等离子体优化修饰技术在固定化酶载体材料中的应用进展

运用等离子体聚合或表面处理技术改变载体材料的表面性质,进而固定酶蛋白的方法主要有4类:等离子体表面处理、等离子体聚合、等离子体接枝共聚和等离子体化学气相沉积。综述了近年来用等离子体优化修饰技术处理载体材料进行固定化酶研究的新进展,指出今后应加强等离子体体系表面改性规律及机理、等离子体单体气体种类、放电条件及底衬材料等方面的研究。     

电化学分析电极的应用研究进展

为了提高工作电极的灵敏度、选择性和稳定性,经常采用滴镀、电化学聚合和电化学沉积等方法对其进行表面改性。综述了工作电极的表面修饰方法和表面修饰电极的应用,最后展望了表面修饰电极在电化学分析中的发展趋势。     

碳纤维布基聚吡咯修饰电极的制备及性能表征

分别用恒电流、恒电位、循环伏安法、电沉积与恒电流相结合等电化学方法,制备了新型碳纤维布基聚吡咯修饰电极,用扫描电子显微镜( SEM)观察了其表面形貌,研究了吡咯在碳纤维布基上的聚合条件和膜的生长过程,研究了聚吡咯修饰电极对氟离子的电流响应特性.结果表明:用电沉积与恒电流相结合的方法制备的碳纤维布基聚吡咯膜具有致密性好、...     

高耐蚀镀涂层研究的新动向

介绍了在提高镀涂层耐蚀性方面的两项成果:一是在镁中加入少量能毒化其阴极腐蚀反应的砷,二是在材料表面构造微-纳米粗糙结构及修饰一层疏水性极强的自组装膜(如硅烷偶联剂、巯基化合物和长链有机羧酸)。综述了通过电沉积、化学沉积、气相化学沉积、蚀刻、涂装等方法来得到超疏水表面的研究进展。指出了这两项领域未来的研究方向。     

电化学掺铜(Ⅱ)普鲁士蓝膜修饰电极的制备及其对苯酚的测定

以玻碳电极作为基底材料,采用电化学沉积法在玻碳表面沉积一层PB膜,然后进行CV扫描掺杂Cu~(2+),从而制得掺杂Cu~(2+)的类PB膜修饰电极。通过CV、CA研究了苯酚在Cu-PB膜修饰电极的电化学行为及其电化学动力学性质。研究表明:掺杂Cu~(2+)的类普鲁士蓝膜对苯酚存在电催化作用,而纯PB膜对苯酚无电催化作用。测定的线性范围5.5×10~(-6)～1×10~(-4) mol/L,检出限5×10~(-6) mol/L。     

TiO2光催化剂的改性与修饰

从TiO2光催化剂表面修饰的类型出发,综述了近年来有关表面光敏化、贵金属沉积、金属离子掺杂、半导体复合和表面螯合等对TiO2光催化剂的改性和修饰技术,并对其原理进行了解释。     

聚多巴胺修饰纳米SiO2颗粒

纳米SiO₂颗粒粒径小、比表面积大,广泛用做填料、涂料、催化剂等。由于纳米SiO₂颗粒表面能高、亲水性强、易团聚、在聚合物基体中的分散性差,需要对其表面修饰改性。多巴胺（DA）分子具有类似贻贝分泌的黏附蛋白的结构单元儿茶酚和活性基团氨基,在碱性条件下,通过氧化自聚可在多种材料表面沉积,形成富含活性基团的聚多巴胺（PDA）包覆层,可进行二次修饰,是近期发展的一种新型表面修饰方法。本文针对纳米SiO₂颗粒表面的PDA功能化修饰,分析了该修饰方法的工艺特点及优势,阐述了SiO₂@PDA纳米颗粒及SiO₂/PDA共聚复合颗粒的制备路线及应用,总结了SiO₂@PDA颗粒表面二次功能化修饰的研究进展。分析表明,SiO₂@PDA表面易于接枝功能化聚合物分子,并可负载功能纳米颗粒,有利于拓展SiO₂纳米颗粒的多功能应用。关于多巴胺与SiO₂纳米颗粒的表面反应机制、沉积动力学、聚合机理等仍需进一步研究。     

锂离子二次电池炭负极材料表面改性与修饰

综述了有关炭负极材料的表面改性与修饰方法,主要有:氧化还原、包覆、化学镀膜等方法,并通过对各种方法的研究效果比较,得出包覆是一种有效且实用的表面改性与修饰方法。     

碳纳米管/聚苯胺复合材料修饰电极制备及应用研究进展

综述了碳纳米管(CNTs)/聚苯胺(PANI)复合材料修饰电极的层层组装法和电共沉积法等制备方法,详细介绍了国内外关于CNTs/PANI复合材料修饰电极在抗坏血酸、葡萄糖、酚类及多酚类化合物、氨基甲酸酯类农药检测方面的研究进展并对该修饰电极的应用和发展前景进行了展望。     

碳纳米管/聚苯胺复合材料修饰电极制备及应用研究进展

综述了碳纳米管(CNTs)/聚苯胺(PANI)复合材料修饰电极的层层组装法和电共沉积法等制备方法,详细介绍了国内外关于CNTs/PANI复合材料修饰电极在抗坏血酸、葡萄糖、酚类及多酚类化合物、氨基甲酸酯类农药检测方面的研究进展并对该修饰电极的应用和发展前景进行了展望。     

The application of fluid dynamic gauging in the investigation of synthetic membrane fouling phenomena

In order to improve the performance of membrane processes there is a need to understand the basic phenomena occurring at the membrane and in the bulk fluid. Fluid dynamic gauging (FDG) is a technique that has been used previously to measure the thickness and strength characteristics of a fouling layer on solid surfaces. Here, its application has been extended to investigate the nature of fouling deposition on membranes in dead-end and cross-flow microfiltration. Two modes of FDG measurement are demonstrated, wherein either (i) the mass flow rate of liquid withdrawn through the gauge or (ii) the pressure drop across the nozzle, are fixed. In dead-end filtration, the deposition of ballotini on a polymeric membrane is monitored quantitatively via measurements of thickness and the permeate flux. FDG has also been integrated with imaging techniques to study the deposition and removal processes. In cross-flow, FDG proved to be able to monitor the growth of fouling layers during molasses processing.     

An integrated theoretical fouling model for convective heating surfaces in coal-fired boilers

Particulate fouling on convective heating surfaces in coal-fired power plant boilers could lead to significant efficiency deterioration and frequent unit outages. In this paper, a new integrated particulate fouling model is presented by considering the combined suspended particles deposition and the fouling removal processes. A pre-deposited medium, rather than the tube wall, is taken as the target surface, while considering its internal microstructure, surface morphology and mechanical properties. To understand the processes of particle deposition and removal in inertial impaction, three fouling criteria are proposed in this paper by defining critical sticking angle and critical velocities. Some influential parameters, such as the interfacial adhesion energy and the fouling porosity, were studied, which revealed good prediction precision of the fouling model. Based on the fouling model presented in this paper, a computation fluid dynamics simulation was implemented to reconstruct the distribution of particulate fouling and the characteristic of fouling growth on economizer tubes.     

Chemical reaction fouling of organic fluids

Chemical reaction fouling of heat exchangers involves deposition that is caused by chemical reactions which occur in the fluid, or on the surface itself. The factors which influence fouling of organic fluids via autoxidation and thermal decomposition processes are described and the dependence of the rate of thermal fouling on chemical effects and process variables demonstrated. Mitigation techniques are outlined in brief.     

Investigation of cake deposition on various parts of the surface of microfiltration membrane due to fouling

The accumulation of deposited layer on membrane surface in cross-flow microfiltration was investigated. This study provides a basis for elucidation of the membrane segments with superior tendency for cake deposition due to fouling. A commercially available GVWP membrane was fouled with a colored (blue indigo suspension in water) feed. The deposition pattern or fouling tendency was obtained using a digital camera, scanning electron microscope (SEM) and image analysis. The effects of feed concentration, transmembrane pressure and cross-flow velocity on cake deposition were investigated. In the early stages of the filtration trials, cake deposition was increased from the commencement portion (feed inlet) towards the furthermost part (concentrate outlet) of the membrane surface. However, at the completion of filtration, no pronounced difference was realized between cake deposition in the median and end parts of the membrane. Computational fluid dynamics (CFD) modeling of the membrane was carried out to predict the fouling behavior in various segments of the membrane at different operating conditions. The results of CFD modeling are in acceptable agreement with the experimental data. Accomplishment of the membrane sections with higher tendency for accumulation of foulants may provide a basis for manipulation of conditions to diminish the buildup of fouling deposition in the proposed segments. This results in lower cake deposition on vital parts to minimize the overall fouling.     

Experimental Study on Microbial Fouling Inhibition Performance of Ni-P-NanoTiO2 Composite Surfaces

Microbial fouling of heat exchangers causes serious issues including increased fuel consumption, flow resistance, and maintenance cost expenditure. Composite Ni-P-nanoTiO₂ coatings were prepared for inhibiting and mitigating the heat exchanger microbial fouling deposition. The surface energy components and wall adhesion work of microbial fouling medium had a significant effect on the microbial fouling deposition process. Compared with carbon steel coupons, the microbial fouling deposition on Ni-P-nanoTiO₂ coatings was reduced by about 90 % and the wall adhesion work and microbial fouling deposition rate of these coatings were less. The Ni-P-nanoTiO₂ coatings might not only be advantageous for controlling the initial microbial adhesion, but also effective for reducing the fouling deposition rate.     

Polymer adsorption on multicomponent surfaces with relevance to membrane fouling

Block copolymer thin films that include low surface energy domains are analyzed as a possible way to overcome the problem of membrane fouling by proteins and other natural organic matter. A model is presented that accounts for both fouling due to chemical interactions between the solute and surface and due to convective deposition. Guidelines for the formation of novel membranes with improved fouling-resistant properties are suggested based on comparison of the relative permeate flux decline due to fouling on different model copolymer membranes. In general, it is observed that copolymer films having small and dispersed polymer blocks that interact unfavorably with the fouling species show an overall decrease in fouling and increase in permeate flux compared with the homopolymer films.     

Effects of fouling on performance of retrofitted heat exchanger networks: A thermo-hydraulic based analysis

The energy recovery performance of crude pre-heat trains (PHTs) in oil refineries is typically impaired by deposition over time of fouling on the thermal surfaces. Such time varying effects are normally not considered in the design or retrofit of heat exchangers networks. In this paper, the importance of taking into account such effects is demonstrated, by means of a case study. An existing industrial PHT network is simulated using a dynamic, distributed mathematical model for shell-and-tube heat exchangers undergoing crude oil fouling. To systematically assess the impact of fouling at the network level, several key performance indicators are proposed and used to analyse three retrofit options aimed at maximising overall heat recovery. Simulation results show that network designs that maximise energy recovery at steady state are not the best when fouling occurs. It is concluded that a proper retrofit design must include consideration of time varying fouling effects.     

Fouling von Wärmeübertragungsflächen

Fouling of heat transfer surfaces . Fouling of heat transfer surfaces in industry causes considerable costs. Overcoming fouling is therefore essential for technical and economic reasons. Solution of the problems requires a better understanding of the physical, chemical and biological processes causing fouling. It is shown, that the prediction of the fouling behaviour of heat transfer equipment based on existing mathematical models is not jet satisfactory. This article presents a new physical model describing particulate and precipitation fouling based on the assumption of a deposition and a removal process. Experiments to prove the results of the theoretical considerations were carried out using an aqueous CaSO₄ solution. The test unit which is also suitable for in-situ measurements is described in detail. Measured and predicted asymptotic fouling factors agree with acceptable accuracy.     

纳米与微米颗粒污垢沉积的表面特性及等效关系

目前对颗粒污垢的研究主要局限于实验研究,通过实验和模拟的手段分别对微米和纳米颗粒污垢沉积的内在关系研究较少。为了研究静止流体中纳米级颗粒污垢与微米颗粒污垢出现相似沉积特点的原因,分别在不同工况下进行纳米颗粒污垢和微米颗粒污垢的沉积实验,并应用扫描电镜对试片表面进行观测。通过模拟方式得出不同粒径微米颗粒污垢的沉积质量,由实验得出颗粒污垢沉积质量呈现出渐进增长趋势。随着浓度的增大其渐进沉积质量越来越大,达到渐进污垢沉积量的时间越来越短。由于颗粒间的团聚效应,使纳米颗粒污垢出现与微米颗粒污垢相似的沉积规律。基于这种规律,提出纳米颗粒污垢等效直径的概念。将实验结果与不同直径微米级颗粒沉积模拟结果相结合,得出浓度0.4g/L的纳米悬浮液团聚后的等效直径约为9.2μm;浓度0.6g/L的纳米颗粒悬浮液团聚后的等效直径约为11.2μm。