共查询到18条相似文献,搜索用时 112 毫秒
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Cr(VI)具有非常大的生物毒性, 去除溶液中的Cr(VI)是当前的一个研究热点。本研究制备了C@K2Ti6O13分级纳米材料, 并用不同表征手段对材料的物相和结构等进行表征, 进一步探究了初始pH、吸附时间、离子强度等对C@K2Ti6O13复合纳米结构吸附Cr(VI)的影响。实验结果表明C@K2Ti6O13复合纳米结构对Cr(VI)有较强的吸附能力, 1 h内去除率能够达到50%以上, 其吸附动力学符合准二级动力学模型, 吸附热力学符合Langmuir等温吸附模型, 表明这种分级纳米材料在环境治理方面应用潜力巨大。 相似文献
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以活化铌酸为铌源,草酸铵为沉积剂,十二烷基苯磺酸钠为模板剂,采用水热法在硅藻土表面原位生长Nb_2O_5纳米棒。采用SEM、TEM、XRD、BET、FT-IR和XPS等分析方法对样品进行表征,反应14 h后,Nb_2O_5纳米棒长度为500~700 nm,直径为25~35 nm;硅藻土原位生长Nb_2O_5纳米棒样品比表面积为157 m~2/g。研究了样品对Cr(Ⅵ)的吸附与光还原行为,可见光条件下对Cr(Ⅵ)吸附量可达220 mg/g;紫外光条件下,可将表面吸附的Cr(Ⅵ)转变为Cr(Ⅲ),样品经过5次循环使用后,对Cr(Ⅵ)(100 mg/L)降解率仍能保持在93%左右。样品可对重金属污染废水中Cr(Ⅵ)进行吸附与毒性降解一体化去除。 相似文献
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以凹凸棒土为载体,合成了乙二胺(EDA)改性凹凸棒土(ATP)吸附剂EDA/ATP复合材料。采用FTIR、TGA对吸附剂进行表征,同时将其应用于对水中Cr(VI)的吸附,研究了溶液初始浓度、吸附时间、溶液pH、Cl?与PO43?阴离子浓度对吸附的影响。FTIR和TGA结果表明乙二胺已成功接枝到凹凸棒土表面。吸附实验表明,25℃时EDA/ATP复合材料对Cr(VI)的最大吸附容量为153.78 mg·g?1,吸附在800~900 min内达到平衡,吸附符合Freundlich吸附等温模型和拟二级动力学模型;在初始溶液pH为2~10条件下,随着pH的增加,吸附量先增加再降低,pH为3时,吸附量最大;Cl?对吸附影响较小,PO43?对吸附的影响较大,当PO43?浓度达到20 mmol·L?1时,Cr(VI)最大吸附量下降了83 mg·g?1;实验表明EDA/ATP可作为一种潜在处理水中Cr(VI)的吸附剂。 相似文献
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研究了MgAl水滑石(LDH)焙烧产物(LDO)对Cr(VI)的吸附性能。考察了吸附温度对LDO吸附性能的影响, 研究了吸附过程的热力学和动力学行为。结合XRD和FT-IR表征, 阐明其吸附机理。结果表明, CrO42–已成功插入水滑石层间, 适当提高吸附温度有利于LDO恢复LDH晶相。在20~60℃范围内, 随吸附温度升高, LDO对Cr(VI)吸附量增大, 50~60℃时, Cr(VI)吸附量为91 mg/g。Cr(VI)的吸附平衡数据符合Langmuir模型方程, ΔGo为负值说明吸附过程为自发过程, ΔSo和ΔHo为正值表明吸附为熵增的吸热过程。吸附动力学符合伪二级动力学模型, LDO 的吸附活化能为20.04 kJ/mol, 表现为扩散控制的活性化学吸附过程。 相似文献
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重金属铬的污染会严重威胁到土壤和水体的环境安全, 而水中的六价铬化合物则具有很强的迁移性、富集性和氧化性等特性, 更具有危害性且难以处理。吸附法是一种能简单、高效地处理含重金属污水的处理技术。在磁力搅拌条件下采用花生壳生物炭分别与高岭土和膨润土混合制备而成两种生物炭-黏土材料, 并分别对这两种生物炭-黏土的表面特性进行表征。结果发现所选用的两种黏土均能不规则地负载在生物炭的表面。吸附实验结果显示, 生物炭-高岭土(Biochar@Kaolin)吸附铬(VI)的能力显著高于生物炭-膨润土(Biochar@Bentonite)。从吸附动力学方程的分析可以看出, 合成的两种生物炭负载黏土吸附水中的铬(VI)均符合伪二级动力学方程。从吸附等温线分析中可以得到, Biochar@Bentonite吸附铬(VI)的过程符合Langmuir模型, 而Biochar@Kaolin吸附铬(VI)的过程符合Freundlich模型。研究结果显示, 采用生物炭-黏土的复合材料修复环境中的重金属污染具有广阔的应用前景。 相似文献
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以NH_4HF_2、氧化铌和氨水为原料,采用水热制备法,通过精确调控Nb前驱体溶液的pH,实现了Nb_2O_5纳米材料的形貌调控,制备得到了六方相Nb_2O_5纳米球及纳米棒材料。采用X射线衍射仪、扫描电子显微镜、比表面积和孔径分布分析仪对Nb_2O_5纳米材料的物相、形貌及比表面积进行了表征分析;采用静态配气法对其进行气敏性能测试,讨论了形貌对Nb_2O_5纳米材料气敏性能的影响。结果表明:Nb_2O_5纳米球与纳米棒均对丙酮表现出良好的选择性。与Nb_2O_5纳米球相比,Nb_2O_5纳米棒表现出更高的气敏响应及更短的响应时间和恢复时间:对50×10~(-6)(体积分数,下同)丙酮气体,Nb_2O_5纳米棒的气敏响应可达3.15,响应时间为7s,恢复时间为10s;Nb_2O_5纳米棒对丙酮表现出更好的气敏性能应归因于其具有更大的比表面积。 相似文献
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Lanju Sun Jikai Sun Shengliang Zhai Hongyan Yang Xiaokang Chen Wei-Qiao Deng Hao Wu 《Small (Weinheim an der Bergstrasse, Germany)》2023,19(26):2300914
Previously, heat treatment was the only feasible route for tuning the crystal phases of niobium pentoxide (Nb2O5). With the use of Nb2CTx MXene precursors, the first case of phase tuning of Nb2O5 in the low-temperature hydrothermal synthesis using sulfuric acid regulating agents is presented. By varying the amount of the agent, four pure-phase Nb2O5 crystals and mixed phases in-between are obtained. The required amount is found to be related to the H-covered surface energy calculated based on density functional theory. Overall, MXene-derived B-phase Nb2O5 is of particular interest due to its exceptionally high capacities as lithium-ion battery anodes, which are three times higher than the routine synthesized one. Oxygen vacancies induced by crystallographic shear would be responsible for the extraordinary performance. The proposed phase tuning strategy encourages the prudent synthesis of difficult-to-obtain crystal phases. 相似文献
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《Advanced Powder Technology》2022,33(3):103481
In this study, we have synthesized high-quality carnation flower-like Bi2O2CO3 hierarchical architectures via a hydrothermal route. The as-synthesized Bi2O2CO3 photocatalyst was systematically characterized and analyzed by various techniques. Its photocatalytic activity was investigated by simulated-sunlight driving photoreduction of Cr(VI), revealing that it exhibits excellent photocatalytic removal of Cr(VI). The effects of various factors (H2SO4, NaOH, Cr(VI) concentration, catalyst dosage) on the photoreduction efficiency and involved mechanism were systematically investigated and discussed. In addition, we have also systematically examined the effects of various parameters (H2SO4 concentration, 1,5-diphenylcarbazide (DPC) concentration, Cr(VI) concentration, reaction time t and reaction temperature T) on the absorbance of the Cr(VI) solution, with the aim of correctly determining the Cr(VI) concentration according to UV–vis absorption measurements using DPC as the chromogenic agent. 相似文献
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Yingchun Dai Guangren Qian Yali Cao Ying Chi Yunfeng Xu Jizhi Zhou Qiang Liu Zhi Ping Xu ShiZhang Qiao 《Journal of hazardous materials》2009,170(2-3):1086-1092
Friedel's salt (3CaO·Al2O3·CaCl2·10H2O or Ca4Al2(OH)12Cl2(H2O)4) is a calcium aluminate hydrate formed by hydrating cement or concrete in seawater at a low cost. In the current study, we carefully examined the adsorption behaviors of Friedel's salt for Cr(VI) from aqueous solution at different concentrations and various initial pHs. The adsorption kinetic data are well fitted with the pseudo-first-order Lageren equation at the initial Cr(VI) concentration from 0.10 to 8.00 mM. Both the experimental and modeled data indicate that Friedel's salt can adsorb a large amount of Cr(VI) (up to 1.4 mmol Cr(VI)/g) very quickly (t1/2 = 2–3 min) with a very high efficiency (>99% Cr(VI) removal at [Cr] < 4.00 mM with 4.00 g/L of adsorbent) in the pH range of 4–10. In particular, the competitive adsorption tests show that the Cr(VI) removal efficiency is only slightly affected by the co-existence of Cl− and HCO3−. The Cr(VI)-fixation stability tests show that only less than 0.2% adsorbed Cr(VI) is leaching out in water at pH 4–10 for 24 h because the adsorption/exchange of Cr(VI) with Friedel's salt leads to the formation of a new stable phase (3CaO·Al2O3·CaCrO4·10H2O). This research thus suggests that Friedel's salt is a potential cost-effective adsorbent for Cr(VI) removal in wastewater treatment. 相似文献
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《Advanced Powder Technology》2022,33(9):103722
Through a facile hydrothermal method, we have successfully prepared Ti3C2/Bi2.15WO6 (TC/BWO) composite, and systematically investigated their reactivity for the photocatalytic reduction of Cr(VI) under visible light. X-ray diffraction and Raman analysis confirm the formation of heterostructure between Bi2.15WO6 and Ti3C2. The resultant 7TC/BWO composite exhibits enhanced photoactivity toward Cr(VI) reduction. After 120 min irradiation, the conversion of Cr(VI) reaches 92.5% with the quasi-first-order kinetic constant of k = 0.0145 min?1, which is higher than that of pure BWO (30% and k = 0.0005 min?1). The electrochemical and photoluminescent characterization confirm that the introduction of Ti3C2 is conducive to the separation of carriers, thus significantly improves the photocatalytic performance of TC/BWO. Furthermore, the radical capture experiments verify that the electrons are important for enhancing reduction of Cr(VI) to Cr(III). As a result, this research provides a comprehensive understanding of the reduction of Cr(VI) by TC/BWO composite under visible light. 相似文献