Metal Ion Extraction with Bipyridine Derivatives as Chelating Ligands in Supercritical Carbon Dioxide

Three fluorinated bipyridine ligands have been designed and synthesized as chelating agents for the extraction of metal ions in supercritical CO₂ (sc‐CO₂). The ligand solubilities in sc‐CO₂ were investigated at different temperatures and pressures, and the measured data have been correlated using a semiempirical model. The calculated results showed satisfactory agreement with the experimental data. Based on these data, metal ion extraction with the three compounds as chelating agents in sc‐CO₂ was performed from spiked filter paper, whereby ligand 1 showed the highest extraction efficiency, especially for Ni²⁺ and Cu²⁺. The extraction constants, K_ex, of the three chelating ligands were seen to increase with increasing extraction efficiency for the same metal ion in the same extraction system.     

Biosorption of Heavy Metals in Leachate Derived from Gold Mine Tailings Using Aspergillus fumigatus

Leachate derived from bioleaching process contains high amount of metals that must be removed before discharging the water. Aspergillus fumigatus was isolated from a gold mine tailings and its ability to remove of As, Fe, Mn, Pb, and Zn from aqueous solutions and leachate of bioleaching processes was assessed. Batch sorption experiments were carried out to characterize the capability of fungal biomass (FB) and iron coated fungal biomass (ICFB) to remove metal ions in single and multi‐solute systems. The maximum sorption capacity of FB for As(III), As(V), Fe, Mn, Pb, and Zn were 11.2, 8.57, 94.33, 53.47, 43.66, and 70.4 mg/g, respectively, at pH 6. For ICFB, these values were 88.5, 81.3, 98.03, 66.2, 50.25, and 74.07 mg/g. Results showed that only ICFB was found to be more effective in removing metal ions from the leachate. The amount of adsorbed metals from the leachate was 2.88, 21.20, 1.91, 0.1, and 0.08 mg/g for As, Fe, Mn, Zn, and Pb, respectively. The FT‐IR analysis showed involvement of the functional groups of the FB in the metal ions sorption. Scanning electron microscopy revealed that surface morphological changed following metal ions adsorption. The study showed that the indigenous fungus A. fumigatus was able to remove As, Fe, Mn, Pb, and Zn from the leachate of gold mine tailings and therefore the potential for removing metal ions from metal‐bearing leachate.     

Rhizofiltration of a Heavy Metal (Lead) Containing Wastewater Using the Wetland Plant Carex pendula

Rhizofiltration is a subset technique of phytoremediation which refers to the approach of using plant biomass for removing contaminants, primarily toxic metals, from polluted water. The effective implementation of this in situ remediation technology requires experimental as well as conceptual insight of plant–water interactions that control the extraction of targeted metal from polluted water resources. Therefore, pot and simulation experiments are used in this study to investigate the rhizofiltration of a lead containing wastewater using plants of Carex pendula, a common wetland plant found in Europe. The metal contaminant extraction along with plant growth and water uptake rates from a wastewater having varying Pb concentration is studied experimentally for 2 wk. The temporal distribution of the metal concentration in the wastewater and the accumulated metal in different compartments of C. pendula at the end are analyzed using atomic absorption spectrometry. Parameters of the metal uptake kinetics are deduced experimentally for predicting the metal removal by root biomass. Further, mass balance equations coupled with the characterized metal uptake kinetics are used for simulating the metal partitioning from the wastewater to its accumulation in the plant biomass. The simulated metal content in wastewater and plant biomass is compared with the observed data showing a good agreement with the later. Results show that C. pendula accumulates considerable amounts of lead, particularly in root biomass, and can be considered for the cleanup of lead contaminated wastewaters in combination with proper biomass disposal alternatives. Also, the findings can be used for performing further non‐hydroponics experiment to mimic the real wetland conditions more closely.     

Removal of Copper,Nickel and Zinc Ions from Aqueous Solution by Chitosan‐8‐Hydroxyquinoline Beads

In this work, 8‐hydroxyquinoline is used as the active sites in cross‐linked chitosan beads with epichlorohydrin (CT‐8HQ). The CT‐8HQ material was shaped in bead form and used for heavy metal removal from aqueous solution. The study was carried out at pH 5.0 with both batch and column methods and the maximum adsorption capacity of metal ions by the CT‐8HQ was attained in 4 h in the batch experiment. The adsorption capacity order was: Cu²⁺ > Ni²⁺ > Zn²⁺ for both mono‐ and multi‐component systems with batch conditions. From breakthrough curves with column conditions, the adsorption capacity followed the order Cu²⁺ > Zn²⁺ > Ni²⁺ for both mono‐ and multi‐component systems. The CT‐8HQ beads maintained good metal adsorption capacity for all five cycles with absorbent restoration achieved with the use of 1.0 mol L^–1 HCl solution, with 90% regeneration.     

中国周边国家金属矿产资源调查与合作潜力分析

中国是矿产资源大国,种类齐全,总量较大,但优势金属矿种多为一般矿产,主要战略性矿产的储量严重偏低,研究中国周边国家资源的供给能力与合作潜力分析对我国经济可持续发展意义重大.     

Post-mine metal transport and attenuation in the Keno Hill mining district, central Yukon, Canada

 The Keno Hill mining district in central Yukon was the second largest silver producer in Canada with mines operating from 1913 to 1989 on more than 65 vein silver deposits. The seven and a half decades of mining activities have generated large volumes of mine waste disposed on the land surface, resulting in elevated metal contents in numerous small drainages. To assess the extent of metal mobilization, old mine workings and the associated mine waste were examined and the water courses draining to a major river valley sampled. The results of field observations and an array of water and sediment analyses led to three major conclusions. 1. Acid mine drainage is not widespread because of galvanic protection of pyrite from oxidative dissolution and neutralization by carbonates in the country rock. 2. Mechanisms operative to limit aqueous metal transport in small streams in the district include cryogenic precipitation, coprecipitation and sorption. 3. The near-surface concentration of metals limits the options of waste disposal in future mining developments due to potential metal-leaching problems. Received: 12 December 1995 · Accepted: 26 March 1996     

Auswirkung von Schwermetallgemischen auf die biologische Behandlung naphthalinsulfonsäurehaltiger Abwässer

Effect of Mixtures of Heavy Metals on the Biological Treatment of Sewages Containing Naphthalenesulfonic Acid Biological wastewater treatment processes can be destabilized considerably by heavy metals. In this investigation, the effect of loadings of heavy metals on the degradation of naphthalene-2-sulfonic acid (2NS) by immobilized bacteria in continuously operated airlift-loop reactors was studied. Shock loadings with mixtures of cadmium and nickel, or cadmium and zinc, respectively, resulted in increases in inhibition compared to those observed with the single metals. In contrast, the 2NS-degradation was less inhibited by shock loadings with mixtures of nickel and zinc than by the single metal ions. Repeated shock loadings up to 100 mg L^?1 nickel and 1000 mg L^?1 zinc effected an adaptation of the microorganisms. Continuous loadings with up to 10 mg L^?1 cadmium and nickel each, or with 50 mg L^?1 nickel and 210 mg L^?1 zinc, respectively, did not inhibit the degradation of 2NS. The permanent loadings led to an adaptation of the bacteria with an increased biosynthesis of proteins from 0.2 to 0.5 g g^?1 cell dry weight. However, if the immobilized cells were incubated with mixtures of cadmium and nickel, the specific polysaccharide content decreased to less than 0.2 g g^?1 cell dry weight, resulting in a detachment of the biofilms.     

方格法采样在金矿床和铅锌多金属矿床中的应用

在地质普查勘探工作中,合理地选择采样方法,能提高地质找矿效果,加快找矿进程。通常应用的采样方法是刻槽法,笔者结合已勘探的金矿床、铅锌多金属矿床的实际情况,在不同矿区中进行了不同采样方法研究试验,试验结果证明l0×10cm规格的方格法是一种应用广泛,代表性强,效益好的采样方法。     

Soil contamination near non-ferrous metal smelters: A review

This review summarizes over 160 studies focused on soil contamination near non-ferrous metal smelters. The methods of these investigations were examined with an emphasis on the combinations of traditional (geo)chemical approaches with various mineralogical and metal isotope techniques that are particularly helpful for depicting the fate of smelter-derived contamination in the soil. Differences in the distributions and binding of metal(loid)s in smelter-affected soils from temperate and (sub)tropical climatic zones indicate the greater vulnerability of the latter. Prevailing wind direction is a key factor affecting the dispersion of smelter emissions and their subsequent deposition into the soils, with greater importance found especially in arid areas. Whereas the greatest contamination is generally observed in the surface soil layers, downward migration of metal(loid)s in the soil profiles has been documented at numerous sites. Contamination of smelter soils significantly affects both plants and soil organisms, but suitable remediation techniques (such as chemical stabilization of soils by amendments) can be used for reducing the bioavailability of contaminants.