颗粒活性炭吸附苯酚模拟废水的热力学和动力学研究

研究了颗粒活性炭对苯酚的静态吸附行为,分析了吸附热力学性质和动力学特征。实验结果表明:颗粒活性炭对水中苯酚的吸附量随其初始浓度的增加而增加,吸附6h可以达到平衡;吸附过程符合McKay二级吸附动力学方程,吸附等温线可用Freundlich等温吸附方程描述;颗粒内扩散不是吸附过程唯一的控制步骤。在不同温度下,颗粒活性炭对苯酚的吸附焓变ΔH、吸附熵变ΔS、吸附吉布斯自由能变ΔG均为负值,说明苯酚在颗粒活性炭上的吸附是一个自发、放热的过程,主要是以物理吸附为主。     

交联淀粉微球对对硝基甲苯的吸附行为研究

以可溶性淀粉为原料,通过反相悬浮聚合的方法合成交联淀粉微球(CSM).研究了CSM对对硝基甲苯(PNT)的吸附行为,利用扫描电镜(SEM)、傅里叶红外光谱仪(FT-IR)、X射线衍射仪(XRD)对CSM及其吸附产物进行表征,并分析了其吸附动力学特性和热力学性质.结果表明:在研究范围内,CSM对PNT吸附100 min后达到平衡,且吸附行为同时符合Langmuir方程和Freundlich方程;在不同温度下,CSM吸附PNT的吸附自由能变(ΔG)、吸附焓变(ΔH)、吸附熵变(ΔS)均为负值,吸附是一个自发、放热过程;CSM主要通过物理吸附方式吸附PNT.     

D301-G大孔树脂吸附菊芋多糖色素机理探究

为了探究菊芋多糖提取液中色素杂质的去除效果,本文采用静态吸附法对六种大孔树脂进行了初步筛选,并研究了D301-G大孔树脂对菊芋多糖色素的静态吸附动力学、静态吸附模型及其吸附热力学,深入探讨了D301-G大孔树脂对菊芋多糖色素的吸附机理。结果表明,在相同的实验条件下,D301-G大孔树脂与其它树脂相比脱色效果最好,吸附菊芋多糖色素速率较快,多糖的损失率最小,脱色率可达到79.63%,多糖保留率为92.28%。此外D301-G大孔树脂对菊芋多糖色素的吸附过程符合准二级吸附动力学方程,主要受颗粒扩散阻力的影响。等温吸附实验表明,在293、303和313 K时Freundlich等温线模型较Langmuir模型更为准确地描述D301-G大孔树脂的吸附行为,它对色素分子的吸附可能是多分子层的。热力学方程表明D301-G大孔树脂吸附过程是一个吸热过程,吸附焓变ΔH 0、吸附自由能变ΔG 0、吸附熵变ΔS 0。     

菠萝蜜果皮吸附亚甲基蓝的研究

以菠萝蜜果皮为原料,经粉碎制成粉末吸附剂。探究了菠萝蜜果皮吸附亚甲基蓝的性能。结果表明,在100 mL 100 mg/L的亚甲基蓝溶液中,菠萝蜜果皮最佳投加量为0.8 g,pH为5、温度为25 ℃、震荡时间为40 min。利用准一级、准二级动力学方程模拟菠萝蜜果皮吸附亚甲基蓝的动力学过程,利用Freundlich和Langmuir方程模拟其热力学行为。结果表明菠萝蜜果皮吸附亚甲基蓝的过程适合于准二级动力学、Freundlich模型。文中计算了焓变(ΔH0)、自由能(ΔG0)、熵变(ΔS0)等热力学参数,菠萝蜜果皮吸附亚甲基蓝的ΔG0小于0,ΔS0小于0、ΔH0小于0,说明菠萝蜜果皮吸附亚甲基蓝的过程是一个自发的趋于有序的放热过程。通过对吸附亚甲基蓝染料前后菠萝蜜果皮材料表面形貌进行分析,发现亚甲基蓝染料填充了菠萝蜜果皮表面的的空隙,导致吸附前后菠萝蜜的表面形貌发生了变化。     

β-环糊精聚合物微球对Zn~(2+)的吸附行为及机理

以β-环糊精为原料,环氧氯丙烷为交联剂,采用反相乳液聚合得到一种交联β-环糊精聚合物(β-CDP)微球,研究其对Zn2+的静态吸附行为,测定吸附等温线,分析吸附热力学性质和动力学特征,并用红外光谱仪、X射线衍射仪和综合热重仪对β-CDP微球吸附Zn2+前后对照分析,探讨吸附机理。结果表明:在实验条件范围内,β-CDP微球对Zn2+吸附等温线同时符合Langmuir等温方程和Freundlich等温方程;在不同温度下,β-CDP微球吸附Zn2+的吸附焓变(ΔH)、熵变(ΔS)、吉布斯自由能(ΔG)均为负值,吸附是自发的放热过程;β-CDP微球主要通过物理吸附和配位吸附等方式吸附Zn2+,这些吸附作用增强了交联链的热稳定性、破坏了β-CDP微球的结晶结构。     

大孔树脂对蜂蜜中羟甲基糠醛的脱除热力学及动力学研究

利用大孔树脂技术脱除蜂蜜中有害物质后,可实现对废弃蜂蜜资源的再利用。以5-羟甲基糠醛(5-hydroxymethylfur fural,5-HMF)含量超标蜂蜜为研究对象,系统研究LSI-3型大孔树脂对蜂蜜中5-HMF的吸附等温线、吸附热力学及动力学性质,考察大孔树脂脱除蜂蜜中5-HMF机理。结果表明:Freundlich吸附等温模型能够可靠描述LSI-3树脂吸附5-HMF过程,吸附过程中焓变ΔH 0,自由能变ΔG 0,熵变ΔS 0,说明LSI-3树脂对蜂蜜中5-HMF属于物理吸附,是自发进行的放热过程,降低温度有利于吸附反应进行,且水分子不容易将5-HMF从树脂上解析;此外,拟二级速率方程适合描述5-HMF吸附过程的动力学规律,Weber-Morris动力学模型证明该吸附过程受液膜扩散和颗粒内扩散共同控制。研究结果为大孔树脂处理5-HMF超标蜂蜜的工业化应用提供了重要理论依据。     

大孔吸附树脂分离纯化女贞子原花青素的动力学和热力学研究

通过用紫外可见光分光光度法测定了不同温度时的吸附等温线和不同起始浓度下的吸附动力学曲线等,来研究几种大孔吸附树脂对女贞子原花青素吸附过程的吸附热力学和吸附动力学特征.动力学结果表明,吸附平衡数据符合Freundlich吸附等温方程、Langmuir平衡吸附速率方程,相关性均良好.热力学结果表明,不同温度下的等温吸附符合Freundlich方程,吸附的焓变为△H(AB-8)=9.327 kJ/mol、△Hm(D3520)=7.648 kJ/mol,熵变△Sm均大于零,Gibbs自由能变△Gm均小于零,且△Gm随温度升高向负方向增加.说明女贞子原花青素在树脂上的吸附属于自发的物理吸附过程,而且是一个液固界面间增加了随机性吸附的过程.本研究的结果对优化原花青素的分离纯化工艺有一定的指导作用.     

D941大孔树脂吸附茶多糖的热力学研究

为了解D941大孔树脂对茶多糖的吸附性能及热力学性质,通过吸附等温线测定及吸附等温方程拟合,得出该树脂对茶多糖的吸附等温方程及相关的热力学参数。实验结果显示,树脂对茶多糖的吸附量随着温度升高而减小;在上样液浓度为2.5～5.5mg/ml之间树脂吸附茶多糖符合Langmuir模型;而在实验浓度范围内即1.5～5.5mg/ml符合Freundlich模型;吸附过程的吉布斯自由能变ΔGm<0,焓变ΔHm<0;树脂对茶多糖的平衡吸附量为16.5mg/g。实验结果表明D941大孔树脂适于茶多糖的吸附。     

微孔淀粉对次甲基蓝的吸附热力学与动力学研究

研究了微孔淀粉对次甲基蓝的吸附效果,考察了温度、pH、吸附时间等因素对吸附的影响,以及微孔淀粉吸附次甲基蓝的热力学及动力学特性。结果表明,在30℃、pH为5.0时,吸附1h后吸附率最佳。微孔淀粉的吸附符合Freundich等温方程,焓变ΔHθ=-44.4026kJ/mol,熵变ΔSθ=-0.1239kJ/mol·K,反应吉布斯自由能ΔGθ随温度升高向负方向增加。热力学参数表明吸附过程为放热和自发的。     

新型啤酒稳定剂对啤酒蛋白质吸附特性的研究

研究了新型啤酒稳定剂BFSA对啤酒蛋白质的吸附特性,初步探讨了BSFA吸附蛋白的作用机理。FT-IR图谱分析可知,BFSA表面含有Si-O-Si键,且含有O-H键。研究了时间、温度、蛋白质浓度对BFSA吸附的影响,发现吸附平衡时间在1 h左右,BFSA吸附啤酒蛋白质量随温度的降低而升高,随着初始蛋白质浓度的升高而升高。研究了BFSA吸附啤酒蛋白质的吸附等温线、动力学和热力学模型,发现BFSA对啤酒蛋白质的吸附等温线更符合Freundlich方程;对啤酒蛋白质的吸附过程更符合准二级动力学方程;由热力学参数ΔG0说明啤酒蛋白质在BFSA表面的吸附为非自发的,ΔH0说明吸附过程是放热的,ΔS0说明吸附是熵减过程;活化能(E)为26.28 kJ/mol表明BFSA吸附啤酒蛋白质是物理吸附;吸附过程放热为6.62 kJ/mol表明该吸附过程的主要作用力可能是范德华力、氢键和疏水作用。     

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.     

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.     

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.     

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.     

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.     

Analysis of benzo[a]pyrene in spiked fatty foods by second derivative synchronous spectrofluorimetry after microwave-assisted treatment of samples

A simple, rapid and inexpensive method has been developed for the determination of benzo[a     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. II: Certification study

This paper describes the second part of a project undertaken to develop certified mussel reference materials for paralytic shellfish poisoning toxins. In the first part two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin and decarbamoyl-saxitoxin in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the certification exercise. Fifteen laboratories participated in this certification study and were asked to measure saxitoxin and decarbamoyl-saxitoxin in rehydrated lyophilized mussel material and in a saxitoxin-enriched mussel material. The participants were allowed to use a method of their choice but with an extraction procedure to be strictly followed. The study included extra experiments to verify the detection limits for both saxitoxin and decarbamoyl-saxitoxin. Most participants (13 of 15) were able to meet all the criteria set for the certification study. Results for saxitoxin.2HCl yielded a certified mass fraction of <0.07 mg/kg in the rehydrated lyophilized mussels. Results obtained for decarbamoyl-saxitoxin.2HCl yielded a certified mass fraction of 1.59+/-0.20 mg/kg. The results for saxitoxin.2HCl in enriched blank mussel yielded a certified mass fraction of 0.48 +/- 0.06 mg/kg. These certified reference materials for paralytic shellfish poisoning toxins in lyophilized mussel material are the first available for laboratories to test their method for accuracy and performance.     

Announcing a new international peer-reviewed journal:Food Science and Human Wellness now accepting manuscript submission in English

<正>We are pleased to announce the launch of a new international peer-reviewed journal-Food Science and Human Wellness,ISSN 2213-4530,which is an open access journal,produced and hosted by Elsevier B.V.on behalf of Beijing Academy of Food Sciences.Food Science and Human Wellness is an international peer-reviewed English journal that provides a forum for the dissemination of the