Occurrence of microcystin-LR in vegetated lagoons used for urban runoff management.

Phytoremediation with aquatic macrophyte has been considered as an eco-friendly technique for controlling harmful cyanobacteria outbreak and proven to be effective. The conventional water quality parameters are frequently measured to evaluate the effectiveness of phytoremediation. However, the concentration of microcystin-leucine-arginine (MC-LR) in different vegetated water still remains uncertain. In this study, the contents of MC-LR in four macrophyte-vegetated lagoons were determined by solid phase extraction and ultra-high-performance liquid chromatography with tandem mass spectrometry technology. Results indicated that MC-LR was found in Nymphaea tetragona lagoon (lagoon-S), Vallisneria spiralis lagoon (lagoon-B) and another Vallisneria spiralis lagoon (lagoon-J). Only in lagoon dominated by Pistia stratiotes L. (lagoon-D), MC-LR concentration was undiscovered regardless of seasonal variation. The levels of MC-LR varied seasonally and were affected by the different vegetated aquatic macrophytes. The results suggest that in addition to conventional physicochemical parameters and indicators of water quality, MC-LR levels should be taken into consideration when the effectiveness of phytoremediation is assessed.

Regeneration of magnetic biochar derived from eucalyptus leaf residue for lead(II) removal.

Regeneration of Pb-loaded magnetic biochar prepared with eucalypts leaf residue was studied by using EDTA-2Na as a regenerant. The desorption efficiency was found to be 84.1% in 120 min with iron leaching amount of 1.1 mg g(-1). Higher SBET and pore volume were observed in regenerated magnetic biochars and no significant band shifts occurred in FTIR spectra during 6 regeneration cycles. The decrease of Pb(II) adsorption capacity (from 52.4 to 41.5 mg g(-1)) was only found in the first regeneration cycle. Magnetic separation performance of adsorbents was not significantly affected by multiple regeneration cycles.

Combined performance of biochar sorption and magnetic separation processes for treatment of chromium-contained electroplating wastewater.

Magnetic biochar was prepared with eucalyptus leaf residue remained after essential oil being extracted. Batch experiments were conducted to examine the capacity of the magnetic biochar to remove Cr (VI) from electroplating wastewater and to be separated by an external magnetic field. The results show that the initial solution pH plays an important role on both sorption and separation. The removal rates of Cr (VI), total Cr, Cu (II), and Ni (II) were 97.11%, 97.63%, 100% and 100%, respectively. The turbidity of the sorption-treated solution was reduced to 21.8NTU from 4075NTU after 10min magnetic separation. The study also confirms that the magnetic biochar still retains the original magnetic separation performance after the sorption process.

[Indirect determination of Cr(III) and Cr(VI) in milks by hydride generation-fluorescence spectrometry].

In the medium of 3 mol x L(-1) hydrochloric acid, Cr(VI) oxidized As(III) to be As(V), the As(III) content, which was left over, was determined by hydride generation-fluorescence spectrometry, giving that it was inversely proportional to Cr(VI) content. Based on the same principle and combined with potassium permanganate oxidation of Cr(III) to be Cr(VI), the Cr(III) was, therefore, determined. The sample digestion procedures and co-existing ions which might have interference were investigated. The instrumental operation parameters, reaction acidity and other influence factors were studied. Under optimum operation conditions, a good linear relationship was obtained in the range of 4.0-20 microg x L(-1) Cr. The detection limit of the method was 2.5 microg x L(-1). When the method was applied to milk analysis, a relative standard deviation (RSD, n = 6) of 1.6%-2.7% was found. The recovery was 96.5%-104.2%.

[Indirect determination of iodine with methyl isobutyl ketone (MIBK) extraction by atomic fluorescence spectrometer].

In this paper, a new method was developed for indirect determination of iodine with methyl isobutyl ketone (MIBK) extraction by atomic fluorescence spectrometer (AFS). Based upon the complex, which can be extacted perfectly by MIBK, formed between I- and Hg2+ in 0.1 mol x L(-1) of nitric acid, indirectly measuring the iodine in organic phase becomes possible. The effects of extraction conditions and other influence factors were investigated. Under the optimized experimental conditions, the results showed that the linearity between its absorbance and the concentration of iodine was 0-12 microg x L(-1), the detection limit is 0.14 microg x L(-1), and the relative standard deviation is 3.3%. The method has been applied to the determination of iodine in eggs, and the recoveries are in the range of 101.8%-110.4%.

[Butanol extraction combined with dilute hydrochloric acid dissolution-atomic fluorescence spectrometric method for indirect determination of molybdenum in Chinese herbal medicine].

A method for indirectly determining the molybdenum in Chinese herbal medicine by butanol extraction and dilute hydrochloric acid dissolution was established for atomic fluorescence spectrometry. The molybdoarsenate heteropoly acid, formed in the presence of As(V) and ammonium molybdate in 0.3 mol x L(-1) sulphuric acid medium, was separated and enriched in the organic solvent, then the evaporation of organic reagent was implemented and the left residue was dissolved in dilute hydrochloric acid in which the arsenic content was determined on behalf of molybdenum. In the optimum experimental conditions, molybdenum content in 0-15 microg x L(-1) range depicts a good linear relationship, the detection limit and relative standard deviation of 0.44 microg x L(-1) and 1.1% were obtained, respectively. Spiked Chinese herbal medicine samples were determined with the proposed method, and recoveries of 95.6%-101.3% were achieved.