查找使用阿拉丁产品的科研文献

Cellulose bridged carbonate hydroxyapatite nanoparticles as novel adsorbents for efficient Cr(VI) removal

Jing Cui,Xinying Li,Shoucheng Ma,Wei Wei

Enhanced adsorption and photocatalytic Cr(VI) reduction and sterilization of defective MoS2/PVP

Yingge Zhang,Hongfen Li,Xiaolei Zhang,Hanfang Zhang,Wang Zhang,Hongwei Huang,Hongling Ou,Yihe Zhang

The exploration of novel nanomaterials to resolve the issues of water pollution with the aid of photocatalytic technology has always been a research hotspot. MoS 2 is acknowledged to be one of the promising photocatalysts for its interesting layered structure, suitable band gap, and good chemical stability. However, the fast recombination of photogenerated electrons and holes within the MoS 2 impedes its extensive application. Here, hydrophilic polymer (polyvinyl pyrrolidone, PVP) and sulfur vacancy (Vs) are simultaneously introduced into the MoS 2 nanosheets to achieve high-efficient photocatalytic hexavalent chromium Cr(VI) removal and antibacterial performance. The incorporation of PVP greatly enhances the adsorption capacity of MoS 2 , and creating Vs essentially strengthens the photogenerated carrier separation of MoS 2 . As a result, the Cr(VI) removal efficiency of MoS 2 -PVP with an appropriate Vs concentration is up to 99.5 % for 3 h. Meanwhile, MoS 2 -PVP with a relatively higher Vs concentration displays a superior Escherichia coli (E. coli) removal efficiency of 91.8 % within 30 min with the initial E. coli concentration of ∼1.0 × 10 7 CFU/mL. This study extends photocatalysts to a higher level in designing advanced materials for environmental remediation and establishes a feasible platform for emphasizing the versatility of defect engineering in regulating catalytic activity.

Efficient removal of Cr(VI) from aqueous solutions by polypyrrole/natural pyrite composites

Fen Zhang,Luyao Xi,Meiqi Zhao,Yaguang Du,Liying Ma,Shaohua Chen,Hengpeng Ye,Dongyun Du,Tian C. Zhang

Easily agglomeration of polypyrrole (PPy) significantly limits its practical applications. In this study, natural pyrite (NP) was applied to disperse PPy and overcome this agglomeration; a novel composite of PPy/NP was synthesized and applied for the efficient removal of hexavalent chromium [Cr(VI)] from aqueous solutions. Results showed that the PPy/NP composites exhibited better Cr(VI) removal performance than PPy alone. This enhanced removal capacity is attributed to the addition of NP, which prevents PPy agglomeration and reduces Cr(VI) to trivalent chromium[Cr(III)]; Cr(VI) removal was significantly dependent on the solution’s pH. The sorption kinetics of Cr(VI) with PPy/NP was described by the pseudo-second-order model and Elovich models, which highlight the chemicalsorption process. The sorption isotherm was well simulated by Langmuir model and the maximum adsorption capacity of Cr(VI) on PPy/NP was 261.78–395.26 mg/g at 303 – 323 K, which is significantly higher than that of PPy alone (124.84–194.17 mg/g). Thermodynamic analyses confirmed that this adsorption process was spontaneous and endothermic. PPy/NP composites could be used as a recyclable absorbents for four Cr(VI) reduction cycles without any evident loss in adsorption performance. The mechanism Cr(VI) removal by PPy/NP composites is attributed to ion exchange (9.47 %), adsorption (31.03 %), and reduction (59.50 %).

Magnetic MnFe2O4/ZnFe-LDH for Enhanced Phosphate and Cr (VI) Removal from Water

Huang Congxin,Tang Chaochun,Wu Qingqing,Zhu Qing

Due to the layered structure and recycling characteristics, magnetic MnFe 2 O 4 /ZnFe-LDH was prepared by co-precipitation. In this study, we intensively explored MnFe 2 O 4 /ZnFe-LDH for water purification compared with the ZnFe-LDH. The morphological and structural characteristics of the obtained products were systematically characterized. MnFe 2 O 4 /ZnFe-LDH exhibits the maximum adsorption capacity of 94.52 mg/g for phosphate and 49.03 mg/g for Cr (VI), respectively, which is superior to that of the ZnFe-LDH, indicating that the magnetic MnFe 2 O 4 effectively enhanced adsorption performance. Meanwhile, the mechanism of adsorption of phosphate and Cr (VI) was briefly studied, where the metal center ion in MnFe 2 O 4 /ZnFe-LDH and between layers of SO 4 2− serves as capture sites for phosphate and Cr (VI) removal. Furthermore, the MnFe 2 O 4 /ZnFe-LDH can be used for magnetic recycled and still maintained excellent removal efficiency (70%) for phosphate and Cr (VI) after five adsorption–desorption cycles. This work could open a new vista of designing magnetic novel adsorbents in environmental remediation.

Design and construction of SnIn4S8/Cd0.5Zn0.5S heterostructure photocatalyst for efficient Cr(VI) reduction

Meng Lan,Hanbing Jia,Xiaoli Dong,Nan Zheng,Xue Li,Yu Wang,Helezi Zhou

The development of highly competent and economical photocatalysts for competent erasure of heavy metal pollutants in water is of momentous import but still a significant challenge. Herein, 3D/0D SnIn 4 S 8 /Cd 0.5 Zn 0.5 S heterostructure photocatalyst was resoundingly fabricated through integrating Cd 0.5 Zn 0.5 S nanoparticles on the surface of SnIn 4 S 8 microsphere via a simple solvothermal method and applied to high efficiency photoreduction Cr(VI). The fabricated SnIn 4 S 8 /Cd 0.5 Zn 0.5 S with optimized composition ratio achieves the exceptional reduction Cr(VI) property and the photoreduction efficiency of 20 % SnIn 4 S 8 /Cd 0.5 Zn 0.5 S can reach 91.1 % within 30 min visible light illumination. The prominent photocatalytic efficiency comes from the intimate contact of heterostructure interface, which effectively expedites the separation and migration of carrier and inhibits the photocorrosion of photocatalyst. This work provides a promising photocatalyst for water environment remediation, and promotes the exploration of heterostructure photocatalyst for wastewater purification.

Novel nitrogen-doped KFeS2/C composites for the efficient removal of Cr(VI)

Qiaohong Su,Adnan Ali Khan,Zhi Su,Chen Tian,Xiaoqin Li,Jiahua Gu,Ting Zhang,Rashid Ahmad,Xintai Su,Zhang Lin

Adsorbents with excellent redox or adsorption properties are beneficial for the efficient removal of heavy metals. In this work, a novel nitrogen-doped KFeS2/C composite (NSC-1.3) was first prepared by a simple one-step pyrolysis method and used to effectively remove Cr(VI) from aqueous solutions. The kinetics and adsorption isotherms of Cr(VI) were in accordance with pseudo-second-order kinetic and Langmuir models, respectively. The maximum adsorption capacity of NSC-1.3 was 575.68 mg g−1 at 318 K and 326.8 mg g−1 at 298 K. The removal mechanism of Cr(VI) by NSC-1.3 was first discussed by X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) simulation. The XPS analysis showed that nitrogen or carbon functional groups provide abundant active sites for Cr(VI) adsorption, and Sn2− or S8 in NSC-1.3 reduces highly toxic Cr(VI) to less toxic Cr(III). The XPS analysis showed that the removal mechanism of Cr(VI) was through adsorption and redox reaction, but the dominant one was the redox reaction. DFT simulations showed that N atoms doping was feasible and thermodynamically stable. In addition, H2CrO4 makes stronger intermolecular hydrogen bonds and larger adsorption energies with the N-doped KFeS2 layer during the adsorption process, indicating that the N-doped system has a higher adsorption capacity for Cr(VI). This study confirms the importance of the adsorption and redox reaction mechanism of this new composite material, and has promising potential for the removal of highly toxic Cr(VI) from aqueous solutions.

Construction of hollow In2S3/CdIn2S4 heterostructures with high efficiency for Cr(VI) reduction

Cheng Cheng,Dongyun Chen,Najun Li,Hua Li,Qingfeng Xu,Jinhui He,Jianmei Lu

Hexavalent chromium (Cr(VI)) poses a serious threat to the environment and human health due to its high-toxicity and carcinogenicity. For efficient removal of Cr(VI), semiconductor photocatalytic reduction methods have been investigated, especially those using hollow structures. In this work, a hollow In2S3/CdIn2S4 composite photocatalyst was prepared via ion exchange for the reduction of Cr(VI). The microstructure, composition, optical properties, and elements of the In2S3/CdIn2S4 composites were characterized via scanning electron microscopy, X-ray diffraction, UV-vis diffuse reflectance spectroscopy, and X-ray photoelectron spectroscopy. Because of the molecular level heterojunction constructed through ion exchange and the hollow structure, the prepared photocatalyst demonstrated excellent catalytic properties for Cr(VI) reduction. Besides, a Cr(VI) aqueous solution (50 mg L−1) was reduced within 12 min. Importantly, the activity and structure of the photocatalyst were maintained after five cycling experiments, which demonstrates its advantageous stability. Finally, the photocatalytic mechanism is discussed in detail.

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.

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.