ABSTRACT
Bismuth modified boron doped diamond (BDD) film electrode was employed for simultaneous determination of trace ZnⅡ,CdⅡand PbⅡby anodic stripping voltammetry.BiⅢwas simultaneously in-situ deposited on bismuth modified boron doped diamond electrode with ZnⅡ,CdⅡ and PbⅡ by pre-concentration.In the presence of BiⅢ,the sensitivity for determination of ZnⅡ,CdⅡ and PbⅡ was remarkably enhanced.Influence factors such as bismuth concentration,boron doped concentrations of BDD electrode,pH,preconcentration potential were investigated and optimized.Under the optimal conditions,the stripping peak currents increased linearly with the increasing concentration of ZnⅡ,CdⅡ and PbⅡ in the range of 10-300 μg/L.The limit of detection was 0.56 μg/L for ZnⅡ,0.32 μg/L for CdⅡand 0.75 μg/L for PbⅡ (S/N=3),respectively.The interference experiments showed that common ions had little influence on the determination except CuⅡ.In addition,the developed electrode displayed a good repeatability.The method was successfully applied to determination of ZnⅡ,CdⅡ and PbⅡ in real water samples with the standard addition recoveries of 92.0%-114.0%.
ABSTRACT
Microbial fuel cells (MFCs) is a highly promising bioelectrochemical technology and uses microorganisms as catalyst to convert chemical energy directly to electrical energy. Microorganisms in the anodic chamber of MFC oxidize the substrate and generate electrons. The electrons are absorbed by the anode and transported through an external circuit to the cathode for corresponding reduction. The flow of electrons is measured as current. This current is a linear measure of the activity of microorganisms. If a toxic event occurs, microbial activity will change, most likely decrease. Hence, fewer electrons are transported and current decreases as well. In this way, a microbial fuel cell-based biosensor provides a direct measure to detect toxicity for samples. This paper introduces the detection of antibiotics, heavy metals, organic pollutants and acid in MFCs. The existing problems and future application of MFCs are also analyzed.
ABSTRACT
Based on the Android platform, a portable electrochemical analyzer was designed for the detection of heavy metal ions. Its output voltage range was ±3 V with accuracy of 0. 1% and resolution of <1 mV. The current acquisition range was±10 mA with accuracy of 0. 1% and the minimum resolution of 10 pA. With the human-computer interaction advantage of Android smart devices, professional and fast detection mode which could meet the needs of professional and ordinary users respectively were developed to simplify the complex process of electrochemical detection and analysis. Some common heavy metal ions including copper, cadmium, lead and mercury were detected with this detector. The results of linearity, repeatability and accuracy were satisfactory.
ABSTRACT
TiO2 coated hollow fiber ( HF) was prepared by sol-gel method and characterized by X-ray powder diffraction and scanning electron microscope. The adsorption performances of the self-prepared TiO2 coated HF for interest metal ions were explored. The sample solution was extracted for 30 min at pH 8. 0 under stirring at speed of 700 r/min, then desorpted with 100μL of 1 mol/L HNO3 . On the basis of this, a method combining TiO2 coated HF micro-solid phase extraction with electrothermal vaporization-inductively coupled plasma mass spectrometry ( ICP-MS ) was developed for the determination of trace metal ions in environmental water samples. Under the optimized conditions, the limits of detection obtained by the proposed method were 0. 039, 0 . 021 , 0 . 009 and 0 . 018 ng/mL for CrⅢ, CuⅡ, CdⅡ and PbⅡ with enrichment factors of 12 . 5 , 11 . 7 , 10. 3 and 18. 6, respectively. The preparation reproducibility of self-prepared TiO2 coated HF ranged from 4. 5% to 6. 8% (n=9) in one batch, and from 7. 7% to 9. 6% (n=7) in batch-to-batch. The developed method has been validated by analyzing a certified reference material ( GSBZ50009-88 200925 ) and also applied to the analysis of CrⅢ, CuⅡ, CdⅡ and PbⅡ in East Lake water and snow water successfully. Meanwhile, TiO2 coated HF stir bar was prepared for a comparison and it was demonstrated that TiO2 coated HF displayed higher extraction efficiency and adsorption capacity for target ions.
ABSTRACT
The rate of changes of heavy metal ions concentrations in the organism or biological system will determine the choice of strategy of realization of heavy metal ions effect and, consequently, the biological effect itself. Which of the possible strategies will dominate, depend on the rate of changes of concentration of heavy metal ions in biological systems, functional activity of organism at the moment of metal action and on metals chemical properties. Keeping this view, the present review deals with the concept of time-based alterations of concentration of heavy metal ions (TACMI) in biological systems. On the basis of TACMI concept formation of organism resistance to metal ions action could be explained. In the event of slow increase of its concentration in organism, it produces induction of metallothioneins, other stress-proteins and relative changes in the whole metabolic system. This, first of all, results in formation of new specific epigenotypes, which provide higher resistance (hormesis effect) not only to metal ions that induced this effect, but also to such stress-factors as high temperature (at least, for micro-algae cells).
ABSTRACT
The protecting effect of “Hypporamine PL” compound isolated from dry leaves of seabuckthorn (Hippophae rhamneides L.) on photosystem 2 (PS 2) activity suppression induced by CdCl2 and CoCl2 treatment in the 7 day old wheat seedlings (Triticum aestivum L.) under different pH of growth medium was investigated by measurement of millisecond delayed fluorescence (ms-DF) of chlorophyll intact leaves. The value o-i/p-s of ms-DF ratio was reduced under the Cd2+ and Co2+ treatments on 60 and 65% respectively at pH 6.7. Acidification of medium (pH 5.0) results in decreasing of ratio o-i/p-s only approximately on 30% in average. In the alkaline medium the lowering of o-i/p-s on 41% is observed in both ions treatments. This decreasing of o-i/p-s ratio occurred due to decreasing of fast phase o-i amplitude. At the same time the widening and increasing of slow phase p-s amplitude was observed. The compound “Hypporamine PL” limited the decrease of ms-DF components induced by heavy metals. It is suggested that the protective effect of “Hypporamine PL” on the photochemical reactions in the PS2 is due to catechins, epicatechins, quercetin and other polyphenols, containing in this compound, preventing the free radicals formation in the PS2 under treatment by heavy metal ions.
ABSTRACT
It was studied that effects of Hg 2+ ,Cu 2+ ,Cd 2+ ,Cr(Ⅵ) and Pb 2+ on 96h average growth rate,conductivity of osmotic luquor and total protein and bacteriochlorophyll content of our Rhodopseudomonas palustris The results showed that the toxicity sequence of these heavy metal ions from high to low is Hg 2+ , Cu 2+ , Cd 2+ ,Cr(Ⅵ)and Pb 2+ according to the results of effects of 5 heavy metal ions on 96h average growth rate of this strain;forcing of Hg 2+ , Cd 2+ ,Cr(Ⅵ) and Pb 2+ lead to increasing of conductivity of osmotic luquor ,and this effect has dose response,but that of Cu 2+ doesn't ;forcing of 5 heavy metal ions could result in reducing of bacteriochlorophyll content,and this effect also has dose response But forcing of 5 heavy metal ions hasn't marked effect on total protein content