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Chu S.-Y.,Zhejiang University | Chu S.-Y.,Zhejiang Agriculture And forestry University | Yang M.,Zhejiang Agriculture And forestry University | Xiao J.-B.,Zhejiang Agriculture And forestry University | And 4 more authors.
Chinese Journal of Applied Ecology | Year: 2013

By using phosphoric acid as activation agent, active carbon was prepared from Thalia dealbata residues. The BET specific surface area of the active carbon was 1174.13 m2·g-1, micropore area was 426.99 m2·g-1, and average pore diameter was 3.23 nm. An investigation was made on the adsorption performances of the active carbon for crystal violet from aqueous solution under various conditions of pH, initial concentration of crystal violet, contact time, and contact temperature. It was shown that the adsorbed amount of crystal violet was less affected by solution pH, and the adsorption process could be divided into two stages, i. e., fast adsorption and slow adsorption, which followed the pseudo-second-order kinetics model. At the temperature 293, 303, and 313 K, the adsorption process was more accordance with Langmuir isotherm model, and the maximum adsorption capacity was 409.83, 425.53, and 438.59 mg·g-1, respectively. In addition, the adsorption process was spontaneous and endothermic, and the randomness of crystal violet molecules increased.

Lin J.,CAS Wuhan Institute of Hydrobiology | Lin J.,University of Chinese Academy of Sciences | Zhong Y.,Hangzhou Urban River Supervision Center | Fan H.,Hangzhou Urban River Supervision Center | And 7 more authors.
Environmental Science and Pollution Research | Year: 2016

In this work, sediments were treated with calcium nitrate, aluminum sulfate, ferric sulfate, and Phoslock®, respectively. The impact of treatments on internal phosphorus release, the abundance of nitrogen cycle-related functional genes, and the growth of submerged macrophytes were investigated. All treatments reduced total phosphorus (TP) and soluble reactive phosphorus (SRP) in interstitial water, and aluminum sulfate was most efficient. Aluminum sulfate also decreased TP and SRP in overlying water. Treatments significantly changed P speciations in the sediment. Phoslock® transformed other P species into calcium-bound P. Calcium nitrate, ferric sulfate, and Phoslock® had negative influence on ammonia oxidizers, while four chemicals had positive influence on denitrifies, indicating that chemical treatment could inhibit nitrification but enhance denitrification. Aluminum sulfate had decreased chlorophyll content of the leaves of submerged macrophytes, while ferric sulfate and Phoslock® treatment would inhibit the growth of the root. Based on the results that we obtained, we emphasized that before application of chemical treatment, the effects on submerged macrophyte revegetation should be taken into consideration. © 2016 Springer-Verlag Berlin Heidelberg

Lin J.,CAS Wuhan Institute of Hydrobiology | Lin J.,University of Chinese Academy of Sciences | Qiu P.,Hangzhou Urban River Supervision Center | Yan X.,Hangzhou Urban River Supervision Center | And 3 more authors.
Water, Air, and Soil Pollution | Year: 2015

Calcium nitrate and a lanthanum-modified bentonite (Phoslock®) were investigated for their ability to control the release of phosphorus from contaminated sediment. Their effectiveness and mode of action were assessed using microcosm experiments by monitoring the variation of physiochemical parameters and phosphorus and nitrogen species over time following the treatment for 66 days. Phoslock® was more effective reducing phosphorus in overlaying water and controlling its release from sediment. Calcium nitrate improved redox condition at the sediment-water interface and temporally reduce phosphorus in overlaying water but phosphorus level returned back in a long run. Phosphorus fractionation suggested that Phoslock® converted mobile phosphorus to more stable species while calcium nitrate increased the fractions of mobile phosphorus species. Phoslock® generally showed no effect on nitrogen species. Whereas calcium nitrate temporally increased nitrate, nitrite, and ammonium concentrations but their concentrations quickly reduced likely due to the denitrification process. Results suggested that Phoslock® can be more effective in controlling the release of phosphorus from sediment than calcium nitrate. However, calcium nitrate can improve the redox condition at the sediment-water interface, which may provide other benefits such as stimulating biodegradation. © 2015 Springer International Publishing Switzerland.

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