查找使用阿拉丁产品的科研文献

Fabrication of Polypyrrole/Graphene Oxide Composite Nanosheets and Their Applications for Cr(VI) Removal in Aqueous Solution

Shangkun Li,Xiaofeng Lu,Yanpeng Xue,Junyu Lei,Tian Zheng,Ce Wang

In this paper, we report on the simple, reliable synthesis of polypyrrole (PPy)/graphene oxide (GO) composite nanosheets by using sacrificial-template polymerization method. Herein, MnO 2 nanoslices were chosen as a sacrificial-template to deposit PPy, which served as the oxidant as well. During the polymerization of pyrrole on surface of GO nanosheets, MnO 2 component was consumed incessantly. As a result, the PPy growing on the surface of GO nanosheets has the morphology just like the MnO 2 nanoslices. This method can provide the fabrication of PPy nanostructures more easily than conventional route due to its independence of removing template, which usually is a complex and tedious experimental process. The as-prepared PPy/GO composite nanosheets exhibited an enhanced properties for Cr(VI) ions removal in aqueous solution based on the synergy effect. The adsorption capacity of the PPy/GO composite nanosheets is about two times as large as that of conventional PPy nanoparticles. We believe that our findings can open a new and effective avenue to improve the adsorption performance in removing heavy metal ions from waste water.

Fluorescent Sensors Based on Organic Polymer-Capped Gold Nanoparticles for the Detection of Cr(VI) in Water

Na Wang,Liangchen Wang,Hong Yang,Tingting Xiong,Shangping Xiao,Jiawen Zhao,Weiping Du

“Turn-off” fluorescent sensors for Cr(VI) have been fabricated based on organic polymer-capped gold nanoparticles. The fluorescence intensity, as well as the response behavior of the sensors, is dependent on the pH values of buffer solution and dilution amounts of the sensors. When diluted 50 times with pH 2.0 buffer solution, the sensors show good linear responses toward Cr(VI) at concentrations between 2.8–5.9 μM and 5.9–29 μM. The calculated detection limit is 0.63 μM (S/N=3). The interference study and real sample assays exhibit satisfying selectivity and reliability results. Furthermore, the quenched intensity of fluorescence could be recovered by Fe(II) ion, which provides a potential method to detect Fe(II) ions. The quenching and recovering mechanisms have also been investigated. It is suggested that the quenching mechanism is based on the combined effects of internal electron transfer and the inner filter effect. Finally, the recovering mechanism is based on the redox reactions between the Cr(VI) and Fe(II) ions.

Magnetically Separable MoS2/Fe3O4/nZVI Nanocomposites for the Treatment of Wastewater Containing Cr(VI) and 4-Chlorophenol

Haijiao Lu,Jingkang Wang,Hongxun Hao,Ting Wang

With a large specific surface area, high reactivity, and excellent adsorption properties, nano zerovalent iron (nZVI) can degrade a wide variety of contaminants in wastewater. However, aggregation, oxidation, and separation issues greatly impede its wide application. In this study, MoS2/Fe3O4/nZVI nanocomposites were successfully synthesized by a facile step-by-step approach to overcome these problems. MoS2nanosheets (MNs) acted as an efficient support for nZVI and enriched the organic pollutants nearby, leading to an enhanced removal efficiency. Fe3O4nanoparticles (NPs) could not only suppress the agglomeration and restacking of MNs, but also facilitate easy separation and recovery of the nanocomposites. The synergistic effect between MNs and Fe3O4NPs effectively enhanced the reactivity and efficiency of nZVI. In the system, Cr(VI) was reduced to Cr(III) by nZVI in the nanocomposites, and Fe2+produced in the process was combined with H2O2to further remove 4-Chlorophenol (4-CP) through a Fenton reaction. Furthermore, the nanocomposites could be easily separated from wastewater by a magnet and be reused for at least five consecutive runs, revealing good reusability. The results demonstrate that the novel nanocomposites are highly efficient and promising for the simultaneous removal of Cr(VI) and 4-CP in wastewater.Keywords:nZVI;modification;nanocomposites;Cr(VI);4-CP;Fenton reaction;pollution treatment;recyclability;wastewater

Construction of the Bi2WO6/Bi4V2O11 heterojunction for highly efficient visible-light-driven photocatalytic reduction of Cr(VI)

Chol-Nam Ri,Kim Song-Gol,Jong Ju-Yong,Sung-Nam Pak,Song-Chon Ri,Jong-Hwa Ri

Herein, a Bi2WO6/Bi4V2O11 heterostructured photocatalyst was fabricated through a facile one-pot solvothermal method. In this heterojunction system, highly homogeneous-dispersed Bi4V2O11 nanocrystals were anchored onto Bi2WO6 nanoflakes, endowing the heterojunction with nanosized interfacial contact. Because of the favorable interfacial contact and band alignment, photoinduced charge carrier transfer is facilitated in the Bi2WO6/Bi4V2O11 heterojunction, which can be verified by photocurrent and photoluminescence measurements. In contrast with pristine Bi2WO6 and Bi4V2O11 samples, the Bi2WO6/Bi4V2O11 heterostructured photocatalyst displays drastically improved photocatalytic Cr(VI) reduction activity under visible-light irradiation. More significantly, the as-fabricated heterojunction possesses superior activity for Cr(VI) relative to the counterpart obtained by mechanical mixing, indicating that the interfacial contact plays a determinant role in promoting charge carrier transfer. Moreover, Bi2WO6/Bi4V2O11 heterojunctions exhibited good cycling stability even after 5 cycles. A plausible photocatalytic Cr(VI) reduction reaction mechanism over the Bi2WO6/Bi4V2O11 heterojunction is proposed on the basis of band alignment. This work reports a high-efficiency photocatalyst for Cr(VI) and might shed light on the decisive factor for optimizing the heterostructure.

Synthesis and evaluation of ion-imprinted composite membranes of Cr(VI) based on β-diketone functional monomers

Peng Li,Xin Wang,Guifang Wang,Li Zhao,Yuwen Hong,Xianzhi Hu,Futing Zi,Huiling Cheng

Using Cr(VI) as the imprinted ions and 2-allyl-1,3-diphenyl-1,3-propanedione (ADPD) (a compound synthesized by independent design) as the functional monomer, a series of chromium ion-imprinted composite membranes (Cr(VI)-IICMs) and corresponding non-imprinted composite membranes (NICMs) were synthesized and tested. The results showed that the Cr(VI)-IICM10 membrane prepared under optimal experimental conditions exhibited a high adsorption capacity towards Cr(VI) (Q = 30.35 mg g−1) and a high imprinting factor (α = 2.70). The structural characteristics of Cr(VI)-IICM10 and NICM10 were investigated using FE-SEM, ATR-FTIR, and BET techniques combined with UV-Vis photometry and inductively coupled plasma emission spectrometry (ICP-OES) to evaluate the adsorption performance and permeation selectivity, while the effect on adsorption permeance of varying the experimental conditions including the solvent type, pH, and temperature was also investigated. The results showed that Cr(VI)-IICM10 is a mesoporous material with excellent permeation selectivity, reusability, and favorable pH response, and that its adsorption behavior is in accordance with the Langmuir model and pseudo-first-order kinetics. Thus, Cr(VI)-IICM10 shows great potential towards utilization as a “smart membrane” to control the separation and removal of Cr(VI) in wastewater, and also proved a reasonable design of the new functional monomer ADPD.

Selective adsorption and separation of Cr(VI) by surface-imprinted microsphere based on thiosemicarbazide-functionalized sodium alginate

Yapei Luo,Heng Li,Minghua Wu,Wei Wang,Lili Wang

Simultaneous measurement of Cr(III) and Cu(II) based on indicator-displacement assay using a colorimetric nanoprobe

Xianfeng Wang,Chengxiang Chu,Jiayi Lv,Yuanyuan Jia,Libo Lin,Mei Yang,Suyi Zhang,Danqun Huo,Changjun Hou

High-performance analysis of heavy metal ions is great importance in both environment and food safety. In this work, a facile and reliable colorimetric sensor was presented for simultaneous detection of Cu 2+ and Cr 3+ based on indicator-displacement assay (IDA). As a typical silicate nanomaterials , ZnSiO 3 hollow nanosphere (ZSHS) exhibited an outstanding ion exchange capacity. Zincon was incorporated with the ZSHS to form a zincon/ZSHS hybrid ionophore with a blue color. Upon the addition of Cr 3+ , IDA reaction and selective ion exchange occurred with the color change of zincon/ZSHS ionophore from blue to yellow. With such a design, colorimetric measurement of Cr 3+ was realized. The linear concentration for Cr 3+ detection ranged from 0.5 μM to 75 μM with the LOD of 83.2 nM. Furthermore, we also screened different kinds of complexing agents that may respond with zincon/ZSHS ionophore and various metal ions. It was found that tartaric acid (TA) showed the chelation capability of Zn 2+ -TA is stronger than that of Zn 2+ -zincon. Thus zincon/ZSHS/TA presented a yellow color due to the chelation reaction of Zn 2+ -TA, releasing the zincon as a free state. After addition of Cu 2+ , a stronger chelation reaction of Cu 2+ -zincon occurred. This process involved in the color change from yellow to blue and realized colorimetric measurement of Cu 2+ . The detection limit of Cu 2+ was calculated to be 43.7 nM with linear range from 0.1 to 20 μM. In addition, the zincon/ZSHS nanoprobe was successfully applied for simultaneous measurement of Cu 2+ and Cr 3+ in sorghum and river water, indicating that the zincon/ZSHS nanoprobe provided a promising sensing platform in environment and food safety.

Enhanced microwave absorption of core-shell SiC@Cr-Si-C absorber fabricated by facile molten salt synthesis

Yong Zhang,Yuchang Qing,Junjie Yang,Chuanyang Jiang

SiC, with outstanding oxidation stability and tunable dielectric property, has been regarded as a promising microwave absorption material for high-temperature applications. However, the application of pristine SiC is restricted by its inadequate dielectric response and weak loss capability. Herein, a novel strategy is proposed to construct Cr-Si-C conductive shell on SiC surface via molten salt method is proposed to introduce heterogeneous interfaces and enhance dielectric loss. The optimal SiC@Cr-Si-C core-shell sample achieves a minimum reflection loss (RL m ᵢ n ) of −36.7 dB at a matching thickness of 1.4 mm. Meanwhile, it exhibits an effective absorption bandwidth (EAB) of 2.41 GHz. Notably, even after heat treatment at 600 °C in air for 5 h, the core-shell absorber maintains an intact core-shell structure and its RL m ᵢ n remains as high as −34.4 dB, demonstrating superior high-temperature stability. This work provides an effective method for high-performance microwave absorption materials targeted at high-temperature applications.

Preparation of a FeS/FeSn carbon cryogel for efficient removal of Cr(VI): adsorption performance and mechanism

Duogui Wu,Rong Li,Yunlong Shi,Yun Li,Mei Yang,Yanyue Xiao,Meiyao Wu,Chunhua Wang,Changjiang Yu,Shuwen Wang

In the present study, sodium alginate (SA) was employed as the precursor and cross-linked with Fe3+ ions to form an SA–Fe3+ hydrogel. In an alkaline Na2S solution, the prepared hydrogel gradually released Fe3+ ions, which subsequently reacted with S2− ions to produce a uniformly dispersed alginate-FeS/S hybrid sol (denoted as SA-FeS/S). The SA-FeS/S sol was then converted into an FeS/FeSn carbon cryogel (BC@FeS/FeSn-T, where BC stands for biochar) through sequential freeze-drying and pyrolysis. The microstructure and composition of the resulting BC@FeS/FeSn-T cryogel were systematically characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The performance for the adsorption of Cr(VI) and the corresponding reaction mechanism of BC@FeS/FeSn-700 were thoroughly investigated. Moreover, BC@FeS/FeSn-700 exhibited superior Cr(VI) removal efficiency over a wide pH range, making it a highly promising candidate for remediating Cr(VI)-contaminated soils. The adsorption process proceeded via five distinct pathways: (i) Cr(VI)'s reduction by Fe2+ and HS− species released from FeS; (ii) direct electron transfer from FeS; (iii) redox reactions with various iron sulfides (FeS2, Fe3S4, and Fe1−xS); (iv) reduction by sulfite ions; and (v) surface adsorption onto biochar or metal oxides.

Enhancing Cr(VI) removal by regulating Fe/Al bimetal adsorption and reduction properties: kinetic and mechanistic studies

Wang Wenhao,Ge Aijun,Xu Yuan,Yang Xuesong,Feng Shiying,Su Ying,Wang Weida,Xing Liqun,Hao Xiujuan

View large Download slide View large Download slide Close modal In the study, a novel Fe/Al bimetal with a high specific surface area and electron transfer capacity was synthesized through ball milling Fe and Al powder. Importantly, this synthesis process did not consume Al powder and did not generate by-products that required treatment. Compared with Fe or Al powder and the ball-milled Fe or Al powder, Fe/Al could rapidly remove Cr(VI) through adsorption–reduction under near-neutral conditions. Nevertheless, the removal efficiency of Cr(VI) by Fe/Al was influenced by the initial pH of the solution and dissolved oxygen (DO). Kinetic studies and adsorption isotherm analysis demonstrated that the pseudo-second-order adsorption kinetic model and the Freundlich model could better describe the Cr(VI) removal data, and the maximum removal amount of Cr(VI) was 6.25 mg/g. Furthermore, based on the characterization analysis of XPS, the adsorbed Cr(VI) was reduced to Cr(III). SEM-EDS analysis revealed that Cr mainly overlapped with the Fe elemental distribution on the surface of Fe/Al particles, suggesting that Fe was the main reaction site. Consequently, the results indicated that highly active Fe/Al could be prepared by solid–solid blending for pollutant removal, which provided technological concepts for the waste utilization of scrap iron and aluminum. Increasing the specific surface area of Fe/Al by ball milling of Fe and Al powder was the key to enhancing Cr(VI) removal. Cr(VI) was mainly removed by adsorption–reduction under near-neutral pH. The removal sites of Cr(VI) by Fe/Al mainly occur on the surface of Fe. The maximum adsorption capacities of Cr(VI) by Fe/Al were 6.25 mg/g.

Triethanolamine interface modification of crystallized ZnO nanospheres enabling fast photocatalytic hazard-free treatment of Cr(vi) ions

Xiaowen Su,Zehua Wang,Yuan Huang,Zhenyu Miao,Shuhua Wang,Jianjun Wang,Xiao Li Zhang,Xiaomin Sun,Hong Liu,Yuanhua Sang

The hazard-free treatment of Cr( vi ) ions is critical in modern industry. Photocatalytic reduction and detoxification are high-potential strategies. Photocatalysts with high efficiency, low cost, environmental friendliness, and easy mass products are required. In this study, we report a facile strategy using triethanolamine (TEOA) as a capping ligand to modify the surface of ZnO nanospheres. The experimental and theoretical results reveal that the presence of TEOA on the surface was beneficial for electron enrichment on Zn and hole transfer to TEOA and can photocatalytically reduce Cr( vi ) by almost 100% in 5 min. The photocatalytic property of TEOA-modified ZnO could be renewed by the reabsorption of TEOA in solution. The great sedimental properties benefit photocatalyst recycling and renewal, which also provides high potential for water pollution and environmental emergency responses applications.

Synthesis of a Molecularly Imprinted Polymer on NH2-MIL-101(Cr) for Specific Recognition of Diclofenac Sodium

Wang Yulin,Qiu Xiuzhen,Li Yangyang,Guo Huishi,Lu Wenguan,Nie Libo

A novel molecularly imprinted polymer material based on the metal-organic framework NH2-MIL-101(Cr) (MOF-MIP) was prepared. The synthesized MOF-MIP was characterized by IR, XRD, SEM and N2 absorption. The characterization results displayed that the MOF-MIP which exhibited an octahedral shape had good dispersibility, good thermal stability and a high surface area. Subsequently, the adsorption behavior of MOF-MIP to diclofenac sodium (DS) in aqueous solution was examined. A series of adsorption experiments demonstrated that the MOF-MIP had high transfer mass rates and high sensitivity and selectivity for DS. Then the MOF-MIP was used as the adsorbent of dispersive micro-solid phase extraction (DMSPE) for the detection of DS in urine. Under optimum conditions, the average recovery of DS ranged from 88.3 to 101.6% with RSD of 5.6%. The described method provides a rapid route for determination of DS in human urine.