The Experts below are selected from a list of 96 Experts worldwide ranked by ideXlab platform
Neža Finžgar - One of the best experts on this subject based on the ideXlab platform.
-
heap leaching of cu contaminated soil with s s edds in a Closed Process loop
Journal of Hazardous Materials, 2006Co-Authors: Neža Finžgar, Alenka ZumerAbstract:Abstract Heap leaching of Cu contaminated soil (412 ± 11 mg kg−1) with 5 mmol kg−1 ethylenediamine disuccinate [S,S]-EDDS as a chelator was tested in a laboratory-scale soil column study. The washing solution was recycled in a Closed Process loop after microbial (using a microbially active permeable bed, composed of substrate and absorbent) and oxidative chemical (using combined ozonation and UV irradiation) degradation of metal–[S,S]-EDDS complexes and retention of released Cu on a commercial absorbent Slovakite. Heap leaching using the permeable bed removed 25.5 ± 3.6% of initial total Cu from the soil. Ozone/UV treatment of the [S,S]-EDDS washing solution removed much more, 47.5 ± 7.4%, of Cu. Both methods yielded a clear and colorless final (waste) washing solution, with 7.0 ± 10.0 and 2.6 ± 0.7 mg L−1 Cu (permeable bed and ozone/UV method, respectively). The results of our study indicate that chemical treatment of chelator washing solution with ozone/UV in a Closed Process loop could lead to the development of a new, efficient and environmentally safe remediation method with controllable Cu emissions.
-
heap leaching of pb and zn contaminated soil using ozone uv treatment of edta extractants
Chemosphere, 2006Co-Authors: Neža Finžgar, Domen LestanAbstract:The feasibility of a novel EDTA-based soil heap leaching method with treatment and reuse of extractants in a Closed Process loop was evaluated on a laboratory scale. Ozone and UV irradiation were used for oxidative decomposition of EDTA-metal complexes in extractants from Pb (1243 mg kg−1) and Zn (1190 mg kg−1) contaminated soil. Released metals were absorbed in a commercial metal absorbent Slovakite. Six-consecutive additions of 2.5 mmol kg−1 EDTA (total 15 mmol kg−1 EDTA) removed 49.6 ± 0.6% and 19.7 ± 1.7% of initial total Pb and Zn from soil (4.6 kg) packed in 22 cm high columns. The efficiency of extraction was similar to small-scale simulations of heap leaching (150 g of soil), where EDTA used in the same manner removed 49.7 ± 1.0% and 13.7 ± 0.4% of Pb and Zn. The new heap leaching method produced discharge extractant with fairly low final concentrations of Pb, Zn and EDTA (1.98 ± 2.17 mg l−1, 4.55 ± 2.36 mg l−1, and 0.05 ± 0.04 mM, respectively), which could presumably be reduced even further with continuation of treatment. The results of our study indicate that for soils contaminated primarily with Pb, treating the EDTA extractants with ozone/UV and reuse of extractants enables efficient soil heap leaching with very little or no wastewater generation, easy control over emissions, and lowers the requirements for Process water.
Domen Lestan - One of the best experts on this subject based on the ideXlab platform.
-
Chelant soil-washing technology for metal-contaminated soil
2014Co-Authors: David Voglar, Domen LestanAbstract:We demonstrate here, in a pilot-scale experiment, the feasibility of ethylenediaminetetraacetate (EDTA)based washing technology for soils contaminated with potentially toxic metals. Acid precipitation coupled to initial alkaline toxic metal removal and an electrochemical advanced oxidation Process were used for average recovery of 76±2% of EDTA per batch and total recycle of water in a Closed Process loop. No waste water was generated; solid wastes were efficiently bitumen-stabilized before disposal. The technology embodiment, using conventional Process equipment, such as a mixer for soil extraction, screen for soil/gravel separation, filter chamber presses for soil/liquid and recycled EDTA separation and soil rinsing, continuous centrifuge separator for removal of precipitated metals and electrolytic cells for Process water cleansing, removed up to 72%, 25% and 66% of Pb, Zn and Cd from garden soil contaminated with up to 6960, 3797 and 32.6 mg kg−1 of Pb, Zn and Cd, respectively, in nine 60 kg soil batches. Concentrations of Pb and Zn remaining in the remediated soil and bioaccessible from the simulated human intestinal phase soil were reduced by 97% and 96% and were brought under the level of determination for Cd. In the most cost-effective operation mode, the material and energy costs of remediation amounted to 50.5≠uro ton−1 soil and the total cost to 299≠uro ton−1.
-
heap leaching of pb and zn contaminated soil using ozone uv treatment of edta extractants
Chemosphere, 2006Co-Authors: Neža Finžgar, Domen LestanAbstract:The feasibility of a novel EDTA-based soil heap leaching method with treatment and reuse of extractants in a Closed Process loop was evaluated on a laboratory scale. Ozone and UV irradiation were used for oxidative decomposition of EDTA-metal complexes in extractants from Pb (1243 mg kg−1) and Zn (1190 mg kg−1) contaminated soil. Released metals were absorbed in a commercial metal absorbent Slovakite. Six-consecutive additions of 2.5 mmol kg−1 EDTA (total 15 mmol kg−1 EDTA) removed 49.6 ± 0.6% and 19.7 ± 1.7% of initial total Pb and Zn from soil (4.6 kg) packed in 22 cm high columns. The efficiency of extraction was similar to small-scale simulations of heap leaching (150 g of soil), where EDTA used in the same manner removed 49.7 ± 1.0% and 13.7 ± 0.4% of Pb and Zn. The new heap leaching method produced discharge extractant with fairly low final concentrations of Pb, Zn and EDTA (1.98 ± 2.17 mg l−1, 4.55 ± 2.36 mg l−1, and 0.05 ± 0.04 mM, respectively), which could presumably be reduced even further with continuation of treatment. The results of our study indicate that for soils contaminated primarily with Pb, treating the EDTA extractants with ozone/UV and reuse of extractants enables efficient soil heap leaching with very little or no wastewater generation, easy control over emissions, and lowers the requirements for Process water.
Alenka Zumer - One of the best experts on this subject based on the ideXlab platform.
-
heap leaching of cu contaminated soil with s s edds in a Closed Process loop
Journal of Hazardous Materials, 2006Co-Authors: Neža Finžgar, Alenka ZumerAbstract:Abstract Heap leaching of Cu contaminated soil (412 ± 11 mg kg−1) with 5 mmol kg−1 ethylenediamine disuccinate [S,S]-EDDS as a chelator was tested in a laboratory-scale soil column study. The washing solution was recycled in a Closed Process loop after microbial (using a microbially active permeable bed, composed of substrate and absorbent) and oxidative chemical (using combined ozonation and UV irradiation) degradation of metal–[S,S]-EDDS complexes and retention of released Cu on a commercial absorbent Slovakite. Heap leaching using the permeable bed removed 25.5 ± 3.6% of initial total Cu from the soil. Ozone/UV treatment of the [S,S]-EDDS washing solution removed much more, 47.5 ± 7.4%, of Cu. Both methods yielded a clear and colorless final (waste) washing solution, with 7.0 ± 10.0 and 2.6 ± 0.7 mg L−1 Cu (permeable bed and ozone/UV method, respectively). The results of our study indicate that chemical treatment of chelator washing solution with ozone/UV in a Closed Process loop could lead to the development of a new, efficient and environmentally safe remediation method with controllable Cu emissions.
Hualiang Jiang - One of the best experts on this subject based on the ideXlab platform.
-
dopamine d1 receptor agonist and d2 receptor antagonist effects of the natural product stepholidine molecular modeling and dynamics simulations
Biophysical Journal, 2007Co-Authors: Jianhua Shen, Guozhang Jin, Xiaomin Luo, Weiliang Zhu, Jiagao Cheng, James M Briggs, Kaixian Chen, Hualiang JiangAbstract:(−)–Stepholidine (SPD), an active ingredient of the Chinese herb Stephania, is the first compound found to have dual function as a dopamine receptor D1 agonist and D2 antagonist. Insights into dynamical behaviors of D1 and D2 receptors and their interaction modes with SPD are crucial in understanding the structural and functional characteristics of dopamine receptors. In this study a computational approach, integrating protein structure prediction, automated molecular docking, and molecular dynamics simulations were employed to investigate the dual action mechanism of SPD on the D1 and D2 receptors, with the eventual aim to develop new drugs for treating diseases affecting the central nervous system such as schizophrenia. The dynamics simulations revealed the surface features of the electrostatic potentials and the conformational “open-Closed” Process of the binding entrances of two dopamine receptors. Potential binding conformations of D1 and D2 receptors were obtained, and the D1-SPD and D2-SPD complexes were generated, which are in good agreement with most of experimental data. The D1-SPD structure shows that the K-167_EL-2-E-302_EL-3 (EL-2: extracellular loop 2; EL-3: extracellular loop 3) salt bridge plays an important role for both the conformational change of the extracellular domain and the binding of SPD. Based on our modeling and simulations, we proposed a mechanism of the dual action of SPD and a subsequent signal transduction model. Further mutagenesis and biophysical experiments are needed to test and improve our proposed dual action mechanism of SPD and signal transduction model.
Hiroto Tachikawa - One of the best experts on this subject based on the ideXlab platform.
-
γ selective cross coupling reactions of potassium allyltrifluoroborates with haloarenes catalyzed by a pd 0 d t bpf or pd 0 josiphos r s cypf t bu complex mechanistic studies on transmetalation and enantioselection
Organometallics, 2009Co-Authors: Yasunori Yamamoto, Shingo Takada, Norio Miyaura, Tetsuji Iyama, Hiroto TachikawaAbstract:Cross-coupling between bromoarenes and [(E)-CH3CH=CHCH2BF3]K (2a) by a catalyst prepared from Pd(OAc)2 and D-t-BPF selectively provided γ-coupling products via SE2′ substitution. Mechanistic study of transmetalation revealed a heretofore unknown Process, namely, formation of a highly electrophilic [Pd(Ar)(D-t-BPF)]+ before transmetalation with 2a. Thus, kinetic data in coupling of 4-substituted bromoarenes with 2a showed a linear positive correlation (ρ = −1.1) accelerated by donating substituents. This rate-determining role of transmetalation was further confirmed by kinetic data between oxidative adducts [Pd(Ar)(Br)(D-t-BPF)] and 2a that exhibited an analogous correlation with a negative ρ-value (−0.50). Theoretical study by density functional theory (DFT) calculation showed that transmetalation between [Ar−Pd]+ and 2a via an SE2′ (open) transition state is a slightly lower energy Process than an SE2′ (Closed) Process. Allylic substitutions with chiral catalysts are the current topics for enantioselecti...