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A reversed-phase high-performance liquid chroma-tography method based on modified pre-column derivati-zation with phenylisothiocyanate was applied to quantify free amino acids in a protein hydrolysate extracted from waste activated sludge. The protein solution was hydro-lyzed with neutral and alkaline proteases. The analytical parameters including linearity (r2≥0.99), precision (2.0-3.0%, RSD), accuracy (97.3-103.6% recovery), limits of detection (0.002-1.71 pM) and quantification range (0.065-5.70 pM) were determined. [ABSTRACT FROM AUTHOR]

In this study, modified expanded graphite (MEG) was prepared by sequence processes of mixed sucrose/ phosphoric acid solution impregnation, carbonization and in-situ H3PO4 activation. MEG was characterized by scanning electron microscopy (SEM), infrared spectroscopy (IR) and X-ray diffraction (XRD). Adsorptive property of MEG as a porous adsorbent for the removal of toxic Cr(VI) from aqueous solution was investigated. Three process parameters namely initial pH value (2.0-6.0), temperature (20- 60°C) and initial Cr(VI) concentration (50-150 mg·L-1) was optimized to obtained the best response of Cr(VI) removal using the statistical Box-Behnken design in response surface methodology (RSM). The response surface data indicated maximum Cr(VI) adsorption (99%) with initial 50 mg·L-1 of Cr(VI) concentration at pH 2.0, temperature 25°C. The MEG adsorbent could remove >80% Cr(VI) from aqueous solution with initial metal concentration of 50-80 mg·L-1. Adsorption data for Cr(VI) removal were analyzed according to Langmuir and Freundlich adsorption models and it was found that the Langmuir isotherm model best fitted the adsorption data. Kinetic studies were done and can be described by a pseudo-second order rate equation very well. [ABSTRACT FROM AUTHOR]

A novel heterogeneous catalytic system, employing sulfate radicals activated by supported cobalt oxide (Co3O4), was applied to degrade the Orange II from aqueous solution. The catalyst of cobalt oxide supported on the surface of graphene oxide (Co3O4/GO) was prepared and characterized by XRD and TEM. Ultrasound (US) and aeration applied were introduced into the system, and the possible beneficial effects were assessed. The heterogeneous catalytic system coupled with US and aeration demonstrates an enhancement in terms of Orange II degradation compared with the absence of US. The experimental parameters, such as initial pH of solution, dosages of catalyst and peroxymonosulfate (PMS), and power of ultrasound as well as different operating conditions, were systematically studied and optimized. Under the optimal parameters, it's worthy to note that Orange II could be completely degraded in a few minutes by heterogeneous catalytic system due to the apply with US and aeration. Apparently, the ultrasonic technique and aeration applied are promising for the treatment of wastewater containing Orange II. [ABSTRACT FROM AUTHOR]