Removal characteristics of polycyclic aromatic hydrocarbons (PAHs) from low-permeable soil using a surfactant-enhanced electrokinetic (EK) process were investigated. Phenanthrene and kaolinite were selected as a representative PAH and a model soil. A nonionic surfactant, alkyl polyglucosides (APG), and an anionic surfactant, Calfax 16L-35, were used to enhance the solubility of phenanthrene. The two surfactants showed similar solubilization capacities for phenanthrene, while only APG was affected by sorption. When surfactants were applied to EK process, the electrical potential gradient was lower than that of water. The electroosmotic flow (EOF) decreased as the concentration of surfactant increased. In the case of APG, the removal efficiency of phenanthrene increased with the surfactant concentration. The APG micelles containing phenanthrene easily migrated to the cathode reservoir by EOF. On the other hand, Calfax 16L-35 did not enhance the removal efficiency even at the highest concentration, because most of Calfax 16L-35 remained in soil, and only small amount existed in effluent. It was thought that, during electrokinetic process, Calfax 16L-35 was adsorbed onto soil and the migration of the surfactant from cathode to anode was superior to EOF due to anionic charges of Calfax 16L-35. A nonionic surfactant, APG, seems to be suitable for surfactant-enhanced electrokinetic remediation. 相似文献
Oxidative hair dyes containing p-phenylenediamine(PPD) are reported to induce an allergic reaction by promoting oxidative stress when absorbed through the skin. Despite the associated risk, these hair dyes remain popular owing to their convenience and sharpness of color. This makes it important to minimize the cytotoxicity and oxidative stress induced by PPD-containing hair dyes. Ecklonia cava extract has been evaluated in different studies for its protective effects against external stress in fibroblasts and keratinocytes. Our study was aimed at using in-vitro and in-vivo models to investigate the extract's effects on cytotoxicity of and oxidative stress induced by PPD-containing hair dyes. Analysis of CIEL*a*b* Color space was first used to determine the range of E. cava extract that would not interfere with the coloring ability of the dye upon addition. Subsequently, the set ranges of E. cava extract(5% and 7%) were added to the hair dye and their toxicity assessed by evaluating the viability of fibroblasts and keratinocytes. The effects on developmental phenotypes and induction of oxidative stress by hair dye were evaluated and compared with those of hair dyes containing different contents of E. cava extract using an in-vivo zebrafish model. Our results showed that E. cava extract in hair dye could significantly decrease the cytotoxicity and levels of oxidative stress caused by hair dyes containing PPD in both in-vitro and in-vivo models.These results suggest that the addition of 7% E. cava extract to 250 μg/mL hair dye does not interfere with the coloring ability of the dye while showing significant protective effects against the hair dye. The study proposes that the use of E. cava extract as an adduct to hair dyes containing PPD reduces the cytotoxicity and oxidative stress induced by these hair dyes. 相似文献
The strong earthquakes in western Yunnan area, mainly occur along great interplate strike-slip faults and have a dominant
depth-layer about 10–20 km; the seismic rupture is characterized by strike-slip rupture. Considering the Yunnan lithospheric
structure and dynamic background, we think that earthquakes occurring at this area might have such a kind of nucleation process:
because of the multi-layers and heterogeneities of lithospheric structure, a zone of concentrated shear strain or of slip
might be formed at the moderate or deep portions of lithosphere, and spread upward along faulting boundary, toward the earth’s
surface under the background field of tectonic movement of lithospheric plates. The slip front will encounter the maximum
shear resistance zone on the fault surface in this process, be barried and blocked, and form a seismic gap. With the increase
of tectonic load, this slip zone will continuously spread forward, traverse and lead to instable crack of the whole blocked
zone, and cause a great earthquake. We have derived an approximate integral equation describing this seismic process; the
numerical results show that the model has an instable nonlinear accelerating evolution period which might have important significance
for the generation of earthquake precursors.
This paper is supported by the Eight Five-Year Target of the State Seismological Bureau, China. 相似文献
The geophysical mechanism behind astronomical time–latitude residuals (ATLR) are discussed. The photoelectric astrolabe at Yunnan Observatory (YO) observed apparent synchronous anomalous ATLR before the Wenchuan M8.0 earthquake (EQ) in May 12, 2008 and the Lushan M7.0 EQ n April 20, 2013. We compared the ATLR from the YO photoelectric astrolabe and EQ data since 1976. Anomalous ATLR was observed before several strong EQs in the Yunnan Province. We believe the photoelectric astrolabe can be used to predict strong EQs and the anomalous ATLR are a potential EQ precursor. 相似文献
Feasibility of electrokinetic (EK) process combined with Fenton-like reaction was investigated for the removal of phenanthrene in a two-dimensional cell. Sandy soil and bentonite were selected as a model soil and a filling material to inhibit the leak of electrolyte solution within the electrode reservoirs into the soil by hydraulic pressure difference, respectively. The effects of parameters including current, electroosmotic flow (EOF), electrolyte pH, and moisture content on the removal efficiency were examined under constant voltage.
At the end of operation for 21 days, the concentration of phenanthrene near the anode was lower than the other positions of soil specimen and increased gradually towards the cathode because hydrogen peroxide solution was supplied from anode to cathode region following the direction of EOF. The concentration of phenanthrene at the bottom soil was lower than that at the top soil. Because capillary attraction in the sandy soil with high porosity was too low to maintain appropriate moisture at the top of the cell, EOF moved through the bottom soil with higher moisture content. Overall removal efficiency at 140 V was 81.6%, which was higher than 68.9% at 100 V because total EOF increased by a factor of 1.5 upon increase of the voltage from 100 to 140 V. In addition, power consumptions at 100 and 140 V were 7.2 and 19.4 kWh, respectively. 相似文献