An evaluation pattern for antimacrofouling procedures: Limnoperna fortunei larvae study in a hydroelectric power plant in South America

The effects of global change and globalization of trade on the biosphere spur an increase in bioinvasions and their subsequent impact on ecosystems. Continental invading bivalves are important because of their impact on artificially-constructed structures. Limnoperna fortunei was first found in the Neotropical region in 1991. Since then it has dispersed upstream in the Plata and Guaíba basins at a rate of 240 km y(-1). This species causes macrofouling in a manner similar to that caused by Dreissena polymorpha. This paper describes the biology of L. fortunei larvae from a hydroelectric power plant in South America. We suggest the importance of knowing the biology of the invading species and the need to consider the settlement patterns and densities of larvae in each of the sectors of the facility in order to achieve a sustainable prevention/control of macrofouling. This study acquires a global significance under the assumption that L. fortunei will eventually invade North America and Europe.     

胞外聚合物对水中Cd(Ⅱ)的吸附性能研究

以Pseudomonas fluorescens C-2产生的胞外聚合物PF-2作为新型生物吸附剂,以傅里叶变换红外光谱(FTIR)对其进行表征。系统地研究了胞外聚合物PF-2对水中Cd(II)的吸附行为。结果表明,在pH值为6.0,该吸附剂对水中的Cd(II)具有很强的吸附能力。聚合物PF-2对Cd(Ⅱ)的吸附较易进行,吸附等温线能较好地用Langmuir模型来描述,最大单分子层吸附量为33.50 mg/g,吸附动力学很好地符合准二级动力学模型。胞外聚合物PF-2含有的主要官能团为羧基、羟基和氨基等,其中羧基、羟基参与了Cd(Ⅱ)的吸附。结果表明利用胞外聚合物PF-2去除环境水样中的Cd(Ⅱ)是可行的。     

Impacts of pH and ammonia on the leaching of Cu(II) and Cd(II) from coal fly ash

Many coal-fired power plants are implementing ammonia-based technologies to reduce NO(x) emissions. Excess ammonia in the flue gas often deposits on the coal fly ash. Ammonia can form complexes with many heavy metals and change the leaching characteristics of these metals. This research tends to develop a fundamental understanding of the ammonia impact on the leaching of some heavy metals, exemplified by Cu(II) and Cd(II), under different pH conditions. Batch results indicated that the adsorption is the main mechanism controlling Cu(II) and Cd(II) leaching, and high concentrations of ammonia (>5,000 mg/l) can increase the release of Cu(II) and Cd(II) in the alkaline pH range. Based on the chemical reactions among fly ash, ammonia, and heavy metal ion, a mathematical model was developed to quantify effects of pH and ammonia on metal adsorption. The adsorption constants (logK) of Cu(2+), Cu(OH)(+), Cu(OH)(2), and Cu(NH(3))(m)(2+) for the fly ash under investigation were respectively 6.0, 7.7, 9.6, and 2.9. For Cd(II), these constants were respectively 4.3, 6.9, 8.8, and 2.6. Metal speciation calculations indicated that the formation of less adsorbable metal-ammonia complexes decreased metal adsorption, therefore enhanced metal leaching.     

Effect of biochars on adsorption of Cu(II), Pb(II) and Cd(II) by three variable charge soils from southern China

The purpose of this study is to compare the relative contribution of different mechanisms to the enhanced adsorption of Cu(II), Pb(II) and Cd(II) by variable charge soils due to incorporation of biochars derived from crop straws. The biochars were prepared from the straws of canola and peanut using an oxygen-limited pyrolysis method at 350 °C. The effect of biochars on adsorption and desorption of Cu(II), Pb(II) and Cd(II) by and from three variable charge soils from southern China was investigated with batch experiments. Based on the desorption of pre-adsorbed heavy metals, the electrostatic and non-electrostatic adsorptions were separated. EDTA was used to replace the heavy metals complexed with biochars and to evaluate the complexing ability of the biochars with the metals. The incorporation of biochars increased the adsorption of Cu(II), Pb(II) and Cd(II) by the soil; peanut straw char induced a greater increase in the adsorption of the three metals. The increased percentage of Cd(II) adsorption induced by biochars was much greater than that for the adsorption of Cu(II) and Pb(II). Cu(II) adsorption on three variable charge soils was enhanced by the two biochars mainly through a non-electrostatic mechanism, while both electrostatic and non-electrostatic mechanisms contributed to the enhanced adsorption of Pb(II) and Cd(II) due to the biochars. Peanut straw char had a greater specific adsorption capacity than canola straw char and thus induced more non-electrostatic adsorption of Cu(II), Pb(II) and Cd(II) by the soils than did the canola straw char. The complexing ability of the biochars with Cu(II) and Pb(II) was much stronger than that with Cd(II) and thus induced more specific adsorption of Cu(II) and Pb(II) by the soils than that of Cd(II). Biochars increased heavy metal adsorption by the variable charge soils through electrostatic and non-electrostatic mechanisms, and the relative contribution of the two mechanisms varied with metals and biochars.     

改性沸石对Cd(Ⅱ)的吸附平衡及动力学

采用等温吸附法比较了氢氧化钠、氯化钠、硝酸铵、硫酸、磷酸、混合盐和高温改性沸石对含镉废水的吸附效果,并采用Langmuir、Freundlich等温线方程及Lagrange假一级动力学方程、假二级动力学方程、粒内扩散方程对实验数据进行了拟合。结果表明,镉浓度大于10 mg/L时,NaOH改性沸石吸附效果最好,吸附率在99.2%以上;沸石对镉的吸附符合Langmuir方程,属单分子层吸附,最大吸附量Qm=6.456 mg/g;改性沸石对Cd2+的吸附动力学符合假二级动力学方程,以化学吸附为主,有多个控速步骤。     

Removal and mechanism of Cu (II) and Cd (II) from aqueous single-metal solutions by a novel biosorbent from waste-activated sludge

The removal and mechanism of Cu²⁺ and Cd²⁺ from aqueous single-metal solutions were investigated by using a novel biosorbent from waste-activated sludge. A series of adsorption experiments was designed to disclose the effects of the key factors on the adsorption capacity of the biosorbent for the metal ions. The mass ratio of the biosorbent to metal ion was optimized as 2 to balance the adsorption capacity and the removal efficiency. A right shaking speed (150 r/min) not only ensured enough contact frequency between the sorbent and the adsorbate but also reduced the mass transfer resistance. The natural pH value (about 5.5) of the metal solutions benefited a high adsorption capacity of the biosorbent and avoided the consumption of acid or base for pH adjustment. The adsorption reactions belonged to the endothermic process between 15 and 45 °C. As the scanning electron microscopy (SEM) images showed, the meshy structure with long chains and many branches was ideal for the biosorbent to quickly capture the metal ions. The energy-dispersive X-ray (EDX) spectra confirmed that the adsorbed metal ions lay in the precipitates of the adsorption reactions. According to the FTIR analyses, the functional groups responsible for Cu²⁺ adsorption majorly consisted of O–H, N–H, COOH, CONH₂, and the groups containing sulfur and phosphorus, while those for Cd²⁺ adsorption contained O–H, N–H, COOH, and CONH₂. The differences in the responsible functional groups explained the phenomenon that the adsorption capacity of the biosorbent for Cu²⁺ was higher than that for Cd²⁺.     

Effect of arsenate on adsorption of Cd(II) by two variable charge soils

The effect of arsenate on Cd(II) adsorption in two variable charge soils and the desorption of Cd(II) pre-adsorbed in the presence of arsenate were studied. The batch type experiments showed, the presence of arsenate led to increase in Cd(II) adsorption and the desorption of pre-adsorbed Cd(II). Further it was observed that the extent of adsorption and desorption of Cd(II) was greatly influenced by the initial concentrations of arsenate and Cd(II), the solution pH, and the nature of the soils. In general the increase in arsenate concentration and pH favored the uptake of Cd(II). Moreover, the arsenate concentration influenced more in Hyper-Rhodic Ferralsol than Rhodic Ferralsol at least for the Cd(II) adsorption/desorption. This may be due to the content of Fe/Al oxides in these soils. The larger the content of Fe/Al oxides, the more the adsorption of arsenate by the soil, hence greater the uptake of Cd(II). It can be assumed that the enhanced Cd(II) adsorption was mainly due to the increase in net negative surface charge of the soil induced by the adsorption of arsenate, because the presence of arsenate led to the decrease in zeta potential of these soil suspensions. The increase of electrostatically adsorbed Cd(II) was responsible for the increase in the desorption of Cd(II) pre-adsorbed in the presence of arsenate.     

Carnauba (Copernicia prunifera) palm tree biomass as adsorbent for Pb(II) and Cd(II) from water medium

Environmental Science and Pollution Research - Plant-based biomass (CFB (carnauba fruit biomass)) obtained from the fruit exocarp of the species Copernicia prunifera (Mill.) H.E. Moore (carnauba)...     

Impact of pyrolysis temperature and activation on oily sludge-derived char for Pb(II) and Cd(II) removal from aqueous solution

Environmental Science and Pollution Research - This study investigated the Pb(II) and Cd(II) sorption from aqueous solution by oily sludge-derived char (OSDC) prepared at different pyrolysis...     

Enhanced adsorption for Pb(II) and Cd(II) of magnetic rice husk biochar by KMnO4 modification

Environmental Science and Pollution Research - Novel KMnO4-treated magnetic biochar (FMBC) was successfully synthesized by addition of Fe(NO3)3 during carbonization and KMnO4 treatment following...     

Assessment of heat-inactivated marine Aspergillus flavus as a novel biosorbent for removal of Cd(II), Hg(II), and Pb(II) from water

Environmental Science and Pollution Research - A novel marine fungus was isolated and classified as Aspergillus flavus strain EGY11. The heat-inactivated form of isolated Aspergillus flavus was...     

Nanocellulosic fiber-modified carbon paste electrode for ultra trace determination of Cd (II) and Pb (II) in aqueous solution

In recent years, increasing awareness of the environmental impact of heavy metals has prompted a demand for monitoring and decontaminating industrial wastes prior to discharging into natural water bodies. This paper describes the preparation and electrochemical application of carbon paste electrode modified with nanocellulosic fibers for the determination of cadmium and lead in water samples using anodic stripping voltammetry. First, cadmium and lead were adsorbed on the carbon paste electrode surface at open circuit potential, followed by anodic stripping voltammetric scan from -1 to 0 V. Different factors affecting sensitivity and precision of the electrode, including accumulating solvent, pH of the accumulating solvent, accumulation time, supporting electrolyte, and scan rate were investigated. The proposed method was also applied to the determination of Cd (II) and Pb (II) in the presence of other interfering metal ions and cetyl trimethyl ammonium bromide, sodium dodecyl sulfate, and Triton X-100 as a representative of cationic, anionic, and neutral surfactants. Linear calibration curves were obtained in the concentration ranges of 150–650 μg?L^?1 and 80–300 μg?L^?1, respectively, for cadmium and lead at an accumulated time of 10 min with limits of detection 88 and 33 μg?L^?1. Optimized working conditions are defined as acetate buffer of pH?5 as accumulating solvent, hydrochloric acid as supporting electrolyte, and scan rate 50 mV/s. This technique does not use mercury and therefore has a positive environmental benefit. The method is reasonably sensitive and selective and has been successfully applied to the determination of trace amounts of Cd (II) and Pb (II) in water samples.     

Simultaneous determination of Cd(II), Cu(II), Pb(II) and Zn(II) by derivative stripping chronopotentiometry in Pittosporum tobira leaves: a measurement of local atmospheric pollution in Messina (Sicily, Italy)

The purpose of this study is to investigate the bio-accumulation of Cd(II), Cu(II), Pb(II) and Zn(II) in Pittosporum tobira (Thunb.) Aiton leaves sampled in different zones of Messina, in order to assess the level of atmospheric metal deposition in correlation with the traffic volume. Derivative stripping chronopotentiometry was used as a practical, precise and sensitive technique to determine simultaneously Cd, Cu, Pb and Zn levels in Pittosporum leaves. In the optimised electro-chemical conditions, detection limits lower than 0.05 microg kg(-1) were achieved, whereas the accuracy, expressed as obtained recoveries from certified materials, was in the range 93.5-102.7%. The obtained data provided evidence that Cd and Pb levels significantly decreased from high to low traffic density zones (p < 0.005, ANOVA), whereas Cu and Zn are accumulated by plants particularly from the soil and their contents is not related to the traffic volume.     

Effect of humic acids on physicochemical property and Cd(II) sorption of multiwalled carbon nanotubes

Carbon nanotubes (CNTs), as a type of superior adsorbents for both organic and inorganic contaminants, are increasingly introduced into the environment. Ubiquitous natural organic matter (NOM) would coat on the released CNTs and change their physicochemical properties and sorption of contaminants. The effects of four sequentially extracted humic acids (HAs, as a model NOM) from a peat soil on the physicochemical properties and Cd(II) sorption of three multiwalled CNTs (MWNTs) with different surface areas were investigated. The MWNTs as purchased with very few oxygen-containing functional groups had relatively low sorption capacities (0.93–1.49 mg g⁻¹) for Cd(II) and the sorption capacity increased with increasing surface area of the MWNTs. Surface-coating with the HAs lowered surface areas of the MWNTs but greatly increased their sorption capacities (5.42–18.4 mg g⁻¹). The MWNT-bound HAs introduced oxygen-containing functional groups and negative charges to the MWNT surfaces, which could thus increase the apparent sorption of Cd(II) through chemical complexation and electrostatic attraction, respectively. The later-extracted HAs with lower polarity were more favorable for the surface-coating but increased less Cd(II) sorption by the MWNTs. The results are expected to shed light on understanding the underlying mechanism of the effect of NOM on the sorption of heavy metal ions by CNTs.     

The influence mechanism of dissolved organic matter on the adsorption of Cd (II) by calcite

Environmental Science and Pollution Research - Dissolved organic matter (DOM) has been widely existed in the soil, which has great influence on the adsorption of heavy metals by minerals. In this...     

Effect of humic acids on physicochemical property and Cd(II) sorption of multiwalled carbon nanotubes

Zinc pyrithione is used as an antifouling agent. However, the environmental impacts of zinc pyrithione have recently been of concern. Zinc induces diverse actions during oxidative stress; therefore, we examined the effect of zinc pyrithione on rat thymocytes suffering from oxidative stress using appropriate fluorescent probes. The cytotoxicity of zinc pyrithione was not observed when the cells were incubated with 3 μM zinc pyrithione for 3 h. However, zinc pyrithione at nanomolar concentrations (10 nM or more) significantly increased the lethality of cells suffering from oxidative stress induced by 3 mM H₂O₂. The application of zinc pyrithione alone at nanomolar concentrations increased intracellular Zn²⁺ level and the cellular content of superoxide anions, and decreased the cellular content of nonprotein thiols. The simultaneous application of nanomolar zinc pyrithione and micromolar H₂O₂ synergistically increased the intracellular Zn²⁺ level. Therefore, zinc pyrithione at nanomolar concentrations may exert severe cytotoxic action on cells simultaneously exposed to chemicals that induce oxidative stress. If so, zinc pyrithione leaked from antifouling materials into surrounding environments would be a risk factor for aquatic ecosystems. Alternatively, zinc pyrithione under conditions of oxidative stress may become more potent antifouling ingredient.     

Uptake of Cd(II) and Pb(II) by microalgae in presence of colloidal organic matter from wastewater treatment plant effluents

The present study addresses the key issue of linking the chemical speciation to the uptake of priority pollutants Cd(II) and Pb(II) in the wastewater treatment plant effluents, with emphasis on the role of the colloidal organic matter (EfOM). Binding of Cd(II) and Pb(II) by EfOM was examined by an ion exchange technique and flow field-flow fractionation coupled to inductively coupled plasma mass spectrometry in parallel to bioassays with green microalga Chlorella kesslerii in ultrafiltrate (<1 kDa) and colloidal isolates (1 kDa to 0.45 μm). The uptake of Cd by C. kesslerii was consistent with the speciation analysis and measured free metal ion concentrations, while Pb uptake was much greater than that expected from the speciation measurement. Better understanding of the differences in the effects of the EfOM on Cd(II) and Pb(II) uptake required to take into account the size dependence of metal binding by EfOM.     

Removal of Pb(II) and Cd(II) ions from water by Fe and Ag nanoparticles prepared using electro-exploding wire technique

Purpose

This work aimed at investigating the adsorption of lead and cadmium onto Fe and Ag nanoparticles for use as a water contaminant removal agent as a function of particle type, sorbent concentration, and contact time.

Methods

Fe and Ag spherical nanoparticles were prepared in water by the lab-made electro-exploding wire (EEW) system and were investigated for their structure properties. Adsorption experiments were carried out at room temperature and pH 8.3 water solutions.

Results

The removal/adsorption of both Pb(II) and Cd(II) ions was found to be dependent on adsorbent dosage and contact time. Pb(II) adsorption onto Fe and Ag nanoparticles showed more or less similar efficiency and behavior. The kinetic data for the adsorption process obeyed pseudo second-order rate equations. The calculated equilibrium adsorption capacities (q _e) were 813 and 800 mg/g for Pb sorption onto Fe and Ag nanoparticles, respectively. Cd(II) ion adsorption onto Fe nanoparticles obeyed pseudo second-order rate equations with q _e equal to 242 mg/g, while their adsorption onto Ag nanoparticles obeyed pseudo first-order rate equations with q _e of 794 mg/g. The calculated q _es are in quite agreement with the experimental values. The removal/uptake mechanisms of metal ions involved interaction between the metal ion and the oxide/hydroxyl layer around the spherical metallic core of the nanoparticle in water medium.

Conclusion

Fe and Ag nanoparticles prepared using the EEW technique exhibited high potentials for the removal of metal ions from water with very high adsorption capacities, suggesting that the EEW technique can be enlarged to generate nanoparticles with large quantities for field or site water purification.     

Effects of Cd(II) on the stability of humic acid-coated nano-TiO2 particles in aquatic environments

Environmental Science and Pollution Research - The stability of nanoparticles (NPs) in aquatic environments is important to evaluate their adverse effects on aquatic ecosystems and human health....