锯屑亚铵法制浆工艺条件探讨

在大力倡导节约原料,降低成本,减少污染的制浆方法下,本实验采用污染较小的亚铵法对锯屑进行蒸煮,找出了较佳的蒸煮工艺条件。其较佳蒸煮工艺条件为:最高蒸煮温度165℃,亚铵用量(18—20)%,液比1:2.5,尿素用量2%.AQ用量0.05%。在此条件下,所得浆耐破度165 kPa,裂断长4 768 m.撕裂指数8.7 mN·m2·g-1。     

用烧碱作亚铵蒸煮缓冲剂生产B级凸版纸

我厂用液体烧碱作亚铵蒸煮缓冲剂生产B级凸版纸效果很好。工艺技术条件是:装锅量2500kg(绝干,25m~3蒸球),亚铵用量17％,液体烧碱用量3％,液比1:2.4,蒸煮有效时间3:50h,粗浆     

亚铵法蒸煮的有关计算

我国的中小型纸厂中,亚铵法制浆厂不少。蒸煮工每天都要计算每球亚铵用量多少?每球应加游离铵多少?若亚铵母液中含亚氢铵时,中和氨需要多少?当液比一     

光叶楮白皮制浆方法的比较及亚铵制浆工艺的优化

采用4种方法对光叶楮白皮制化学浆进行了探讨,并且对光叶楮白皮亚硫酸铵法制浆工艺进行了优化,系统讨论了亚铵用量、尿素用量、蒽醌用量、液比、保温温度和时间对制浆效果的影响,确定出光叶楮白皮亚铵法制浆的最佳工艺条件为:亚铵用量18%,尿素用量5%,AQ用量0.15%,液比1:6,最高温度165℃,保温时间2h.最优化条件下纸浆的粗浆得率为50.3%,细浆得率为48.6%,高锰酸钾值为3.24,白度为51.0%ISO.     

氧化镁作亚铵法缓冲剂制取红麻浆的试验

目前,一些小草浆厂为了减轻蒸煮废液对土壤和水源的污染危害,采用了亚铵法制浆,并将蒸煮废液用作农肥。但亚铵法蒸煮对生产设备有一定腐蚀,为了防腐,一般在亚铵蒸煮液中添加过量氨水以提高pH值。由于氨的气味大,掌握也较难,有的企业在蒸煮液中添加烧碱或纯碱作为缓冲剂。这样虽较易控制,但给蒸煮废液中带入了大量钠离子,以此用作农肥是不利的。本文介绍的采用氧化镁作为亚铵法蒸煮液的缓冲剂蒸煮红麻浆,取得了较好效果。估计用于麦草等其他草类浆的蒸煮,也可以取得类似效果,希望能引起亚铵法草类浆厂的重视。     

麦草亚铵法用MgO作缓冲剂的生产试验

新疆和静7235厂生产主要品种为52克/米~22号凸版纸。原料为麦草,用亚硫酸铵法加氢氧化钠缓冲剂。所用蒸煮条件为:亚铵用量14.5％;氢氧化钠用量2.5％;最高蒸煮压力0.65MPa;保温4:00h;纸浆硬度15左右(高锰酸钾值)。从1991年10月至12月,试验了用氧化镁作亚铵蒸煮缓冲剂,蒸煮了30球,证明用MgO作亚铵蒸     

构皮过氧化氢草酸盐法制浆初探

本论文研究了蒸煮最高温度、蒸煮液的酸碱度、保温时间、草酸钠及过氧化氢用量对构皮过氧化氢草酸盐法制浆的影响。研究表明：蒸煮液的酸碱度对木素脱除影响较显著，中性偏弱酸性条件有利于木素的去除，较佳的构成过氧化氢草酸盐法蒸煮工艺条件为：草酸钠用量20％，碳酸钠0.5%，过氧化氢10％，最高温度90℃，保温时间1h，液比1∶10,pH值4.82-8.71。蒸煮结果为：粗浆得率71.22%，卡伯值36.12。     

亚铵法蒸煮工艺改进的思考

亚铵法制浆、蒸煮设备被腐蚀的原因是多方面的，其中蒸煮终点的pH值下降为酸性是造成腐蚀的重要原因之一。蒸煮过程中产生的H 离子的逐渐积累最终导致pH下降的因果关系，为我们解决问题提供了基本的思路和方向。如何恒定蒸煮的pH值，提高蒸煮液的缓冲能力，这就需要对传统蒸煮工艺进行重大改进的原因。1确定蒸煮的初pH=9．26在亚铵法制浆的诸多理论与实践中都讲到了缓冲剂氨水的作用和用量问题，却少有对pH值确定的讨论，这是一个不可忽略的问题。本人在《纸和造纸》1997年第4期发表的《亚铰法蒸煮中亚按和氨水用量的计算》一文中提到了p…     

低能耗亚铵法蒸煮制浆与废液回收利用消除污染

低能耗亚铵法蒸煮制浆与废液回收利用消除污染汪仲熙（四川宜宾造纸厂６４４００７）亚铵制浆在我国已有几十年经历，在非木材植物制浆领域用此法，制半化学浆，半漂白浆较为普遍，早有试验表明，亚铵蒸煮废液由氮、磷、钾含１０％左右和有机物组成，可作为农业肥料。但因...     

亚铵法玉米秆浆过氧化氢强化氧脱木素的研究

对亚铵法除髓玉米秆浆H2O2强化氧脱木素进行了研究,并通过正交实验得出H2O2强化氧脱木素的最佳工艺条件:浆浓9%,H2O2用量3%,用碱量4%,氧压0.6MPa,温度70℃,时间60min,MgSO4用量0.5%,Na2SiO3用量3%。在此条件下,漂白浆的白度可达72.5%,黏度为762mL/g。     

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.     

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.     

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.     

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.     

Contribution of European research to risk analysis

The European Commission's, Quality of Life Research Programme, Key Action 1—Health, Food & Nutrition is mission-oriented and aims, amongst other things, at providing a healthy, safe and high-quality food supply leading to reinforced consumer confidence in the safety of European food. Its objectives also include the enhancing of the competitiveness of the European food supply. Key Action 1 is currently supporting a number of different types of European collaborative projects in the area of risk analysis. The objectives of these projects range from the development and validation of prevention strategies including the reduction of consumers risks; development and validation of new modelling approaches; harmonization of risk assessment principles, methodologies, and terminology; standardization of methods and systems used for the safety evaluation of transgenic food; providing of tools for the evaluation of human viral contamination of shellfish and quality control; new methodologies for assessing the potential of unintended effects of genetically modified (genetically modified) foods; development of a risk assessment model for Cryptosporidium parvum related to the food and water industries; to the development of a communication platform for genetically modified organism, producers, retailers, regulatory authorities and consumer groups to improve safety assessment procedures, risk management strategies and risk communication; development and validation of new methods for safety testing of transgenic food; evaluation of the safety and efficacy of iron supplementation in pregnant women; evaluation of the potential cancer-preventing activity of pro- and pre-biotic ('synbiotic') combinations in human volunteers. An overview of these projects is presented here.