Papers by Keyword: Cadmium (Cd)

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Authors: Jian Guo Liu, Yi Cheng Huang, Ming Xin Wang
Abstract: Cadmium (Cd) accumulation and distribution in rice plants were investigated with six rice cultivars under different soil Cd levels. The results showed that Cd accumulations in different organs were in the order: root » stem > leaf > grain. The magnitudes of the differences among rice organs in Cd accumulations were larger for soil Cd treatments than for the control. The magnitudes of the variations among rice cultivars in Cd accumulations were the largest in grains, followed by roots, and the smallest in stems and leaves, and these were also larger for soil Cd treatments than for the control. Cd absorbed by rice plants were mostly accumulated in roots (about 80% for the control and more than 90% for soil Cd treatments), and only a very small portion was transferred into grains (about 2% for the control and less than 1% for soil Cd treatments). The magnitudes of the variations among rice cultivars in Cd distributions were larger for soil Cd treatments than for the control.
Authors: David Marchat, Didier Bernache-Assollant, Eric Champion, Eric Bêche, Gilles Flamant
Abstract: The removal of cadmium from water by fixation into a calcium phosphate apatite Ca10(PO4)6(OH)2 (CaHA) was investigated in batch experiments. These ones were carried out using a wide range of initial Cd2+ concentration, three different temperatures, and several CaHA surface areas. The amount of immobilized cadmium was proportional to the surface area of CaHA, whatever the experimental parameters might be. It could reach 7.1 mol of Cd per mol of starting CaHA. Thermal and XPS analyses on the exchanged powders proved that a part of cadmium was quickly adsorbed at the grains surface in the form of hydrated complexes [Cd(OH2)n]2+. The latter were formed by an ionic exchange between adsorbed calcium and cadmium of the solution. Adsorption reaction was mainly limited by the number of specific sites available on the grains surface. Structural analyses showed that another part of Cd was slowly incorporated into a solid solution Ca10-xCdx(PO4)6(OH)2 (CaCdHA) onto the CaHA crystals surface. Results demonstrated unambiguously that the incorporation process was a surface precipitation and not an intracrystalline diffusion.
Authors: Qing Shan Pan, Dai Qi Li, Jian Qiang Li, Wei Liu, Mei Gui Ma, He Ping Yan, Bo Zhou, Du Shu Huang, Shi Juan Xu
Abstract: Peanut shell Cellulose Xanthate (PCX) was prepared by reacting with carbon disulphide after mercerized by sodium hydroxide solution. The preparing conditions (hydroxide solution concentration, carbon disulphide dosage, temperature) were optimized in this study. And the effects of PCX amount and contact time on the removal of Cd (II) ion from aqueous solution was studied,the results indicated that when the initial Cd (II) ion concentration was 10mg/L, the adsorption capacity of PXC was high effective with the PCX amount was 1g/L and the contact time was 1.5h,the equilibrium adsorption capacity of PCX was 9.87 mg/g and the removal rate of Cd (II) ion was 98.72%.Then the regeneration capacities of PCX adsorbent was investigated, the results indicated that the removal rate of Cd (II) ion was more than 75% after regeneration. All the results indicated that the PCX can be used as a low cost but effective biosorbent for heavy metals remediation.
Authors: M.S. Rosmi, S. Azhari, R. Ahmad
Abstract: The use of low-cost adsorbent derived from agricultural waste has been investigated for the removal of Cd (II) from aqueous solution. This research reports the feasibility of using solid pineapple waste (SPW), sugarcane bagasse (SCB) and activated carbon (AC) derived from palm kernel for the removal of Cd (II) under different experimental conditions. Batch experiments were carried out at various pH (3-12), adsorbent dosage (0.01-2 g) and contact time (15-150 min). The maximum Cd (II) removal was shown by SPW (90%) followed by SCB (55%) and AC (30%) at pH 7 with a contact time of 120 min, adsorbent dosage of 1.0 g and at 1.0 ppm of the initial concentration of Cd (II) solution. The kinetics study shows that the adsorption process fitted the pseudo-second-order-model. The experimental data was analysed by both Freundlich and Langmuir isotherm models. It was found that the Langmuir model appears to well fit the isotherm. The Langmuir maximum adsorption capacity calculated from Langmuir for SPW, SBC and AC were 0.3332 mg/g, 0.1865 mg/g and 0.1576 mg/g respectively. The order of Cd (II) removal by the adsorbents was SPW>SCB>AC. Thus, SPW may be an alternative adsorbent for the removal of Cd (II) ions form aqueous solution. The characterization of the SPW, SCB and AC were also carried out by using Scanning Electron Microscopy (SEM) and Nitrogen Gas Adsorption Single Point Surface Area Analyzer (BET).
Authors: Ling Zhi Liu, Zong Qiang Gong, Yu Long Zhang, Pei Jun Li
Abstract: The effects of three arbuscular mycorrhizal fungi (AMF) on the growth, Cd uptake and some physio-biochemical indexes of Solanum lycopersicum seedlings under different levels of Cd stress were investigated in a pot study. Generally, the symbiotic relationship between Solanum lycopersicum and AMF can be well established under Cd stress. This was reflected by the better physio-biochemical index of the plants inoculated with G. constrictum, G. mosseae and G. intraradices whose colonization rates were between 41.4% and 76.1%. Compared with the non-inoculated ones, G. constrictum inoculation enhanced the plant biomass at 50 mg kg-1 Cd addition level. AM colonization increased the Cd distribution to the roots in plants and alleviated shoots from high Cd stress, and thus increased the shoot biomass in the end. At the high Cd addition level, mycorrhizal plants reacted differently in the reduction of the contents of MDA, by influencing the soluble sugar, POD activity, SOD activity and so on. Our results showed that mycorrhizal colonization was beneficial to the Cd translocation in plants and reduced the membrane lipid peroxidation in plants under serious Cd stress. However, the mechanisms of mycorrhizal protection in plants were influenced by many factors and still need to be further studied.
Authors: Xue Lian Liu, Hong Guang Cheng, Jing Xie, Lin Wang
Abstract: In order to estimate the present exposure risk of Cadmium dietary intake by inhabitants in a W-Mo mining area, South China, a dietary investigation was conducted with stratified cluster random sampling method. According to the result, a total of 7 food groups, including rice, vegetable, meat, chicken and egg, were sampled from contaminated areas using the total dietary study method. Rice consumption took up 81.5% of food consumption. Cadmium content in 45.8% of 306 rice samples, 11.1% of 252 vegetable samples, and 4.8% of 21 chicken samples exceeded the limit. Risks of cadmium in study area are between 1.0E-06 and 1.0E-03, which is acceptable but need further attention to reduce them. Rice products were the highest contribution, which took up about 80.1%. The results showed that Cadmium intake was much higher around W-Mo ore deposit than that in reference area.
Authors: Chang Li Yu, Zhi Peng Lu, Fa Zhi Ge, Er Li Zhao
Abstract: The present study was undertaken to evaluate the feasibility of Pseudomonas fluorescens biomass for the removal of cadmium ions from aqueous solutions. Batch experiments were performed to study the adsorption of cadmium on pH, Pseudomonas fluorescens biomass adsorbent with respect to initial Cd(II) concentration, contact time and biomass dose. The experimental data were modeled by Langmuir and Freundlich isotherm models. Langmuir model resulted in the best fit of the adsorption data. The maximum adsorption capacity for Cd(II) was 66.25 mg/g (pH 5.0 and 5 g/L biomass dose). Kinetics of adsorption followed second-order rate equations. The FTIR results of Pseudomonas fluorescens biomass showed that biomass has different functional groups and these functional groups are able to react with metal ion in aqueous solution. The results of the present study suggest that Pseudomonas fluorescens biomass can be used beneficially in treating industrial effluents containing heavy metal ions.
Authors: Tong Bao, Li Na Sun, Qing Hua Xue
Abstract: Corn (Zea Mays L.) seedlings were in four cadmium (Cd) levels of 0-1mg/L in a hydroponic system to analyze the antioxidant enzyme system, Cd content in the shoots and roots and growth responces in the leaves of corn. There was a significant increase in malondialdehyde (MDA) concentration from Cd 0mg/L to 1mg/L, and peroxidase (POD) and catalase (CAT) activities in the leaves of corn subjected to 0-1mg/L Cd. However there was a significant decrease in superoxide dismutase (SOD) activities subjected to 0-1mg/L Cd. This indicated that Cd stress induced an oxidative stress response in corn seedlings, characterized by an accumulation of MDA, decrease in activities of SOD and increase in activities of POD and CAT. Root and leaf Cd contents of corn increased with their exposure Cd level, and the highest Cd concentration occurred in roots, followed by leaves.
Authors: Qin Ping Sun, Ji Jin Li, Ben Sheng Liu, Li Juan Gao, Jun Xiang Xu, Guo Yuan Zou, Bao Cun Liu
Abstract: A field experiment with six treatments was conducted from Apr. 2006 to Nov. 2008 to study the Cadmium (Cd) accumulation in soil and the effect on the plant uptake after a three years application with using different organic fertilizer. The six treatments were (1)Control (with no manure input), (2)Cattle compost, (3)Biogas residua, (4)Chicken compost (with low level input), (5)Chicken compost (with middle level input), (6)Chicken compost (with high level input). The treatments (2), (3) and (5) had the same total N input. The results showed that the soil ETPA-Cd from manured treatments had increased trend compared with the control after 3 years. The celery which was the last crop during the whole cropping history of the manured treatments (except Biogas residua) had higher Cd content compared with the control, and celery of the chicken compost with high level input had highest Cd content than others. There was a significant relationship (r=0.92**) between the soil Cd content and the celery Cd content. However the soil Cd limitation laws in some countries seem to be strict than the celery Cd limitation law under this soil condition.
Authors: J. Plaza, Eric Guibal, J.M. Taulemesse, M. Viera, Edgardo R. Donati
Abstract: Macrocystis pyrifera was used for the recovery of Zn2+ and Cd2+ from slightly acidic solutions (i.e., pH 4). Sorption isotherms were obtained from mono- and bi-component solutions. For the study of metal desorption, EDTA, HNO3 and Ca(NO3)2 were used as eluents. Metal release (Ca2+, Mg2+, K+ and Na+) was monitored in order to evaluate ion exchange mechanisms. After metal sorption/desorption steps the sorbent was characterized using SEM-EDAX analysis. SEM-EDAX analysis also allowed identifying the presence of elements such as Si, Al, Co, Ag, S, P, and Fe in the cell wall. Zinc desorption was almost complete when using 0.1 M nitric acid solution and the sorbent was not significantly damaged by the acidic treatment. Cadmium was completely removed from loaded sorbent when using EDTA, but at the expense of a partial degradation of the biomass as evidenced by the decrease in the intensity of the C and O peaks (SEM-EDAX).
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