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.

[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.