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    Geochemical fractions and modeling adsorption of heavy metals into contaminated river sediments in Japan and Thailand determined by sequential leaching technique using ICP-MS
    (2019-09-01)
    Wijaya, Anugrah Ricky
    ;
    Ohde, Shigeru
    ;
    Shinjo, Ryuichi
    ;
    Ganmanee, Monthon
    ;
    Cohen, Michael Dustin
    In order to provide information on the chemical processes in sediment fractions and their adsorption models, we investigated the contaminated sediments of the Sumida River in Tokyo, Japan and the Chao Phraya River in Bangkok, Thailand. Samples were leached through a sequential leaching technique to perform metal concentration analysis for the sediment fraction assessment and then samples were tested for the model adsorption of the highest level of sediments contaminated by heavy metals using the isotherm Langmuir and Freundlich equations. Metal (Pb, Cd, Zn, As, Cu, Ca, Fe, and Mn) concentration in the leached solutions was analyzed by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). The pattern of geochemical fractions in both sediment samples showed the maxima leached levels of Cd (38.6 %), Ca (55.2%), and Mn (41.3%) in the soluble fraction; Pb (52.1%), and Zn (56.7%) in the reducible fraction; Cu (61.2%) in the oxidizable fraction; and As (47.1%) and Fe (55.9%) in the residual fraction. The total level fractions of Pb (62.6 ppm), Zn (240 ppm), As (27.2 ppm), Fe (16,636 ppm) and Mn (419 ppm) in the Chao Phraya River sediments were higher compared to those in the Sumida River, indicating the high anthropogenic effect in Bangkok. In the most contaminated sediments, the higher adsorption capacity of heavy metal concentrations was contributed by SiO<inf>2</inf>, CaCO<inf>3</inf>, and Al<inf>2</inf>O<inf>3</inf> determined by the X-ray diffraction and organic contents. The model of adsorption of Cd fitted to the linear form of Langmuir's equation with the correlation coefficients (r<sup>2</sup> = 0.94), b (0.467) and k (7137), whereas Pb, Cu, Cr, and Zn conformed to the model of the Freundlich equation.
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    Effects of low pH and Pb2+ stress on living cyanobacterium, Phormidium angustissimum West & G.S.West: A test of its feasibility as a living biosorbent
    (2013-06-01)
    Ruangsomboon, Suneerat
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    Wongrat, Ladda
    ;
    Choochote, Sakchai
    ;
    Ganmanee, Monthon
    ;
    Saparnklang, Atiya
    Pb<sup>2+</sup> adsorption by the living cyanobacterium, Phormidium angustissimum followed the Langmuir adsorption model, with the maximum adsorption capacity (q <inf>max</inf>) of 295.4 ± 13.8 mg g<sup>-1</sup>. This result suggests that P. angustissimum is a promising living biosorbent to remove Pb<sup>2+</sup> from wastewaters. Living biosorbents are better able to remove Pb<sup>2+</sup> from wastewater than dead biosorbents, however there are practical limitations for their use are encountered in extreme conditions such as low pH and high Pb<sup>2+</sup> concentration. The feasibility of using cyanobacterium, P. angustissimum, as a living biosorbent for the extraction of Pb<sup>2+</sup> from wastewater was studied by investigating its photosynthestic performance and tolerance under Pb<sup>2+</sup> (0-5 mg L<sup>-1</sup>) contamination and low pH (pH 3-7). Decreased photosynthetic performance caused by Pb<sup>2+</sup> contamination and low pH stress was detected in this study by means of a reduction of the maximum photochemical efficiency of PSII (F<inf>v</inf>/F<inf>m</inf>). Detoxification mechanisms of P. angustissimum on Pb<sup>2+</sup> appeared to increase its intracellular polysaccharides (IPS), exocellular polysaccharides (EPS), and protein. Living P. angustissimum could increase the pH of the solution which resulted in Pb<sup>2+</sup> precipitation. The unique ability of P. angustissimum to remove Pb<sup>2+</sup> and to grow under toxic conditions, demonstrated herein, indicates that it is a promising living biosorbent for mildly acidic water contaminated with Pb<sup>2+</sup> in bioremoval systems in the which pH is not lower than 5 and Pb<sup>2+</sup> is not higher than 5 mg L<sup>-1</sup>. © 2013 Springer Science+Business Media Dordrecht.