JOURNAL OF HAZARDOUS MATERIALS
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2019
·
IF 7.65
Songxue Wang,Shanshan Gao,Jiayu Tian,Qiao Wang,Tianyu Wang,Xiujuan Hao,Fuyi Cui
A direct one-step calcination preparation of CuO catalyst (CuO-3) using polyethylene glycol (PEG) as nonionic polymeric structure directing agent was developed for activation of peroxymonosulfate (PMS). The morphological and physicochemical properties of the CuO-3 were characterized and the catalytic activity for degradation of organic pollutants was evaluated. The resultant CuO-3 with significantly enhanced surface area exhibited excellent catalytic performance of phenolic organic pollutants degradation. The reaction mechanism of the PMS/CuO system was systematically investigated with a series of radical quenching tests and the analysis of electron paramagnetic resonance (EPR) spectroscopy. Quite different from traditional hydroxyl radicals ( OH) and sulfate radical (SO 4 − ) based advanced oxidation processes, singlet oxygen ( 1 O 2 ) was identified as the dominate reactive species responsible for the degradation of organic pollutants. Moreover, the main formation pathway of 1 O 2 was also investigated. The results indicated that the superoxide radical (O 2 − ) was involved in the generation of 1 O 2 as a crucial precursor. Also, the PMS/CuO-3 system exhibited satisfactory stability and reusability under neutral conditions as well as high removal of organic pollutants in the presence of inorganic anions. This work not only provides a novel and stable preparation method for CuO catalyst, but also gives a deeper insight into the mechanisms of PMS activation by CuO.
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WATER RESEARCH
·
2019
·
IF 7.913
Xinran Zhang,Pengfei Ren,Weiguang Li,Yu Lei,Xin Yang,Ernest R. Blatchley
The presence of ammonium (NH 4 + ) in drinking water treatment results in inhibition of disinfection efficiency and formation of nitrogenous disinfection by-products. Our previous study found monochloramine (NH 2 Cl) photolysis under 254 nm UV irradiation can be effective for removal of NH 4 + ; however, the mechanisms of NH 4 + degradation in this process were unknown. The kinetics and fundamental radical chemistry responsible for NH 4 + removal in the UV/NH 2 Cl process were investigated in this study. The results showed that the pseudo first-order rate constant for NH 4 + degradation in the UV/NH 2 Cl process ranged between 3.6 × 10 −4 to 1.8 × 10 −3 s −1 . Solution pH affected radical conversion and a higher NH 4 + degradation efficiency was achieved under acidic conditions. The effects of chloride were limited; however, the presence of either bicarbonate or natural organic matter scavenged radicals and inhibited NH 4 + removal. NH 2 Cl photolysis generated an aminyl radical (NH 2 • ) and a chlorine radical (Cl • ) that further transformed to a chlorine dimer (Cl 2 •- ) and a hydroxyl radical (HO • ). The second-order rate constants for Cl • and Cl 2 •- reacting with NH 4 + were estimated as 2.59 × 10 8 M −1 s −1 and 3.45 × 10 5 M −1 s −1 at pH 3.9, respectively. Cl • , Cl 2 •- , and HO • contributed 95.2%, 3.5%, and 1.3% to NH 4 + removal, respectively, at the condition of 3 mM NH 2 Cl and pH 7.5. Major products included nitrite and nitrate, possibly accompanied by nitrogen-containing gases. This investigation provides insight into the photochemistry of NH 4 + degradation in the UV/NH 2 Cl process and offers an alternative method for drinking water production.
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INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
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2019
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IF 4.346
Hao Feng,Xun Zhu,Rong Chen,Qiang Liao
In this work, the gas consumption characteristics were investigated by gas-liquid two-phase flow in a capillary microreactor using the catalytic hydrogenation of nitrobenzene as a reference gas-liquid reaction. Image processing technique was used to measure the gas consumption from the variation in the gas phase through the recorded images. The influence of the inlet nitrobenzene concentration and both the gas and liquid flow rates on the gas consumption and the microreactor performance was investigated. The experimental results showed that there existed a discrete hydrogen consumption process, i.e. the waiting stage and inburst stage. Hydrogen consumption was mainly attributed to the waiting stage in each bubble formation cycle. Minimal hydrogen was consumed in the inburst stage. In addition, there was a clear difference between the H 2 consumption rates under each operating condition. As the gas flow rate and nitrobenzene concentration increased, the H 2 consumption rate was gradually decreased with each successive formation cycle. Although the consumption rate was gradually reduced with each successive formation cycle with increasing liquid flow rate, the downward trend became increasingly gradual and clearly stabilized at 20 μL/min. The microreactor performances under different operating conditions were also investigated. The results showed that the nitrobenzene conversion was first increased and then gradually decreased with increasing the gas flow rate, whereas it was gradually decreased with increasing both the liquid flow rate and nitrobenzene concentration. The results obtained in this work are beneficial for not only understanding process intensification but also promoting the use of microreactor technology in additional industrial applications.
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CHEMICAL ENGINEERING JOURNAL
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2019
·
IF 8.355
Xinfeng Chen,Congming Sun,Yang Liu,Long Yu,Kui Zhang,Abdullah M. Asiri,Hadi M. Marwani,Hua Tan,Yuejie Ai,Xiangke Wang,Suhua Wang
As a new family of fluorescent materials, all inorganic perovskite quantum dots (PQDs) CsPbX 3 (Cl, Br, I) have attracted rising attention due to their intrinsic optical superiorities and potential applications in various fields. This work takes advantage of the bright fluorescence of PQDs and the strong electrophilic properties of picric acid (PA) to construct an analytical method for sensitive and selective discrimination of PA against other nitroaromatic explosives, and the limit of detection is as low as 0.8 nM. The quenching mechanism was elucidated as the formation of electrostatic complex and the electron transfer between PA and PQDs. To facilitate visual and on-site detection, the CsPbBr 3 PQDs were printed onto microfiltration membrane by inkjet printing to fabricate test papers for rapid and on-site detections of explosive and pollutant PA, showing a great research prospect in the detection of ultratrace PA at different sites.
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CHEMICAL ENGINEERING JOURNAL
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2019
·
IF 8.355
Jianhua Zheng,Lei Zhang
In this study, a novel 3D magnetic Co 3 O 4 @CoO/g-C 3 N 4 ternary hybrid possessing double Z-scheme mechanism has been designed and architected by wet-impregnation and subsequent controlled oxidation process . In the Co 3 O 4 @CoO/g-C 3 N 4 ternary hybrid system, g-C 3 N 4 ultrathin nanopieces uniformly dispersed on each nanopetal of peony flower cobalt oxides , which not only helps to enhance the light absorption efficiency and avoid the aggregation but also readily promote the separation of photo-induced charge. Benefiting from the special hierarchical architecture, large open space between nanopetals and the synergistic effect between cobalt oxides and g-C 3 N 4 , when employed as photocatalyst for reduction of nitrobenzene (NB) and degradation of tetracycline (TC), 3D Co 3 O 4 @CoO/g-C 3 N 4 exhibited superior redox reactivity. Notably, a double Z-scheme heterojunctions and well matched band structures could further facilitate effective charge transfer. Meanwhile, Co 3 O 4 @CoO/g-C 3 N 4 ternary hybrids also exhibited excellent magnetic separation property and super cycling stability after four cycles, which make it a promising candidate as a visible light photocatalyst for practical application.
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RSC Advances
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2019
·Vol. 9
·期 41
·23560-23569
·
IF 3.049
Jian Liu,Rong Chen,Xun Zhu,Qiang Liao,Dingding Ye,Biao Zhang,Ming Liu,Gang Chen,Kun Wang
In this study, we proposed a Pd–polyelectrolyte multilayer (PEM) hybrid film grafted on the polydopamine coated interior wall of a microreactor for nitrobenzene hydrogenation. Here, Pd nanoparticles were in situ synthesized in the PEMs consisting of poly(diallyldimethylammonium chloride) and poly(styrene sulfonate) via a two-stage ion-exchange and reduction process. The preparation process was monitored by UV-vis spectroscopy, which confirmed the formation of Pd in the PEM film. In addition, SEM and ICP-OES results indicated that the Pd content in the PEM film could be controlled by the number of the ion exchange and reduction cycles. Experimental results also showed that the prepared Pd–PEM hybrid film was active for the hydrogenation of nitrobenzene. The microreactor with the Pd–PEM hybrid film via multiple times had the increased catalyst loading, leading to a high yield of aniline and much better durability. In addition, it was also found that the NaCl concentration in the polyelectrolyte solution could affect the structure of the PEM film and therefore the Pd loading and catalytic performance.
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ANALYTICAL CHEMISTRY
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2019
·
IF 6.35
Jingyun Huang,Bo Yang,Jinian Shu,Zuojian Zhang,Zhen Li,Kui Jiang
Excited-state CH2Cl2-induced associative ionization (AI) is a newly developed ionization method that is very effective for oxygenated organics. However, this method is not widely known. In this study, an unprecedented ionization efficiency and ultrafast reaction rate of AI toward nitro compounds were observed. The ionization efficiencies of o-nitrotoluene (o-NT), m-nitrotoluene (m-NT), and nitrobenzene (NB) were as high as (28 ± 3)%, (27 ± 2)%, and (13 ± 1)%, respectively (∼1–3 ions for every 10 molecules). The measured reaction rate coefficients of these nitroaromatics were (0.5–1.3) × 10–7 molecule–1 cm3 s–1 (∼300 K). These unusual rate coefficients indicated strong long-range interactions between the two neutral reactants, which was regarded as a key factor leading to the ultrahigh ionization efficiency. The detection sensitivities of the nitroaromatics, (1.01–2.16) × 104 counts pptv–1 in 10 s acquisition time, were obtained by an AI time-of-flight mass spectrometer (AI-TOFMS). These experimental results not only provide new insight into the AI reaction but also reveal an excellent ionization method that can improve the detection sensitivity of nitroaromatics to an unprecedented degree.
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MICROCHIMICA ACTA
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2019
·Vol. 186
·期 3
·1-9
·
IF 5.479
Ma Yujun,Yu Ying,Lin Bixia,Zhang Li,Cao Yujuan,Guo Manli
Copper nanoclusters (CuNCs) were synthesized starting from glutathione and copper(II) nitrate. They show blue fluorescence peaking at 432 nm when excited at 334 nm. In the presence of o -phenylenediamine (OPD), the blue fluorescence is decreased, but a yellow fluorescence appears with a peak at 557 nm. UV-visible absorptiometry, fluorometry and fluorescence lifetime measurements were used to show that OPD is oxidized by the small fraction of copper(II) ions present in the CuNCs to form the oxidized form of o -phenylenediamine (oxOPD) which displays weak yellow fluorescence, while the blue fluorescence decreases. The ratio of fluorescences at 557 and 432 nm increases linearly in the 0.15 to 110 μg·L −1 OPD concentration range, and the detection limit is 93 ng·L −1 . Compared to the method based on the use of dissolved Cu(II), the employment of CuNCs reduces the detection limit by a factor of 40. The method was applied to the determination of OPD in spiked environmental water and industrial wastewater samples. Recoveries ranged from 96.8 to 100.3%.
Schematic presentation of a ratiometric fluorometric method for detection of o-phenylenediamine (OPD) based on copper nanoclusters (CuNCs). OPD is oxidized by Cu 2+ present in CuNCs to form the oxidized form of o -phenylenediamine (oxOPD). FRET occurred between oxOPD and CuNCs, and the F 557 /F 432 value is amplified.
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RSC Advances
·
2019
·Vol. 9
·期 32
·18098-18105
·
IF 3.049
Lamaocao Ma,Hengchang Ma
In this study, we report the synthesis of π-conjugated network polymers via palladium-catalyzed direct arylation polycondensation of triphenylamine (TPA) and tetraphenylethylene (TPE) with different active substrates. Moreover, six conjugated porous polymers were obtained (named as TPA-TPA-MA, TPA-PB-MA, TPA-TFB-MA, TPA-TPE-MA, TPE-PB-MA, and TPE-TFB-MA). Then, the fluorescence properties in the solid and dispersed states, the corresponding microporous structures, and the Brunauer–Emmett–Teller (BET) surface areas of all polymers were well studied. Among the obtained materials, TPA-PB-MA possessed not only largest BET surface area (686 m2 g−1) and largest pore volume (0.716 cm3 g−1), but also the smallest pore size of 0.823 nm. These properties are very beneficial for the application of TPA-PB-MA in CO2 storage and PA sensing. At 1 bar, TPA-PB-MA demonstrated the significant CO2 uptake of 2.70 and 1.35 mmol g−1 at 273 and 298 K, respectively. Furthermore, TPA-PB-MA was most sensitive and selective towards PA recognition. The KSV constant was measured as 4.0 × 104 M−1.
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GREEN CHEMISTRY
·
2019
·Vol. 21
·期 17
·4732-4747
·
IF 9.405
Shenghui Zhou,Fanglin Dai,Chao Dang,Ming Wang,Detao Liu,Fachuang Lu,Haisong Qi
Exploring both high-performance catalytic materials from non-edible lignocellulosic biomass and selective hydrodeoxygenation of bioderived molecules will enable value-added utilization of renewable feedstocks to replace rapidly diminishing fossil resources. Herein, we developed a scale-up and sustainable method to fabricate gram-quantities of highly dispersed cobalt nanocatalysts sheathed in multilayered N-doped graphene (Co@NG) by using a biomacromolecule carboxymethyl cellulose (CMC) as a raw material. The ionic gelation of CMC, urea and Co2+ ions leads to uniform dispersion and chelation of different species, consequently resulting in the formation of highly distributed Co nanoparticles (NPs) (10.91 nm) with N-enriched graphene shells in the solid-state thermolysis process. The usage of urea as a non-corrosive activation agent can introduce a porous belt-like nanostructure and abundant doped nitrogen. Among all the prepared catalysts in this work, the optimized Co@NG-6 with the largest specific surface area (627 m2 g−1), the most and strongest basic sites, and the highest proportion of pyridinic-N (37.6%) and mesopores exhibited excellent catalytic activity (99% yield of 2-methoxy-p-cresol) for base-free transfer hydrodeoxygenation (THD) of vanillin using bioderived formic acid (FA) as a H source at 160 °C for 6 h. The poisoning tests and electron paramagnetic resonance (EPR) spectra verified that the strong interaction between N atoms and encapsulated Co NPs provided synergistic effects, which were essential for the outstanding catalytic performance of Co@NG-6. The deuterium kinetic isotope effect study clearly demonstrated that the formation of Co-H−via β-hydride elimination and protonation was the rate-determining step, and protic N–H+ and hydridic Co-H− were considered to be active intermediate species in the THD reaction. Furthermore, Co@NG-6 was highly stable for recycling owing to the graphene shells preventing Co NPs from corrosion and aggregation.
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ChemCatChem
·
2019
·Vol. 11
·期 14
·3327-3338
·
IF 4.495
Man Yuan,Hongbo Zhang,Chen Yang,Fanhao Wang,Zhengping Dong
Graphical It′s nanoreactor time : Co@ZDC@mC nanoreactor with a hierarchical mesoporous yolk-shell structure was successfully prepared by the high-temperature carbonization of a ZIF-67@polymer composite. The Co@ZDC@mC-700 exhibited superior catalytic efficiency in the catalytic reduction of nitrobenzene with N 2 H 4 ⋅H 2 O, and also showed good reusability and recyclability. Porous nanoreactors demonstrate immense potential for applications in heterogeneous catalysis due to their excellent mass-transfer performance and stability. The design of a simple, universal strategy for fabricating nanoreactor catalysts is of significance for organic transformation. In this study, a nanoreactor with a hierarchical mesoporous yolk-shell structure was successfully prepared by the high-temperature carbonization of a ZIF-67@polymer composite. The core of the resultant Co@ZDC@mC material comprised Co NPs anchored in the ZIF-67-derived carbon framework, while the shell comprised resin-polymer-derived mesoporous carbon. The as-obtained Co@ZDC@mC-700 catalyst enriched reactants, efficiently catalyzed the reaction in the core, and permitted the desorption of the product from the nanoreactor. In the catalytic reduction of nitrobenzene with N 2 H 4 ⋅H 2 O, Co@ZDC@mC-700 exhibited superior catalytic efficiency (TOF=1136.3 h −1 ). In addition, Co@ZDC@mC-700 exhibited excellent performance for the catalytic reduction of various functionalized nitroarenes, as well as good reusability and recyclability. Hence, a simple, useful approach for fabricating a metal-organic-framework-derived non-noble metal-based yolk-shell nanoreactor for effective catalytic transformation is proposed.
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Catalysts
·
2019
·Vol. 10
·期 1
·12
·
IF 3.444
Xiaohui Wang,Xin Ding,Houbing Zou
The channel lengths of mesoporous materials have a crucial impact on the catalytic performances of as-loaded active components. However, it remains a challenge to precisely tune the mesochannel length in a wide range from ≤50 nm to 200 nm. In this paper, we developed a top-down strategy, that is to say, crushing hollow microspheres, for preparing mesoporous silica nanosheets (MSSs) with perpendicular mesochannels and tunable thicknesses. Owing to the heterogeneous growth of the mesoporous silica layer on the surfaces of polystyrene microspheres (hard template), it was achieved to regulate the mesochannel length continuously in the range of 20–200 nm. The obtained materials were characterized by X-ray diffraction (XRD), nitrogen sorption, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The effect of channel lengths on the catalytic activity of metal nanoparticles was then investigated in the selective hydrogenation reaction of nitroarenes. It was found that a short channel not only favored dispersing metal nanoparticles uniformly and then avoiding pore blocking, but also improved the accessibility of metal nanoparticles largely during reactions.Keywords:mesoporous silica;nanosheet;channel length;molecular diffusion;hydrogenation
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