查找使用阿拉丁产品的科研文献

Microstructures and Electrical Conduction Behaviors of Gd/Cr Codoped Bi3TiNbO9 Aurivillius Phase Ceramic

Huajiang Zhou,Shaozhao Wang,Daowen Wu,Qiang Chen,Yu Chen

In this work, a kind of Gd/Cr codoped Bi3TiNbO9Aurivillius phase ceramic with the formula of Bi2.8Gd0.2TiNbO9+ 0.2 wt% Cr2O3(abbreviated as BGTN−0.2Cr) was prepared by a conventional solid-state reaction route. Microstructures and electrical conduction behaviors of the ceramic were investigated. XRD and SEM detection found that the BGTN−0.2Cr ceramic was crystallized in a pure Bi3TiNbO9phase and composed of plate-like grains. A uniform element distribution involving Bi, Gd, Ti, Nb, Cr, and O was identified in the ceramic by EDS. Because of the frequency dependence of the conductivity between 300 and 650 °C, the electrical conduction mechanisms of the BGTN−0.2Cr ceramic were attributed to the jump of the charge carriers. Based on the correlated barrier hopping (CBH) model, the maximum barrier heightWM, dc conduction activation energyEc, and hopping conduction activation energyEpwere calculated with values of 0.63 eV, 1.09 eV, and 0.73 eV, respectively. Impedance spectrum analysis revealed that the contribution of grains to the conductance increased with rise in temperature; at high temperatures, the conductance behavior of grains deviated from the Debye relaxation model more than that of grain boundaries. Calculation of electrical modulus further suggested that the degree of interaction between charge carriersβtended to grow larger with rising temperature. In view of the approximate relaxation activation energy (~1 eV) calculated fromZ″andM″ peaks, the dielectric relaxation process of the BGTN−0.2Cr ceramic was suggested to be dominated by the thermally activated motion of oxygen vacancies as defect charge carriers. Finally, a high piezoelectricity ofd33= 18 pC/N as well as a high resistivity ofρdc= 1.52 × 105Ω cm at 600 °C provided the BGTN−0.2Cr ceramic with promising applications in the piezoelectric sensors with operating temperature above 600 °C.Keywords:Aurivillius phase ceramic;Bi3TiNbO9;electrical conduction behaviors;impedance spectrum;electrical modulus

Cr(VI) removal by cellulose-based composite adsorbent with a double-network structure

Yanbo Pei,Menglin Li,Wei Li,Kai Su,Junmin Chen,Hongwei Yang,Daiyan Hu,Shengli Zhang

A cellulose-based composite adsorbent (PEI-PAM-CF) was fabricated via a facile cross-linking of polyethyleneimine/polyacrylamide (PEI/PAM) and cellulose using epichlorohydrin as the cross-linker. It possessed a double-network structure and emitted blue fluorescence. Compared with the control samples (PEI-CF and PAM-CF), the PEI-PAM-CF showed a synergy effect for the Cr(VI) removal. It can effectively remove Cr(VI) at low concentration with no structure destroyed for the adsorbent. Other coexisting anions (NO 3 - , Cl - , H 2 PO 4 - and CH 3 COO - ) and cations (Na + , K + , Mg 2+ , Ca 2+ and Cr 3+ ) had no significant effect on Cr(VI) removal except SO 4 2- . After five adsorption/desorption cycles, the Cr(VI) removal only decreased with a loss of 7%, suggesting that the PEI-PAM-CF had good regeneration performance. Most importantly, the electrostatic adsorption mechanism between Cr(VI) and the PEI-PAM-CF was revealed by a reversible fluorescence “on-off-on” phenomenon and the DFT calculation. The adsorption sites on the PEI-PAM-CF were attributed to the amino groups of the PEI and PAM . Hence, the PEI-PAM-CF was potential for the treatment of Cr(VI)-containing wastewater at low concentration.

Ti/Cr(III) conversion coating on aluminium foil for lithium-ion battery package

Songnan Wang,Shiai Xu

Trivalent chromium (Cr(III)) was added into a titanium (Ti)-based solution in this study to prepare Ti/Cr(III) conversion coatings on the aluminium (Al) foil for lithium-ion battery package. Their surface morphology and chemical composition were characterized by field-emission scanning electron microscope (FE-SEM), energy-dispersive spectroscopy and X-ray photoelectron spectroscopy (XPS). The corrosion resistance and the adhesive strength between Al foil and hot melt adhesive (modified polypropylene film) were determined. The results reveal that the Ti/Cr(III) conversion coating is mainly composed of Al2O3, TiO2, Cr(OH)3 and Cr2O3, and possesses the best anticorrosive performance with a corrosion current density of 1.05 µA cm−2, which is one order of magnitude lower than pure Al foil. The adhesive strength between Ti/Cr(III)-treated Al foil and the adhesive is 14.3 N/15 mm with an increase of 250% compared with the pure Al foil, which meets the industry standard (12 N/15 mm).

Ag@MIL-101(Cr) Film Substrate with High SERS Enhancement Effect and Uniformity

Qinchao Shao,De Zhang,Cai-e Wang,Zhexiang Tang,Mingqiang Zou,Xiaobing Yang,Huaping Gong,Zhi Yu,Shangzhong Jin,Pei Liang

Surface-enhanced Raman scattering (SERS), owing to its high sensitivity and rapid response, has been widely used in various fields. However, it is still a challenge to prepare SERS substrates with high stability and reproducibility. Metal–organic frameworks (MOFs), with excellent enrichment capacity and stability, provide a new material for high-performance SERS substrates. In this paper, we prepare a MIL-101(Cr) film via a secondary growth method, and Ag+ is reduced to Ag NPs by UV irradiation and attach to the film to synthesize the Ag@MIL-101(Cr) film SERS substrate. Then, we change the time of UV light illumination and the amount of silver nitrate in order to obtain the optimal substrate. The detection capability of this sample can be up to 10–11 M for 4-ATP, and the relative standard deviation (RSD) is only about 5%, which demonstrates that the substrate has excellent SERS effect and reproducibility. Finally, the prepared substrate has been applied for the determination of nitrofurantoin, with its detection capability up to 10–7 M. This work proposes a simple method to synthesize MOF-based film substrate with high SERS performance and uniformity and provides potential for the sensitive detection of chemical or antibiotic residue.

Single-atom nanozyme enabled fast and highly sensitive colorimetric detection of Cr(VI)

Yu Mao,Shengjie Gao,Lili Yao,Lu Wang,Hao Qu,Yuen Wu,Ying Chen,Lei Zheng

As a high biologically toxic heavy metal ion , Cr(VI) will cause environmental pollution and endanger human health. Therefore, the development of fast, simple and visible detection methods for Cr(VI) is extremely important to control its harm. Toward this end, we report the establishment of a colorimetric sensing method for Cr(VI) based on single-atom nanozymes for enhanced detection performance. Firstly, we prepared SA-Fe/NG as peroxidase mimetic by anchoring Fe single-atom onto a single-layer of two-dimensional nitrogen-doped graphene. The SA-Fe/NG showed superiorly high oxidation catalytic activity due to its 100% atomic utilization and existing Fe-N-C structure. Furthermore, with 3,3′,5,5′-tetramethylbenzidine (TMB) as a colorimetric sensing probe, and 8-hydroxyquinoline (8-HQ) as an inhibitor for the oxidation of TMB, the detection of Cr(VI) was realized through specific interaction between Cr(VI) and 8-HQ, which led to the recovery of oxTMB in blue color. Our established method showed superior sensitivity with a detection limit of 3 nM and a linear range of 30 nM to 3 μM. It also exhibited high selectivity for a series of metal cations, and has been successfully applied to the detection of Cr(VI) in tap water and tuna samples.

Enhanced adsorptive removal of Cr(VI) in aqueous solution by polyethyleneimine modified palygorskite

Jiahong Wang,Tongtong Sun,Atif Saleem,Yao Chen

Polyethyleneimine (PEI) modified palygorskite (Pal) was used for the adsorption of Cr(VI) in aqueous solution. The absorbent was characterized by Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA). Characterized results confirmed that the Pal has been successfully modified by PEI. The modification of PEI increased the Cr(VI) adsorption performance of the Pal by the adsorption combined reduction mechanism, and amino groups of the adsorbent play the main role in the enhanced Cr(VI) adsorption. The maximum adsorption capacity was 51.10 mg·g −1 at pH 4.0 and 25 °C. The adsorption kinetics of Cr(VI) on the adsorbent conforms to the Langmuir isotherm model. The maximum adsorption occurs at pH 3, and then the adsorption capacity of PEI-Pal was decreased with the increase of pH values. The adsorption kinetics of Cr(VI) on PEI-Pal was modeled with pseudo-second-order model. The addition of Cl − , SO 4 2− and PO 4 3− reduced the Cr(VI) adsorption by competition with Cr(VI) for the active sites of PEI-Pal. The Cr(VI) saturated PEI-Pal can be regenerated in alkaline solution, and the adsorption capacity can still be maintained at 30.44 mg·g −1 after 4 cycles. The results demonstrate that PEI-Pal can be used as a potential adsorbent of Cr(VI) in aqueous solutions.

Removal of Cr(VI) from Aqueous Solution by Polypyrrole/Hollow Mesoporous Silica Particles

Linlin Du,Peng Gao,Yuanli Liu,Tsuyoshi Minami,Chuanbai Yu

The removal of Cr(VI) in wastewater plays an important role in human health and environment. In this work, polypyrrole/hollow mesoporous silica particle (PPy/HMSNs) adsorbents have been newly synthesized by in-situ polymerization, which prevent the aggregation of pyrrole in the process of polymerization and exhibit highly selective and powerful adsorption ability for Cr(VI). The adsorption process was in good agreement with the quasi-second-order kinetic model and the Langmuir isotherm model. And the maximum adsorption capacity of Cr(VI) was 322 mg/g at 25 °C. Moreover, the removal rate of Cr(VI) by PPy/HMSNs was ~100% in a number of binary systems, such as Cl−/Cr(VI), NO3−/Cr(VI), SO42−/Cr(VI), Zn2+/Cr(VI), Fe3+/Cr(VI), Sn4+/Cr(VI), and Cu2+/Cr(VI). Thus, the PPy/HMSNs adsorbents have great potential for the removal of Cr(VI) in wastewater.Keywords:polypyrrole/hollow mesoporous silica particle;chromium(Cr);adsorption

Humic acid modified nano-ferrous sulfide enhances the removal efficiency of Cr(VI)

Youru Yao,Na Mi,Cheng He,Huan He,Yong Zhang,Yongcai Zhang,Li Yin,Jing Li,Shaogui Yang,Shiyin Li,Lixiao Ni

The dissolved hexavalent chromium (Cr(VI)) in natural water system poses a significant risk for public health and the environment. Nanoscale ferrous sulfide (FeS) has been widely used to treat soils, sediments, groundwater, and natural waters contaminated with Cr(VI), but the reactivity of FeS can be significantly reduced due to its easy agglomeration and therefore decreased the remove rate of the dissolved Cr(VI). To overcome this problem, the present study used humic acid (HA) to modify FeS in order to reduce its agglomeration and increase stability. Results showed that the HA modified FeS (HA-FeS) had good stability and reduced FeS agglomeration. The hydrodynamic diameter of HA-FeS was between 235 and 241 nm, which was much smaller than that of the unmodified FeS. The maximum removal quantity of Cr(VI) by HA-FeS was 7.74 and 2.35 times higher that of HA and the unmodified FeS, respectively, and the maximum removal quantity of HA-FeS was 675.03 mg/g. Further, HA-FeS performed better efficiency in removing the dissolved Cr(VI) with high or low concentration. With an increasing concentration of Ca 2+ and Mg 2+ , the efficiency of HA-FeS to remove Cr(VI) showed a decreasing trend. The removal mechanism of Cr(VI) mainly relies on the reducibility of Fe 2+ and S 2− . XPS and XRD measurements further revealed that 95.03% of Cr(VI) was converted to Cr(III) (FeCr 2 O 4 , Cr(OH) 3 and Cr 2 O 3 ), and another 4.58% of Cr(VI) was adsorbed by HA-FeS. Therefore, this study demonstrated an efficient method to improve the nano-FeS stability and reactivity for the rapid repair of Cr(VI) contamination in natural water.

Adsorption of Cr (VI) onto Attapulgite/UiO-66-NH2 Composites from Aqueous Solution

Peiyi Bao,Haiying Du,Xiangning Xu,Junya Li,Yao Wu,Shaojiang Zhou,Lingyun Li,Ningfei Lei

Electrospun Cellulose Acetate/Polyethylenimine Porous Fibers toward Highly Efficient Removal of Cr(VI)

Dan Luo,Shao-zhong Hu,Ting Huang,Nan Zhang,Yan-zhou Lei,Yong Wang

The development of an efficient, economical, and environmentally friendly monolithic adsorbent for the removal of toxic hexavalent chromium Cr(VI) has invariably been a topic of great concern to researchers. In this paper, cellulose acetate (CA) and polyethylenimine (PEI) homogeneously blending porous fiber membranes with high porosity were successfully prepared by electrospinning, and PEI was further immobilized by cross-linking to form a stable biological adsorbent. The adsorption behavior and eliminating mechanism toward Cr(VI) by the CA-c-PEI fibrous membranes were comprehensively explored. The maximum adsorption capacity was up to 285.7 mg/g (25 °C), higher than most of the biomass-based adsorbents. Specifically, the concentration of Cr(VI) could be dramatically reduced from the initial 50 mg/L to 0.03 mg/L, much lower than the concentration standard for drinking water recommended by the World Health Organization. Even after being reused several times, the fibrous membrane still exhibited high removal efficiency.

Preparation of covalent triazine-based framework for efficient Cr(VI) removal from water

Shuangxi Zhou,Ziming Zhou,Donghai Zhu,Huanhuan Jiang,Yue Qi,Shiyi Wang,Ye Jia,Wei Wang

To overcome problems associated with heavy metal pollution, lots of new functional materials have been used. As potential emerging environmental materials, covalent triazine frameworks (CTFs) have received extensive attention because of their high nitrogen content and the feature of pre-design to obtain the required molecular framework for specific applications. In this study, three CTFs were synthesized by terephthalonitrile (TPA) with the catalyzer of ZnCl 2 under different temperatures from 300 °C to 500 °C. Preparation temperature significantly affected the adsorption kinetics and capacity of CTFs. The CTF prepared under 500 °C (CTF500) showed the highest Cr(VI) adsorption capacity of 97.84 mg g −1 . The CTF500 was characterized with three different types of N, including pyrrolic N, pyridinic N, and quaternary N, thus providing support for the efficient adsorption of Cr(VI) from water. The mechanism of Cr(VI) removal was verified by a strong ion exchange interaction driving with the structure of quaternary N on CTF500. In addition, CTF500 also showed a stable Cr(VI) removal rate under a high ionic strength surrounding. In this study, CTFs with pre-designed functional groups could efficiently remove Cr(VI) by controlling their synthesis progress and showed great potential in future environmental applications.

Effective removal of Cr(VI) from aqueous solution by biochar supported manganese sulfide

Shiqiu Zhang,Haiqing Zhang,Fang Liu,Fan Yang,Shengnan Zhou,Kui Zheng,Chunli Chu,Le Liu,Meiting Ju

In order to remove hexavalent chromium (Cr(VI)) efficiently and simplify the adsorbent preparation process, we employed a single step method to prepare a new biochar supported manganese sulfide material. The nanoscale MnS particles were highly soldered on the biochar support surface, and this adsorbent displayed the effective removal of Cr(VI) (98.15 mg L−1) via synergistic effect between adsorption and reduction/precipitation under weak acid conditions (pH = 5.0–6.0). The adsorption kinetic data were described well by the pseudo second-order kinetic model, suggesting that the reaction process was a chemisorption process. The adsorption isotherm data were described well by the Redlich–Peterson model, further suggesting that this reaction was a hybrid chemical reaction-sorption process. In addition, the Dubinin–Radushkevich isotherm model with 8.28, 8.57, and 12.91 kJ mol−1 adsorption energy also suggests that it was a chemisorption process. The simple and eco-friendly preparation process, low-cost, and the high removal efficiency could make it a promising material for the purification of Cr(VI)-contaminated wastewater.