Уточнить поиск
Результаты 1-10 из 22
Effects of prevalent freshwater chemical contaminants on in vitro growth of Escherichia coli and Klebsiella pneumoniae
2008
Higgins, J. | Hohn, C.
Many surface and ground waters in the continental US are contaminated with a variety of chemical pollutants, which are usually present in concentrations in the ppm and ppb range. The effects of these pollutants on coliform bacteria, which are prominent members of the aquatic flora, are poorly understood. Using a microtiter plate assay, isolates of Escherichia coli (from chicken intestine and fresh water), and an isolate of Klebsiella pneumoniae (from bovine milk) were exposed to varying concentrations of common pollutants over a 24 h period. The herbicides/pesticides simazine, atrazine, and diazinon; the VOCs trichloroethene and MTBE; the estrogens estradiol and estrone; and caffeine, all failed to inhibit bacterial growth at ppm levels. Only ethylene glycol, and the herbicide 2,4-D, significantly inhibited bacterial growth compared to controls. These results suggest that the replication of coliform bacteria in fresh waters is not adversely impacted by many common pollutants. Using a microtiter plate assay, E. coli and Klebsiella bacteria were exposed to a panel of common chemical pollutants of fresh water; only ethylene glycol and 2,4-D inhibited bacterial replication.
Показать больше [+] Меньше [-]A novel and green sulfur fertilizer from CS2 to promote reproductive growth of plants
2020
Yue, Xiaoqing | Wang, Haozhe | Kong, Jing | Li, Bin | Yang, Jinrong | Li, Qiang | Zhang, Jianbin
Carbon disulfide (CS₂) is seen an odor-toxic organic sulfur compound, which presents a major impact on global climate change. Therefore, the conversion of CS₂ into valuable chemicals is the key to reduce the concentration of CS₂ in the atmosphere. On the basis of a CS₂ fixation strategy, CS₂-storage materials (CS₂SMs) are firstly synthesized by the reaction of CS₂ with a binary ion-like liquid systems of ethylenediamine (EDA) and ethylene glycol derivatives (EGs) under mild condition. In view of the serious shortage of sulfur fertilizer and its important position in global agricultural production, it is a promising choice to use the CS₂SMs as a new type of green sulfur fertilizer to promote the growth of eggplant, tomato, sweet pepper and cucumber. In this work, the influence of CS₂SMs on the growth of plants were studied by taking plants irrigated by using various aqueous CS₂SMs solutions as experimental groups, and those irrigated by using water and NH₄HCO₃ as control groups. The experimental results showed that all CS₂SMs could promote plant height, stem diameter, root weight, flower bud number and leaf size. Especially, several CS₂SMs presented significant influence on fluorescence and fruit number. Further studies showed that the CS₂SMs as new energy resources sulfur-containing boosted leaf area, improved root development, enhanced photosynthesis and soil nutrient uptake, and promoted vegetative and reproductive growth of these four types of plants. Thus, this work provided a new strategy for the use of CS₂ as an indirect energy source for the experimental four plants.
Показать больше [+] Меньше [-]Study of molecularly imprinted solid-phase extraction of gonyautoxins 2,3 in the cultured dinoflagellate Alexandrium tamarense by high-performance liquid chromatography with fluorescence detection
2013
Lian, Zi-Ru | Wang, Jiang-Tao
A highly selective sample cleanup procedure combined with molecularly imprinted solid-phase extraction (MISPE) was developed for the isolation of gonyautoxins 2,3 (GTX2,3) from Alexandrium tamarense sample. The molecularly imprinted polymer microspheres (MIPMs) were prepared by suspension polymerization using caffeine as the dummy template molecule, methacrylic acid as the functional monomer, ethylene glycol dimethacrylate as the cross-linker and polyvinyl alcohol as the dispersive reagent. The polymer microspheres were used as a selective sorbent for the solid-phase extraction of gonyautoxins 2,3. An off-line MISPE method followed by high-performance liquid chromatography (HPLC) with fluorescence detection for the analysis of gonyautoxins 2,3 was established. Finally, the extract samples from Alexandrium tamarense were analyzed. The results showed the imprinted polymer microspheres exhibited high affinity and selectivity for gonyautoxins 2,3. The interference matrix in the extract were obviously cleaned by MISPE and the extraction efficiency of gonyautoxins 2,3 in the sample ranged from 81.74% to 85.86%.
Показать больше [+] Меньше [-]Quantification of polyethylene terephthalate microplastics and nanoplastics in sands, indoor dust and sludge using a simplified in-matrix depolymerization method
2022
Tian, Lei | Skoczynska, Ewa | Siddhanti, Deepti | van Putten, Robert-Jan | Leslie, Heather A. | Gruter, Gert-Jan M.
An effective 3-step method for the quantification of mass of polyethylene terephthalate microplastics and nanoplastics (PET MNPs) in complex environmental matrices was developed based on a simplified in-matrix depolymerization. Liquid chromatography (LC) coupled with ultraviolet (UV) detection was used for detection and quantification. Recoveries for PET-spiked sand samples were 99 ± 2% (1 mg/L) and 93 ± 7% (30 mg/L). The limit of quantification (LOQ) for PET was 0.4 μg/g for sand, 1 mg/g for indoor dust and 0.2 μg/g for wet sludge. This method was applied to seven beach sand samples, 20 indoor dust samples and one sewage sludge sample. PET MNPs levels in sand samples were all below the limit of detection (LOD) of LC-UV (0.1 μg/g). The concentrations of PET MNPs in indoor dust samples ranged from 1.2 to 305 mg/g and the PET MNPs in liquid sludge was 1.5 mg/L.
Показать больше [+] Меньше [-]Molecularly imprinted polymer for selective extraction of malachite green from seawater and seafood coupled with high-performance liquid chromatographic determination
2012
Lian, Ziru | Wang, Jiangtao
In this paper, a highly selective sample cleanup procedure combining molecular imprinting technique (MIT) and solid-phase extraction (SPE) was developed for the isolation of malachite green in seawater and seafood samples. The molecularly imprinted polymer (MIP) was prepared using malachite green as the template molecule, methacrylic acid as the functional monomer and ethylene glycol dimethacrylate as the cross-linking monomer. The imprinted polymer and non-imprinted polymer were characterized by scanning electron microscope and static adsorption experiments. The MIP showed a high adsorption capacity and was used as selective sorbent for the SPE of malachite green. An off-line molecularly imprinted solid-phase extraction (MISPE) method followed by high-performance liquid chromatography with diodearray detection for the analysis of malachite green in seawater and seafood samples was also established. Finally, five samples were determined. The results showed that malachite green concentration in one seawater sample was at 1.30μgL⁻¹ and the RSD (n=3) was 4.15%.
Показать больше [+] Меньше [-]Selective extraction and concentration of mebendazole in seawater samples using molecularly imprinted polymer as sorbent
2015
Lian, Ziru | Liang, Zhenlin | Wang, Jiangtao
A high selective pre-treatment method for the extraction and analysis of mebendazole in environmental water samples was developed based on molecularly imprinted solid-phase extraction (MISPE). The mebendazole imprinted polymers were synthesized in acetonitrile using methacrylic acid and ethylene glycol dimethacrylate as functional monomer and cross-linker respectively. The imprinted materials showed high adsorption ability for mebendazole and were applied as special solid-phase extraction sorbents for selective separation of mebendazole. An off-line MISPE procedure was developed for the purification and enrichment of mebendazole from natural seawater samples prior to high-performance liquid chromatography analysis. The recoveries of spiked seawater on the MISPE cartridges were from 83.0% to 90.6%, and the values of the relative standard deviation were in the range of 2.78–4.13% (n=3). The satisfied results showed that this pre-treatment methodology for extracting mebendazole in seawater was simple and effective.
Показать больше [+] Меньше [-]Investigation of long-term hazards of chemical weapon agents in the environment of Sardasht area, Iran
2022
Vaezihir, Abdorreza | Pirkhezranian, Asra | Sehati, Negar | Hosseinzadeh, Mohammad Reza | Salehi-Lisar, Seyed Yahya | Sanderson, Hans
The present study aimed to investigate the persistence and existence of chemical warfare agents (CWAs) and related dissipation products in the environment of Sardasht area, Iran. Three types of environmental samples including water, soil, and native local plant materials were collected and analyzed. Gas chromatography-mass spectrometry in the electron impact ionization mode has been developed for the separation, screening, identification, and qualification of chemicals after the sample preparation methods. The initial results revealed that no trace of related compounds or CWAs was detected in the soil and water samples. However, trace amounts of some degradation products of blistering agents like mustard gas (HD) and lewisite were found in a tree wood from a house subjected to chemical attack as well as in barley samples (a mixture of leaves and root) collected from an agricultural field in the area indicating chronic low exposure to the environment and people. In order to validate the applied extraction procedures, ethylene glycol was spiked to some of the samples including groundwater, surface soil, grape, and alfalfa plants. All the recoveries were in the range of 83.6–107.4% with the relative standard deviations varying from 4.9% to 12.4% (n = 3) successfully.
Показать больше [+] Меньше [-]A Needle Extraction Device Packed with Molecularly Imprinted Polymer Functionalized Fiber for the Determination of Polycyclic Aromatic Hydrocarbon in Water
2022
Yue, Boying | Zhang, Xiaoyu | Wang, Xiyue | Lian, Lili | Gao, Wenxiu | Zhang, Hao | Hou, Shuang | Lou, Dawei
Polycyclic aromatic hydrocarbon (PAHs) is an important organic contaminant substance in the environment. Their concentration monitoring is of great significance for predicting the potential environmental risk and protecting the organism safety. Here, molecularly imprinted polymers (MIPs) coating was prepared on zylon heat-resistant fiber by in situ polymerization, which was packed to a stainless steel needle to develop a needle-type device (NTD) for the analysis of PAHs. Pyrene was used as the template molecule in this MIPs. To obtain excellent selectivity and adsorption efficiency, 4-vinylpyridine (4-VP) and ethylene glycol dimethacrylate (EDMA) were chosen as functional monomers and cross-linker, respectively, and the ratio of ingredients was optimized. The scanning electron microscope (SEM) was used for identifying micro-morphologic characteristics of the obtained MIPs-coating fiber. The PAHs from environmental water samples were extracted with the NTD by headspace extraction and detected by gas chromatography with a flame ionization detector (GC-FID). Under optimized conditions, the proposed method exhibited a good linearity dynamic range (LDR) of 0.5–1800 µg·L⁻¹ with the correlation coefficients (R²) between 0.9953 and 0.9977. The limits of detection are in the ranges of 0.09–0.40 µg·L⁻¹ and the limits of quantification are in the ranges of 0.37–1.40 µg·L⁻¹. Furthermore, the device showed remarkable durability and storage capacity. It could be reused 60 times, and the loss ratio was less than 15% with relative standard deviations (RSDs) less than 6.4% after 3 days of storage. The developed method is easy, sensitive, and accurate, and it can be used for detection of trace PAHs in water sample.
Показать больше [+] Меньше [-]A modified exergy evaluation of using carbon-black/water/EG nanofluids as coolant of photovoltaic modules
2022
To provide the progressive global demand for energy, the use of renewable energies is being rapidly developed. Since solar radiation is available in most parts of the earth, the photovoltaic (PV) power plant is one of the worthwhile solutions. As a deficiency, temperature rise in photovoltaic cells leads to a drop in their electrical output power. In this experimental study, the circulation of carbon black nanofluid was investigated as a coolant of PV modules. Both water and ethylene glycol (EG) were used as the base fluids. It is found that all modified cases generate more output power than the conventional one. For instance, water + carbon nanofluid yields 54% more output power compared with the conventional one. To make a real assessment of using nanofluid as a coolant, the electrical consumption by pump and fan must be counted. Therefore, in this study, the net output power is calculated. In the cases of EG and EG + carbon, the net output powers get lower than the conventional module. So, they are not justifiable. In this paper, a modified formula is proposed to calculate the exergy efficiency, in order to achieve more accurate results. Accordingly, from an exergy viewpoint, 16.3% and 4.5% in electrical and thermal exergy efficiencies are achieved, when water + carbon nanofluid was used. Moreover, the values of entropy generation and lost exergy were reported for all considered cases.
Показать больше [+] Меньше [-]Photoreduction of Cr(VI) in wastewater by anodic nanoporous Nb2O5 formed at high anodizing voltage and electrolyte temperature
2022
Alias, Nurhaswani | Hussain, Zuhailawati | Tan, Wai Kian | Kawamura, Go | Muto, Hiroyuki | Matsuda, Atsunori | Lockman, Zainovia
In this study, nanoporous anodic film was produced by anodization of niobium, Nb in a fluoride ethylene glycol electrolyte. The effect of anodization voltage and electrolyte temperature was studied to find an optimum condition for circular, ordered, and uniform pore formation. The diameter of the pores was found to be larger when the applied voltage was increased from 20 to 80 V. The as-anodized porous film was also observed to comprise of nanocrystallites which formed due to high field-induced crystallization. The nanocrystallites grew into orthorhombic Nb₂O₅ after post-annealing treatment. The Cr(VI) photoreduction property of both the as-anodized and annealed Nb₂O₅ samples obtained using an optimized condition (anodization voltage: 60 V, electrolyte temperature: 70 °C) was compared. Interestingly, the as-anodized Nb₂O₅ film was found to display better photoreduction of Cr(VI) than annealed Nb₂O₅. However, in terms of stability, the annealed Nb₂O₅ presented high photocatalytic efficiency for each cycle whereas the as-anodized Nb₂O₅ showed degradation in photocatalytic performance when used continually.
Показать больше [+] Меньше [-]