Search

Mixed [C8bet]Br/[C4mim][NTf2] ionic liquids were used as a new extraction system to extract Pd(II) from multimetal-ion solutions. The separation factors KPd/M (M: Cu, Fe, Ni, Zn, Co) are greater than 103. Thiourea was found to be an effective stripping agent. After three cycles, the recovery efficiency was higher than 91.0%. Direct electrodeposition of palladium from the mixed ionic liquid phase was also studied. The Pd(II) complex in [C8bet]Br/[C4mim][NTf2] system was studied by cyclic voltammetry at 348 K. The results indicate the existence of three types of Pd(II) complex in the [C8bet]Br/[C4mim][NTf2] system, leading to three reductive waves. The reduction of Pd(II) to Pd(0) in this system is irreversible. A uniform black coating was obtained by constant-potential deposition at −1.7 V on a nickel foil, confirmed to be palladium metal by energy-dispersive spectrometry, X-ray photoelectron spectroscopy, and high-resolution transmission electron microscopy analyses. After three cycles of continuous extraction–electrodeposition, over 90.0% of palladium was recovered.

The increasingly serious environmental problems make it urgent to develop a new type of sustainable green material which can degrade pollutants and monitor human health. However, the traditional preparation methods are frequently limited by tedious operations, high-energy consumption, and massive pollution. Herein, we present a facile and green method for preparation of MnO2 nanoflakes mediated by macrocyclic molecule calix[8]arene. The MnO2 nanoflakes in situ grew on the preformed gold nanoparticles, forming an impressive core–shell Au@MnO2 flake-like nanocomposite. The catalytic properties of Au@MnO2 composite for reduction of 4-NP and degradation of MB were 2.4 and 187 times better than commercial Pd/C, respectively. Meanwhile, the as-synthesized Au@MnO2 nanocomposite exhibited specially excellent sensitivity and selectivity for detection of GSH with a limit of detection (LOD) of 0.11 μM. The core–shell nanostructured Au@MnO2 shows great potential value for the sustainable development of the environmen...

In this study, four novel functionalized ionic liquids ([C4mim][DDTC], [C5mim][DDTC], [C6mim][DDTC], and [BMPip][DDTC]) were synthesized and used for the selective extraction of Pd(II) from an HCl medium containing Pt(IV), Pd(II), and Rh(III). The extraction mechanism was investigated using Job’s plots, UV–Vis, SXRD, and MS analysis. A mechanistic investigation revealed the formation of hydrophobic extraction complexes Pd(DDTC)2 and PdClDDTC via coordination between [DDTC]− and Pd(II). In addition, the solubility and polarity of the solutes were investigated using DFT calculations to determine the optimal extractant and diluent. From the results of the theoretical analysis, [C5mim][DDTC]/CHCl3 was selected as the optimum system for the selective extraction of Pd(II). The effects that factors have on Pd(II) extraction, including temperature, [C5mim][DDTC] amount, HCl concentration, and O/A ratio, were investigated and optimized using single-factor and response surface experiments. Under the optimized conditions, Pd(II) extraction efficiencies were higher than 99%, and the separation factors (βPd(II)/Pt(IV) and βPd(II)/Rh(III)) were greater than 104. After extraction, Pd and Rh were directly recovered from the organic and aqueous phases via photocatalytic reduction, respectively. TEM, XPS, and PXRD results revealed that the resulting nanoparticles were Rh(0) or Pd(0). The recovery of Pd and Rh exceeded 95%. Overall, a simple hydrometallurgical process with low reagent consumption was developed to yield nanometer-scale Pd(0) and Rh(0) from simulated secondary resource leaching solutions.

In this study, based on a cyano-functionalized ionic liquid, 1-nitrile-1-octylpyrrole bromide ([C8Y3Pr]Br), a [C8Y3Pr]Br/cyclohexane/tributyl phosphate (TBP)/NaCl microemulsion system was constructed and used for the extraction of Pd(II) and preparation of Pd nanoparticles from multimetal solutions. The key extraction parameters including vibration time, [C8Y3Pr]Br concentration, phase ratio (RW/O), and HCl concentration were evaluated. Compared with other ionic-liquid microemulsion systems, the cyano-functionalized ionic liquid [C8Y3Pr]Br microemulsion system showed excellent extraction performance for Pd(II). Almost all Pd(II) was extracted (>98.0%) from a multimetal solution using the microemulsion system, while the separation factors (βPd/M) of [C8Y3Pr]Br-based microemulsions for Pd(II) with Cu2+, Fe3+, Ni2+, Zn2+, Co2+, and Mg2+ exceeded 1.0 × 103. The mechanism extracting Pd(II) using [C8Y3Pr]Br was confirmed to be an anion-exchange reaction via Job’s method, spectral analysis (UV, FTIR), and DFT calculations. Alcohols and hydrazine hydrate were used as demulsifiers, and Pd nanoparticles were directly obtained from the microemulsion phase. The Pd nanoparticles were identified by TEM, XPS, and XRD analyses. The chemical structures of extracted species based on the microemulsion system and the mechanism of demulsification of alcohols were studied. Thus, an effective new process was developed in this study for the direct preparation of Pd nanoparticles from mixed metal solutions via solvent extraction.

Developing an efficient method to recover and reuse soil-base lead (Pb) poses significant challenges. Herein, we designed a remediation method to achieve the dual goal of separating and reusing Pb from soil based on Bacillus megaterium-secreted surfactin with pH-response. Under weakly alkaline, B. megaterium-secreted surfactin efficiently captured Pb(II) from soil and also converted it into biological Pb/PbO nanoparticles (bio-Pb/PbO NPs). Further, surfactin’s sensitivity to pH enables bio-Pb/PbO NPs to be readily separated from the soil through simple pH adjustments. The highest yield of bio-Pb/PbO NPs (77.54%) was achieved at an initial concentration of 1 mg/g Pb(II). The recovered bio-Pb/PbO NPs showed a mesoporous structure and an average size of ~47 nm. More importantly, bio-Pb/PbO NPs exhibited highly efficient catalytic activity for the hydrogen evolution reaction in 1 M KOH. These results demonstrated that this method efficiently recovered and converted Pb into high value-added NPs, and was thereby a sustainable and feasible technique for Pb(II) recovery and reuse. As such, this methodology offers a new, efficient, and practical approach for sustainable remediation of heavy metal contamination in soils.

Although phosphonium-based ionic liquids (ILs) have become popular green solvents for the separation of precious metals, these solvents have not been used thus far to recover Pd(II) from alkaline cyanide solutions. In this study, three novel phosphonium-based ILs, viz. tributyl(2-ethylhexyl) phosphonium bromide (TBEHPB), trioctyl (2-ethylhexyl) phosphonium bromide (TOEHPB), and trioctyl undecyl phosphonium bromide (TOUPB), were synthesized, respectively, and these ILs were used for the recovery of Pd(CN)42− for the first time. With the increase in the length of the alkyl chain in the phosphonium cation, the extraction percentage of Pd(II) increased. Under optimum conditions (i.e., contact time of 5 min, pH of 10.5, and temperature of 298 K), the TOUPB system exhibited a Pd(II) extraction percentage of greater than 99.0%. Furthermore, the TOUPB system exhibited excellent selectivity for Pd(II) in a mixed solution (separation factors of βPd/Fe and βPd/Co were greater than 2.0 × 103). The Pd(II) recovery percentage was still greater than 90.0% after five consecutive extraction-stripping cycles. The Job’s method, infrared spectroscopy, mass spectrometry, nuclear magnetic resonance spectroscopy, and UV–vis spectroscopy revealed that the extraction mechanism is ion exchange. The supramolecular structure of the extraction complex was established on the basis of density functional theory (DFT) calculations and Karl Fischer titration, and the extraction mechanism was further described at the molecular structure level. This study provides a new process for recovering Pd(II) from an alkaline cyanide medium.

BACKGROUND Thus far, separation and recovery of Pd(CN)42- and Pt(CN)42- from cyanide liquors have not been reported. In this study, the process of co-extracting and separating Pd(II) and Pt(II) over Fe(III), Cu(I), Co(III), and Ni(I) from alkaline cyanide liquors was investigated. RESULTS The results showed that almost all Pd(II) and Pt(II) (>98.0%) could be simultaneously extracted by phenoxyethyl dimethyl palmitylammonium bromide (PDPB), whereas Fe(III), Cu(I), Co(III), and Ni(I) was below 3.0% under optimum conditions. Furthermore, Pd(CN)42- and Pt(CN)42- were separated and recovered by the two-step stripping process. First, Pd(CN)42- in mixed organic phase was stripped by a 2.0 mol L−1 ammonium thiocyanate solution. The stripping percentage of Pd(CN)42- was >98%, whereas the stripped Pt(CN)42- was below 1%. Second, more than 97.5% Pt(CN)42- in the loaded organic phase could be stripped using 1.0 mol L−1 thiodiglycol solution. Recovery ratios for both Pd(II) and Pt(II) were above 95%. The organic phase could be reused for at least 6 cycles of extraction–stripping processes. The mechanisms of extraction reaction were deduced to be ion-association mechanisms. CONCLUSION The process could be applied for extracting and separating palladium and platinum from the cyanide leaching liquor of the flotation concentrate. © 2016 Society of Chemical Industry

A novel functional ion-exchange/adsorption metal organic resin (MOR), TEBAC-HKUST-1, was prepared and characterized. Ethanedithiol was used as the grafting agent to introduce thiol groups onto HKUST-1, and 4-vinylbenzyl chloride was then grafted onto SH-HKUST-1 using thiol groups. Finally, the quaternary ammonium functional group was immobilized onto the carrier by performing a quaternization reaction. The structure and property of TEBAC-HKUST-1 MOR were characterized by TGA, N2 adsorption&ndash, desorption, FTIR, SEM, and XRD. TEBAC-HKUST-1 MOR was used to remove metal cyanide complexes from wastewater. The adsorption was rapid, and the metal cyanide complexes including Pt(CN)42&minus, Co(CN)63&minus, Cu(CN)32&minus, and Fe(CN)63&minus, were removed in 30 min. TEBAC-HKUST-1 MOR exhibited a high stability in neutral and weak basic aqueous solutions. Furthermore, Pt(II) could be efficiently recovered through two-step elution. The recovery rate of Pt(II) for five cycles were over 92.0% in the mixture solution containing Pt(CN)42&minus, The kinetic data were best fitted with the pseudo second-order model. Moreover, the isothermal data were best fitted with the Langmuir model. The thermodynamic results show that the adsorption is a spontaneous and exothermic process. TEBAC-HKUST-1 MOR not only exhibited excellent ability for the rapid removal of metal cyanide complexes, but also provided a new idea for the extraction of noble metals from cyanide-contaminated water.

In this study, five new imidazolium ionic liquids (ILs) were synthesized, and their efficiencies toward the precipitation of PtCl62− in HCl media were evaluated. The prepared compounds were identified as 1-alkyl-3-propylimidazolium bromide ([CnPIm]Br, n = 12, 14, and 16), 1-tetradecyl-2-aminoethylimidazolium bromide ([C14PImNH2]Br), and 1-tetradecyl-3-butylimidazolium bromide ([C14PIm]Br). FT-IR, 1H NMR, and continuous variation method analysis were used to establish the ion-exchange model of Pt(IV) precipitation. To extract Pt(IV) from mixed metal solutions, and a novel mixed-ILs system was obtained through the dissolution of 1-tetradecyl-3-propylimidazolium bromide ([C14PIm]Br) in hydrophobic ILs ([C8MIm][PF6]). The mixed-ILs ([C14PIm]Br/[C8MIm][PF6]) exhibited excellent extraction efficiency compared to single [C8MIm][PF6]. Also, Pt(IV) ions were selectively separated from mixed metal solutions containing Rh(III), Fe3+, Ni2+, Cu2+, and Zn2+ metal ions. The separation factor βPt/M (M: Fe, Ni, Cu, Zn, or Rh) was above 105 for all systems. The optimal potentiostatic deposition voltage of Pt was estimated to −1.75 V. Direct electrodeposition from ILs containing [C14PIm]Br/[C8MIm][PF6] with Pt(IV), more than 97% of Pt(IV) was reduced to Pt(0) on the copper cathode, while the system could also be regenerated for PtCl62− extraction. Surface characterization techniques like SEM, TEM, and XPS identified the deposited silver-grey films on cathode surfaces as Pt metal with metallic luster.

Metal-cyanide complexes are hazardous and toxic pollutants that can accumulate in organisms, and their natural degradation is difficult. These complexes are primarily present in alkaline wastewater effluents, and an effective technique for their removal must be developed. Herein, we have successfully synthesized a novel quaternary ammonium-functionalized Zr4+ metal-organic resin (MOR) (H16[Zr6O16(MPATP)4]Cl8·xH2O, MPATP = 2-((1-methylpyridin-1-ium-2-ylmethyl)amino)-terephthalic acid), which we refer to as MOR-2-QAS. With alkali resistance, high surface area, and high anion exchange capacity, it acts by introducing positively charged pyridine into the organic ligand. The experimental results indicate that MOR-2-QAS becomes rapidly attached and efficiently removes Pt(CN)42−, Pd(CN)42−, Co(CN)63−, and Fe(CN)63−. Valuable metals (Pt(II) and Pd(II)) can be effectively recovered from the simulated wastewater containing four-component cyanide complexes via the two-step elution process. The recovery efficiency of Pt(II) and Pd(II) was higher than 90.0% after three adsorption-desorption cycles. The adsorption mechanism, which proceeded via ionic association (ion-exchange) and complied with the minimum surface charge density experiential principle, was confirmed using density functional theory. This study provides ideas for developing efficient and stable MORs to enable the simultaneous removal of multiple metal–cyanide complexes and recovery of valuable metals.

In this study, quaternary-ammonium-functionalized metal&ndash, organic frameworks (MOFs) Et-N-Cu(BDC-NH2)(DMF), were prepared, characterized, and applied for the highly effective removal of metal cyanide complexes, including Pd(CN)42&minus, Co(CN)63&minus, and Fe(CN)63&minus, Batch studies were carried out, and the maximum adsorption capacities of Pd(II), Co(III), and Fe(III) reached 172.9, 101.0, and 102.6, respectively. Adsorption was rapid, and equilibrium was established within 30 min. Et-N-Cu(BDC-NH2)(DMF) exhibited high thermal and chemical stability. Furthermore, absorbed Pd(CN)42&minus, was selectively recovered by two-step elution. First, Co(CN)63&minus, were eluted with a 1.5 mol L&minus, 1 KCl solution. Elution rates of Co(CN)63&minus, were greater than 98.0%, whereas the elution percentage of Pd(CN)42&minus, was less than 2.0%. Second, &gt, 97.0% Pd(CN)42&minus, on the loaded MOFs was eluted using a 2.0 mol L&minus, 1 KI solution. The recovery rate of Pd(CN)42&minus, was greater than 91.0% after five testing cycles. Adsorption isotherms, kinetics models, and adsorption thermodynamics of Pd(CN)42&minus, on Et-N-Cu(BDC-NH2) (DMF) were also systematically investigated. The Et-N-Cu(BDC-NH2) (DMF) absorbent exhibited a rapid, excellent ability for the adsorption of metal cyanide complexes.

Conventional separation methods are not suitable for recovering palladium present in low concentrations in ore leaching solutions. In this study, a novel isopentyl sulfide (S201)-impregnated α-MnO2 nanorod adsorbent (BISIN) was prepared, characterized, and applied for the selective adsorption and separation of palladium from the leaching liquor of ores. Batch studies were carried out, and the main adsorption parameters were systematically investigated, in addition to the relevant thermodynamic parameters, isotherms, and kinetic models. The thermodynamic parameters reflected the endothermic and spontaneous nature of the adsorption. Moreover, the experimental results indicated that the Langmuir isotherm model fits the palladium adsorption data well and the adsorption was well described by the pseudo-second-order kinetic model. The main adsorption mechanisms of palladium were elucidated at the molecular level by X-ray crystal structure analysis. Thiourea was found to be an excellent desorption agent, and the palladium-thiourea complex was also confirmed by X-ray crystal structure analysis. The results indicated that almost all of the Pd(II) (>99.0%) is adsorbed on BISIN, whereas less than 2% of the adsorbed Pt(IV), Fe3+, Cu2+, Ni2+, and Co2+ is observed under the optimum conditions. The proposed method can be used for the efficient adsorption and separation of palladium from the leaching liquor of ores.

PTEN is proposed to function at the plasma membrane, where receptor tyrosine kinases are activated. However, the majority of PTEN is located throughout the cytoplasm. Here, we show that cytoplasmic PTEN is distributed along microtubules, tethered to vesicles via phosphatidylinositol 3-phosphate (PI(3)P), the signature lipid of endosomes. We demonstrate that the non-catalytic C2 domain of PTEN specifically binds PI(3)P through the CBR3 loop. Mutations render this loop incapable of PI(3)P binding and abrogate PTEN-mediated inhibition of PI 3-kinase/AKT signaling. This loss of function is rescued by fusion of the loop mutant PTEN to FYVE, the canonical PI(3)P binding domain, demonstrating the functional importance of targeting PTEN to endosomal membranes. Beyond revealing an upstream activation mechanism of PTEN, our data introduce the concept of PI 3-kinase signal activation on the vast plasma membrane that is contrasted by PTEN-mediated signal termination on the small, discrete surfaces of internalized vesicles.

Growth factor receptor levels are aberrantly high in diverse cancers, driving the proliferation and survival of tumor cells. Understanding the molecular basis for this aberrant elevation has profound clinical applications. Here we show that the PH domain leucine-rich repeat protein phosphatase (PHLPP) suppresses the steady-state levels of receptor tyrosine kinases (RTKs) by a novel mechanism unrelated to its previously described function as the hydrophobic motif phosphatase for AKT, protein kinase C and S6 kinase. Specifically, genetic depletion and pharmacological studies reveal that PHLPP1 and PHLPP2 promote histone deacetylase (HDAC)-dependent repression of the transcription of diverse growth factor receptors, including the EGF receptor. These data uncover a novel, and much broader, role for PHLPP in regulation of growth factor signaling beyond its direct inactivation of AKT: by suppressing RTK levels, PHLPP dampens the downstream signaling output of two major oncogenic pathways, the PI3 kinase/AKT and...

PTEN is thought to function at the plasma membrane where receptor tyrosine kinases activate PI 3-Kinases. Yet the majority of PTEN is located throughout the cytoplasm so that only a fraction of PTEN could be actively suppressing PI 3-K signaling at any time. Here we show that cytoplasmic PTEN is distributed along microtubules, tethered to vesicles via interaction with phosphatidylinositol 3- phosphate (PI(3)P), the signature lipid of endosomes. We demonstrate that the C2 domain of PTEN specifically binds PI(3)P via the CBR3-loop. Mutations that render the CBR3-loop incapable of PI(3)P binding abrogate PTEN function in cells but not in vitro. The loss-of-function in cells is rescued by fusion of the canonical PI(3)P vesicle targeting domain, FYVE, to CBR3-loop mutant PTEN, demonstrating the functional relevance of PTEN activity on endosomal membranes. These findings introduce an entirely unexpected site of action of the PTEN tumor suppressor. Furthermore, they introduce the concept of PI 3-K signal activation over the vast surface of the plasma membrane that is contrasted by PTEN-mediated signal termination on the discretely sized and much smaller surfaces of endocytic vesicles. Implications of these results for cancer signaling and growth control will be discussed. Note: This abstract was not presented at the meeting. Citation Format: Adam Naguib, Gylua Bencze, Hyejin Cho, Wu Zheng, Ante Tocilj, Elad Elkayam, Christopher R Faehnle, Nadia Jaber, Christopher Pratt, Muhan Chen, Wei-Xing Zong, Michael S Marks, Leemor Joshua-Tor, Darryl J Pappin, Lloyd C. Trotman. PTEN function is controlled by recruitment to cytoplasmic vesicles. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr LB-063. doi:10.1158/1538-7445.AM2015-LB-063