• Title, Summary, Keyword: speciation

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Geochemical speciation of dissolved heavy metals in acid mine drainage: effects of pH and total concentration

  • Jung, Hun-Bok;Yun, Seong-Taek;Kwon, Jang-Soon;So, Chil-Sup;Lee, Pyeong-Koo
    • Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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    • pp.404-408
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    • 2003
  • In this study, we examined the influences of pH and total concentration on the speciation of heavy metals (Cd, Cu, Zn) in acid mine drainage. Their labile concentrations were analyzed by Anodic Stripping Voltammetry (ASV) at both natural pH and adjusted pHs (from 2 to 8). We obtained regression equations for predicting labile concentrations as a function of the water pH and contamination level (total dissolved metal concentration). Our data show that labile Cu depends on both the total concentration and pH, while labile Cd and Zn concentrations are controlled mainly by their total concentration rather than pH. Therefore, the pH variation of AMD may significantly change the toxicity and bioavailability especially of Cu, owing to its speciation change.

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INORGANIC AND BIO-MATERIALS IN THE REMOVAL/SPECIATION OF RADIOCESIUM AND RADIOSTRONTIUM : AN OVERVIEW

  • Tiwari, Diwakar;Prasad, S.K.;Yang, Jae-Kyu;Choi, Bong-Jong;Lee, Seung-Mok
    • Environmental Engineering Research
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    • v.11 no.2
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    • pp.106-125
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    • 2006
  • Cesium and strontium are two important fission products and the removal/speciation of these two cations with several inorganic/bio-materials is an interesting topic to discuss. It is to be noted that inorganic materials are found to be fairly effective and efficient in the removal/speciation of these cations. Moreover, these solids are to be found promising as they show fairly good radiation and temperature stability. Hence, they play an important role in the radioactive waste management studies. However, various studies reveal that in addition to inorganic materials various biosorbents can also be employed in the removal/speciation of these ions. But the radiation and temperature stability of these bio-sorbents and dead biomasses are still the topic lying among the researchers to be investigated.

Evaluation of effect of rapid mixing intensity on chemical phosphorus removal using Al hydrolysis speciation (가수분해 산물 분포를 이용한 급속혼화강도가 화학적 인 제거 효율에 미치는 영향의 규명)

  • Kim, Seung-Hyun;Yoon, Dong-Soo;Moon, Byung-Hyun
    • Journal of Korean Society of Water and Wastewater
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    • v.25 no.3
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    • pp.367-373
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    • 2011
  • Mechanism of rapid mixing effect on chemical phosphorus removal is evaluated in this study. Assuming that chemical phosphorus removal is unaffected by mixing time, only rapid mixing intensity is evaluated. In order to find out the mechanism, it is hypothesized that rapid mixing affects the Al hydrolysis speciation, and that formation of more monomeric species ($Al^a$) results in better removal of phosphorus. According to a ferron assay, more $Al^a$ formed at higher mixing intensity than at lower intensity. Subsequent experiments revealed that better phosphorus removal was obtained at higher intensity than at lower intensity, in terms of the molar ratio of $Al_{added}/P_{removed}$. The proposed hypothesis was proved in this study. Chemical phosphorus removal is affected by rapid mixing intensity due to its effect on the Al hydrolysis speciation.

Increasing Diversity of Evolvable Hardware with Speciation Technique (종분화 기법을 이용한 진화 하드웨어의 다양성 향상)

  • Hwang Keum-Sung;Cho Sung-Bae
    • Journal of KIISE:Software and Applications
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    • v.32 no.1
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    • pp.62-73
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    • 2005
  • Evolvable Hardware is the technique that obtains target function by adapting reconfigurable digital' devices to environment in real time using evolutionary computation. It opens the possibility of automatic design of hardware circuits but still has the limitation to produce complex circuits. In this paper, we have analyzed the fitness landscape of evolvable hardware and proposed a speciation technique of evolving diverse individuals simultaneously, proving the efficiency empirically. Also, we show that useful extra functions can be obtained by analyzing diverse circuits from the speciation technique.

Speciation of Cr(III)/Cr(VI) in Tannery Waste Waters by Using Ion-Exchange Resins

  • Kartal, S.;Tokalloglu, S.;Ozkan, B.
    • Bulletin of the Korean Chemical Society
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    • v.27 no.5
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    • pp.694-698
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    • 2006
  • A method has been described for the chemical speciation, preconcentration and determination of Cr(III) and Cr(VI) species in filtered tannery waste waters by flame atomic absorption spectrometry using ion-exchange resins. Amberlite IR-120($H^+$) strongly acidic cation exchanger and Amberlite IRA-410($CI ^-$) strongly basic anion exchanger resins were used for the separation and preconcentration of Cr(III) and Cr(VI) species, respectively. Optimum condition for preconcentration and speciation was obtained by testing pH of sample and eluent, flow rates of sample and eluent, amount of resins, volume of sample and eluents, and effect of foreign ions. The recommended method has been successfully applied for the preconcentration and determination of chromium species in the dissolved phase of waste water samples collected from a tannery waste water treatment plant in Kayseri, Turkey. The detection limits achieved were 0.73 $\mu$g/L for Cr(III) and 0.81 $\mu$g/L for Cr(VI). Recovery studies showed 99% for Cr(III) and 98% for Cr(VI), for samples spiked with single species.