Highly efficient catalytic transfer hydrogenation for the conversion of nitrobenzene to aniline over PdO/TiO2: The key role of in situ switching from PdO to Pd.

The reduction of nitrobenzene to aniline is very important for both pollution control and chemical synthesis. Nevertheless, difficulties still remain in developing a catalytic system having high efficiency and selectivity for the production of aniline. Herein, it was found that PdO nanoparticles highly dispersed on TiO2 support (PdO/TiO2) functioned as a highly efficient catalyst for the reduction of nitrobenzene in the presence of NaBH4. Under favorable conditions, 95% of the added nitrobenzene (1 mmol/L) was reduced within 1 min with an ultra-low apparent activation energy of 10.8 kJ/mol by using 0.5%PdO/TiO2 as catalysts and 2 mmol/L of NaBH4 as reductants, and the selectivity to aniline even reached up to 98%. The active hydrogen species were perceived as dominant species during the hydrogenation of nitrobenzene by the results of isotope labeling experiments and ESR spectroscopic. A mechanism was proposed as follows: PdO activates the nitro groups and leads to in-situ generation of Pd, and the generated Pd acts as the reduction sites to produce active hydrogen species. In this catalytic system, nitrobenzene prefers to be adsorbed on the PdO nanoparticles of the PdO/TiO2 composite. Subsequently, the addition of NaBH4 results in in-situ generation of a Pd/PdO/TiO2 composite from the PdO/TiO2 composite, and the Pd nanoclusters would activate NaBH4 to generate active hydrogen species to attack the adsorbed nitro groups. This work will open up a new approach for the catalytic transfer hydrogenation of nitrobenzene to aniline in green chemistry.

Magnetically separable Pd-iron-oxides composites as highly efficient and recyclable catalysts for ultra-rapid degradation and debromination of polybrominated diphenyl ethers.

When precious nano-metals are used as environmental catalysts, it is important to tune the particle sizes and the reusability of the nano-metals for achieving their highly efficient catalytic performance at a low cost. In the present work, magnetic iron oxides (FeOx-Y) nanoparticles were pre-prepared as supports of nano-metals, where Y represented the mole percentage of Fe(III) in the total iron (Y ≥ 50 %). FeOx-Y (support), PdCl42- (Pd source) and NaBH4 (reducing agent) were added into the organic pollutant solution containing 2,2',4,4'-tetrabromodiphenyl ether (BDE47). After the NaBH4 was added, the followed reaction realized not only the rapid in-situ preparation of a Pd-loaded FeOx-Y composite catalyst (Pd-FeOx-Y), but also the ultra-fast and complete debromination of BDE47 within 30 s. Comparing the case without adding FeOx-Y, the debromination efficiency of BDE47 was much promoted in the presence of FeOx-Y. The support-induced enhancing effect on the catalytic ability of Pd nanoparticles was improved by increasing the Fe(III) content in the support, being attributed to the much more hydroxyl groups on the support surface. Considering both the catalytic and recovery abilities of Pd-FeOx-Y, Pd-FeOx-75 was the optimal choice because it could be magnetically recovered and re-used for multiple cycles with high catalytic activities. The presently developed "catalyst preparation-pollutant degradation" one-pot system could be applied to conduct complete debromination of all the PBDEs.

Chemical reductive technologies for the debromination of polybrominated diphenyl ethers: A review.

Polybrominated diphenyl ethers (PBDEs) are widely used as brominated flame retardants, which had attracted amounts of attention due to their harmful characteristics of high toxicity, environmental persistence and potential bioaccumulation. Many chemical reductive debromination technologies have been developed for the debromination of PBDEs, including photolysis, photocatalysis, electrocatalysis, zero-valent metal reduction, chemically catalytic reduction and mechanochemical method. This review aims to provide information about the degradation thermodynamics and kinetics of PBDEs and summarize the degradation mechanisms in various systems. According to the comparative analysis, the rapid debromination to generate bromine-free products in an electron-transfer process, of which photocatalysis is a representative one, is found to be relatively difficult, because the degradation rate of PBDEs depended on the Br-rich phenyl ring with the lowest unoccupied molecular orbital (LUMO) localization. On the contrary, the complete debromination occurs easily in other systems with active hydrogen atoms as the main reactive species, such as chemically catalytic reduction systems. The review provides the knowledge on the chemical reductive technique of PBDEs, which would greatly help not only clarify the degradation mechanism but also design the more efficient system for the rapid and deep debromination of PBDEs in the future.

Mechanochemical Preparation of Edge-Selectively justify Hydroxylated Graphene Nanosheets Using Persulfate via a Sulfate Radical-Mediated Process.

The production of water-dispersed graphene with low defects remains a challenge. The dry ball milling of graphite with additives produces edge-selectively functionalized graphene. However, the "inert" additives require a long milling time and cause inevitable in-plane defects. Here, the mechanochemical reaction of graphite with persulfate solved the above drawback and produced edge-selectively hydroxylated graphene (EHG) nanosheets through a 2 h ball-milling and a subsequent 0.5 h sonication. The mechanochemical cleavage of persulfate yielded SO4 ⋅- to spontaneously oxidize graphite to form the carbon radical cations selectively at edges, followed by hydroxylation with water of moisture. Because the O-O bond dissociation energy of persulfate is 20 % of the graphitic C-C bond, the rather low milling energy allowed the hydroxylation of graphite at edges with nearly no in-plane defects. The obtained EHG showed high water-dispersibility and excellent photothermal and electrochemical properties, thereby opening up a new door to fabricate graphene-based composites.

Advanced oxidative degradation of sulfamethoxazole by using bowl-like FeCuS@Cu2S@Fe0 catalyst to efficiently activate peroxymonosulfate.

A novel hierarchical bowl-like FeCuS@Cu2S@Fe0 nanohybrid catalyst (B-FeCuS@Cu2S@Fe0) was synthesized for removing sulfamethoxazole (SMX) through catalytic activation of peroxymonosulfate (PMS). It was found that this catalyst exhibited excellently high catalytic activity. Under optimized reaction conditions, all the added SMX (12 mg/L) could be completely degraded within 5 min. The SMX degradation followed pseudo first order kinetics with a rate constant k of 0.89 min-1, being 1.38, 4.51, 8.99 and 35.6 times greater than that of other catalysts including Fe0 (0.644 min-1 in the very initial stage), bowl-like iron-doped CuS (B-FeCuS, 0.197 min-1), bowl-like CuS (B-CuS, 0.099 min-1) and Cu2O (0.025 min-1), respectively. During the degradation, several reactive oxygen species (·OH, SO4·- and 1O2) were generated with ·OH as the main one as confirmed by electron paramagnetic resonance analysis. The SMX degradation in the present system included both radical and non-radical mediated processes. A possible mechanistic insight of the PMS activation by bowl Fe0 decorated CuS@Cu2S-based catalyst was proposed according to X-ray photoelectron spectroscopic (XPS) analysis, and the degradation pathway of SMX was speculated by monitoring the degradation intermediates with liquid chromatography coupled with mass spectrometry (LC-MS).

Complete mechanochemical defluorination of perfluorooctanoic acid using Al2O3 and Al powders through matching electron-mediated reduction with decarboxylation.

This work reports a mechanochemical (MC) method for complete defluorination of perfluorooctanoic acid (PFOA) by using Al and Al2O3 as milling agents. Both the Al/Al2O3 molar ratio ( [Formula: see text] ) and the pre-thermal treatment of Al2O3 strongly influenced the defluorination of PFOA. When commercial γ-Al2O3 was pre-treated at 1200 °C, the use of Al and heat-treated γ-Al2O3 with [Formula: see text] of 1: 1 led to PFOA defluorination of 100% after ball milling for 26 min at 350 rpm, being much higher than those (8.3%-58.1%) for using singlet milling agents or binary milling agents containing γ-Al2O3 pre-heated at temperatures lower than 700 °C. It was clarified that the carboxylate-mediated adsorption of PFOA on Al2O3 was essential for the MC decarboxylation as a degradation initiation step, and the in-situ generated electron on milled Al consequently caused the reductive dissociation of C-F bonds in the decarboxylation intermediate. A larger [Formula: see text] increased the in-situ electron generation rate (re), and a higher heat-treatment temperature decreased OH-/H2O adsorbed on Al2O3 to low the PFOA decarboxylation rate (rdec). The re/rdec ratio determined defluorination pathways, and the percentage of the defluorination of PFOA in its total degradation including the generation of any degradation intermediates increased linearly with increasing re/rdec.

Predicting adsorption of micropollutants on non-functionalized and functionalized multi-walled carbon nanotubes: Experimental study and LFER modeling.

It is of great importance to predict the adsorption of micropollutants onto CNTs, which is not only useful for exploring their potential adsorbent applications, but also helpful for better understanding their fate and risks in aquatic environments. This study experimentally examined the adsorption affinities of thirty-one micropollutants on four multi-walled CNTs (MWCNTs) with different functional groups (non-functionalized, -COOH, -OH, and -NH2). The properties of each adsorbent were predicted based on the linear free energy relationship (LFER) model. The experimental results showed that MWCNTs-COOH has remarkable adsorption affinities for positively charged compounds (1.996-3.203 log unit), whereas MWCNTs-NH2 has high adsorption affinities for negatively charged compounds (1.360-3.073 log unit). Regarding neutral compounds, there was no significant difference in adsorption affinities of all types of CNTs. According to modeling results, the adsorption affinity can be accurately predicted using LFER models with R2 in the range of 0.81-0.91. Based on the developed models, the adsorption mechanism and contribution of individual intermolecular interactions to the overall adsorption were interpreted. For non-functionalized MWCNTs, molecular interactions induced by molecular volume and H-bonding basicity predominantly contribute to adsorption, whereas for functionalized MWCNTs, the Coulombic interaction due to the charges is an important factor.

Influence of Inclination of Welding Torch on Weld Bead during Pulsed-GMAW Process.

This work is about the influence rule of inclination of welding torch on the formation and characteristics of weld bead during the pulsed-gas metal arc welding (GMAW) process based on the robotic operation. The inclination of welding torch was an important operation condition during the pulsed-GMAW process, because it can affect the formation and quality of weld bead, which was the output of the process. In this work, the different inclination modes and values were employed to conduct actual welding experiments, and some influence rules can be obtained according to examine the surface topography and cross section. Then, to obtain further rules, serious measurements for the geometry characteristic parameters were conducted and corresponding curve fitting equations between inclination angles and the bead width, penetration and bead height were obtained, and the largest error of these curve fitting equations was 0.117 mm, whose corresponding mean squared error (MSE) was 0.0103. Corresponding verification experiments validated the effectiveness of the curve fittings and showed the second order polynomials were proper, and the largest errors between measurements and curve fitting equations for inclination angle under backward mode were larger than those under forward mode, and were 0.10 mm and 0.15 mm, respectively, which corresponded to the penetration and were below 10%, therefore the equations can be used to predict the geometry of the weld bead. This work can benefit the process and operation optimization of the pulsed-GMAW process, both in the academic researches and actual industrial production.

Ion chromatographic determination of total bromine in electronic devices in conjunction with a catalytic reduction debromination pretreatment.

A new determination method for total bromine in electronic devices was developed by using ultrasound assisted extraction, copper-catalyzed reductive debromination and ion chromatography (UAE-RD-IC). It was found that all the added brominated flame retardants (polybrominateddiphenyl ethers, polybrominated biphenyls, tetrabromobisphenol A, and hexabromocyclododecane) could be completely debrominated by using copper-based catalysts and reducing agent N2H4•H2O. The complete debromination of brominated flame retardants released all of their bromine in the form of bromide ions, which could be determined by ion chromatography. After the extraction parameters were optimized by achieving the maximum IC signal in the certified reference material GBW(E) 082725, the UAE-RD-IC method was established for the determination of total bromine in solid samples. By analyzing the certified reference material, the Br content was obtained as 695.3 ±â€¯16.0 mg kg-1, being well consistent with its standard value (694.54 ±â€¯30.63 mg kg-1). The relative standard deviation (RSD) of five parallel determinations was 1.7%, indicating the good repeatability of the developed method. The proposed method was further applied to analyze the samples of cables and computer mouse shells. For all these practical samples, the Br contents obtained by the UAE-RD-IC method were in good agreement with that obtained by the standard oxygen bomb combustion-IC method. It was noted that the new method has a detection limit of Br of about 20 mg kg-1, being much lower than that (75 mg kg-1) of the traditional oxygen bomb combustion-IC method for total bromine detection. Therefore, the proposed method was qualified as a practical method to measure total bromine content in actual electronic devices with good analytical performances of accuracy, precision and sensitivity.

A functional Au array SERS chip for the fast inspection of pesticides in conjunction with surface extraction and coordination transferring.

The fast inspection of the pesticide residues on fruits and vegetables requires the development of facile, sensitive and accurate methods. Surface enhanced Raman scattering (SERS) is a promising way to provide a fast inspection method, which requires significant improvements in the reproducibility and feasibility. In the present work, an SERS method was developed for the fast inspection of pesticides on fruit peels in conjunction with surface extraction and coordination transferring. In this new method, the residual pesticides were directly extracted from fruit peels with an appropriate extraction solution and then quantitatively transferred onto an organic solvent-compatible Au array SERS chip through the strong chemical interactions between the heteroatoms in the pesticides and the gold surface. The functional SERS chip was fabricated by the interfacial assembly of an Au array on a membrane, which produced dense and uniformly distributed SERS hot spots and enabled compatibility with random curvature surfaces and handheld Raman spectrometers. As a proof of concept, sulfur atoms containing thiram on apples were detected at a concentration as low as 5 ng cm-2 with good reproducibility (relative standard deviation lower than 10%). The strong interactions between the sulfur atoms and gold surface during the coordination transferring process were confirmed by the enhanced vibrations of the specified bands occurring in both the Raman and IR spectra. This surface extraction-coordination transferring-based method holds wide applicability for heteroatom-containing pesticides, as demonstrated by the detection of various S- and P-containing pesticides.

Effects of Operational Parameters on the Characteristics of Ripples in Double-Pulsed GMAW Process.

This study focuses on the characteristics of the ripples of the weld bead formed during the double-pulsed gas metal arc welding (DP-GMAW) process. As a special output of the process, ripples include many useful information and can reflect the quality of the welding process. The work analyzed the operational characteristics of the DP-GMAW process based on robot operation which used the latest twinpulse XT DP control process, and then selected five key operational parameters, such as average current, welding speed, twin pulse frequency, twin pulse relation, and twin pulse current change in percent, to explore their effects on the formation and characteristics of ripples. A reliable method of measuring the distance of the ripples was used to provide convincing data. According to a series of experimental observations and analyses, the distance of ripples and appearance under different conditions were obtained. Also, curve fitting equations between each operational parameter and corresponding distances of ripples was obtained. To testify the effectiveness of the curve fitting equations, corresponding verifying experiments were conducted, and the results showed that all the errors were below 10%. In addition, the different levels of the operational parameters on the formation and characteristics of ripples were provided. This work can be a reference for the process and quality control improvement for the DP-GMAW process.

Complete Defluorination and Mineralization of Perfluorooctanoic Acid by a Mechanochemical Method Using Alumina and Persulfate.

Perfluorooctanoic acid (PFOA) is a persistent organic pollutant that has received concerns worldwide due to its extreme resistance to conventional degradation. A mechanochemical (MC) method was developed for complete degradation of PFOA by using alumina (Al2O3) and potassium persulfate (PS) as comilling agents. After ball milling for 2 h, the MC treatment using Al2O3 or PS caused conversion of PFOA to either 1-H-1-perfluoroheptene or dimers with a defluorination efficiency lower than 20%, but that using both Al2O3 and PS caused degradation of PFOA with a defluorination of 100% and a mineralization of 98%. This method also caused complete defluorination of other C3∼C6 homologues of PFOA. The complete defluorination of PFOA attributes to Al2O3 and PS led to the weakening of the C-F bond in PFOA and the generation of hydroxyl radical (•OH), respectively. During the MC degradation, Al2O3 strongly anchors PFOA through COO--Al coordination and in situ formed from Lewis-base interaction and PS through hydrogen bond. Meanwhile, mechanical effects induce the homolytic cleavage of PS to produce SO4•-, which reacts with OH group of Al2O3 to generate •OH. The degradation of PFOA is initiated by decarboxylation as a result of weakened C-COO- due to Al3+ coordination. The subsequent addition of •OH, elimination of HF, and reaction with water induce the stepwise removal of all carboxyl groups and F atoms as CO2 and F-, respectively. Thus, complete defluorination and mineralization are achieved.

Reductive Debromination of Polybrominated Diphenyl Ethers: Dependence on Br Number of the Br-Rich Phenyl Ring.

Reductive debromination has been widely studied for the degradation of polybrominated diphenyl ethers (PBDEs), although the reaction mechanisms are not so clear. In the present study, the photocatalytic degradation and debromination of ten PBDEs were carried out with CuO/TiO2 nanocomposites as the photocatalyst under an anaerobic condition. The pseudo-first-order rate constants were obtained for the photocatalytic debromination of PBDEs, and their relative rate constants ( kR) were evaluated against kR= 1 for BDE209. Unlike the generally accepted summary that kR is dependent on the total Br number ( N) of PBDEs, kR is found to depend on the Br number on a phenyl ring with more Br atoms than the other one. In other words, a phenyl ring substituted by more Br is more reactive for the reductive debromination. The calculated LUMO energies ( ELUMO) of all PBDEs are well correlated to the more reactive phenyl ring with more Br, compared with the N of two phenyl rings. The result was explained by LUMO localization on the Br-rich phenyl ring, suggesting that the reductive debromination occurs on the phenyl ring.

Efficient degradation of organic pollutants by low-level Co2+ catalyzed homogeneous activation of peroxymonosulfate.

Dissolved cobalt ions (Co2+) are an excellent catalyst for activating peroxymonosulfate (PMS) to generate SO4- for the degradation of organic pollutants, but fairly high level of Co2+ is generally required, which may cause secondary pollution due to its toxicity. Herein, we demonstrate a novel strategy for this catalytic oxidation treatment in which the required Co2+ addition is very small, being much less than the emission limit of 17 µmol L-1. This new strategy is based on the much enhanced catalytic effect by the addition of small organic acids (SOAs). In a typical case, all the added diclofenac (30 µmol L-1) was degraded in 20 min by using 2 µmol L-1 Co2+, 0.15 mmol L-1 PMS and 0.5 mmol L-1 acetate with a degradation rate constant of 0.482 min-1, which was about 10 times higher than that (0.048 min-1) of equivalent Co2+-PMS system without acetate. The formation of SO4- was greatly enhanced by introducing acetate, and this novel system is universal for enhanced degradation of various organic pollutants. Similarly, formate, propionate, and butyrate also exhibited enhancing effects on the catalytic ability of Co2+. The enhancement mechanism of SOAs on catalytic activation of PMS by low-level Co2+ was also proposed.

Efficient degradation of drug ibuprofen through catalytic activation of peroxymonosulfate by Fe3C embedded on carbon.

Ibuprofen (IBU), a nonsteroidal anti-inflammatory drug, is becoming an important member of pharmaceuticals and personal care products (PPCPs) as emerging pollutants. To degrade IBU, magnetic Fe3C nanoparticles embedded on N-doped carbon (Fe3C/NC) were prepared as a catalyst by a sol-gel combustion method. As characterized, the Fe3C/NC nanoparticles were composed of a NC nano-sheet and capsulated Fe3C particles on the sheet. The Fe3C/NC nanoparticles were confirmed an efficient catalyst for peroxymonosulfate (PMS) activation to generate sulfate radicals (SO4•-), single oxygen (1O2) and hydroxyl radicals (•OH) toward the degradation of IBU. The added IBU (10 mg/L) was almost completely removed in 30 min by using 0.1 g/L Fe3C/NC and 2 g/L PMS. The catalyst was confirmed to have good ability and excellent reusability through leaching measurements and cycle experiments. A catalytic mechanism was proposed for the catalytic activation of PMS on Fe3C/NC, which involves both Fe3C reactive sites and N-doped carbon matrix as reactive sites in Fe3C/NC. Moreover, the degradation pathway of IBU in the Fe3C/NC-PMS system was proposed according to the detections of degradation intermediates.

Highly efficient catalysis of chalcopyrite with surface bonded ferrous species for activation of peroxymonosulfate toward degradation of bisphenol A: A mechanism study.

Chalcopyrite nanoparticles (CuFeS2 NPs) with abundant surface bonded ferrous were successfully prepared, characterized and used as a catalyst for peroxymonosulfate (PMS) activation and BPA degradation. The effect of reaction parameters such as initial pH, catalyst load, PMS concentration, initial BPA concentration and reaction temperature on BPA degradation in CuFeS2-PMS system was systematically investigated. As a bimetallic sulfide, CuFeS2 exhibits ultra-high activity for PMS activation compared with Cu2S, FeS2, CuFeO2 and Co3O4. It was found that by co-use of 0.1 g L-1 CuFeS2 and 0.3 mmol L-1 PMS, 20 mg L-1 of BPA was almost completely degraded (99.7%) and reached a mineralization rate of 75% within 20 min. The highly catalytic activity of CuFeS2 is closely related to two aspects: one is that S2- in the catalysts promotes the cycling of Fe3+/Fe2+ and Cu2+/Cu+ cycles on the surface, and the other is the synergistic effect of Fe3+/Fe2+ and Cu2+/Cu+ cycles in the PMS activation. These interesting findings shed some new insight on the development of metal sulfides for the oxidative treatment of organic contaminants.

Ultrarapid and Deep Debromination of Tetrabromodiphenyl Ether over Noble-Metal-Free Cu/TiO2 Nanocomposites under Mild Conditions.

Fast and deep debromination of polybrominated diphenyl ethers (PBDEs) under mild conditions is a challenge in the field of pollution control. A strategy was developed to achieve it by exploiting Cu/TiO2 composites as a noble-metal-free catalyst. Toward the debromination of 2,2',4,4'-tetrabromodiphenyl ether (BDE47) as a typical PBDE, the use of Cu/TiO2 as a catalyst and hydrazine hydrate (N2H4·H2O) as a reducing agent yielded a degradation removal of 100% and a debromination efficiency of 87.7% in 3 s. A complete debromination of BDE47 at 1500 mg L-1 was possible by successively adding N2H4·H2O. A debromination pathway involving active H atom species was proposed for the catalytic transfer hydrogenation (CTH) of PBDEs according to the identified degradation intermediates. A mechanism was further clarified by density functional theory calculations: electrons are delivered from N2H4·H2O to the metallic Cu atom via a coordination of N in N2H4·H2O with Cu atoms. The electron-trapped Cu atom interacts with adsorbed BDE47 to form a transition complex, and then the debromination of this complex occurs on the surface of Cu nanoparticles due to the hydrogen donation of N2H4·H2O through the CTH process. The new method provides a highly efficient method to remove brominated pollutants.

Variable-valence metals catalyzed solid NaBiO3 nanosheets for oxidative degradation of norfloxacin, ofloxacin and ciprofloxacin: Efficiency and mechanism.

In this work, we report metal ions catalyzed oxidative degradation of three typical fluoroquinolones norfloxacin (NOR), ofloxacin (OFL) and ciprofloxacin (CIP) by using NaBiO3 nanosheets. It was found that variable-valence metal ions such as Cu2+, Fe2+, Mn2+, Ce3+, Ag+ and Co2+ could obviously enhanced degradation of NOR, OFL and CIP by NaBiO3. The pseudo-first-order kinetic rate for the degradation of 20 µmol L-1 NOR by NaBiO3 (2 mmol L-1) in the presence of 0.1 mmol L-1 Cu2+, Fe2+, Mn2+, Ce3+, Ag+ and Co2+ was 0.021, 0.084, 0.019, 0.23, 0.25 and 0.28 min-1, 2.1, 8.4, 19, 23, 25 and 28 times that by NaBiO3 without any metal ions. In comparison, Ca2+ and Fe3+ exhibited no obviously promotive or depressive effect for the degradation of NOR by NaBiO3. Singlet oxygen (1O2) was suggested as the main reactive species from NaBiO3 in the presence of metal ions by electron spin resonance technology and radicals scavenging experiments. The evolution of NaBiO3 was tracked with scanning electron microscope, energy dispersive spectrometer, X-ray diffraction, X-ray photoelectron spectroscopy and Raman spectroscopy. It was found that the metal ions were embedded into the crystal structure of NaBiO3 through ion-exchange between Na in NaBiO3 and metal ions. In the subsequent step, an electron transformation from lattice oxygen to Bi(V) sites was mediated by embedded variable-valence metal species, resulting in an enhanced generation of 1O2 from the crystal structure of NaBiO3. These results can shed light on the application of NaBiO3 for the organic pollutant decontamination.

Polyaniline Nanofibers: Their Amphiphilicity and Uses for Pickering Emulsions and On-Demand Emulsion Separation.

The wetting property of nanomaterials is of great importance to both fundamental understanding and potential applications. However, the study on the intrinsic wetting property of nanomaterials is interfered by organic capping agents, which are often used to lower the surface energy of nanomaterials and avoid their irreversible agglomeration. In this work, the wetting property of the nanostructured polyaniline that requires no organic capping agents is investigated. Compared to hydrophilic granular particulates, polyaniline nanofibers are amphiphilic and have an excellent capability of creating Pickering emulsions at a wide range of pH. It is suggested that polyaniline nanofibers can be easily wetted by water and oil. Furthermore, the amphiphilic polyaniline nanofibers as building blocks can be used to construct filtration membranes with a small pore size. The wetting layer of the continuous phase of emulsions in the porous nanochannels efficiently prevents the permeation of the dispersed phase, realizing high-efficiency on-demand emulsion separation.

Rapid Surface Enhanced Raman Scattering (SERS) Detection of Sibutramine Hydrochloride in Pharmaceutical Capsules with a ß-Cyclodextrin- Ag/Polyvivnyl Alcohol Hydrogel Substrate.

Sibutramine hydrochloride (SH) is a banned weight-loss drug, but its illegal addition to health products is still rampant. This suggests a very urgent need for a fast and precise detection method for SH. Surface Enhanced Raman Scattering (SERS) is a promising candidate for this purpose, but the weak affinity between SH and bare metal limits its direct SERS detection. In the present work, ß-cyclodextrin was capped in situ onto the surface of Ag nanoparticles to function as a scaffold to capture SH. The obtained Ag nanoparticles were encapsulated into polyvinyl alcohol (PVA) to fabricate a SERS active hydrogel with excellent reproducibility. A facile SERS strategy based on such substrate was proposed for trace SH quantification with a linear range of 7.0-150.0 µg·mL-1, and a detection limit low to 3.0 µg·mL-1. It was applied to analyze seven types of commercial slimming capsules with satisfactory results, showing good prospect for real applications.