卤氧化铋薄膜的制备及其在海洋防污应用中的进展

海洋生物污损引起的一系列经济损失和安全问题,是海洋开发过程中必须面临的重要问题之一,因此开发新型高效的防污技术具有重要意义。随着光催化抗污技术的发展,其在海洋防污的应用受到了广大研究者的关注。卤氧化铋（BiOX,X=Cl、Br、I）薄膜作为一种新型半导体薄膜,由于具有优异光催化性能、较高的机械强度和易于回收等优点,而成为应用于光催化防污领域中新的研究热点。综述了BiOX半导体薄膜的制备方法及其应用领域的最新进展。首先,在海洋污损与现存防污技术的研究背景下,概述了光催化技术应用于海洋防污的潜力。其次,综述了国内外当前BiOX薄膜制备技术及其应用领域,并介绍了各种方法的优缺点。之后总结了BiOX半导体膜在海洋防污领域的最新应用研究,其中特别强调了海洋环境中膜材料应用的必要性。最后,展望了BiOX半导体薄在海洋防污领域的发展前景,概述了可能产生突破性研究成果的发展方向,为进一步将BiOX薄膜应用于海洋防污领域打开了新的视角。     

水利工程污损生物沼蛤的物理去除技术研究

我国南方水利工程常受到沼蛤(limnoperna fortunei)生物污损的危害,沼蛤高密度粘附在结构面上会改变建筑物功能结构,影响水利工程安全运营。通过研究沼蛤在离水干燥、高温水浴、超声波、电流作用下的死亡特征,探讨利用物理方法去除沼蛤的工程技术可行性。研究结果表明沼蛤在环境温度为28 ℃的离水干燥条件下,3d就会因缺水而死亡;沼蛤在水浴温度为44 ℃的环境中的死亡时间为10h,当水浴温度＞55 ℃时,在其接触高温水体瞬间就会死亡,内部组织与角质壳分离、脱落;在沼蛤集中的水环境中加载超声波和高压电流也能灭杀沼蛤幼虫及成贝,有效抑制其大量繁殖。研究了4种去除沼蛤的物理方法,其中离水干燥法和高温水浴法灭杀效率较高,而超声波和电流灭杀法具有较好的预防特性。     

泄漏柴油对杀菌剂生物黏泥控制效果的影响

在油品泄漏情况下,循环水水质发生变化,常规的杀菌剂投加模式将不能满足循环水系统生物黏泥控制要求。利用现场循环冷却水中的微生物,在挂片上培养出稳定附着期的生物黏泥后,以柴油为泄漏介质,考察了不同质量浓度泄漏柴油对氧化型杀菌剂ClO₂和非氧化型杀菌剂1427生物黏泥控制效果的影响。结果表明,随着柴油添加质量浓度从100 mg/L增大到900 mg/L,无论是在ClO₂还是在1427作用下,溶液COD均呈现上升趋势,生物黏泥脂磷浓度和细菌数量呈现先快速下降后平稳趋势,杀菌率呈现先快速上升后平稳趋势。相对于1427来说,柴油质量浓度的变化对ClO₂的杀菌作用影响更大。     

Initial fouling of nontoxic coatings in fresh,brackish, and sea water

Objectives of this project were to evaluate benefits — over the short term — that might derive from control of the surface properties of materials used in energy transfer devices; and to identify preferred ranges of surface parameters that might be specified to minimize deposits of biological fouling known to deteriorate energy exchange efficiencies in seawater, brackish water, and freshwater systems. By modifying the surface chemistry and surface energy of test plates with very thin coatings (nontoxic) and examining the acquired films at various time intervals, the earliest events of biofouling caused by macromolecules and microbial organisms were defined. Overall, the results were remarkably similar for all systems tested in showing that deliberate modification of the initial material surface qualities can significantly reduce the retention of biofouling layers.     

Mechanisms of biofilm formation on aluminium tubes

The development of biofilms in contact with flowing liquids was monitored in a biofouling culture apparatus which contained aluminium tubes and which was inoculated with Pseudomonas fluorescens. Tests were carried out in which, alternately, the nutrient feed or the bacterial supply was stopped. Results showed that once the surface is colonised, the predominant mechanism for biofilm development was growth within the film. Maximum biofilm development occurred at liquid flow velocities around 1 m s^?1. Rapid development occurred even in the presence of very small amounts of nutrient.     

循环冷却水中营养物水平与生物黏泥生长特性的相关性

为研究循环冷却水系统内循环水水质与生物黏泥形成规律之间的相关关系,设计了以BOD₅（碳源）、NH₄⁺-N（氮源）、TP（磷源）为主要影响因素的正交实验,并对生物黏泥内的优势微生物进行了菌种鉴定。结果表明：各因素对EPS浓度、湿重和机械强度的影响最大是BOD₅,其次是TP,NH₄⁺-N对其浓度的影响最小,控制循环水中BOD₅浓度是控制生物黏泥生长最有效的措施。为控制生物黏泥的生长,循环冷却水中营养物的最佳浓度BOD₅为5 mg/L、NH₄⁺-N为10 mg/L、TP为1 mg/L。当循环冷却水系统中营养物质的浓度及比例构成发生变化时,主要的微生物种类以及生物黏泥胞外聚合物中多糖和蛋白质的浓度均发生了变化。     

Biofouling Growth in Cold Estuarine Waters and Evaluation of Some Chitosan and Copper Anti-Fouling Paints

Ecological concerns about antifouling paints containing non-green tin and copper compounds have highlighted the need for environmentally friendly alternatives. We report here a field test conducted in estuarine waters over two months designed to evaluate the efficiency of a number of active natural and man-made chemical ingredients added into a silicon-polyurethane marine paint. Early steps of biofouling in cold seawater of the St. Lawrence Estuary (Canada) were observed. Analyses, including dry biomass, flow cytometry and spectrofluorimetry, demonstrated a short-term antibacterial action of chitosan-based paints although no significant anti-algal action was observed. Cuprous oxide paints were efficient against bacteria and algae invasion in the first two weeks, especially those with added organic biocides such as isothiazolone and copper pyrithione. However, the overall dry biomass and chlorophyll a content were similar for all chitosan-and copper-based paints after 63 days. Microscopic observations revealed variation in the highly diverse benthic diatom population including species Navicula, Melosira, Cocconeis, Nitshzcia, Fragilaria and Amphora. Results suggest no real long-term efficiency for tested antifouling paints and highlight a particular need for green antifouling ingredients that are active under northern estuarine conditions.     

Assessment of the Antibiofilm Performance of Chitosan-Based Surfaces in Marine Environments

Marine biofouling is a natural process often associated with biofilm formation on submerged surfaces, creating a massive economic and ecological burden. Although several antifouling paints have been used to prevent biofouling, growing ecological concerns emphasize the need to develop new and environmentally friendly antifouling approaches such as bio-based coatings. Chitosan (CS) is a natural polymer that has been widely used due to its outstanding biological properties, including non-toxicity and antimicrobial activity. This work aims to produce and characterize poly (lactic acid) (PLA)-CS surfaces with CS of different molecular weight (Mw) at different concentrations for application in marine paints. Loligo opalescens pens, a waste from the fishery industry, were used as a CS source. The antimicrobial activity of the CS and CS-functionalized surfaces was assessed against Cobetia marina, a model proteobacterium for marine biofouling. Results demonstrate that CS targets the bacterial cell membrane, and PLA-CS surfaces were able to reduce the number of culturable cells up to 68% compared to control, with this activity dependent on CS Mw. The antifouling performance was corroborated by Optical Coherence Tomography since PLA-CS surfaces reduced the biofilm thickness by up to 36%, as well as the percentage and size of biofilm empty spaces. Overall, CS coatings showed to be a promising approach to reducing biofouling in marine environments mimicked in this work, contributing to the valorization of fishing waste and encouraging further research on this topic.     

Optical assessment of a fouling-resistant surface (PHEMA/ benzalkonium chloride) after exposure to a marine environment

A hydrogel based on poly(2-hydroxyethyl methacrylate) (PHEMA) containing benzalkonium chloride (BAK) can be used as an environmentally acceptable, fouling-resistant material in the marine environment. The loaded hydrogel system is transparent and has the potential to be used in the protection of optical ports in underwater instruments. Ultraviolet–visible (UV–vis) spectroscopy was used to study the optical properties of the material after a marine exposure period. The optical transmittance of PHEMA/ BAK was higher for 10 weeks than that detected for poly(methyl methacrylate) (PMMA), a material currently used in commercial instruments, which confirmed the superior fouling resistance of the PHEMA/ BAK combination. The UV–vis spectroscopic method was quick, relatively cheap and accurate enough to allow the effects of the development of marine fouling on transparent surfaces for use in marine underwater optical applications to be monitored. © 1998 John Wiley & Sons, Ltd.     

Towards a nanomechanical basis for temporary adhesion in barnacle cyprids (Semibalanus balanoides)

Cypris larvae of barnacles are able to use a rapidly reversible temporary adhesion mechanism for exploring immersed surfaces. Despite decades of research interest, the means by which cyprids maintain attachment with surfaces prior to permanent settlement remain poorly understood. Here, we present novel observations on the morphology of 'footprints' of a putative adhesive secretion deposited by cyprids during surface exploration. Atomic force microscopy (AFM) was used to image footprints at high resolution and to acquire measurements of interaction forces. R-CH3- and R-NH2-terminated glass surfaces were used for comparison of footprint morphology, and it was noted that on R-NH2 each footprint comprised three times the volume of material deposited for footprints on R-CH3. Direct scaling of adhesion forces derived from AFM measurements did not adequately predict the real attachment tenacity of cyprids, and it is suggested that a mixture of 'wet' and 'dry' adhesive mechanisms may be at work in cyprid adhesion. High-resolution images of cyprid footprints are presented that correlate well with the known morphology of the attachment structures.