Papers by Keyword: Cd

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Authors: Shuai Liu, Ming Da Liu, Xu Wang, Yi Shi, Xin Chen
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.
Authors: Xiang Rong Qu
Abstract: Coexistence of chlorimuron-ethyl and Cd is very common in Chinese soils. Adsorption of chlorimuron-ethyl and Cd on soils strongly affects their mobility. This study was conducted to investigate the effect of Cd on the adsorption of chlorimuron-ethyl on two typical Chinese soils, brown earth (BE) and black soil (BS). Batch equilibration methods were applied. The presence of Cd enhanced the adsorption of chlorimuron-ethyl on BE and BS, which resulted from the decrease of equilibrium solution pH caused by Cd2+ exchange with H+ ions of soil surface. Besides that, chlorimuron-ethyl adsorption possibly takes place on sites where Cd was previously adsorbed and the adsorbed Cd acted as a bridge between the soil and chlorimuron-ethyl. Such results suggested that Cd in field may decrease the mobility and bioavailability of chlorimuron-ethyl and correspondingly decrease its environmental risk.
Authors: Wen Bian, Yan Yu, Dong Yao Xu
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.
Authors: Hyung Suk So, Yeong Seok Yoo, Andreas Schaeffer
Abstract: To develop the extraction media for Cd and Ni from aqueous solutions, magnetic beads containing IDA group with strong attraction to heavy metals were produced using the activating agents Epichlorhydrin (Ep) and 1,4-Butanedioldiglycidylether (Bu), respectively. Then the beads were agitated at a pH of 6 after being added to Cd and Ni aqueous solutions of various concentrations. It was confirmed that the heavy metals combined with the magnetic beads within a short time through the process. After the process, the magnetic beads were collected with a magnet, and then dissolved in acid for the analysis of heavy metal concentration. The analysis of heavy metals in the acid solution could be analyzed with an AAS (atomic absorption spectrometer). The results showed that the heavy metal extraction efficiency of Bu was relatively higher than that of the Ep. It supported the hypothesis that the relatively longer length of Bu’s spacer made more free positioning possible when the IDA group combined with the heavy metal.
Authors: Zhan Chao Li, Hong Tao Fan, Ting Sun
Abstract: This study investigated the application of an ion imprinted polymer (IIP) with (3-mercaptopropyl) trimethoxysilane (MPS) functionalized the surface of silica gel as a potential sorbent (IIP- MPS/SiO2) for the selective removal and recovery of Cd2+ from industrial wastewaters. IIP- MPS/SiO2 was prepared by a sol–gel method and characterized by IR. Batch studies were performed to evaluate the adsorption process and it was found that the sorbents were found to adsorb selectively Cd2+ in the presence of Co2+, Ni2+, Zn2+ and Cu2+ interferences in the same medium. IIP-MPS/SiO2 sorbent show the selectivity order under competitive conditions: Cd2+ > Co2+ > Ni2+ > Zn2+ > Cu2+. The removal rate of IIP- MPS/SiO2 sorbent for Cd2+ was about 80 % from synthetic wastewater and mine wastewater spiked with 10, 20 and 50 mg•L-1 Cd2+. This work proved that can IIP-MPS/SiO2 sorbent be used as an efficient adsorbent material for selective removal of Cd2+ from wastewaters.
Authors: Li Yun Yang, Song Tao Wu
Abstract: The soil heavy metal pollution have be paid more attention because the sources of soil heavy metals become multiple and complicated with the accelerated urbanization. According to this research, the order of spatial distribution of soil heavy metal Cu, Zn and Cd pollution in Beijing shows that: the center district > suburb > outer suburb. The soil pollution by Zn is more serious in Beijing and the grade of the soil Zn pollution has reached highest in the central district. By comparison, the soil pollution by Cu and Cd is slight, the soil in central district, Chaoyang, Changping and Miyun has caught light Cu pollution, and only in center district, Chaoyang and Fengtai has caught light Cd pollution.
Authors: Xiao Ping Luo, Lan Ting Xia, Ming Gang Zhang
Abstract: The effect of Cd and Sb addition on the microstructural and mechanical properties of as-cast AZ31 alloys was investigated and compared. The results indicate that the difference of Sb and Cd in the microstructure and mechanical properties of as-cast AZ31 magnesium alloy is significant. Addition of 0.15%Sb (mass fraction) to AZ31 alloy can refine the matrix and β-Mg17Al12 phase but not form a new phase Mg3Sb2. Oppositely, by addition of 0.3-0.7% Cd to AZ31 alloy, Cd was dissolved into the AZ31 alloy, the phase composition did not change but was refined also. Accordingly, the Cd-refined AZ31 alloy exhibits higher tensile and impact toughness and Brinell hardness properties than the Sb- refined one. The difference of Sb and Cd in the mechanical properties is possibly related to the solid solution of Cd into the matrix and formation of Mg3Sb2 which has the same close-packed hexagonal structure as α-Mg.
Authors: Yuan Hua Zhang
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.
Authors: Zi Li Liu, Gui Bin Zhou, Ping Shen, Xi Qin Liu, Huai Tao Wang
Abstract: Mg-1.5%Zr-x%Cd alloys (x=0, 0.5, 1.0, 1.5, mass%) were prepared by PM (powder metallurgy) technology, and the microstructure, mechanical properties and damping capacities of the alloys were researched by OM, three-point bending test and DMA, etc. The results show that the microstructure becomes into strip or block shaped morphology, granular particles Zr appear at grain boundaries or inside grains, and the grains are more refined with the increase of Cd additions. Micro-hardness(HV) and bending strength(σbb) of the alloys increase with increasing addition of Cd. Damping capacities of the Mg-1.5%Zr-x%Cd alloys improves with Cd additions, and increase with the temperature. The damping peak temperature increases with increasing frequencies, showing the characteristic of relaxation damping.
Authors: Zhang Wei Li, Yun Ying Wu
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.
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