皮革和毛皮中甲醛的来源及去除方法

高浓度的甲醛会对人体产生一定的危害。皮革和毛皮生产过程中,部分工艺及所用化工材料并不能完全脱离甲醛。本文对皮革和毛皮中甲醛的主要来源及其去除方法进行综述,同时探讨了制革用甲醛捕获剂的发展趋势。     

活泼亚甲基类超支化聚合物甲醛捕获剂的合成及应用

以二乙醇胺(DEA)和丙烯酸甲酯(MA)为原料通过Michael加成反应制得AB2型单体;经由"一步法"使单体与核(三羟甲基丙烷,TMP),在对甲苯磺酸(P-TSA)催化下,通过酯交换反应制得一种端羟基超支化聚(胺-酯)(HPAE);使用丙二酸二乙酯(DEM),在无水K2CO3催化下,通过酯交换反应对HPAE进行端基改性,从而制备活泼亚甲基类超支化聚合物(HPAM)。通过单因素试验筛选出了活泼亚甲基类超支化聚合物(HPAM)的最优反应条件;采用IR、DSC-TG等手段;对聚合的分子结构及热性能进行了表征;并将HPAM应用于捕获醛鞣革(猪皮)中游离甲醛的应用试验,优化出了最佳捕获条件:捕获剂用量为2%,捕获时间为5h,该条件下对甲醛的捕获率可达56.25%,捕获效果明显。     

毛皮中游离甲醛的清除研究

为了考察表面活性剂对水貂皮和貉子皮中游离甲醛的清除效果,将毛皮于1.0 g/L表面活性剂溶液中60℃浸泡2 h后,检测毛皮处理样的甲醛质量分数。结果表明,阴离子表面活性剂对甲醛的去除效率较高,采用α-烯基磺酸钠进行4次处理,可将毛皮中的游离甲醛去除90%以上,而且不会对毛皮产生伤害。该方法可用于裘皮加工行业毛皮产品去除甲醛的工艺。     

关于甲醛鞣制毛皮制品的甲醛挥发性的研究及思考

把已知游离甲醛含量的甲醛鞣制的白色兔毛皮置于四种不同的环境条件下,每隔一段时间对其甲醛含量进行测定。通过对测定结果的分析,对甲醛鞣制的毛皮成品所含的游离甲醛的挥发性进行分析和探讨。结果表明,在光线良好,空气流通顺畅的环境条件下,毛皮成品中游离甲醛的挥发速率大,挥发率高;在相对密闭,甲醛浓度含量过高的环境条件下,毛皮成品会吸附空气中所含的游离甲醛,使得自身的甲醛含量变大。参照这一结果,人们在日常生活中的所用的甲醛鞣制的毛皮制品,不应该一直放在密闭的环境条件下。     

人造汗液萃取毛皮中甲醛及其检测研究

将毛皮中的甲醛用人造汗液萃取后,用乙酰丙酮分光光度法检测,可以定量检测分析毛皮中甲醛的含量.通过对显色反应体系的pH、温度、反应时间和存放时间的优化,得到了显色体系的最佳反应条件,以及对采用该方法分析皮革中人造汗液可萃取毛皮中的甲醛进行了分析,并且对该方法的准确性进行了评估.结果表明:显色体系的最佳反应pH为6.91、温度为(40±2) ℃、显色剂配制的有效期为2周、反应时间为60 min,人造汗液萃取皮革样品中的甲醛含量,重复试验的相对标准偏差(n=8)是2.03%,回收率可以达到96%～107%.说明人造汗液萃取毛皮样品中的甲醛含量分析是可行的.     

茶多酚与甲醛的反应特性研究

水产品、香菇等食品会产生内源甲醛,从食品安全的角度考虑,应该在其贮藏加工过程中尽可能去除.本文研究了荼多酚与甲醛的反应特性,探讨茶多酚作为甲醛捕获剂的可能性;研究了不同pH值、反应温度及反应时间对荼多酚-甲醛反应的影响;研究了儿茶素类单体及简单酚类物质与甲醛反应的特性.通过试验发现,pH对反应的影响最显著,温度次之,反应时间的影响最小;强酸及碱性条件下反应活性较高;较高反应温度条件下.延长反应时间.有利于茶多酚与甲醛的反应.儿茶素类化合物与甲醛的较强反应活性是由于它们的A环中存在间苯三酚型结构.而B环上羟基的数目基本不影响其与甲醛的反应活性.没食子酰基的存在使表儿茶素没食子酸酯、表没食子儿茶素没食子酸酯与甲醛的反应活性比儿茶素、表儿荼素、表没食子儿萘素的强.因此茶多酚是一种良好的甲醛捕获剂.对捕获食品中的甲醛有应用价值.     

水对毛皮中甲醛含量的影响研究

不同温度的条件下，毛皮在水中与在空气中存放，甲醛含量的变化显著。研究结果表明，不同的毛皮，在水的作用下，甲醛含量均会显著提高。但受毛皮鞣制工艺以及除醛剂的影响，不同的毛皮甲醛含量的最高值变化随温度变化趋势不一致。     

端氨基超支化聚酰胺—胺皮革游离甲醛捕获剂的合成

以二乙烯三胺和丁二酸酐为单体,四氢呋喃为溶剂,低温下合成结构中含一个羧基、2个氨基的AB2型单体,再以逐步滴加AB2型单体的方式熔融聚合得到端氨基超支化聚合物;以红外光谱、核磁共振对聚合物结构进行了表征;以GPC测定了聚合物分子质量;将合成的聚合物用做皮革甲醛捕获剂,结果表明:当捕获剂加入量为皮质量的4.0%时,配合水洗工艺,最终能将皮革中的甲醛含量由约560mg/kg降低至280mg/kg,且对皮革具有良好的助染效果。     

超低甲醛涂料印花粘合剂

本文介绍超低甲醛涂料印花粘合剂的制备及应用。将丙烯基单体和环氧氯丙烷反应,制成自交联反应性单体丙烯酸环氧丙烷,然后与丙烯酸酯类单体乳液聚合,制得超低甲醛涂料印花粘合剂。该粘合剂一改以往自交联反应单体采用羟甲基丙烯酰胺,使粘合剂游离甲醛超标的弊端。用于印花工艺中,游离甲醇含量仅为8mg/kg,摩擦牢度达3～4级。     

毛皮制品中甲醛在水介质下的解吸附行为研究

将毛皮制品在水介质下进行甲醛解吸附试验,以解吸液中甲醛含量为考察指标,研究了相关因的素对解吸附行为的影响,并通过数据拟合对解吸附动力学进行了分析。试验表明:毛皮制品的毛被是甲醛释放的主要来源,其他各因素依据对解吸附行为影响的显著性,排序为:解吸附温度解吸附时间解吸液体积解吸液种类。试验条件下,毛皮制品中甲醛其解吸附过程很好地符合指数增长模型,为预测甲醛在水介质下的释放行为提供了理论支撑,并能够指导毛皮的工业生产。     

多元氨缩聚物游离甲醛捕获剂的研制

利用缩聚法合成一种多氨基游离甲醛捕获剂,考察了水分含量、反应温度、反应时间等因素对聚合物黏度的影响及合成的缩聚物对皮革中游离甲醛的捕获效果。     

制革废弃物提取蛋白制备低甲醛高性能脲醛树脂

通过探究四种甲醛捕捉剂对脲醛树脂游离甲醛含量和黏度的影响,结果表明将制革废弃物提取蛋白和亚硫酸钠复配且质量比为1∶2时,获得脲醛树脂的游离甲醛含量为0.160%,黏度为17.2 s。此胶粘剂制备刨花板的各项物理性能均符合国家标准。制革废弃物提取蛋白和亚硫酸钠的复配能有效抑制脲醛树脂中的游离甲醛并提高其黏度,扩大了制革废弃物提取蛋白的应用。     

降低真丝绸防缩抗皱树脂整理中游离甲醛的办法

真丝绸用含甲醛树脂整理时,为降低游离甲醛含量,采取消除树脂初缩体中的游离甲醛、选择树脂和高效催化剂、适当提高焙烘温度或延长焙烘时间、采用氨水和平平加水洗、在整理浴中加入甲醛吸收剂等方法,可获得较好效果。     

水产品来源的甲醛膳食暴露评估初步研究

应用MonteCarlo模拟技术定量评估我国人群通过食用水产品途径的甲醛膳食暴露状况。结果表明,我国城乡普通居民通过食用水产品途径的甲醛暴露水平较低,且通过食用水产品途径城市人群摄入甲醛面临的健康风险高于农村人群;不同年龄群体的膳食暴露量存在差异,幼年消费者(2～13岁)的暴露量均高于成年人;7岁前,女孩的暴露水平高于男孩,7岁后,男孩的暴露水平高于女孩。我国普通居民仅通过食用水产品途径摄入甲醛对人体健康状况造成风险的可能性不大,但是幼儿、儿童是食用水产品途径甲醛暴露的敏感性群体,应在后续的风险管理过程中应给予足够的关注和重视。     

甲壳胺纤维对甲醛的吸附性能

为测定甲壳胺纤维对甲醛的吸附性能,在不同的条件下用甲壳胺非织造布处理含甲醛的水溶液。首先将甲壳胺非织造布在不同pH值的硫酸水溶液中进行预处理以提高其对甲醛的反应活性。结果显示:甲壳胺纤维对甲醛有明显的吸附性能,每克纤维最多能吸附66.6 mg甲醛,预处理溶液的pH值对吸附性能有一定的影响,而反应温度的影响较小。由于处理过程中纤维是固体状态,吸附的速度比较慢,为了使甲壳胺纤维充分吸附甲醛,接触时间应该控制在24 h以上。     

Effects of bonding types and functional groups on CO2 capture using novel multiphase systems of liquid-like nanoparticle organic hybrid materials

Novel liquid-like nanoparticle organic hybrid materials (NOHMs) which possess unique features including negligible vapor pressure and a high degree of tunability were synthesized and their physical and chemical properties as well as CO(2) capture capacities were investigated. NOHMs can be classified based on the synthesis methods involving different bonding types, the existence of linkers, and the addition of task-specific functional groups including amines for CO(2) capture. As a canopy of polymeric chains was grafted onto the nanoparticle cores, the thermal stability of the resulting NOHMs was improved. In order to isolate the entropy effect during CO(2) capture, NOHMs were first prepared using polymers that do not contain functional groups with strong chemical affinity toward CO(2). However, it was found that even ether groups on the polymeric canopy contributed to CO(2) capture in NOHMs via Lewis acid-base interactions, although this effect was insignificant compared to the effect of task-specific functional groups such as amine. In all cases, a higher partial pressure of CO(2) was more favorable for CO(2) capture, while a higher temperature caused an adverse effect. Multicyclic CO(2) capture tests confirmed superior recyclability of NOHMs and NOHMs also showed a higher selectivity toward CO(2) over N(2)O, O(2) and N(2).     

啤酒发酵过程中甲醛代谢影响因素初步研究

甲醛是啤酒酵母的一种代谢产物,在啤酒发酵过程中,甲醛经历了积累和随后的还原两个阶段,通过引入甲醛峰值和谷值两个概念研究了啤酒生产过程中的一些影响甲醛积累和还原的控制,结果表明:(1)过低或过高的麦汁溶氧量均会增加甲醛的积累,在12～13mg/L的麦汁溶氧条件下甲醛积累最小。(2)低代酵母甲醛积累要少于高代酵母,并且低代酵母在后期甲醛的还原能力要高于高代酵母,酵母接种量在2×107个/ml时甲醛峰值最低。(3)相对较高的还原温度有利于甲醛还原。(4)麦汁浓度对甲醛的积累影响较大,高麦汁浓度条件下的甲醛峰值要比低麦汁浓度高出许多。(5)啤酒酿造后期延长还原时间并不能显著增加甲醛的还原量。     

Migration of formaldehyde and melamine monomers from kitchen- and tableware made of melamine plastic

Migration of one or both formaldehyde and/or melamine monomers was found in seven of ten tested melamine samples bought on the Danish market. The samples were a bowl, a jug, a mug, a ladle, and different cups and plates. No violation of the European Union-specific migration limits for melamine (30 mg kg^-1) and formaldehyde (15 mg kg^-1) was found after three successive exposures to the food stimulant 3% acetic acid after 2 h at 70°C. To investigate the effects of long-term use, migration tests were performed with two types of cups from a day nursery. Furthermore, medium-term use was studied by ten successive exposures of a plate to 3% acetic acid for 30 min at 95°C. The results indicate that continuous migration of formaldehyde and melamine takes place during the lifetime of these articles. The molar ratio of released formaldehyde to melamine was seen to decrease from 12 to about 5. This indicates that, first, the migration of residual monomers is most important, but in the long-term, breakdown of the polymer dominates. Two CEN methods were used to determine the concentration of monomers: a spectrophotometric method for formaldehyde and a UV-HPLC method for melamine.     

Digestion,milk production,milk composition,and blood composition of dairy cows fed formaldehyde treated flaxseed or sunflower seed

Forty midlactation Holstein cows averaging 635 kg of body weight (SE = 8) were allotted at wk 25 of lactation to ten groups of four cows blocked for similar calving dates to determine the effects of formaldehyde treatment of flaxseed and sunflower seed on fatty acid composition of blood and milk, milk yield, feed intake, and apparent digestibility. Cows were fed a total mixed diet based on grass silage and supplements for ad libitum intake over a 10-wk period. Cows within each block were assigned to one of the four isonitrogenous supplements based on either untreated whole flaxseed, formaldehyde-treated whole flaxseed, untreated whole sunflower seed, or formaldehyde-treated whole sunflower seed. Cows fed whole flaxseed compared with sunflower seed maintained greater dry matter (DM) intake (20.3 vs. 18.9 kg/d). Intake of DM, expressed as a percentage of body weight, was increased by adding formaldehyde to oilseeds (3.24 vs. 2.98%). Milk production was similar for cows fed flaxseed and those fed sunflower. Formaldehyde treatment of flaxseed and sunflower seed increased milk production by an average of 2.65 kg/d. Efficiency of fat-corrected milk yield per kilogram of DM intake was increased by formaldehyde treatment (1.31 vs. 1.21), and it was greater with sunflower seed than with flaxseed (1.33 vs.1.21). Protein concentration in milk was greater for cows fed flaxseed (3.38%) compared with those fed sunflower seed (3.21%) and formaldehyde had no effect. Apparent digestibility of DM was not affected by type of seed but it was greater for cows fed formaldehyde-treated seeds. Cows fed formaldehyde-treated flaxseed had the greatest apparent digestibilities of acid detergent and neutral detergent fiber compared with those fed the other diets. Apparent digestibilities of fatty acids were greater for sunflower seed than for flaxseed-based diets. In general, formaldehyde treatment had limited effect on milk fatty acid composition, suggesting that formaldehyde was not very effective in protecting polyunsaturated fatty acids against ruminal biohydrogenation. Feeding flaxseed resulted in the lowest omega 6 to omega 3 fatty acid ratio. The data suggest that both flaxseed and sunflower seed are acceptable fat sources for midlactating cows and that flaxseed increases milk protein percentage compared to sunflower seed.