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Cai J.,Hubei Provincial Research Institute of Environmental Science | Feng L.,Hubei Environmental Monitoring Central Station | Kang J.,Hubei Provincial Research Institute of Environmental Science | Kang J.,Wuhan University | And 3 more authors.
Fresenius Environmental Bulletin | Year: 2013

The adsorption of methylene blue on activated carbon derived from brewer's yeast was systematically investigated in this study. Activated carbon prepared by chemical activation with Na2CO3 (weight ratio of Na2CO3/yeast was 2:1) at 700 °C for 2 h, presenting high BET surface (957.7 m2/g) and large pore volume (0.81 mL/g), was more effective for methylene blue removal than those prepared under other conditions. 88% of the uptake of methylene blue by this activated carbon occurred in 2.0 h, and the equilibrium was obtained within 3.0 h, which was well described by pseudo-second-order kinetics. The methylene blue adsorption on activated carbon decreased as the solution pH was increased from 3.0 to 4.0 and then increased obviously as the pH was further increased, which was caused by the pH-dependent surface charge of activated carbon. The adsorption isotherm was better described by the Freundlich isotherm than the Langmuir isotherm. The maximum methylene blue uptake was estimated to be 407.78 mg/g. Fourier transform infrared spectroscopy studies showed that carbonyl and amine groups in activated carbon were involved in the adsorption of methylene blue. © by PSP. Source

Wu Y.-X.,Wuhan University | Li A.-M.,Hubei Environmental Monitoring Central Station | Wang D.-H.,Wuhan University | Zhang W.-H.,Wuhan University
Huanjing Kexue/Environmental Science | Year: 2015

The experiments were conducted to investigate the adsorption behavior of tetracycline on a kind of nano-sized amorphous carbon, which was synthetized in a molten salt electrochemical system, comprising a eutectic mixture of Li-Na-K carbonates. The results showed that, the carbon powder had a good adsorption performance. At 298K, the maximum adsorption capacity of tetracycline was 127.76 mg·g-1. The adsorption data could be well fitted by the pseudo-second-order model and the Freundlich isotherm. Also, the thermodynamic tests for the adsorption were conducted. The adsorption was endothermic and spontaneous reaction with chemical bond as the dominant. The adsorption was pH dependent. The adsorption capacity reached the maximum when solution pH was 4 in the range from 2 to 11. The existence of cations had little effects on the adsorption. The adsorption capacity increased with the concentration of cations to a certain extent. Ion exchange may be one of the adsorption mechanisms, as well as, electric attraction and hydrogen bond. Moreover, desorption experiments were carried out in 0.25 mol·L-1 CaCl2 or NaCl solution respectively. Desorption efficiency ranged from 7.42% to 25%, which was at a relatively low level. The result indicated that the chemical adsorption process was strong. ©, 2015, Science Press. All right reserved. Source

Han X.,Central China Normal University | Zhu X.,Central China Normal University | Zhu S.,Central China Normal University | Wei L.,Central China Normal University | And 8 more authors.
Journal of Chemical Information and Modeling | Year: 2016

In the present study, a series of novel maleimide derivatives were rationally designed and optimized, and their inhibitory activities against cyanobacteria class-II fructose-1,6-bisphosphate aldolase (Cy-FBA-II) and Synechocystis sp. PCC 6803 were further evaluated. The experimental results showed that the introduction of a bigger group (Br, Cl, CH3, or C6H3-o-F) on the pyrrole-2′,5′-dione ring resulted in a decrease in the Cy-FBA-II inhibitory activity of the hit compounds. Generally, most of the hit compounds with high Cy-FBA-II inhibitory activities could also exhibit high in vivo activities against Synechocystis sp. PCC 6803. Especially, compound 10 not only shows a high Cy-FBA-II activity (IC50 = 1.7 μM) but also has the highest in vivo activity against Synechocystis sp. PCC 6803 (EC50 = 0.6 ppm). Thus, compound 10 was selected as a representative molecule, and its probable interactions with the surrounding important residues in the active site of Cy-FBA-II were elucidated by the joint use of molecular docking, molecular dynamics simulations, ONIOM calculations, and enzymatic assays to provide new insight into the binding mode of the inhibitors and Cy-FBA-II. The positive results indicate that the design strategy used in the present study is very likely to be a promising way to find novel lead compounds with high inhibitory activities against Cy-FBA-II in the future. The enzymatic and algal inhibition assays suggest that Cy-FBA-II is very likely to be a promising target for the design, synthesis, and development of novel specific algicides to solve cyanobacterial harmful algal blooms. © 2015 American Chemical Society. Source

Zhang L.,Wuhan University | Zhang L.,Jiangxi Normal University | Chen X.-L.,Wuhan University | Chen X.-L.,Jiangxi Normal University | And 3 more authors.
Zhongguo Huanjing Kexue/China Environmental Science | Year: 2014

Based on the in situ measurements from the field survey in July, 2011, the objective of this paper was to investigate the spatial distribution of the total suspended sediment (TSS), total nitrogen (TN), total phosphorus (TP), and chlorophyll a (Chl a), where their impacting factors were also studied by dividing the lake into 8 hydro-geomorphological partitions considering the hydrodynamic conditions. Results show that the TSS concentration was 33.65 mg/L, which was three times higher than that of the average conditions before 2003. The N, P concentrations were 1.61 mg/L and 0.075 mg/L respectively, which appears much higher than the requirements of eutrophication. The average Chl a concentration was 5.99 μg/L, which was smaller than the threshold of being a eutrophic lake. Correlation analysis showed that TP and TSS were significantly correlated with each other in high sediment concentration regions, while no significant correlation was observed between the Chl a and other water quality parameters. In different hydro-geomorphological sections, due to pollution inputs from the watershed and sand mining activities within the lake, the TSS concentration of the northern high velocity water regions was three times higher than the river estuary area. TN and TP concentrations of the Ganjiang and Raohe river estuary area was larger than the northern high velocity water regions, where Xiuhe River estuary area and some central lake area showed minimum TN and TP concentration. The hydrodynamics also played an important role in regulating the spatial distribution of TSS, TN, TP and Chl a in the lakes, Chl a concentration of the river estuary area was larger than the northern high velocity regions, while the Rao-Xin-Tong Jin River estuary area even reached 12.53 μg/L, exceeding the low bound value of being a eutrophic lake. ©, 2014, Editorial Board of China Environmental Science. All right reserved. Source

Zhang S.-H.,Yunnan University | Guo L.,Hubei Environmental Monitoring Central Station | Cao J.-Y.,Yunnan University | Chang J.-J.,Yunnan University
Polish Journal of Environmental Studies | Year: 2015

The extracts of three emergent macrophytes (Acorus calamus, Oenanthe javanica, and Sagittaria sagittifolia) were tested to study their allelopathic activities on unicellular Microcystis aeruginosa, Anabaena flosaquae, Aphanizomenon flosaquae, and natural phytoplankton assemblages. The 72 h EC50 of the most active extracts were measured. The results demonstrated the obvious species-specific activities of macrophytes on algae. Anabaena flosaquae and Aphanizomenon flosaquae was sensitive to the three macrophytes extracts, while unicellular M. aeruginosa was only sensitive to A. calamus and O. javanica extracts under the extracts concentration of 100 mg·L-1. Only the extract of A. calamus roots showed high growth inhibition on the natural phytoplankton assemblages in Dianchi Lake (Microcystis water bloom). The 72 h EC50 of A. calamus roots hexane extract on unicellular M. aeruginosa was 13.59 mg·L-1, while that on natural phytoplankton assemblages was 48.75 mg·L-1. These results demonstrated that the growth inhibitory activities of allelochemicals on unicellular M. aeruginosa cannot instead of the efficacies for controlling Microcystis bloom completely. And according to the different sensitivities of Microcystis species, the colonial Microcystis strains or natural Microcystis bloom will be proposed as the target organism when searching for Microcystis bloom control. © 2015, HARD Publishing Company. All rights reserved. Source

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