Papers by Keyword: Cd

Abstract: This research paper describes the effect of hydrogen peroxide concentrations (0; 1; 3; 5 and 7 wt%) on fluorescence properties of carbon dots (CDs) from high-density polyethylene (HDPE) plastic. Synthesis of CDs has been carried out using modified pyrolysis and hydrothermal methods. The CDs obtained were characterized by FTIR, XRD, UV-Visible and fluorescence spectrophotometer. Based on UV-Visible spectra, the maximum wavelength of carbon dot ranges from 287 to 291 nm, indicating there is an π -π* electron transition belonging to the core site (C=C), then the absorption widens to 400 nm which indicated n-π* electron transition relating to the CDs surface functional group (carbonyl, hydroxyl, and carboxyl). The use of hydrogen peroxide (5 wt%) can produce CDs with the best fluorescence properties based on fluorescence spectra. CDs has a structure like graphite which is rich in functional groups on its surface. The photocatalytic activity of carbon dot has been tested and it showed that CDs can degrade methylene blue (MB) dye under visible light (80.3%).

Abstract: Modifications of red mud for activating available silicon (Si) by phosphates were carried on in this paper. And then the modified red mud materials were used to stabilize Cd in an ore soil. Results indicated that phosphates efficiently increase the content of available Si in red mud. In the stabilization, exchange Cd was decreased by 90.97% when using 5% potassium dihydrogen phosphate modified red mud, which was better than using raw re mud as the decrease was 77.08%. In rice pot soil, increases of residue Cd were positively correlated with the increases of available Si (P<0.05, R=0.9965). Contents of Cd in root increased 53.87% while it in rice decreased 24.17% by adding 3% modified red mud.

Abstract: The phytoremediation of jointly contaminated farmland soil with Cd and PAHs was studied in the long-term and representative wastewater irrigation area in Northeast China. Black nightshades (Solanum nigrum L), proved to be a Cd-hyperaccumulator was taken to remove the Cd contaminant from soil during one growing seasons in field test and thirteen lawn grasses and pasture grasses were taken to remediate the PAHs in pot experiments. Results showed that the residual concentrations Cd and PAHs were 1.94~3.69 mg/kg (dry weight) and 1.69~2.71 mg/kg (dry weight), respectively, still much higher than the Soil Quality Standard after the stop of wastewater irrigation for more than 20 years. The black nightshades could tolerate and grow well in the jointly contaminated farmland, with the distribution sequence of Cd in the order of leaf> stem> fruit> root, and the removal rate in the high-density black nightshade treatment was 1.40 percent in one growing season, higher than that in the moderate-density treatment and low-density treatment. Alfalfa, rye grass, Balin, tall fescue and white clover were more efficient than others of the tested thirteen grasses for the remediation of PAH-contaminated soil.

Abstract: The article analyzed the adsorptive ability of acorus calamus to Pb,Cd in soil through pot experiment. The results show that with the increase of concentration of this two kinds of heavy metals,the growth of acorus calamus have been obviously affected.The concentration of two kinds of heavy metals in the acorus calamus root is far more than in the cauline leaf,which show that acorus calamus have very strong retention effect on these five kinds of heavy metals. As acorus calamus absorb the Pb much more than Cd can be seen through the experiment.

Abstract: Cd accumulation characteristic of 8 Chinese cabbage cultivars was evaluated to screen Chinese cabbage cultivars with low-level Cd accumulation. The results showed that significant differences (P<0.05) in Cd content, bioaccumulation factors (BFs) and translocation factors (TFs) were found among the 8 cultivars Chinese Cabbages. The levels of Cd accumulation by Beijingxin3 and Dongbao were less than 0.5 mg · kg^-1, and their BFs and TFs were lower than 1. This indicated that these two cultivars had the low-level Cd accumulation potential and could be recommended for cultivation in areas mildly polluted with Cd. Although the level of Cd accumulation by Qiumei also was less than 0.5 mg · kg^-1, the TF was higher than 1. So, the Qiumei cultivar could be planted in the renovation process of contaminated soils.

Abstract: The natural transfusion and activated reagent (environmental material) enhanced migration efficiency was studied by the experiments in Cd contaminated groundwater in this work. The experimental results showed that the variation rule of Cd reflected that its migration was weak and the removal efficiency was only 11.36% near the anode zone in the natural seepage condition, but under the enhanced migration function, the pollutants could be enriched and removed faster. The main migrating direction of pollutant was mainly from upstream anode zone to downstream cathode zone, which indicated that the washing function could enhance the migrating efficiency of pollutants. And the Cd of in anode zone decreased relatively quickly and its removal rate was 25.75 %, which made known that this enhanced migration of Cd in contaminated groundwater was more effective method than that of natural seepage migration.

Abstract: A pot experiment was conducted to investigate the effect of nano particle hydroxyapatite (nHAP) on Cadmium(Cd) contaminated soil. The Cd uptake of pakchoi in Cd polluted soil treated with various concentration of nHAP were studied. In addition, the effect of nHAP on chemical fraction distribution in Cd contaminated soil was evaluated. Results indicated that by adding the nHAP, the Cd level in pakchoi shoots and roots decreased significantly compared to the control. The mechanism of this treatment involved bioavailability reduction and immobilization of Cd in soil, resulting in the transformation of available fractions to unavailable fractions. In conclusion, with the addition of nHAP, the resistance to Cd of pakchoi in contaminated soil could be significantly enhanced and the quality of the plants improved.

Abstract: In this paper the harm of Cd in soil and current situation of soil contaminated by Cd were discussed, and then the remediation technologies of Cd contaminated soils, which included engineering remediation methods, chemical remediation methods, bioremediation methods and agriculture remediation methods at home and abroad were roundly introduced. At the same time, pointed out existing problems and proposed research directions in the future.

Abstract: The metobolism of K, Ca, Mg and microelement in the root of Phaseolus raditus L. were studied. By flame atomic absorption spectromentry (FAAS), the concentration of K, Ca, Mg, Zn, Cu, Fe and Mn in the root of mung bean seedlings at the initial stage of growth under cadmium stress (1 μmol/L) were determined. It shows that the concentration of K, Mg and Mn in the root are decreased，but Ca, Zn, Cu, and Fe are increased. So, it indicated that Cd did harm, indirectly, to the root of mung bean seedlings at the initial stage of growth.

Abstract: Humic acid (HA) and 3-Mercaptopropyltriethoxysilane (MPTES) were successfully coated onto the surface of Fe₂O₃ (α and γ) nano-particles as characterized using IR and BET-N2 analysis, the potential use of the naked and functionalized nano-Fe₂O₃ particles as novel nano-sorbents for removal of Cd, Pb and Cu ions in solution was investigated in this study. The result indicated that the sorption of Cd, Pb and Cu ions by the nano-particles can be fitted well using langmuir isotherm; all the adsorbents exhibited definitely adsorption ability to Cd, Pb and Cu ions in solution. The sorption maximum and sorption affinity on the nano-particles for Pb (aq) were always higher than Cu (aq) and Cd (aq), the sorption maxima for the Pb, Cd and Cu followed the order Pb>Cu>Cd. Among the nano-sorbents, the Fe₂O₃ (α and γ) nano-particles coated with HA exhibited higher sorption ability to metal ions than the naked and thiolated Fe₂O₃ nano-particles, the sorption maxima of α-Fe₂O₃/HA for Pb(aq) reached 151.5 mg/g, which was significantly higher than the values of 116.3 and 84.0 mg/g observed for the α-Fe₂O₃ and α- Fe₂O₃/MPTES particles. However, no increased sorption maxima was observed for the thiolated Fe2O3 nano-particles (Fe2O3/MPTES) for the metal ions compared with the naked Fe₂O₃ nano-particles in this study. The greater capability of Fe₂O₃/HA to adsorb Cd(aq), Pb(aq), Cu(aq) indicates its potential use as another promising way to remediate metals-contaminated water.