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Efficient removal of 99 TcO 4 - from radioactive effluents while recovering drinking water remains a challenge. Herein, an excellent ReO 4 - (a nonradioactive surrogate of 99 TcO 4 - ) scavenger is presented through covalently bonding imidazolium poly(ionic liquids) polymers with an ionic porous aromatic framework (iPAF), namely iPAF-P67, following an adsorption-site density-addition strategy. It shows rapid sorption kinetics, high uptake capacity, and exceptional selectivity toward ReO 4 - . Notably, the residual concentration of TcO 4 - /ReO 4 - in the radioactive wastewater after iPAF-P67 treatment is as low as 0.046 ppb, fully meeting the drinking water standards of World Health Organization (WHO, 0.159 ppb) and United States Environmental Protection Agency (U.S. EPA, 0.053 ppb). Density functional theory (DFT) calculations show that the imidazolium groups in iPAF-P67 provide stronger electrostatic interactions and higher binding energies between iPAF-P67 and TcO 4 - anions, leading to its superior adsorption performance. Furthermore, the scale-up synthesized iPAF-P67 materials are shaped with polyethersulfone (PES) to fabricate PAF-P67/PES beads and nanofibers via phase inversion method and electrospinning technique, respectively. Both composites demonstrate outstanding ultra-purification abilities toward ReO 4 - to meet the WHO criteria even after multiple dynamic adsorption/desorption cycles. This work develops a design strategy for adsorbents applicable in the sequestration of low-concentration radioactive pollutants., (© 2025 The Author(s). Advanced Science published by Wiley‐VCH GmbH.)

Sustainable photocatalysis can effectively reduce the radioactive 99 TcO 4 - to less soluble TcO 2 · n H 2 ). Here, we quantitatively investigate photocatalytic remediation conditions for Tc-contaminated water stimulated by the analogue perrhenate (ReO 3 - ). Here, we quantitatively investigate photocatalytic remediation conditions for Tc-contaminated water stimulated by the analogue perrhenate (ReO 4 - ) in the presence of NO 3 - , and we elucidate the influence mechanism of NO 3 - by in situ characterizations. The interfering NO 3 - can compete with Re(VII) for the carbonyl radical (·CO 2 - ) produced by formic acid (HCOOH) oxidation to generate nitrogen-containing products such as NH 4 + , NO 2 - , and NO x , resulting in the decrease in the Re(VII) reduction ratio. Under the conditions of 4% (volume ratio) HCOOH and pH = 3, the yield of NO x is the lowest, and the selectivity of N 2 reaches 93%, which makes the overall reaction more in line with the pollution-free concept. The X-ray absorption fine structure reveals that the redox product Re(IV) mainly exists in the form of ReO 2 · n H 2 O(s) and is accompanied by a decrease with the increase in NO 3 - concentration. Re(VII)/Tc(VII) reduction suffers from a serious interferential effect of NO 3 - , whereas the higher the concentration of NO 3 - , the more conducive to slowing down the reoxidation of the reduction products, which is advantageous for the subsequent sequestration or separation.

Pertechnetate ( 99 TcO 4 - ), a physiologically toxic radioactive anion, is of great concern due to its high mobility in environmental contamination remediation. Although the soluble oxyanion can be photoreduced to sparingly soluble TcO 2 · n H 2 O, its effective removal from a strongly acidic aqueous solution remains a challenge. Here, we found that low-crystalline nitrogen-doped titanium oxide (N-TiO 2 ) could effectively uptake perrhenate (ReO -1 ) could effectively uptake perrhenate (ReO 4 - , 10 mg L -1 , a nonradioactive surrogate for TcO 4 - ) with 50.8% during 360 min under simulated sunlight irradiation at pH 1.0, but P25 and anatase could not. The nitrogen active center formed by trace nitrogen doping in N-TiO 2 can promote the separation and transfer of photogenerated carriers. The positive valence band value of N-TiO 2 is slightly higher than those of P25 and anatase, which means that the photogenerated holes have a stronger oxidizability. These holes are involved in the formation of strong reducing • CO 2 - radicals from formic acid oxidation. The active radicals convert ReO 4 - to Re(VI), which is subsequently disproportionated to Re(IV) and Re(VII). Effective photocatalytic reduction/removal of Re(VII)/Tc(VII) is performed on the material, which may be considered a potential and convenient strategy for technetium decontamination and extraction in a strongly acidic aqueous solution.

In this manuscript we evaluate the X-ray structure of five new pertechnetate derivatives of general formula [M(H 2 O) 4 (TcO 4 ) 2 ], M=Mg, Co, Ni, Cu, Zn (compounds 1-5) and one perrhenate compound Zn(H 2 O) 4 (ReO 4 ) 2 (6). In these complexes the metal center exhibits an octahedral coordination with the pertechnetate units as axial ligands. All compounds exhibit the formation of directional Tc⋅⋅⋅O Matere bonds (MaBs) that propagate the [M(H 2 O) 4 (TcO 4 ) 2 ], into 1D supramolecular polymers in the solid state. Such 1D polymers are linked, generating 2D layers, by combining additional MaBs and hydrogen bonds (HBs). Such concurrent motifs have been analyzed theoretically, suggesting the noncovalent σ-hole nature of the MaBs. The interaction energies range from weak (~ -2 kcal/mol) for the MaBs to strong (~ -30 kcal/mol) for the MaB+HB assemblies, where HB dominates. In case of M=Zn, the corresponding perrhenate Zn(H 2 O) 4 (ReO 4 ) 2 complex, has been also synthesized for comparison purposes, resulting in the formation of an isostructural X-ray structure, corroborating the structure-directing role of Matere bonds., (© 2024 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

The selective removal of the β-emitting pertechnetate ion ( 99 TcO 4 - ) from nuclear waste streams is technically challenging. Herein, a practical approach is proposed for the selective removal of 99 TcO 4 - (or its surrogate ReO 4 - ) under extreme conditions of high acidity, alkalinity, ionic strength, and radiation field. Hollow porous N-doped carbon capsules loaded with ruthenium clusters (Ru@HNCC) are first prepared, then modified with a cationic polymeric network (R) containing imidazolium-N + units (Ru@HNCC-R) for selective 99 TcO 4 - and ReO 4 - binding. The Ru@HNCC-R capsules offer high binding affinities for 99 TcO 4 - /ReO 4 - under wide-ranging conditions. An electrochemical redox process then transforms adsorbed ReO 4 - to bulk ReO 3 , delivering record-high removal capacities, fast kinetics, and excellent long-term durability for removing ReO 4 - (as a proxy for 99 TcO 4 - ) in a 3 m HNO 3 , simulated nuclear waste-Hanford melter recycle stream and an alkaline high-level waste stream (HLW) at the U.S. Savannah River Site (SRS). In situ Raman and X-ray absorption spectroscopy (XAS) analyses showed that adsorbed Re(VII) is electrocatalytically reduced on Ru sites to a Re(IV)O 2 intermediate, which can then be re-oxidized to insoluble Re(VI)O 3 for facile collection. This approach overcomes many of the challenges associated with the selective separation and removal of 99 TcO 4 - /ReO 4 - under extreme conditions, offering new vistas for nuclear waste management and environmental remediation., (© 2023 The Authors. Advanced Science published by Wiley-VCH GmbH.)

Adaptable redox-active materials hold great potential for electrochemically mediated separation processes via targeted molecular recognition and reduced energy requirements. This work presents molecularly tunable vinylferrocene metallopolymers (P(VFc-co-X)) with modifiable operating potentials, charge storage capacities, capacity retentions, and analyte affinities in various electrolyte environments based on the hydrophobicity of X. The styrene (St) co-monomer impedes hydrophobic anions from ferrocene access, providing P(VFc-co-St) with specific response capabilities for and greatly improved cyclabilities in hydrophilic anions. This adjustable electrochemical stability enables preferential chromium and rhenium oxyanion separation from both hydrophobic and hydrophilic electrolytes that significantly surpasses capacitive removal by an order of magnitude, with a robust perrhenate uptake capacity of 329 mg/g VFc competitive with established metal-organic framework physisorbents and 17-fold selectivity over 20-fold excess nitrate. Pairing P(VFc-co-X) with other solution-specific electroactive macromolecules such as the pH-dependent poly(hydroquinone) (PHQ) and the cesium-selective nickel hexacyanoferrate (NiHCF) generates dual-functionalized electrosorption cells. P(VFc-co-X)//PHQ offers optimizable energetics based on X and pH for a substantial 4.6-fold reduction from 0.21 to 0.04 kWh/mol rhenium in acidic versus near-neutral media, and P(VFc-co-St)//NiHCF facilitates simultaneous extraction of rhenium, chromium, and cesium ions. Proof-of-concept reversible perrhenate separation in flow further highlights such frameworks as promising approaches for next-generation water purification technologies.

Efficient and sustainable methods for 99 TcO 4 - removal from acidic nuclear waste streams, contaminated water, and highly alkaline tank wastes are highly sought after. Herein, we demonstrate that ionic covalent organic polymers (iCOPs) possessing imidazolium-N + nanotraps allow the selective adsorption of 99 TcO 4 - under wide-ranging pH conditions. In particular, we show that the binding affinity of the cationic nanotraps toward 99 TcO 4 - can be modulated by tuning the local environment around the nanotraps through a halogenation strategy, thereby enabling universal pH 99 TcO 4 - removal. A parent iCOP-1 possessing imidazolium-N + nanotraps showed fast kinetics (reaching adsorption equilibrium in 1 min), a high adsorption capacity (up to 1434.1 ± 24.6 mg/g), and exceptional selectivity for 99 TcO 4 - and ReO 4 - (nonradioactive analogue of 99 TcO 4 - ) removal in contaminated water. By introducing F groups near the imidazolium-N + nanotrap sites (iCOP-2), a ReO 4 - removal efficiency over 58% was achieved in 60 min in 3 M HNO 3 solution. Further, introduction of larger Br groups near the imidazolium-N + binding sites (iCOP-3) imparted a pronounced steric effect, resulting in exceptional adsorption performance for 99 TcO 4 - under super alkaline conditions and from low-activity waste streams at US legacy Hanford nuclear sites. The halogenation strategy reported herein guides the task-specific design of functional adsorbents for 99 TcO 4 - removal and other applications.

The β - emitter, rhenium-188 ( 188 Re), has long been recognized as an attractive candidate for targeted cancer radionuclide therapy (TRNT). This transition metal shares chemical similarities with its congener element technetium, whose nuclear isomer technetium-99m ( 99m Tc) is the current workhorse of diagnostic nuclear medicine. The differences between these two elements have a significant impact on the radiolabelling methods and should always receive critical attention. This review aims to highlight what needs to be considered to design a successful radiopharmaceutical incorporating 118 Re. Some of the most effective strategies for preparing therapeutic radiopharmaceuticals with 188 Re are illustrated and rationalized using the concept of the inorganic functional group (core) and a simple ligand field theoretical model combined with a qualitative definition of frontiers orbitals. Of special interest are the Re(V) oxo and Re(V) nitrido functional groups. Suitable ligands for binding to these cores are discussed, successful clinical applications are summarized, and a prediction of viable future applications is presented. Rhenium-188 decays through the emission of a high energy beta particle (2.12 MeV max energy) and a half-life of 16.9 h. An ideal biological target would therefore be a high-capacity target site (transporters, potential gradients, tumour microenvironment) with less emphasis on saturable targets such as overexpressed receptors on smaller metastases.

Ionic covalent organic framework (COF) materials with high specific surface areas and well-defined pore structures are desired for many applications yet seldom reported. Herein, we report a cationic pyridinium salt-based COF (PS-COF-1) with a Brunauer-Emmett-Teller (BET) surface area of 2703 m 2  g -1 , state-of-the-art for an ionic COF. Aided by its ordered pore structure, chemical stability, and radiation resistance, PS-COF-1 showed exceptional adsorption properties toward aqueous ReO 4 - (1262 mg g -1 ) and 99 TcO 4 - . Its adsorption performance surpassed its corresponding amorphous analogue. Importantly, PS-COF-1 exhibited fast adsorption kinetics, high adsorption capacities, and selectivity for 99 TcO 4 - and ReO 4 - at high ionic strengths, leading to the successful removal of 99 TcO 4 - under conditions relevant to low-activity waste streams at US legacy Hanford nuclear sites. In addition, PS-COF-1 can rapidly decontaminate ReO 4 - / 99 TcO 4 - polluted potable water (∼10 ppb) to drinking water level (0 ppb, part per billion) within 10 min. Density functional theory (DFT) calculations revealed PS-COF-1 has a strong affinity for ReO 4 - and 99 TcO 4 - , thereby favoring adsorption of these low charge density anions over other common anions (e.g., Cl - , NO 3 - , SO 4 2- , CO 3 2- ). Our work demonstrates a novel cationic COF sorbent for selective radionuclide capture and legacy nuclear waste management., Competing Interests: Conflict of interest The authors declare that they have no conflict of interest., (Copyright © 2022 Science China Press. Published by Elsevier B.V. All rights reserved.)

There are few effective technologies for the sequestration of highly water-soluble pertechnetate (TcO 4 - were investigated for perrhenate (ReO 3 were investigated for perrhenate (ReO 4 - ), a surrogate of TcO 4 - , sequestration from artificial groundwater. Cl - , I - , and CF 3 SO 3 - exchanged MIL-101-Cr proved more effective at ReO 4 - removal than the parent MIL-101-Cr-F. Compared to the parent framework, CTAB functionalized MIL-101-Cr-NO 3 increased ReO 4 - removal capacity from 39 to 139 mg/g, improved the reaction kinetics from ~30 to <10 min to reach full adsorption capacity and the selectivity for ReO 4 - over competing NO 3 - , CO 3 2- , SO 4 2- , and Cl - . Spectroscopic data indicated that the chemical speciation of Re in the exchanged MIL-101-Cr remained ReO 4 - , indicating synergistic sequestration through both anion exchange and non-ion exchange binding with the positively charged ligand of CTAB. These studies foreshadow potential applications of MOFs for the remediation of 99 TcO 4 - from contaminated environments., (Published by Elsevier Ltd.)

Radioactive pertechnetate (TcO4 - ) has been detected in nuclear waste affected soil and groundwater, posing significant effect on human health and the environment. Yet, cost-effective remediation of Tc-contaminated soil and groundwater remains challenging. To address this critical technology need, we prepared a class of pyrite (FeS 2 ) particles for effective immobilization of pertechnetate. Using perrhenate (ReO 4 - ) as a non-radioactive surrogate of TcO 4 - , we tested the immobilization effectiveness of the material through batch kinetic experiments, and evaluated the remobilization potential of immobilized Re under anoxic (sealed from air) and oxic (exposed to air) conditions and in the presence of humic acid (HA), EDTA, nitrate, and a Chinese loess soil. The results showed that more acidic pH gave faster Re(VII) removal due to more abundant electron sources (Fe 2+ and S 2 2- ). X-ray diffraction (XRD) and/or X-ray photoelectron spectroscopy (XPS) analyses confirmed formation of ReO 2 /ReS 2 as the major reduction products. The immobilized Re remained highly stable when aged for 360 days under anoxic conditions at different influence factors. Yet, the immobilized Re was vulnerable to oxygen oxidation, and about 78% of Re was remobilized after 40 days of exposure to air regardless of the initial pH (3.5-9.0) due to excessive pyrite oxidation and the associated pH drop (~2). HA at 120 mg/L inhibited Re remobilization under oxic conditions, which lowered the Re remobilization by ~21% after 40 days of oxic aging. The presence of EDTA facilitated dissolution of Fe but inhibited the dissolution of Re under oxic conditions. Nitrate showed negligible effect on Re remobilization. The presence of a Chinese loess soil effectively inhibited Re remobilization under both oxic and anoxic conditions, lowering the leachable Re by ~32% under oxic conditions. The findings may guide engineered application of pyrite particles as a long-lasting reducing material for immobilization pertechnetate or similar redox-active contaminants in soil and water., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

A methodology was developed to design superior sorbents of oxoanions. To integrate the high efficiency of chemisorption, selectivity, and recyclability into one sorbent, understanding the nature of oxoanions-sorbent interactions and the structural evolution of the sorbents is essential. Three cationic Ag(I) coordination polymers (CPs) are synthesized for dichromate (Cr 2 O 7 2- ) removal, and three distinct oxoanion-exchange mechanisms are identified, namely, the replacement , breath processes, depending on the degree of framework distortion induced by the dichromate-CP interactions. The single crystal to single crystal transformation during the oxoanion exchange has been investigated by using single-crystal X-ray diffraction and energy-dispersive X-ray microanalysis. The replacement process, due to a weak chemisorption, shows excellent recyclability at the cost of reduction of efficiency and selectivity of adsorption. The reconstruction process may achieve a high efficiency and selectivity, but it loses recyclability. Due to the formation of a Ag-O(dichromate) bond and the breathing effect of the framework, the sorbent with the breath mechanism shows both superior efficiency and high recyclability in dichromate removal. The study of perrhenate (ReO reconstruction ) removal using the same CPs demonstrates that one CP performing the reconstruction process during dichromate removal turns to the breath process in removal of perrhenate anions. These results of mechanism-property correlation provide an insight into improvement of the methodology to fabricate a superior CP sorbent for oxoanion removal.4 - ) removal using the same CPs demonstrates that one CP performing the reconstruction process during dichromate removal turns to the breath process in removal of perrhenate anions. These results of mechanism-property correlation provide an insight into improvement of the methodology to fabricate a superior CP sorbent for oxoanion removal.

Technetium-99 ( 99 Tc) is a major contaminant at nuclear power plants and several US Department of Energy sites. Its most common aqueous species, pertechnetate (TcO 4 - and perrhenate (ReO 4 - and perrhenate (ReO 4 - ) sequestration from artificial groundwater. The pFe was significantly more effective than granular iron for both TcO 4 - and ReO 4 - sequestration under oxic conditions. The Tc removal capacity was 27.5 mg Tc/g pFe at pH ˜6.8, while the Re removal capacity was 23.9 mg Re/g pFe at pH ˜10.6. Tc K-edge XANES and EXAFS analyses indicated that the removed Tc species was 70-80% Tc(IV) that was likely incorporated into Fe corrosion products (i.e., Fe(OOH), Fe 3 O 4 ) and 20-30% unreduced TcO 4 - . In contrast, the removed Re species was ReO 4 - only, without detectable Re(IV). In addition, the sequestered ReO 4 - was not extracted (<3%) by 0.1 M Na 2 SO 4 and 1 M KI solution, which indicated that ReO 4 - and by chemical analogy, unreduced TcO 4 - , was likely incorporated into Fe corrosion products. This inexpensive pFe material may be applied to the sequestration and stabilization of 99 TcO 4 - from contaminated environments and nuclear waste streams., (Copyright © 2019 Elsevier B.V. All rights reserved.)

The title hydrated salt, tris-[hexa-amminecobalt(III)] tetraoxidorhenate(VII) tetra-kis-[hexa-fluorido-rhenate(IV)] hexa-hydrate, arose unexpectedly due to possible contamination of the K 2 ReF 6 starting material with KReO 4 . It consists of octa-hedral [Co(NH 3 ) 6 ] 3+ cation (Co1 site symmetry 1), tetra-hedral [Re VII O 4 ] - anions (Re site symmetry 1) and octa-hedral [Re IV F 6 ] 2- anions (Re site symmetries 1and ). The [ReF 6 ] 2- octa-hedral anions (mean Re-F = 1.834 Å), [Co(NH 3 ) 6 ] 3+ octa-hedral cations (mean Co-N = 1.962 Å), and the [ReO 4 ] - tetra-hedral anion (mean Re-O = 1.719 Å) are slightly distorted. A network of N-H⋯F hydrogen bonds consolidates the structure. The crystal studied was refined as a two-component twin.

Various types of polyoxometalates (POMs) have been synthesized since the 19th century, but their assortment has been mostly limited to Groups 5 and 6 metals. Herein, a new family of POMs composed of a carbon group element as the addenda atoms with two distinct phases, LnPbOClO 4 -1 (Ln = Sm to Ho, Y) and LnPbOClO 4 -2 (Ln = Er and Tm) is reported. Both structures are built from [Ln 6 O 8 ] rare-earth metal hexamers being incorporated in [Pb 18 O 32 ]/[Pb 12 O 24 ] polyplumbites, and unbound perchlorates as charge-balancing anions. Impressively, YPbOClO 4 -1 and ErPbOClO 4 -2 exhibit exceptional uptake capacities (434.7 and 427.7 mg g -1 ) toward ReO 4 - , a chemical surrogate for the key radioactive fission product in the nuclear fuel cycle 99 TcO 4 to a perrhenate-containing complex - , which are the highest values among all inorganic anion-exchange materials reported until now. The sorption mechanism is clearly elucidated and visualized by single-crystal-to-single-crystal structural transformation from ErPbOClO 4 -2 to a perrhenate-containing complex ErPbOReO 4 , revealing a unique ReO 4 - uptake selectivity driven by specific interaction within Pb···O-ReO 3 - bonds., Competing Interests: The authors declare no conflict of interest.

Technology used to produce high purity anhydrous rubidium perrhenate on an industrial scale from high purity perrhenic acid and rubidium nitrate by the ion-exchange method is described in this paper. This material is dedicated to catalyst preparation, therefore, strict purity requirements have to be fulfilled. These are satisfied by combining rubidium ion sorption on an ion exchange column and the subsequent elution of the high purity perrhenic acid solution, followed by crystallization, evaporation, purification, and drying. In the current study, rubidium and rhenium contents were found to be 22.5 wt.% and 55.4 wt.%, respectively, while contaminations were as follows: <2 ppm As, <2 ppm Bi, <5 ppm Ca, <5 ppm Cu, <3 ppm Fe, <10 ppm K, <3 ppm Mg, <5 ppm Mo, <2 ppm Na, <5 ppm Pb, and <3 ppm Zn.

Tetraamminepalladium(II) perrhenate, a double complex salt, has significant utility in PdRe catalyst preparation; however, the vibrational spectra of this readily prepared compound have not been described in the literature. Herein, we present the infrared (IR) and Raman spectra of tetraamminepalladium(II) perrhenate and several related compounds. The experimental spectra are complemented by an analysis of normal vibrational modes that compares the experimentally obtained spectra with spectra calculated using DFT (DMol 3 ). The spectra are dominated by features due to the ammine groups and the ReO stretch in T d ReO 4 - ; lattice vibrations due to the D 4h Pd(NH 3 ) 4 2+ are also observed in the Raman spectrum. Generally, we observe good agreement between ab initio calculations and experimental spectra. The calculated IR spectrum closely matches experimental results for peak positions and their relative intensities. The methods for calculating resonance Raman intensities are implemented using the time correlator formalism using two methods to obtain the excited state displacements and electron-vibration coupling constants, which are the needed inputs in addition to the normal mode wave numbers. Calculated excited state energy surfaces of Raman-active modes correctly predict relative intensities of the peaks and Franck-Condon activity; however, the position of Raman bands are predicted at lower frequencies than observed. Factor group splitting of Raman peaks observed in spectra of pure compounds is not predicted by DFT., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Technetium(Tc)-99 is one of major risk drivers in low level radioactive liquid waste at the U.S. Department of Energy sites. Cementitious waste technology (CWT) has been considered immobilizing pertechnetate, Tc(VII)O 4 , in brine and alkaline waste solutions, as Tc(IV) oxides and/or sulfides with the use of reducing agents like slag. In this study, zero valent iron (ZVI) was evaluated as a potential reducing agent in CWT as a function of pH and [nitrate] (0-0.1M) using perrhenate, Re(VII)O - , in brine and alkaline waste solutions, as Tc(IV) oxides and/or sulfides with the use of reducing agents like slag. In this study, zero valent iron (ZVI) was evaluated as a potential reducing agent in CWT as a function of pH and [nitrate] (0-0.1M) using perrhenate, Re(VII)O 4 - , as an analogue for Tc(VII)O 4 - . Batch Re(VII)O 4 - sorption experiments in conjunction with X-ray absorption spectroscopic analysis showed that the Re(VII) sorption occurred via the reductive precipitation of Re(IV)O 2 (s) and the extent of sorption decreased with increasing pH from 8 to 10. Interestingly, pseudo 2nd order kinetic rates increased with increasing [nitrate] which was attributed to co-adsorption of NH 4 + (i.e., a reaction product of reduced nitrate by ZVI), facilitating electrostatic attraction towards ReO 4 - under alkaline conditions. Considering the thermodynamically favorable reduction of Tc(VII) over Re(VII), ZVI might have potential for improving the reduction capacity of the current CWT., (Copyright © 2016 Elsevier B.V. All rights reserved.)

In this work, a biochar was prepared from bamboo (Acidosasa edulis) shoot shell through slow pyrolysis (under 300-700 °C). Characterization with various tools showed that the biochar surface was highly hydrophobic and also had more basic functional groups. Batch sorption experiments showed that the biochar had strong sorption ability to perrhenate (a chemical surrogate for pertechnetate) with maximum sorption capacity of 46.46 mg/g, which was significantly higher than commercial coconut shell activated carbon and some adsorbents reported previously. Desorption experiments showed that more than 94% of total perrhenate adsorbed could be recovered using 0.1 mol/L KOH as a desorption medium. Pearson correlation analysis showed that the recovery of perrhenate by the biochars was mainly through surface adsorption mechanisms involving both high hydrophobicity and high basic sites of biochar surface., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

2-pyridyl thiourea and methyl-2-pyridyl ketoxime based perrhenate, Re(VII), UV-vis spectrophotometric methods were evaluated in nitrate and bicarbonate solutions ranging from 0.001 M to 0.5 M. Standard curves at [Re]=2.5-50 mg L(-1) for the Re(IV)-thiourea and the Re ketoxime complexes were constructed at 405 nm and 490 nm, respectively. Detection of limits for N-(2-pyridyl) thiourea and methyl-2-pyridyl ketoxime methods in ultrapure water are 3.06 mg/L and 4.03 mg/L, respectively. Influences of NaHCO3 and NaNO3 concentration on absorbance spectra, absorptivity, and linearity were documented. For both methods, samples in ultrapure water and NaHCO3 have an R(2) value>0.99, indicating strong linear relationships. Statistical analysis supports that NaHCO3 does not affect linearity between standards for either method. NaNO3 causes major interference with the ketoxime method above 0.001 M NaNO3. Data provides information for practical use of Re spectrophotometric methods in environmental media that is high in bicarbonate and nitrate., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Quaternary ammonium perrhenates were applied as catalyst to promote the hydrolysis of cellulose in 1-allyl-3-methylimidazolium chloride ([Amim]Cl). The quaternary ammonium perrhenates displayed good catalytic performance for cellulose hydrolysis. Water was also proven to be effective to promote cellulose hydrolysis. Accordingly, 97% of total reduced sugar (TRS) and 42% of glucose yields could be obtained under the condition of using 5mol% of tetramethyl ammonium perrhenate as catalyst, 70μL of water, ca. 0.6mmol of microcrystalline cellulose (MCC) and 2.0g of [Amim]Cl as solvent under microwave irradiation for 30min at 150°C (optimal conditions). The influence of quaternary ammonium cation on the efficiency of cellulose hydrolysis was examined based on different cation structures of perrhenates. The mechanism on perrhenate catalyzed cellulose hydrolysis is also discussed, whereas hydrogen bonding between ReO4 anion and hydroxyl groups of cellulose is assumed to be the key step for depolymerization of cellulose., (Copyright © 2015. Published by Elsevier Ltd.)