Cadmium and lead in female cattle livers and kidneys from Vojvodina,northern Serbia

ABSTRACT

Concentrations of cadmium (Cd) and lead (Pb) were determined in livers (n = 52) and kidneys (n = 52) of female cattle (345–2717 days old) from dairy farms in the region Vojvodina. Cd and Pb were analysed by inductively coupled plasma-optical emission spectrometry, after microwave digestion. Cd and Pb concentrations did not exceed the Serbian and European maximum set limits in any sample. The Cd concentrations in the livers and kidneys ranged from 0.033 to 0.151 mg kg^?1 wet weight and from 0.055 to 0.510 mg kg^?1 wet weight, respectively. The corresponding Pb concentrations were 0.015-0.159 mg kg^?1 wet weight and 0.021-0.196 mg kg^?1 wet weight, respectively. Mean Cd and Pb concentrations were significantly lower (p < 0.001) in the liver (0.072 and 0.053 mg kg^?1 wet weight) than in the kidney (0.190 and 0.075 mg kg^?1 wet weight). There were good correlations between Cd in liver and Cd in kidney, Pb in liver and Pb in kidney, Cd level and age and Pb level and age in both tissues.     

Kinetics and thermodynamics of cadmium ion removal by adsorption onto nano zerovalent iron particles

Nano zerovalent iron (nZVI) is an effective adsorbent for removing various organic and inorganic contaminants. In this study, nZVI particles were used to investigate the removal of Cd(2+) in the concentration range of 25-450 mg L(-1). The effect of temperature on kinetics and equilibrium of cadmium sorption on nZVI particles was thoroughly examined. Consistent with an endothermic reaction, an increase in the temperature resulted in increasing cadmium adsorption rate. The adsorption kinetics well fitted using a pseudo second-order kinetic model. The calculated activation energy for adsorption was 54.8 kJ mol(-1), indicating the adsorption process to be chemisorption. The intraparticle diffusion model described that the intraparticle diffusion was not the only rate-limiting step. The adsorption isotherm data could be well described by the Langmuir as well as Temkin equations. The maximum adsorption capacity of nZVI for Cd(2+) was found to be 769.2 mg g(-1) at 297 K. Thermodynamic parameters (i.e., change in the free energy (ΔG(o)), the enthalpy (ΔH(o)), and the entropy (ΔS(o))) were also evaluated. The overall adsorption process was endothermic and spontaneous in nature. EDX analysis indicated the presence of cadmium ions on the nZVI surface. These results suggest that nZVI could be employed as an efficient adsorbent for the removal of cadmium from contaminated water sources.     

Adsorption behavior and mechanism of Cd(II) on loess soil from China

Cadmium is a toxic heavy metal that has caused serious public health problems. It is necessary to find a cost effective method to deal with wastewater containing Cd(II). Loess soils in China have proven to be a potential adsorbent for Cd(II) removal from wastewater. The adsorption capacity of loess towards Cd(II) has been determined to be about 9.37 mg g⁻¹. Slurry concentration, initial solution pH, reaction time and temperature have also been found to significantly influence the efficiency of Cd(II) removal. The adsorption isotherms and kinetics of loess soil from China can be best-fit with the Langmuir model and pseudo-second order kinetics model, respectively. The thermodynamic analysis revealed that the adsorption process was spontaneous, endothermic and the system disorder increased with duration. The natural organic matter in loess soil is mainly responsible for Cd(II) removal at pH < 4.2, while clay minerals contribute to a further gradual adsorption process. Chemical precipitation dominates the adsorption stage at pH > 8.97. Further studies using X-ray diffraction, Fourier transform infrared spectra of Cd(II) laden loess soil and Cd(II) species distribution have confirmed the adsorption mechanism.     

镉胁迫对玉米生理特性的影响

通过玉米砂培试验,用不同质量浓度的镉对玉米进行处理,对其生理特性进行了研究,以探讨其能否作为重金属镉生物有效性的指示植物,结果表明,镉对玉米的毒害受到时间和镉质量浓度双重因子的制约,从表现上看镉毒害症状很少,但镉对玉米的毒害随着在植株体内的积累逐步显现出来。苗期及营养生长前期镉对玉米的毒性临界点质量浓度为1.0 mg/L左右,严重毒害质量浓度为5.0 mg／L。同时还发现植株体内游离脯氨酸的质量分数的变化比其它生理指标明显,因此脯氨酸可以作为某些植物对重金属离子的同期抗逆性指标。由于玉米对镉胁迫的忍受能力比较强,作为土壤镉污染修复植物有一定的研究价值。     

固体直接进样原子荧光光谱法测定扇贝中镉

本文通过提高灰化功率和添加石墨粉,建立了固体直接进样原子荧光光谱法测定扇贝中镉的检测方法。使用基于多孔石墨管电热蒸发器（PGT-ETV）和钨丝阱（TC）原子在线捕获技术,直接进样测镉仪（DCD-200）,测定了扇贝样品中痕量镉。当灰化功率为120 W且石墨粉的稀释比例提高至5倍时,该方法的准确性能达到94.0%¹07%且精密度RSD<5%。该分析方法与常规镉元素检测技术比较而言,是一种无需消解、免化学试剂、绿色、安全环保的分析方法,适用于扇贝中镉的直接、快速、准确测定。      

锌精矿冶炼中镉回收工艺研究

这是一篇冶金工程领域的论文。本文主要用响应曲面法（Response surface methodology,RSM）研究和优化浸出参数对从铅冶炼烟尘中高效浸出镉的影响。以镉的浸出回收率（Y1）为响应值,以浸出时间（A,h）、硫酸浓度（B,mol/L）和浸出温度（C,℃）为考查变量。研究表明：响应曲面二次回归模型参数显著,温度、时间、硫酸浓度这三个影响因素对Cd浸出率的影响顺序为C＞A＞B。AB的F值为2.16,AC的F值为0.051,BC的F值为0.2,在交互影响过程中对Cd浸出率的影响顺序为AB＞BC＞AC。在温度75 ℃、时间1.62 h、硫酸浓度为0.26 mol/L时,预测镉的浸出率为99.2%,通过三次实验验证,镉浸出率的平均值为98.18%,与预测值偏差1.02,吻合度较高,此条件是镉的浸出较佳工艺条件。     

硫酸镍钴溶液中萃取除镉的试验研究

研究用萃取法从硫酸镍钴溶液中脱除镉。实验采用10 %N235 + 5 %TBP+85 %煤油的油相为萃取剂,稀硫酸为洗涤剂,氢氧化钠溶液为反萃剂。实验结果表明,萃取的最佳条件是：添加氯化钠的量为18 g/L,油水比为1:2、常温萃取5 min,三级逆流萃取率达99.4 %。反萃的最佳条件是：氢氧化钠溶液浓度为120 g/L、油水比为4:1、常温反萃5 min,反萃率达到98.0 %,实现了镉从硫酸镍钴溶液中脱除的目的。     

Development of highly efficient cost-effective CdS/Ag nanocomposite for removal of azo dyes under UV and solar light

Water pollution by toxic dyes is an environmental problem that threatens human health. A green technology to solve this problem is the use of highly efficient photocatalysts under visible/solar light to degrade these organic molecules. However, develop affordable photocatalytic particles with high luminescence performance, enhanced stability, and low degradation is still a challenge. Here, it is reported the hydrothermal synthesis of an advanced and cost-effective nanocomposite based on a ceramic, cadmium sulphide, covered by silver nanoparticles (CdS/Ag), with outstanding photocatalytic efficiency for toxic dyes degradation under ultraviolet and direct solar light. The CdS/Ag nanocomposite completely degrade the Reactive Red 120 (RR 120), Acid Black 1 (AB 1) and Direct Blue 15 (DB 15) dyes in both light irradiations. Without scavenger, about 93% of degradation was observed at 75 min, remaining a high stability (more than 90%) after fourth degradation cycles.     

Boosting performance of CdTe photocathode with pulse-reverse electrodeposited nickel telluride-nickel phosphide dual co-catalysts

Herein, noble-metal free Ni–Te/Ni–P dual co-catalysts are investigated as attractive candidates for improving the photoelectrochemical (PEC) performance of CdTe photocathodes. The Ni–Te/Ni–P dual co-catalysts are deposited on CdTe photocathodes via pulse-reverse electrodeposition and post annealing. The Ni–Te/Ni–P catalyzed CdTe photocathodes show a remarkable PEC performance, especially in terms of the photocurrent density, which is approximately 11.06 times higher than that of the pristine CdTe photocathode. The Ni–Te/Ni–P dual co-catalysts boost the catalytic activity via enhanced charge transfer and surface reaction kinetics. The photogenerated electrons and holes are effectively separated by the Schottky contact between the Ni–Te/Ni–P dual co-catalysts and the CdTe absorbing layer. Thus, the rational design of the CdTe photocathode with the Ni–Te/Ni–P dual co-catalysts can dramatically enhance the PEC performance of the CdTe photocathodes.