PubMed · 8092483
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D R Louder, B A Parkinson. 1994-06-15. Scanning probe microscopy.. https://doi.org/10.1021/ac00084a005
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Bioremediation of metal-contaminated wastestreams has been successfully demonstrated. Normally, whole cells or microbial exopolymers are used to concentrate and/or precipitate metals in the wastestream to aid in metal removal. Analogous remediation of metal-contaminated soils is more complex because microbial cells or large exopolymers do not move freely through the soil. The use of microbially produced surfactants (biosurfactants) is an alternative with potential for remediation of metal-contaminated soils. The distinct advantage of biosurfactants over whole cells or exopolymers is their small size, generally biosurfactant molecular weights are less than 1500. A second advantage is that biosurfactants have a wide variety of chemical structures that may show different metal selectivities and thus, metal removal efficiencies. A review of the literature shows that complexation capacities of several bacterial exopolymers was similar to the complexation capacity of a rhamnolipid biosurfactant produced by Pseudomonas aeruginosa ATCC 9027.
The method of the atomic emission spectrometry with an excitation in the inductively coupled plasma ICP-AES has been applied to the simultaneous analysis of the elements: Al, Cd, Cr, Cu, Fe, Li, Mg, Mn, Ni, P, Pb, S, Sr and V in the tobacco leaves samples CTA-OTL-1. The spectrometric analyses have been carried out on the emission spectrometer Spectroflame ICP M. About 300 mg of the sample and 1 cm3 of the concentrated HNO3 acid have been sealed in the quartz tube and mineralized by the pressure method. Since the ICP-AES technique is the most suitable to the direct analysis of the solutions, the main problem to solve was a mineralization of the sample. An application of the HNO3 acid alone did not give satisfactory results--unsolved residue remained. As a consequence the results for Mg, Ni, Pb were too low, whereas for the Al-nearly twice lower than the respective values given in the sample reference data. It has been observed that an addition of the conc. HF acid helps to dissolve the residue and, consequently, the optimalization of the mineralization process in the presence of the HNO3-HF mixture has been carried out. The results show that the appropriate amount of the HF acid to be added is 0.25 cm3. The other methods of mineralization using various mixtures of acids did not give good results. Only HNO3-HF mixture used in appropriate proportions give results in agreement with provided sample characteristics.(ABSTRACT TRUNCATED AT 250 WORDS)
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