Distributions of chlorophyll a and carbon fixed strength of phyto-plankton in autumn of the southern Huanghai Sea waters

Chlorophyll a （Chl a） concentration and primary productivity （PP）, namely, carbon fixed strength of phytoplankton along four transects in the southern Huanghai Sea （SHS） were studied for their distribution features and controlling mechanisms based on the investigations from 17 October to 3 November 2005. The Chl a concentration in the study waters dynamically changed spatially. Surface Chl a concentrations ranged from 0.11 to 2.38 mg/m^3 with higher and lower values observed in the nutrient-laden inshore waters and central part of the SHS occupied by oligotrophic current, respectively. The vertical distribution of Chl a concentration showed a predominant pattern of subsurface concentration maximum profile. It followed the previous result of the deep dissolved oxygen concentration maximum profile, which was significantly correlated with phytoplankton and regional water mass. The primary productivity of carbon in autumn of the SHS, ranging from 95 to 1 634 rag/（ m^2· d） mainly varied with nutrient condition, especially phosphate concentration in seawater and hydrological condition. Furthermore, associating the present study results together with previous studies, the annual value of carbon fixed production of phytoplankton in the entire marginal seas of East China （including the Bohai Sea, the Huanghai Sea and the East China Sea） was estimated to be 222 Mt, which accounted for 2% of that in the global margins. Besides, it was as 16.2 times as the annual value of apparent carbon sink strength （ 13.96 Mt） in the marginal seas of East China. This multiple was different in different sea areas （ 3.0 in the Bohai Sea, 6. 7 in the Huanghai Sea and 81.6 in the East China Sea）.

Characterization of P-nitrophenol Adsorption Kinetic Properties in Batch and Fixed Bed Adsorbers

P-nitrophenol（PNP） adsorption in batch and fixed bed adsorbers was studied. The homogeneous surface diffusion model（HSDM） based on external mass transfer and intraparticle surface diffusion was used to describe the adsorption kinetics for PNP in stirred batch adsorber at various initial concentrations and activated carbon dosages. The fixed bed model considering both external and internal mass transfer resistances as well as axial dispersion with non-linear isotherm was utilized to predict the fixed bed breakthrough curves for PNP adsorption under the conditions of different flow rates and inlet concentrations. The equilibrium parameters and surface diffusivity（Ds） were obtained from separate experiments in batch adsorber. The obtained value of Ds is 4.187×1012 m2/s. The external film mass transfer coefficient（kf） and axial dispersion coefficient（DL） were estimated by the correlations of Goeuret and Wike-Chang. The Biot number determined by HSDM indicated that the adsorption rate of PNP onto activated carbon in stirred batch was controlled by intraparticle diffusion and film mass transfer. A sensitivity analysis was carried out and showed that the fixed bed model calculations were sensitive to Ds and kf, but insensitive to DL. The sensitivity analysis and Biot number both confirm that intraparticle diffusion and film mass transfer are the controlling mass transfer mechanism in fixed bed adsorption system.

Investigating on a Process Method of Beneficiating and Increasing the Graphite Purity to 99% Grade

The main aim of this project was to come up with an efficient method for the purification of graphite to at least 99%. There has been an increasing demand for high-grade graphite products with up to 99.99% carbon that has resulted in the development of various approaches to remove impurities even to parts per million range. Removal of impurities from 94% graphite is important to achieve a high-purity graphite product. Microwave irradiation was used to prepare high-purity graphite from 94% graphite concentrate. The results showed that microwave irradiation could enhance the fixed carbon of flake graphite to a higher level. Under the optimum conditions selected of 4 minutes’ reaction time and 100% microwave output (800 W), a graphite product with a fixed carbon content of 98.845% was obtained from flake graphite concentrate. According to XRD, FTIR and Handheld XRF analysis, impurities mainly composed of Fe, Co, Sr and Zr were present before treatment. After treatment under optimum conditions Fe, which was the major impurity in the sample was reduced from 3.566% to 1.031%. The ash content of graphite under optimum conditions was 1.55%. The crystal structure of flake graphite showed no change. It can be concluded from this study that graphite purification using microwave irradiation increases the carbon content of graphite.