粒状复合镁铝氧化物对碘离子的吸附性能

将层状氢氧化镁铝粉末成型、焙烧得到粒状复合镁铝氧化物,该复合材料具有230.59 m2/g的比表面积和14.87 nm的平均孔径.考察了碘离子溶液初始浓度,pH值,流速和吸附剂床层高度对其动态吸附性能的影响.在碘离子溶液初始浓度为200 mg/L,pH=7,流速为5 mL/min,吸附剂床层高度为10 cm的动态吸附条件下,饱和吸附量为217.09mg/g,明显优于粉状复合镁铝氧化物(25.61 mg/s).     

焙烧层状氢氧化镁铝对溴离子吸附性能研究

研究了500℃下焙烧层状氢氧化镁铝对溴离子吸附性能,考察了吸附时间、吸附剂用量、吸附温度、吸附初始pH值等条件对吸附性能的影响.实验结果表明,焙烧层状氢氧化镁铝对溴离子具有较好的吸附性能,35℃下饱和吸附量为133.33mg/g,其吸附等温线可以用Langmuir等温方程描述.     

改性玉米芯吸附污水中重金属的研究

通过对玉米芯化学改性处理,将其用于废水中重金属离子的吸附试验,从pH值、重金属初始浓度、吸附时间、吸附剂投加量等干扰因素考察了改性玉米芯的吸附特性,试验结果表明：在pH值为7.0、重金属初始浓度47.07 mg/L、吸附时间为24.63 h,改性玉米芯吸附剂对重金属吸附量达96.4 mg/g以上。     

球形纤维素吸附剂对亚甲基蓝的吸附热力学研究

以离子液体(BMIMCl)为反应介质,选用丙烯酸为单体,在均相条件下对纤维素进行接枝改性,后经反相悬浮技术制得球形纤维素吸附剂。通过静态吸附方法研究该吸附剂对阳离子型染料亚甲基蓝的吸附性能,探讨了影响吸附效果的各种因素(溶液pH值,染料初始浓度,吸附时间及温度),并研究了吸附的热力学特征以及吸附剂的再生性能。结果表明,在一定范围内提高pH值,增加染料初始浓度以及延长吸附时间都可以提高吸附效果;吸附剂对亚甲基蓝的吸附符合Langmuir吸附等温式;吸附过程是自发的放热过程;该球形纤维素对亚甲基蓝的吸附具有可循环利用性,再生性能良好。     

改性半纤维素吸附剂的制备及其对Pb~(2+)的吸附

为了提高蔗渣半纤维素对重金属离子的吸附性能,以顺丁烯二酸酐为单体对蔗渣半纤维素进行改性,制备出新型重金属离子吸附剂—羧基化半纤维素材料。同时通过傅里叶红外光谱仪、扫描电镜、同步热分析仪对制备的吸附剂进行表征,并且探究了吸附剂用量、吸附浓度和温度、溶液pH以及吸附时间对改性半纤维素吸附Pb~(2+)的影响。结果表明:羧基化半纤维素在35℃下150min时吸附达到平衡,其最优的吸附pH值为6.0,吸附浓度为500mg/L,此时对Pb~(2+)的吸附量达最大98.5mg/g。     

改性棉纤维中的铜离子吸附性能研究

分别用丙酮(20%)、丙酮-氢氧化钠、丙酮-柠檬酸和低温等离子体改性工艺对棉纤维进行处理,用改性后的棉纤维吸附溶液中的铜离子,探讨了吸附剂投加量、pH值、溶液初始浓度等对吸附性能的影响。结果表明,在中性条件下,采用丙酮-氢氧化钠溶液改性的棉纤维吸附效果最好,最佳吸附条件为吸附剂投加量0.15g/25 ml,吸附时间2.5h;在酸性条件下,采用丙酮-柠檬酸改性的棉纤维的吸附率最高。     

落叶吸附剂的制备及其对重金属离子Pb(Ⅱ)的吸附性能研究

文章以大量散落的树叶作为原材料制备吸附剂,研究对铅离子的吸附性能。通过单因素考察添加量、pH值、吸附时间、温度、初始浓度等条件对吸附效果的影响,通过吸附动力学和吸附等温线拟合探究了吸附机理。研究发现,在添加量为0.1 g、中性环境、室温下的吸附效果最佳,1 h内去除率可达74.6%,最大吸附量为20.45 mg/g。拟二级动力方程和Langmuir等温吸附模型可以很好地拟合吸附过程。     

生物吸附剂对含铜废水的吸附性能研究

利用水稻秸秆发酵后碱液浸提酸沉淀的方法制备生物质吸附剂,对该吸附剂的性质和含铜废水的吸附性能展开了研究。采用平衡吸附法研究吸附剂的投入量、体系pH 、铜离子浓度对吸附剂吸附水中铜离子的影响。研究结果表明,吸附剂适合处理低浓度含铜废水（铜离子浓度低于100 m g/L,吸附去除率高于80%）,当吸附剂用量1.5 g/L、pH 5.0时,对20 m g/L C u2＋的去除率达到最大值为96.45%。该生物吸附剂以单分子层吸附为主,吸附等温线符合Langm uir方程,饱和吸附量为61.9763 m g/g,动力学行为符合拟二级动力学模型。     

羧基化胶原纤维吸附剂对Cr(Ⅲ)的吸附性能研究

以乙醛酸为改性剂对胶原纤维进行羧基化改性,制备羧基化胶原纤维吸附剂,并以铬粉溶液为处理对象,对比研究了羧基化改性前后胶原纤维吸附剂对Cr(Ⅲ)的吸附性能。通过单因素试验分别考察了温度、时间、pH、吸附剂用量、铬液初始浓度及盐离子(Na+、Ca2+)浓度对吸附过程的影响,结果表明:羧基化改性后胶原纤维对Cr(Ⅲ)的吸附能力比改性前提高了74.13%,吸附的佳pH值及温度分别为4.5和45℃,溶液中Na+、Ca2+离子的存在会对吸附过程产生抑制作用,并且随着其离子浓度的增加,抑制作用增强。     

乌贼墨黑色素对Pb~(2+)的吸附特性研究

以乌贼墨黑色素作为吸附剂对Pb2+进行吸附,分别考察初始离子浓度、溶液pH、吸附温度、吸附作用时间、乌贼墨黑色素添加量对吸附的影响。结果表明,pH4~5时,吸附率最高,温度对吸附基本不产生影响,乌贼墨黑色素对Pb2+的吸附率随初始离子浓度增大而下降,随吸附时间延长和吸附剂添加量增加而增加直至吸附饱和。乌贼墨黑色素对Pb2+的吸附过程符合Langmuir等温线方程和准二级动力学方程,吸附过程以单层吸附为主。     

Reliable identification of grapevine rootstock varieties using RAPD PCR on woody samples

Since grapevine ( Vitis spp .) rootstock material is being traded increasingly as disbudded woody material a lack of distinctive morphological features on such material necessitates an alternative and reliable means of identification. Methods described here were developed for rapid and efficient extraction of DNA from woody samples rich in phenolic compounds and polysaccharides, and for subsequent identification of varieties by RAPD PCR. Using these methods, and with the application of only one selected RAPD primer, we were able to differentiate sixteen rootstock varieties, including the seven varieties most commonly used in Germany. Problems commonly encountered with reproducibility of RAPD patterns were avoided by choosing primers with a dinucleotide sequence and a high G/C content that allowed a rather high annealing temperature of 45°C. Methods described here should also be useful for other horticultural crops, especially those with woody tissues rich in phenolic compounds and polysaccharides.     

An internet compendium of analytical methods and spectroscopic information for monomers and additives used in food packaging plastics

An internet website (http://cpf.jrc.it/smt/) has been produced as a means of dissemination of methods of analysis and supporting spectroscopic information on monomers and additives used for food contact materials (principally packaging). The site which is aimed primarily at assisting food control laboratories in the European Union contains analytical information on monomers, starting substances and additives used in the manufacture of plastics materials. A searchable index is provided giving PM and CAS numbers for each of 255 substances. For each substance a data sheet gives regulatory information, chemical structures, physico-chemical information and background information on the use of the substance in particular plastics, and the food packaging applications. For monomers and starting substances (155 compounds) the infra-red and mass spectra are provided, and for additives (100 compounds); additionally proton NMR are available for about 50% of the entries. Where analytical methods have been developed for determining these substances as residual amounts in plastics or as trace amounts in food simulants these methods are also on the website. All information is provided in portable document file (PDF) format which means that high quality copies can be readily printed, using freely available Adobe Acrobat Reader software. The website will in future be maintained and up-dated by the European Commission's Joint Research Centre (JRC) as new substances are authorized for use by the European Commission (DG-ENTR formerly DGIII). Where analytical laboratories (food control or other) require reference substances these can be obtained free-ofcharge from a reference collection housed at the JRC and maintained in conjunction with this website compendium.     

Chlorohydrins of bisphenol A diglycidyl ether (BADGE) and of bisphenol F diglycidyl ether (BFDGE) in canned foods and ready-to-drink coffees from the Japanese market

BADGE.2HCl and BFDGE.2HCl were determined in 28 samples of ready-to-drink canned coffee and 18 samples of canned vegetables (10 corn, 5 tomatoes and 3 others), all from the Japanese market. HPLC was used as the principal analytical method and GCMS for confirmation of relevant LC fractions. BADGE.2HCl was found to be present in one canned coffee and five samples of corn, BFDGE.2HCl in four samples of canned tomatoes and in one canned corn. No sample was found which exceeded the 1mg/kg limit of the EU for the BADGE chlorohydrins. However the highest concentration was found for the sum of BFDGE.2HCl and BFDGE.HCl.H₂O at a level of 1.5mg/kg. A Beilstein test confirmed that all cans containing foods contaminated with BADGE.2HCl or BFDGE.2HCl had at lest one part coated with a PVC organosol.     

Aroma characterization of various apricot varieties using headspace–solid phase microextraction combined with gas chromatography–mass spectrometry and gas chromatography–olfactometry

The characterization of the aromatic profile of several apricot cultivars with molecular tracers in order to obtain objective data concerning the aromatic quality of this fruit was undertaken using headspace–solid phase microextraction (HS–SPME). Six apricot cultivars were selected according to their organoleptic characteristics: Iranien, Orangered, Goldrich, Hargrand, Rouge du Roussillon and A4025. The aromatic intensity of these varieties measured by HS–SPME–Olfactometry were defined and classified according to the presence and the intensity of grassy, fruity and apricot like notes. In the six varieties, 23 common volatile compounds were identified by HS–SPME–GC–MS. Finally, 10 compounds, ethyl acetate, hexyl acetate, limonene, β-cyclocitral, γ-decalactone, 6-methyl-5-hepten-2-one, linalool, β-ionone, menthone and (E)-hexen-2-al were recognized by HS–SPME–GC–O as responsible of the aromatic notes involved in apricot aroma and considered as molecular tracers of apricot aromatic quality which could be utilized to discriminate apricot varieties.     

European priorities for research to support legislation in the area of food contact materials and articles

A strong science base is required to underpin the planning and decision-making process involved in determining future European community legislation on materials and articles in contact with food. Significant progress has been made in the past 5 years in European funded work in this area, with many developments contributing to a much better understanding of the migration process, and better and simpler approaches to food control. In this paper this progress is reviewed against previously identified work-areas (identified in 1994) and conclusions are reached about future requirements for R&D to support legislation on food contact materials and articles over the next 5 or so years.     

Tests of potential functional barriers for laminated multilayer food packages. Part I: Low molecular weight permeants

The advent of the functional barrier concept in food packaging has brought with it a requirement for fast tests of permeation through potential barrier materials. In such tests it would be convenient for both foodstuffs and materials below the functional barrier (sub-barrier materials) to be represented by standard simulants. By means of inverse gas chromatography, liquid paraffin spiked with appropriate permeants was considered as a potential simulant of sub-barrier materials based on polypropylene (PP) or similar polyolefins. Experiments were performed to characterize the kinetics of the permeation of low molecular weight model permeants (octene, toluene and isopropanol) from liquid paraffin, through a surrogate potential functional barrier (25 μm-thick oriented PP) into the food simulants olive oil and 3% (w/v) acetic acid. These permeation results were interpreted in terms of three permeation kinetic models regarding the solubility of a particular model permeant in the post-barrier medium (i.e. the food simulant). The results obtained justify the development and evaluation of liquid sub-barrier simulants that would allow flexible yet rigorous testing of new laminated multilayer packaging materials.     

Textural Properties of Cold-set Gels Induced from Heat-denatured Whey Protein Isolates

A 9% whey protein (WP) isolate solution at pH 7.0 was heat-denatured at 80°C for 30 min. Size-exclusion HPLC showed that native WP formed soluble aggregates after heat-treatment. Additions of CaCl2 (10–40 mM), NaCl (50–400 mM) or glucono-delta-lactone (GDL, 0.4–2.0%, w/v) or hydrolysis by a protease from Bacillus licheniformis caused gelation of the denatured solution at 45°C. Textural parameters, hardness, adhesiveness, and cohesiveness of the gels so formed changed markedly with concentration of added salts or pH by added GDL. Maximum gel hardness occurred at 200 mM NaCl or pH 4.7. Increasing CaCl2 concentration continuously increased gel hardness. Generally, GDL-induced gels were harder than salt-induced gels, and much harder than the protease-induced gel.     

Influence des ions sur le pouvoir hydratant de l'ure e: e tude sur peau de porc ex vivo

This study deals with the influence of ions (NaCl and MgSO4) in a W/O emulsion containing 10% urea. Moisturization kinetics are assessed by corneometry on pig skin ex vivo. The formula's influence on urea penetration is measured by infrared spectrometry with an ATR device and the stripping method. Corneometry and spectroscopy were chosen to record simultaneously the hydratation levels and urea localization into superficial cell layers. Urea crystallization after evaporation of emulsions and aqueous solutions is described. Results show that urea does not hydrate nor penetrate when applied to the skin through an aqueous gel. In a W/O emulsion, sodium chloride increases the ability of urea to moisturize without improving penetration. In vitro urea crystallization is disturbed by sodium chloride or magnesium sulphate for solutions and emulsions. This stabilization by ions is correlated with good moisturization values. The stabilization of urea in the solute state provided by ions increases its water epidermal binding capacity without enhancing penetration.     

Occurrence of bisphenol-F-diglycidyl ether (BFDGE) in fish canned in oil

The levels of bisphenol-F-diglycidyl ether (BFDGE) were quantified as part of a European survey on the migration of residues of epoxy resins into oil from canned fish. The contents of BFDGE in cans, lids and fish collected from all 15 Member States of the European Union and Switzerland were analysed in 382 samples. Cans and lids were separately extracted with acetonitrile. The extraction from fish was carried out with hexane followed by re-extraction with acetonitrile. The analysis was performed by reverse phase HPL C with fluorescence detection. BFDGE could be detected in 12% of the fish, 24% of the cans and 18% of the lids. Only 3% of the fish contained BFDGE in concentrations considerably above 1mg/kg. In addition to the presented data, a comparison was made with the levels of BADGE (bisphenol-A-diglycidyl ether)analysed in the same products in the context of a previous study.