Highly Charged Swelling Mica Reduces Free and Extractable Cu Levels in Cu-Contaminated Soils
ABSTRACT Smelting of copper (Cu) results in the atmospheric deposition of Cu onto surrounding soils. Excess concentrations of Cu in soils can be absorbed by soil biota to toxic levels or leached into the groundwater, threatening the entire ecosystem. A means to restrict Cu mobility and uptake by plants is to remove it from the aqueous phase by applying an adsorptive material. A synthetic clay (highly charged swelling mica) was tested for its ability to decrease the levels of free and 0.1 M KNO3-extractable Cu in 15 surface soils from three different Cu mining areas in central Chile. The soils contained excessive total Cu levels (112-2790 mg Cu (kg soil)(-1)), while extractable Cu ranged from 0.3 to 22.9 mg Cu L(-1). The mica was applied to each soil at rates of 0.1%, 1%, and 2% (w/w). A 2% sodium-montmorillonite treatment and the nonamended soil served as controls. The order of treatment efficacy in reducing extractable Cu and free Cu2+ for low pH soils (<pH 5.5) was: 2% mica > 1% mica > 2% montmorillonite > 0.1% mica. At 120 days, the 2% mica treatment maintained reductions of up to 93% in the free Cu2+ activity and up to 75% in the extractable Cu concentration upon acidification to the original soil pH value. In addition, Cu retention in mica-treated soils was more resistant to acidification than in lime-treated soils. This mica has promise for the remediation of acidic soils with metal contamination at the surface.
Biophysical Journal 02/2011; 100(3). DOI:10.1016/j.bpj.2010.12.1740 · 3.83 Impact Factor
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ABSTRACT: The living ring-opening polymerization of l-lactide was carried out by using organocatalyst to synthesize the molecular weight controlled poly(l-lactide) with an phenylacetylenyl end group (HCCPLLA), then the homopolymerization of HCCPLLA was performed by using two different rhodium catalysts. Low molecular weight poly-PLLA6-1 (Mw,SEC-MALLS=46,700) was synthesized by using Rh(nbd)BPh4 as the catalyst, and higher molecular weight poly-PLLA6-2 (Mw,SEC-MALLS=471,000) was synthesized by using the [Rh(nbd)Cl]2/Et3N catalyst system. Then high molecular weight poly-PLLA20, poly-PLLA29, and poly-PLLA68 were successfully synthesized by using the [Rh(nbd)Cl]2/Et3N catalyst system. The α values of the poly-PLLAs using [Rh(nbd)Cl]2/Et3N catalyst system were all in the range of 0.6–0.8, this means that these polymers possess linear flexible chain. It is concluded that [Rh(nbd)Cl]2/Et3N was more suitable for the synthesis of the cylindrical polymer brush, poly-PLLA with high molecular weight. The analyses of the CD spectra indicated that poly-PLLA possesses a predominantly one-handed helical conformation, temperature and solvents had significant influences on the helical structure of poly-PLLA.European Polymer Journal 10/2011; 47(10):1923-1930. DOI:10.1016/j.eurpolymj.2011.07.003 · 3.24 Impact Factor
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ABSTRACT: In acidic soils, copper (Cu) availability may be high because of Cu impurities of various agricultural additives. This research was aimed at assessing liming and zeolite application as availability reduction methods. In a soil with pH 3.8, lime was added at 6.6 Mg ha−1, and zeolite was added at 3.3% and 10% in a 100-day pot trial with ryegrass. On day 50 zeolite was more effective in reducing Cu availability [as expressed by diethylenetriaminepentaacetic acid (DTPA) soil extractions and plant concentration measurements] than liming. On day 100, Cu levels were further reduced in both treatments, indicating the effectiveness of both zeolite and liming over the study period to retain Cu. Zeolite alone reduced Cu concentration in plants to 26%, liming alone reduced it by 21%, and the combination of the two reduced it by 43%. The orders in the DTPA extractions and the soil-to-plant Cu transfer coefficients were similar.Communications in Soil Science and Plant Analysis 04/2014; 45(7). DOI:10.1080/00103624.2014.882351 · 0.42 Impact Factor