C12O was not detected in both isolates. Naphthalene dioxygenase was detected in Bulkholderia cepacia strain AJ1 but not found in Corynebacterium kutscheri strain AJ2. After treatment the waste water was filtered in the secondary tank. The results of physicochemical parameters in the outlet vessel essentially confirmed that the mixed culture in the two column model successfully carry out bioremediation of refinery wastewater. Therefore, aerobic treatment model for the bioremediation of refinery Petroleum refineries generate great amounts of wastewaters that may become seriously dangerous, leading to the accumulation of toxic products in the receiving water bodies with potentially serious long term effects to aquatic biota. Due to extreme toxicity of contaminants in refinery wastewater, there is a need to develop an economical technique to remove the pollutants from the wastewater is highly recommended owing its environmental friendliness.
显示更多 [+] 显示较少 [-]Landfill Leachate Treatment through Electro-Fenton Oxidation 全文
2019
Mohajeri, S. | Hamidi, A. A. | Isa, M. H. | Zahed, M. A.
Advanced Oxidation Processes (AOPs) have been employed to degrade biorefractory organic matters. This study investigates the combination of classical Fenton reaction with electrochemical oxidation, the electro-Fenton process, for the treatment of semi aerobic landfill leachate, collected from Pulau Burung Landfill Site (PBLS), Penang, Malaysia. The investigation has been carried out in batch reactors with aluminum electrodes to establish the optimal treatment conditions. The effects of applied current, pH, reaction time, electrodes separation distance, H2O2/Fe2+ molar ratio, and H2O2 and Fe2+ concentrations, significant process parameters by themselves, have also been investigated. According to the obtained results, electro-Fenton process is very efficient for the treatment of landfill leachate. Optimum oxidation efficiency has been achieved when neither H2O2 nor Fe2+ are overdosed, so that the maximum amount of OH radicals is available for the oxidation of organic compounds. The highest COD and color removals have been 92% and 93%, respectively; obtained at initial pH=3, H2O2/Fe2+ molar ratio=1, applied current= 2A, treatment duration= 30 min, and electrodes separation distance= 3 cm. The current efficiency declines from 94% to 38% when the current rises from 0.5A to 2A.
显示更多 [+] 显示较少 [-]Monitoring of SO2 column concentration over Iran using satellite-based observations during 2005-2016 全文
2019
Salmabadi, H. | Saeedi, M.
For the first time, sulfur dioxide concentration was monitored between 2005 and 2016 over Iran which is among the countries with a high SO2 emission rate in the world. To that end, SO2 column concentration at Planetary Boundary Layer (PBL) from Ozone Monitoring Instrument (OMI) was analyzed. OMI is a sensor onboard the Aura satellite which can measure daily SO2 concentration on the global scale. From OMI maps, 19 notable SO2 hotspots were detected over Iran. The results indicate that the most elevated level of SO2 among these 19 hotspots belong to Khark Island and Asaluye in Bushehr province, southwest of Iran. Annual trend analysis shows that SO2 concentration has been slightly augmented during 2005-2016 over this country. Distribution analysis of SO2 concentration over Iran showed that the most polluted provinces are Bushehr, Khuzestan and Ilam lied in the southwest of Iran. On the contrary, the lowest level of SO2 has observed over northwest of Iran at West and East Azerbaijan and Ardabil provinces. The correlation coefficient between total energy production in Iran and SO2 concentration from 2005 to 2016 is as high as ~0.7. Hence, it can be derived that energy production, most notably production of crude oil, plays a pivotal role in SO2 concentration over Iran.
显示更多 [+] 显示较少 [-]Degradation of Hydrocarbons and Lignin-like compounds by Alcaligenes sp. strain 3k isolated from Ilorin 全文
2019
Adetitun, D. O. | Fathepure, B. | Hugh, H. | Kolawole, O. M. | Olayemi, A. B.
The primary goal of this study was to isolate hydrocarbon-degrading organisms and assess their ability to bioremediate petroleum-contaminated soil and water. Nigeria is one of the major oil producing countries and petroleum contamination is widespread in agricultural soil. Alcaligenes sp. strain 3k was isolated from a kerosene-polluted soil in Ilorin, Nigeria. We also assessed its ability to degrade plant lignin, as lignin is a complex aromatic heteropolymer commonly found in soil and aquifer environment. Strain 3k was originally grown on mineral salts medium with kerosene as a sole energy and carbon source. The capacity of the isolate to degrade both aromatic, aliphatic hydrocarbons and lignin-like compounds was tested. Among the tested compounds, the organism utilized kerosene, hexadecane, cyclohexane, phenol and benzoate as the sole sources of carbon. In addition, strain 3k also degraded various lignocellulose compounds as the sole source of carbon. However, hexane, benzene, toluene, ethylbenzene and xylene were not metabolized. Our study demonstrates that soil organisms like Alcaligenes could play important role in the reclamation of petroleum-contaminated soil and water. Utilization capacity of lignin as the sole carbon source suggest that these organisms can survive on plant detritus and also have the ability to degrade hydrocarbons upon accidental or deliberate contamination of agricultural soil and water.
显示更多 [+] 显示较少 [-]