Modulating charge separation and transfer for high-performance photoelectrodes via built-in electric field

Constructing a built-in electric field has emerged as a key strategy for enhancing charge separation and transfer,thereby improving photoelectrochemical performance.Recently,considerable efforts have been devoted to this endeavor.This review systematically summarizes the impact of built-in electric fields on enhancing charge separation and transfer mechanisms,focusing on the modulation of built-in electric fields in terms of depth and orderliness.First,mechanisms and tuning strategies for built-in electric fields are explored.Then,the state-of-the-art works regarding built-in electric fields for modulating charge separation and transfer are summarized and categorized according to surface and interface depth.Finally,current strategies for constructing bulk built-in electric fields in photoelectrodes are explored,and insights into future developments for enhancing charge separation and transfer in high-performance photoelectrochemical applications are provided.

One-step crosslinking preparation of tannic acid particles for the adsorption and separation of cationic dyes

In this study,a new tannic acid adsorbent(ethylene glycol diglycidyl ether crosslinked tannic acid,TAEGDE)for adsorptive removal of dyes from water was prepared using EGDE as a cross-linking agent.The resultant TA-EGDE was in particulate form with rough surface morphology and a diameter ranging from 10 to 30μm.The adsorption performance of the TA-EGDE was evaluated in a flow-through mode using water samples contaminated with methylene blue(MB)and two-component mixed dyes,respectively.The TA-EGDE provided adsorption capacity up to 721.8 mg·g^(-1)at 65°C for MB.It showed a high removal efficiency(99%)of MB(50 mg·L^(-1))from the water sample and could recovery 90%of the adsorbed MB by eluting with acidic ethanol aqueous solution.The excellent adsorption of MB and neutral red on the TA-EGDE may be the result of the synergy of electrostatic interaction andπ-πinteraction.Furthermore,the TA-EGDE could separate dyes from water samples contaminated with twocomponent mixed dyes with a separation coefficient ranging from 1.8 to 36.5.The anionic TA-EGDE would be an effective adsorbent to remove and recycle dyes from the contaminated water.

Separation of Clay Minerals from Host Sediments Using Cation Exchange Resins

Classic physical and chemical treatments applied to separating clay minerals from the host sediments are often difficult or aggressive for clay minerals. A technique using cation exchange resins (amberlite IRC\|50H and amberlite IR\|120) is used to separate clay minerals from the host sediments. The technique is based on the exchange of cations in the minerals that may be associated clay minerals in sediments, such as Ca and Mg from dolomite; Ca from calcite, gypsum and francolite with cations carried by resin radicals. The associated minerals such as gypsum, calcite, dolomite and francolite are removed in descending order. Separation of clay minerals using cation exchange resins is less aggressive than that by other classic treatments. The efficiency of amberlite IRC\|50H in the removal of associated minerals is greater than that of amberlite IR\|120.

Waste acid recovery utilizing monovalent cation permselective membranes through selective electrodialysis

Selective electrodialysis(SED)has surfaced as a highly promising membrane separation technique in the realm of acid recovery owing to its ability to effectively separate monovalent ions through the utilization of a potential difference.However,the current SED process is limited by conventional commercial monovalent cation permselective membranes(MCPMs).This study systematically investigates the use of an independently developed MCPM in the SED process for acid recovery.Various factors such as current density,volume ratio,initial ion concentration,and waste acid systems are considered.The independently developed MCPM offers several advantages over the commercial monovalent selective cation-exchange membrane(CIMS),including higher recovered acid concentration,better ion flux ratio,improved acid recovery efficiency,increased recovered acid purity,and higher current efficiency.The SED process with the MCPM achieves a recovered acid of 95.9%and a concentration of 2.3 mol·L^(–1) in the HCl/FeCl_(2) system,when a current density of 20 mA·cm^(-2) and a volume ratio of 1:2 are applied.Similarly,in the H_(2)SO_(4)/FeSO_(4) system,a purity of over 99%and a concentration of 2.1 mol·L^(–1) can be achieved in the recovered acid.This study thoroughly examines the impact of operation conditions on acid recovery performance in the SED process.The independently developed MCPM demonstrates outstanding acid recovery performance,highlighting its potential for future commercial utilization.

Influence of monovalent cations and CuO nanoparticles on X-nanozeolite in uranium anionic species separation from contaminated drinking water

The main purpose of this work was the modification of NaX nanozeolite using copper oxide nanoparticles and various monovalent cations such as K^+, Cs^+, and Ag^+in order to make the negatively charged zeolite surface accessible for anionic forms of uranium which are the most dominant species of uranium in the contaminated radioactive waters at natural p H. Various methods such as the X-ray fluorescence(XRF), X-ray powder diffraction(XRD), field emission scanning electron microscopy(FE-SEM), transmission electron microscopy(TEM), Fourier transform infrared spectroscopy(FT-IR), and atomic absorption spectroscopy(AAS) were used to characterize the final synthesized absorbents. Batch technique was used to study the adsorption behavior of uranium ions from polluted drinking water by Na X nanozeolite and its modified forms. In order to better understand the performance of them, the results were compared with those that were obtained for synthesizing bulk NaX zeolite and Na-form of clinoptilolite natural zeolite. Preliminary results indicated that uranium sorption increased as the loading level of CuO nanoparticles on NaX nanozeolite increased from 2.1 wt% to 11.2 wt%. In addition,from the obtained data, an increase in uranium removal efficiency resulted as charge/ionic radius ratio of exchanged cation decreased. Also, the effect of contact time, solid–liquid ratio, initial concentration and temperature on the adsorption process was studied. It is worth mentioning that, in this study, the sorption of uranium was performed under natural conditions of pH and the presence of competing cations and anions which are available in drinking waters.

Poly [ (chloromethyl) styrene-co-divinylbenzene] Continuous Rod Column of Weak Cation Exchange Chromatography and its Applications in the Separation of Biopolymers

Macroporous poly [(chloromethyl) styrene-co-divinylbenzene] continuous rod was prepared by direct polymerization of the monomers in the presence of a porogenic diluent inside an empty chromatographic column. A new 'in-situ' technique was used to modify the synthesized polymer rod for a weak cation exchanger and it has been used successfully for the separation of biopolymers. It was found that the back pressure of the continuous rod column was much lower and its surface was proved to be modified well.

Adsorption equilibrium, kinetics, and dynamic separation of Ca2+ and Mg2+ ions from phosphoric acid–nitric acid aqueous solution by strong acid cation resin

The separation of Ca2+and Mg2+ions from phosphoric acid-nitric acid aqueous solution is very significant for the neutralization process of nitrophosphate fertilizer.This paper studied the adsorption equilibrium,kinetics,and dynamic separation of Ca2+and Mg2+ions by strong acid cation resin,and the effects of phosphoric acid and nitric acid on the adsorption process were investigated.The results reveal that the adsorption process of Ca2+and Mg2+ions in pure water on resin is in good agreement with the Langmuir isotherm model and their maximal adsorption capacities are 1.86 mmol·g-1 and 1.83 mmol·g-1,respectively.The adsorption kinetics of Ca2+and Mg2+ions on resin fits better with the pseudo-first-order model,and the adsorption equilibrium in pure water is reached within 10 min contact time,while at the present of phosphoric acid,the adsorption rate of Ca2+and Mg2+ions on resin will go down.The dynamic separation experiments demonstrate that the designed column adsorption is able to undertake the separation of metal ions from the mix acids aqueous solution,but the dynamic operation should control the flow rate of mix acid solution.Besides nitric acid solution was proved to be effective to completely regenerate the spent resin and achieve the recyclable operation of separation process.

Purification, characterization and evaluation of insecticidal activity of trypsin inhibitor from Albizia lebbeck seeds

A Bowman-Birk inhibitor with activity against gut proteases of Helicoverpa armigera was extracted in 0.I M sodium phosphate buffer from defatted seed flour of Albizia lebbeck. It was purified to 29.62 folds with 51.43% recovery using ammonium sulfate precipitation, gel filtration chromatography on Sephadex G-100 column and ion ex- change chromatography on DEAE-Sephadex As0. The purified protein had a molecular weight of 12,303 daltons as determined by SDS-PAGE. It was found to be heat stable up to 60~C and had two pH optima of 7.5 and 9.0. The inhibitor exhibited non-competitive pattern of inhibition with a low Ki value of 0.2 ~tM. The inhibitoi- was found to be susceptible to varying concentrations of reducing agents like DTT and 2- mercaptoethanol, thereby indicating the role of disulphide bridges in maintaining its three dimensional structure and stability. The purified inhibitor caused mortality and suppressed larval growth ofPieris brassi- cae larvae. It was also found to be effective against gut trypsin extracted from Spodoptera littoralis. The sequence of the genes encoding for such inhibitors can be determined and the genes expressing protease inhibitors can be used in vegetable crops to confer resistance against insect pests and other plant pathogens.

PURIFICATION AND SOME PROPERTIES OF Fe PROTEIN OF NITROGENASE FROM Anabaena cylindrica

The Fe protein of Anabaena cylindrica was first separated and purified by chromatography through DEAE-cellulose columns then by gel electrophoresis.The specific activity was up to 142.46 nmol C2H4/mg protein . min. It was homogeneous as shown by 1 )a single band in the gel electrophorogram ; 2)absence ofMo and tryptophan ;3)content of about 3.4 atoms ofFe per mole protein.The molecular weight of the Fe protein of A . cylindrica was about 61,000 daltons as estimated by SDS-gel electrophoresis and calculated from the amino acid composition. The residues of aspartate and glutamate were about 2.6 times that of arginine and lysine in the Fe protein. Crossing Fe protein of A . cylindrica with Mo-Fe protein of Azotobacter vinelandii gave positive result. The reciprocal crossing also showed activity.

酒钢悬浮焙烧磁铁矿选矿工艺优化研究

对酒钢悬浮焙烧磁铁矿进行了磨矿-选矿工艺优化研究。采用110 mT低场强磁选机预提精、中矿再磨后采用磁选富集抛尾、富集精矿经阳离子反浮选,最终获得TFe品位60.06%、SiO_(2)含量5.17%、金属回收率84.27%的综合精矿;与原工艺指标相比,精矿TFe品位提高了1.96个百分点,金属回收率提高了1.38个百分点,SiO_(2)含量降低了1.06个百分点。

膜法分离一/二价阳离子的研究进展

各类工业过程如水质软化、食用盐纯化、盐湖卤水提锂、酸和重金属资源回收等对一/二价阳离子高效分离的需求日益增长,近年来,针对上述分离体系的膜材料的研究取得了诸多进展。本文详细总结了针对一/二价阳离子分离的选择性阳离子交换膜、纳滤膜、支撑液膜和离子印迹膜的研究进展,重点梳理了相关膜材料的离子选择性优化思路和机理,对比分析了上述膜过程的特点和适用场景。基于此,作者认为,离子筛分精细化是膜分离技术的重要发展方向。在分子尺度明晰分离层的形成和演化机理,对于提高界面聚合反应可控度,实现在亚纳米尺度膜结构的精细调控至关重要。通过在膜基体内可控构建目标离子的特异性识别位点和传质通道,有望实现高选择性离子筛分。此外,具有本征规则孔道结构的新型分离膜材料,如MOFs、COFs、二维层状结构膜等,在精细筛分方面具有良好的发展潜力。

松茸粗多糖的提取工艺优化、单糖组成及体外抗氧化活性

【目的】提高松茸粗多糖提取率,探究松茸多糖纯化组分及抗氧化作用。【方法】采用超声波辅助水提醇沉法提取松茸粗多糖,优化提取工艺,使用DEAE-Sepharose Fast Flow离子柱分离纯化粗多糖,采用离子色谱法分析单糖成分,并测定体外抗氧化活性。【结果】最优提取工艺参数为:浸提时间2.25 h,料液比1∶31(g∶mL),浸提温度83.50℃,该条件下多糖提取率为8.67%。松茸粗多糖经分离纯化后收集到3种多糖组分(TMP-1、TMP-2、TMP-3),主要由岩藻糖、盐酸氨基葡萄糖、半乳糖、葡萄糖和甘露糖组成,其中TMP-1存在鼠李糖,TMP-2和TMP-3存在葡萄糖醛酸。松茸粗多糖和3种纯化多糖组分均具有一定的抗氧化活性且存在量效关系,抗氧化能力强弱为:松茸粗多糖>TMP-2>TMP-3>TMP-1。【结论】松茸多糖有一定的抗氧化活性,且松茸粗多糖效果最好,分离纯化后的多糖组分抗氧化活性有所降低。本研究为松茸多糖的开发利用提供了理论基础,对其功能食品研发具有重要意义。

“Grafting from”法制备高载量大孔弱阳离子交换层析介质

针对大孔聚合物层析介质孔径大、比表面积低而导致的蛋白结合容量低的问题,采用“graftingfrom”策略,以大孔聚丙烯酸酯微球为基质,通过氧化还原引发甲基丙烯酸在微球表面接枝聚合,制备了高载量弱阳离子交换层析介质.研究了单体浓度、过硫酸钾浓度及反应温度等因素对蛋白结合容量的影响.所得介质的蛋白静态结合容量和动态结合容量分别达到252.21和157.25mg/mL;同时发现具有一定离子交换容量的该类介质能够在0.2 mol/L NaCl缓冲液中保持100 mg/mL的蛋白结合容量.将该层析介质用于鸡卵清中溶菌酶的纯化,获得了较高的纯化效率.

新时期装饰装修污染现状分析及控制措施探讨

随着城镇化步伐的加快,人们集中在城镇落户且在室内的时间达到80%以上,装饰装修造成的污染,已成为影响人体健康的主要因素。为了控制室内空气质量,保证人们的身心健康,有关部门制定了一些与室内空气质量相关的标准。在人们环境保护意识不断发展的过程中,装饰装修污染净化及检测治理成为新兴行业。本文针对新时期装饰装修现状进行分析,并探讨相关控制措施。

锂同位素阳离子交换树脂分离纯化方法与应用进展

锂(Li)同位素是良好地球化学示踪工具,被广泛应用于壳幔物质循环、行星起源与演化、大陆风化、古环境与气候变迁、成矿机制及环境污染等领域。然而,分析测试过程中同质异位素的潜在干扰使得自然样品中Li的高效分离纯化成为关键需求。近几十年来,锂同位素阳离子交换树脂分离纯化法得到了广泛应用和发展,形成了多类型不同自然样品中Li分离纯化的一系列方法体系。从早期Li的分离纯化方法仅注重于实现自然样品Li的分离效果,使之满足TIMS分析需求,逐渐发展到注重减少分离纯化过程中引入空白污染、简化操作提高分离效率以及对不同类型自然样品具有广泛适用性等方面。本文阐述了近年来基于阳离子交换树脂法的锂同位素分离纯化方法研究进展,重点总结了单柱法、双柱法、多柱法和套柱法的操作流程与技术特点,从树脂类型选择及用量、淋洗液类型选择及其在不同类型自然样品中的适用性和应用效果等方面,分析了各类方法的应用优势。目前单柱法和双柱法是Li分离纯化研究中应用较为广泛的方法,在不断优化过程中,一些方法的树脂用量低至1mL,淋洗液用量少于10mL,流程空白控制在1‰以下,整个淋洗流程被缩短至数小时之内。但不同分离纯化方法仍在很大程度上依赖于样品Li含量及其他基质离子等因素。因此,在兼顾分离效率、适用范围以及经济性等因素下,进一步优化现有方法体系、扩展不同类型样品适用范围,对于提升锂同位素分析效率和精度以及推动锂同位素应用研究发展具有重要意义。随着测试设备和技术的不断进步,逐步探索自动化淋洗设备在自然样品Li高效分离纯化中的应用,将成为锂同位素分析技术的主要发展方向之一。

CO_(2)驱产出气回注工艺及配套压缩装置的应用研究

CO_(2)驱油田产出气主要来源于注入气和油田伴生气,是目前油田CO_(2)驱环节过程中造成温室效应的一个主要排放源。以草舍油田小井组CO_(2)驱油产出气为研究对象,设置了若干单元对产出气进行提纯净化,有效除油降水,满足压缩装置的进气要求。同时针对性改造压缩装置,实现装置的自动化、撬装化,不仅降低了装置运行成本,也实现了CO_(2)的循环利用,该研究对CO_(2)驱产出气回收、实现碳减排具有积极意义。

两性纤维素多孔凝胶球的制备及其动态吸附性能

用于废水处理的多孔凝胶球存在制备工艺繁琐,吸附种类单一,吸附效率低等不足;为提高多孔凝胶球的性能,采用滴入相分离、酯化反应引入羧基及希夫碱反应引入氨基的化学改性方法,制备得到兼具高孔隙率、高力学性能和羧基/氨基活性基团的两性纤维素多孔凝胶球(ACM),并构建动态吸附柱装置以探究不同条件下ACM对染料的动态吸附性能。结果表明:通过降低染料初始质量浓度,增加填料高度和减慢进液流速的方式可有效提高吸附柱的动态吸附效率;0.8 g的ACM可处理7.5 L含染料的废水;对ACM的动态吸附过程进行动态模型拟合,其与Thomas和Yoon-Nelson模型的拟合程度高,表明吸附是均匀表面的单分子层吸附,动态吸附过程中存在2个或多个速率控制步骤,内部扩散和外部扩散均不是吸附过程中的限速步骤。基于ACM优异的分级孔结构、丰富的活性位点和低传质阻力等优势,认为ACM展现出良好的动态吸附性能,在印染废水处理方面有较大应用潜力。

The Adsorption Properties of TEMPO Oxidized Cellulose against the Mixture of Methylene Blue and Rhemazol Yellow FG

TEMPO/NaOCl/NaBr treatment significantly increased the number of negative charges on the cellulose surface.Two concentrations of NaOCl,5 and 30 mmol/g of cellulose,were used in this study.The number of carboxyl groups in the two cellulosic samples oxidized using TEMPO/NaOCl/NaBr was 0.5160 and 1.8461 mmol/g of cellulose,respectively.The oxidized cellulose samples treated with 5 and 30 mmol/g NaOCl exhibited higher crystallinity,at 81.15%and 80.14%,respectively,compared to untreated cellulose,which had a crystallinity of 75.95%.The pH effect indicated that the highest adsorption capacity for methylene blue was achieved under alkaline conditions(pH 9),while the highest adsorption capacity for rhemazol yellow FG was achieved under acidic conditions.The kinetic model of TEMPO-oxidized cellulose for methylene blue and rhemazol yellow FG conformed to the pseudo-second-order model.The initial concentration parameter revealed that the isotherm model for the adsorption of methylene blue and rhemazol yellow FG by TEMPO-oxidized cellulose conformed to the Langmuir model.The dye removal efficiencies for methylene blue and rhemazol yellow FG using TEMPOoxidized cellulose(30 mmol/g)were approximately 80.17%and 59.52%,respectively.These results demonstrate that TEMPO/NaOCl/NaBr-oxidized samples can effectively separate cationic and anionic dye mixtures.Furthermore,the use of TEMPO-oxidized cellulose showed good regeneration capability,maintaining more than 95%of its adsorption capacity after 8 cycles.

组合人工湿地技术在污水处理厂尾水深度净化中的应用

针对盐城市大丰污水处理厂出水为一级A标准,直排入河将污染周边水系,影响周边环境生态安全等问题,采用“强化净化湿地+深度涵养湖泊”的组合湿地工艺对污水处理厂尾水进行深度净化,结果表明,组合人工湿地系统对COD、NH3-N、TN及TP的平均去除率分别为76.01%、54.83%、63.46%及40.72%,该技术对污水处理厂尾水深度净化的效果较好,出水能稳定达到《地表水环境质量标准》(GB 3838—2002)III类标准。

人工湿地技术在污水处理厂尾水深度净化中的应用研究

当前各地都在加强污水处理厂的建设和改进污水处理方法,如果污水处理厂的尾水未进行深度净化就直接排放,作为主要点源污染,会影响水环境。而湿地建设可建设成为集水质净化、景观湿地、文化宣传、科普教育于一体的生态文明体验中心,将其融入污水处理厂的尾水净化工作中,可以有效提升尾水深度净化效果。基于此,本文重点分析人工湿地技术在污水处理厂尾水深度净化中的应用,希望能为污水处理单位提供一些启示与思考。