MXenes的制备及其在环境领域的应用

MXenes是一类新型的二维过渡金属碳/氮化物或碳氮化物,是由Mn₊₁AXn相物质(MAX相)通过剥离而得到的单层或薄层纳米片。独特的二维层状结构、较大的比表面积以及出色的导电性、机械稳定性和磁性等性能,使MXenes迅速成为研究热点,并已广泛应用于储能、催化、吸附等众多领域。本文总结介绍了二维材料MXenes的制备方法,并重点综述其近年来在环境领域的应用研究进展,如吸附重金属、吸附放射性金属、吸附有机物、二氧化碳的选择性吸附、光催化、电催化、膜分离、传感器、生物活性、电磁吸收与屏蔽等进行了总结与回顾,最后对现阶段存在的问题和未来发展进行了分析。     

Optimization of Square Wave Voltammetry (SWV) Parameters by Design of Experiment (DoE) Methodologies for the Determination of Mifepristone at Glassy Carbon Electrode (GCE)

In the present study, an electroanalytical method that permits the optimization of factors affecting SWV for sensitive detection of mifepristone at glassy carbon electrode (GCE) using response surface methodology (RSM) with desirability function (DF) is presented. Factors selected for optimization after screening using full factorial design were frequency (X₁), amplitude (X₂), and pH (X₃). The central composite design as a response surface methodology with desirability function (DF) was applied for obtaining the optimum level. The optimum conditions were obtained as follows: Frequency (X₁=50 Hz), amplitude (X₂=33.4 mV), and pH (X₃=9.4), with an overall desirability function of 0.97. Subsequently, confirmatory experiments were performed in triplicates to validate the optimum conditions. The results obtained were satisfactory and agreed well with less only 11.9 % deviation from the values predicted by the model. The limit of detection (LOD) and limit of quantification (LOQ) were found to be 0.54 and 1.80 ppm, respectively. The proposed method was applied for a quantitative determination of mifepristone in spiked tap water samples. The recovery tests showed that the detection of mifepristone at GC could be evaluated on environmental samples.     

搅拌萃取–分光光度法检测水环境中阴离子表面活性剂

建立搅拌萃取–分光光度法快速检测水环境中阴离子表面活性剂的含量。用三氯甲烷以800~1 200 r/min搅拌萃取水样与亚甲蓝溶液合成的活性物质,搅拌时间为2 min,静置分层后经脱脂棉过滤,待测。阴离子表面活性剂质量浓度在0.050~0.500 mg/L范围内与吸光度线性良好,相关系数大于0.999 0,方法检出限为0.010 mg/L。选择饮用水源水、农村地下水、湖泊水、城市河道水作为研究对象,平行检测结果的相对标准偏差(RSD)为1.9%~6.5%(n=6),加标回收率为91.3%~110%;对标准物质检测结果的相对误差为–2.3%~3.5%,满足实验室分析质量控制要求和现行地表水、地下水质量标准的评价要求。该方法与国标检测方法相比,在准确度、精密度、灵敏度、分析效率及试剂用量方面均有明显优势,具有推广应用价值。     

脉冲输入毒素对具有阶段结构的单种群生存影响的研究

研究了一类小容量污染环境中脉冲输入毒素对具有阶段结构的单种群生存问题,分别找到了种群生存与灭绝的阈值,利用不等式放缩技巧,得到了种群灭绝和持久生存的充分条件.利用MATLAB数值仿真,验证了理论结果的正确性,分析了毒素输入量,毒素输入周期及种群成长时间对种群生存的影响.     

可持续供应链管理实践对企业绩效的影响:基于中国的实证研究

本文基于我国172家企业的问卷调查数据,运用结构方程模型,对企业可持续供应链管理实践及其对绩效的影响进行实证分析。结果表明,企业实现内部可持续管理能够对企业管理供应商的行为有着显著的影响;同时,企业管理供应商的行为作为企业外部管理实践对企业的绩效有着显著的正向影响;在企业绩效中,环境绩效和社会绩效对经济绩效有着显著的正向影响,企业的外部管理实践能够通过环境绩效和社会绩效的提高实现最终经济绩效的明显增加。     

Aligned Poly(ε‐caprolactone) Nanofibers Guide the Orientation and Migration of Human Pluripotent Stem Cell‐Derived Neurons,Astrocytes, and Oligodendrocyte Precursor Cells In Vitro

Stem cell transplantations for spinal cord injury (SCI) have been studied extensively for the past decade in order to replace the damaged tissue with human pluripotent stem cell (hPSC)‐derived neural cells. Transplanted cells may, however, benefit from supporting and guiding structures or scaffolds in order to remain viable and integrate into the host tissue. Biomaterials can be used as supporting scaffolds, as they mimic the characteristics of the natural cellular environment. In this study, hPSC‐derived neurons, astrocytes, and oligodendrocyte precursor cells (OPCs) are cultured on aligned poly(ε‐caprolactone) nanofiber platforms, which guide cell orientation to resemble that of spinal cord in vivo. All cell types are shown to efficiently spread over the nanofiber platform and orient according to the fiber alignment. Human neurons and astrocytes require extracellular matrix molecule coating for the nanofibers, but OPCs grow on nanofibers without additional treatment. Furthermore, the nanofiber platform is combined with a 3D hydrogel scaffold with controlled thickness, and nanofiber‐mediated orientation of hPSC‐derived neurons is also demonstrated in a 3D environment. In this work, clinically relevant materials and substrates for nanofibers, fiber coatings, and hydrogel scaffolds are used and combined with cells suitable for developing functional cell grafts for SCI repair.

     

Applying green analytical chemistry for development and validation of RP-HPLC stability indicating assay method for estimation of fenoverine in bulk and dosage form using quality by design approach

A green and robust reverse-phase liquid chromatographic method has been developed for the determination of fenoverine (FEN), by applying combined principles of green analytical chemistry and quality by design approaches on a Spherisorb C18 column (150?×?4.6?mm, 3?µm) with UV detection at 262?nm. A two level fractional factorial design (2^^7-3) Res IV was used for screening of influential chromatographic factors. The critical method parameters actively affecting critical quality attributes (CQAs) were identified and further optimized using Box–Behnken design. The predicted optimum assay conditions comprised of methanol and ammonium acetate buffer 20?mM, in an extent of 81:19% v/v individually having a flow rate of 1.0?mL/min with a column oven temperature of 33°C. The drug was stressed in hydrolytic, oxidative, reductive, thermal, and photolytic conditions. The developed method was validated successfully. The detector response was linear in the concentration of 0.5–160?µg/mL with a limit of detection (LOD) and limit of quantitation (LOQ) as 0.1 and 0.3?µg/mL, respectively. The % recovery was found to be 99.7%. The analytical method volume intensity value for developed method was 45?mL and the environment assessment tool (EAT) score was 41.07. The method is simple, environmentally benign, rapid, and robust for the determination of FEN in bulk and in its dosage form.     

Photochemically Produced Superhydrophobic Silane@polystyrene-Coated Polypropylene Fibrous Network for Oil/Water Separation

Cost-effective separation of oil and immiscible organic contaminants from water has become an urgent challenge to protect aquatic and human life from devastating effects. Therefore, it has become imperative to develop super-selective materials for efficiently separating oil from water. In this work, a superhydrophobic surface has been formed that consists of a silane@polystyrene-coated polypropylene fibrous network (silane@PS-PPF) for efficient separation of accidentally spilled oil from water. The superhydrophobic PPFs were designed by a simple, cost-effective two-step process that includes photochemically controlled polymerization of styrene and subsequent dip coating in octadecyltrichlorosilane solution. The hydrophobic surface (CA=129°±4°) of the PS coated PPF after treating with silane was turned into a superhydrophobic body (CA=161°±2°). The achieved silane@PS-PPF fibrous network selectively allowed the fast permeation of the oils and non-polar organic liquids by altogether rejecting water during operation. The separation efficiency for various oils from the contaminated water was 96 to 99%, with a high flux in the range of 7606±312 L m⁻²h⁻¹ to 9870±151 L m⁻²h⁻¹. Apart from being used as a filter, the silane@PS-PPF was also used as an oil absorber and has shown an absorption capacity in the range of 1185 to 1535% for various oils. We anticipate that the developed silane@PS-PPF, due to its facile synthetic route, cost-effectiveness, and high performance, can be effectively used in oily wastewater treatment and clean-up of large oil spills from water.     

微波消解-ICP-MS测定电镀污泥中的重金属

采用微波消解系统对某电镀污泥进行消解,利用ICP-MS对污泥中的重金属进行测定。称取制备后样品,置于消解罐中充分反应后,赶酸、定容后利用电感耦合等离子体质谱法进行测定。电镀污泥中的铬为18845.2mg/kg、镉为10.3mg/kg、镍为5200.0mg/kg、铅为189.7mg/kg、铜为3271.7mg/kg、锌为49632.6mg/kg。测定结果表明所检测项目工作曲线线性关系好,相关系数r均大于0.999。铬加标回收率在91.6～97.7%之间、镉加标回收率在92.0～97.0%之间、镍加标回收率在95.1～98.0%之间、铅加标回收率在94.3～95.2%之间、铜加标回收率在97.1～102%之间、锌加标回收率在96.3～98.7%之间,均满足相关测定要求。计算的潜在生态危害系数、潜在生态危害指数结果表明,电镀污泥中的铬、镉、铅、铜、锌为轻微生态危害,镍为强生态危害;潜在生态危害指数RI计算值为216.69,属于中等生态危害。     

电解水金属单原子催化剂的研究进展

氢能因其能量密度高、清洁无污染等特点,作为替代化石燃料的能源载体得到了广泛的研究.如何清洁高效地制备氢气受到了大量研究者的关注.当前,以化石能源的热反应所得副产氢气是主要来源.然而,采用该类方法不仅不能摆脱化石能源的使用以及温室气体的排放,还会造成生产氢气的纯度不高,碳氧化物杂质浓度过高的问题,严重影响氢气的后续使用.采用可再生能源(太阳能、风能等)所产富余电,进行电解水制氢,产生的氢气不含碳氧化合物杂质,纯度很高,可以真正实现碳的零排放,被认为是未来氢气来源的重要方式.目前,电解水制氢在制氢市场的所占份额较小,而造成这样局面的主要因素是该过程中的高能耗问题.为了降低能耗,开发高效催化剂加速两个电极上的电解反应的动力学尤为重要.近年,金属单原子催化剂(SACs)因其独特的结构,在很多研究中被用作电解水催化剂,进而开发出大量高性能的金属单原子电解水催化剂.本文综述了近年SACs在电解水催化方面的应用.首先,针对电解水反应本身,总结了阴阳极两侧的电极反应机制以及影响电极催化性能的关键吸附中间物种;然后,根据载体的不同,即合金、碳以及其它化合物将SACs分为三类,总结了相关电解水催化研究现状,并且针对不同类型SACs目前的发展情况,提出了它们各自存在的问题.其次,进一步总结了影响SACs电解水催化活性的因素,提出了四种决定SACs催化性能的影响因子,分别为金属原子的固有元素性质、配位环境、几何结构和负载量;同时讨论了这四类影响因素对SACs催化活性的影响机制,总结了调控各类影响因素的方法,为SACs的设计提出了一些建议.最后,展望了SACs在电解水催化中的应用,探讨了SACs在催化剂设计及催化机制研究方面的问题,提出了SACs在电解水催化中的未来发展方向.