Time series of nanoparticle number concentration during new particle formation (NPF) events in the urban environment of Brisbane, Australia, showed that the formation of charged particles often occurred before that of neutral particles. We monitored 241 days during the calendar year 2012 over which NPF events were observed on 108 days. We studied the times at which the charged and neutral particle concentrations in the size range 1.8–3.2 nm reached their peak values and found that they were clearly different in 50 events with the peak neutral particle concentration lagging behind the charged particle concentration during 42 of these events with a mean time lag of 24±12 min. While the charged particles were more likely to form before the neutral particles, once formed, the growth rate of the particles did not depend on their charge. While ion-induced nucleation is not the dominant mechanism of NPF in the atmosphere, our observations suggest that the presence of ions in the atmosphere plays a role that cannot be ignored.
• Electrode fouling is characterized by non-destructive characterization.• Electrode fouling is highly dependent on electrochemical process.• Active chlorine can prevent the formation of polymeric fouling film. Electrode fouling is a problem that commonly occurs during electro-oxidation water purification. This study focused on identifying the fouling behavior of Pt electrode associated with the formation of polymeric layer during electro-oxidation of phenol. The in situ electrochemical measurements and non-destructive observation of the electrode morphology were reported. The results demonstrated that the electrode fouling was highly dependent on thermodynamic process of electrode that was controlled by anode potential. At anode potential lower than 1.0 V vs SHE, the direct electro-oxidation caused the electrode fouling by the formation of polymeric film. The fouling layer decreased the electrochemically active surface area from 8.38 cm2 to 1.57 cm2, indicated by the formation of polymeric film with thickness of 2.3 mm, increase in mass growing at a rate of 3.26 μg/cm2/min. The degree to which the anode was fouled was independent of anion in the electrolyte. In comparison, at anode potential higher than 2.7 V vs SHE, the anions (e.g., chloride) could exert a major influence to the behavior of electrode fouling. The presence of chloride was shown to mitigate the fouling of electrode significantly through preventing the formation of polymeric film by active chlorine (e.g., Cl• and Cl2) produced from anodic oxidation of chloride. Since chloride is the most abundant anionic species existing in both natural and engineered water system, this study not only offers a deep insight into the mechanism of electrode fouling, but also suggests strategies for anti-fouling in the presence of chloride in electro-oxidation process. 相似文献
In the present study, an attempt has been made to quantify the fenvalerate accumulated in different tissues (gill, muscle and liver) and observe changes involved in the levels of sodium, potassium and calcium ions and Na+–K+, Mg2+ and Ca2+ adenosine triphosphatase (ATPase) activities in the freshwater fish, Cirrhinus mrigala on short-term and long-term exposure to the median lethal and sublethal concentration of fenvalerate. Residue analysis using gas–liquid chromatography (GLC) technique revealed that fenvalerate accumulated in highest quantity in gill followed by liver and muscle under median lethal concentration (6?µg?L?1). Whereas in sublethal concentration (0.6?µg?L?1), muscle accumulated highest quantity followed by gill and liver, which might be due to the fact that fenvalerate is highly lyphophilic. The ion concentration and ATPase activity were found effected in fish exposed to lethal and sublethal concentrations of fenvalerate. Concentration of Na+, K+ and Ca2+ ions decreased in gill, muscle and liver on being exposed to median lethal concentration to a significant level. Whereas the changes were not highly pronounced at sub lethal level indicating low concentration of fenvalerate and its non-toxic effect at chronic exposure. Na+–K+, Mg2+ and Ca2+ ATPases activity were also found decreased in correspondence to the ionic change under median lethal and sub lethal concentrations in target tissues. This might have lead to behavioural changes and create wide-spread disturbance in the normal physiology, ultimately causing the death of the fish. The results suggest that in biomonitoring programmes, ions and associated ATPases can be a good diagnostic tool for fenvalerate toxicity. 相似文献
The technical feasibility of using a suitable sorbent for the removal of some heavy metal ions from their aqueous solutions was investigated. The scope of the work covers the use of low-class native wool or wool wastes from industrial processes or from recycled woolen textiles for the removal of copper, nickel, cobalt, chromium, and zinc ions from their effluents. The sorption efficiency of the aforementioned metals by wool is in the following order: copper?>?cobalt?=?nickel?>?zinc?>?chromium. The effect of time of sorption, temperature of the effluent, and concentration of metal ions on the rate of sorption was examined. The effect of oxidation or reduction of wool on its sorption power of copper ions is studied. The reduced wool was found to be better than native or oxidised wool in the sorption of copper metal from its effluents. The reuse of wool as metal sorber after elution of the metal, using hydrochloric acid, was also studied. It was found that wool can be reused for sorption after elution of copper up to 25 times of elution; a very limited amount of permanently fixed copper was observed. The use of sufficient woolen layers displays the best way of obtaining an effluent of zero copper content. 相似文献
A resin synthesized from tamarind kernel powder possesses high selectivity for metal ions. Distribution coefficients for some metal ions has been determined by the batch method. The influence of pH on ion exchange capacity and Kd value of metal ions were studied. The resin has been characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, chemical composition and ion exchange capacity (IEC). The selectivity order is Pb2+?>?Cu2+?>?Fe2+?>?Zn2+?>?Ni2+. Removal of metal ions from the aqueous solution and from effluents of a steel mill has been studied. 相似文献