臭氧改性对活性炭表面性能的影响及在卷烟中的应用

为了研究臭氧改性对活性炭表面性能的影响,开发适用于卷烟中的香精缓释材料,对臭氧改性前后活性炭的比表面积、孔隙结构、表面官能团、表面酸性基团含量等进行了测定,并以2-环戊烯酮为模型分子,考察了臭氧改性活性炭在卷烟中的应用情况。结果表明:(1)随着改性时间的延长,臭氧改性活性炭的比表面积和孔容增大,活性炭表面酸性基团含量增加。(2)臭氧改性活性炭的红外光谱图上碳氧键的吸收峰数量增加,改性后活性炭表面官能团的种类增加。(3)臭氧改性后活性炭对2-环戊烯酮的吸附位点种类增加,使其脱附活化能增大,吸附量增加。在卷烟抽吸过程中,臭氧改性活性炭使2-环戊烯酮的释放量升高,而对主流烟气常规化学成分释放量无明显影响。     

五乙烯六胺改性介孔材料及其在印染废水处理中的应用

利用五乙烯六胺（PEHA）改性介孔材料SBA-3,利用氨基基团与酸性染料之间的静电吸引力和氢键力作用,提高介孔材料对酸性染料的吸附能力。利用低温N2吸附对SBA-3和SBA-3/PEHA样品进行表征,发现PEHA改性后吸附剂的比表面积、孔容,平均孔径均减少。研究不同吸附条件下PEHA功能化介孔材料SBA-3对酸性染料染色废液的吸附能力,主要包括吸附时间、初始浓度、吸附剂用量、搅拌速度、溶液pH值和吸附温度几个方面。确定最优吸附条件为：吸附时间60min,搅拌速度150rpm,吸附温度为20℃,且初始浓度越大,pH越低,吸附量越大。     

核桃壳活性炭对靛蓝的吸附

以核桃壳为原料,采用磷酸活化法制备核桃壳活性炭,表征活性炭对亚甲基蓝的吸附值、孔结构和表面形貌,考察吸附剂用量、吸附时间和pH对吸附效果的影响,并对吸附机理进行分析.结果表明,AC2颗粒大小不一,表面光滑,亚甲基蓝吸附值、比表面积和孔体积分别为16 mL/0.1 g、1127.8 m2/g、1.077 cm3/g.在酸...     

活性炭孔隙结构对活性炭过滤纸吸附性能的影响

用氮气吸附法、扫描电镜对4种不同活性炭(木质活性炭AC1、AC2,煤质活性炭AC3,椰壳质活性炭AC4)的孔隙结构进行表征,通过抄纸方法制备活性炭过滤纸,用亚甲基蓝和苯酚吸附效率表征活性炭过滤纸的吸附性能,研究了活性炭孔隙结构对过滤纸吸附性能的影响.结果表明,两种木质活性炭的比表面积和总的孔容积较高,分别为1054 m2/g、1.165 cm3/g和1125 m2/g、1.083 cm3/g;4种活性炭微孔平均孔径相差不大,但两种木质活性炭的大中孔平均孔径较大;其中,木质活性炭AC2的微孔和大中孔孔容积均较大,孔径在0.64、1.2和2.3 nm附近的孔隙发达,具有较强的选择性吸收能力,用其抄造的过滤纸对亚甲基蓝和苯酚均有较好的吸附效率,3次过滤吸附效率分别为92.2%和93.8%.     

改性多级孔分子筛的合成及其对酸性橙Ⅱ的吸附性能

为增强分子筛的吸附性能,采用离子交换法对微孔分子筛13X进行改性,再通过水热晶化法制备成型的改性多级孔分子筛。利用XRD和N_2吸附-脱附等方法表征了改性分子筛的结构,并评价了其对酸性橙Ⅱ的吸附性能。结果表明:改性多级孔分子筛兼具微孔和介孔分子筛的特点,比表面积为893.7 m~2/g,总孔容为0.87 cm~3/g,平均孔径为3.15 nm;在pH=3、温度25℃、酸性橙Ⅱ初始质量浓度20 mg/L的条件下,0.20 g/L改性多级孔分子筛吸附70 min后对酸性橙Ⅱ的去除率可达97.05%。此吸附过程属于单分子层吸附,可通过Langmuir等温吸附模型进行描述。     

氧化对高强对位芳纶纤维复合材料力学性能的影响北大核心

对位芳纶(PPTA)纤维用H2O2溶液进行氧化改性,制备改性芳纶增强环氧树脂基复合材料。研究表明,低浓度的H2O2可以有效地在芳纶纤维上引入极性基团,刻蚀纤维表面,同时增加纤维的比表面积。20层0.3 mol/L双氧水改性PPTA增强环氧树脂基复合材料的弯曲性能最佳,达405.0 MPa。     

CO_2固体吸附剂研究述评

由于介孔材料具有比表面积大和空隙较多等优点,被广泛地应用于对空气中或工业废气中的CO2的吸附.活性炭、沸石、硅胶等传统的吸附剂具有制备方法简单、制造工艺成熟、成本低廉等优点,是吸附空气中CO2的首选材料,但较强的吸湿性使其不能用于高湿度的吸附环境等,而通过对传统的介孔材料进行表面改性,接枝胺类等碱性物质,将单纯的物理吸附转变为物理吸附和化学吸附共同作用的吸附方式,在改善吸附剂适应环境能力的同时也能增加吸附量.开发具有最佳结构且物理及化学性能稳定的功能复合吸附剂将是该领域的研究热点和主要方向.     

丝瓜络基活性炭的制备及其吸附性能

以丝瓜络为原料,ZnCl2为活化剂制备了丝瓜络基活性炭(LAC)。利用扫描电子显微镜(SEM)、比表面积及孔径测定仪对LAC进行表征,LAC对亚甲基蓝的吸附性能采用分光光度计进行测试。结果表明:LAC具有高的比表面积和丰富的孔结构(孔洞以微孔为主);随着炭化活化温度的升高,比表面积和孔体积增大,微孔比例下降;当炭化活化温度为900℃时,LAC的比表面积高达2 333 m2/g,孔体积为1.658 cm3/g;LAC对亚甲基蓝具有较快的吸附速率,在5 min内达到吸附平衡,吸附率高达99%以上。     

FeCl3改性柚子皮对亚甲基蓝的吸附性能

以柚子皮为原料,FeCl3为改性剂,分别制得柚子皮、FeCl3质量比为50∶1、25∶1、5∶1的改性吸附剂(依次记作M50、M25、M5,原始柚子皮记作M0),比较4种吸附剂的外观,并用扫描电镜(SEM)、比表面积(BET)、傅里叶变换红外光谱(FTIR)进行表征。在实验条件[亚甲基蓝(MB)初始质量浓度140 mg/L、pH=8、吸附剂用量4 g/L、温度25℃、时间60 min]一致时,对比4种吸附剂对MB的去除率及解吸率,选取性能最好的吸附剂进行工艺优化。结果表明:改性后的柚子皮层状褶皱结构更复杂,比表面积增大,为介孔材料,且表面官能团更丰富;M0的吸附性能最差;改性吸附剂对MB的去除率比M0最大增加18.10%,解吸率最大增加26.86%;用优化吸附剂M50处理MB溶液,在吸附剂用量为1 g/L、吸附20 min时,去除率已达96.76%;处理要求低时可进一步减少吸附剂用量并缩短时间,适用于一般pH、温度及质量浓度的染液处理,可大大节约成本。     

改性聚氯化铝残渣吸附剂的制备及对亚甲基蓝的吸附

采用聚氯化铝压滤残渣(PACR)改性制备新型吸附剂(M-PACR),考察该吸附剂对亚甲基蓝的吸附效果及脱色性能。SEM表明:M-PACR较PACR表面孔隙结构更加明显;BET分析数据显示:M-PACR较PACR比表面积增大了近3倍;吸附实验结果表明:M-PACR的最佳吸附pH为8。M-PACR对亚甲基蓝的吸附符合二级吸附动力学模型与Langmuir等温吸附模型。     

Modeling trichloroethylene adsorption by activated carbon preloaded with natural dissolved organic matter using a modified IAST approach

A model was developed, using an approach based on the Ideal Adsorbed Solution Theory (IAST), to predict trichloroethylene (TCE) adsorption by granular activated carbon (GAC) preloaded with natural dissolved organic matter (DOM) isolated from three surface water sources. The IAST model was formulated for a bi-solute system in which TCE and DOM single-solute uptakes were described by the Langmuir-Freundlich and Freundlich isotherms, respectively. The effect of DOM molecular size and polarity (as measured by XAD 8 resin fractionation) on TCE uptake by preloaded GAC was assessed to identify a reactive fraction of natural water DOM for the purpose of modeling competitive adsorption. Consistent with previous work that identified low molecular weight species as the most reactive with regard to preloading effects (i.e., reducing target compound uptake), the low molecular weight components of the polar (hydrophilic) and nonpolar (hydrophobic) DOM fractions, isolated using ultrafiltration (1 kDa molecular weight cutoff membrane), exhibited significant competitive effects. Furthermore, the effects of these fractions on TCE uptake were similar; therefore, theywere considered together to represent a single "reactive fraction" of DOM. On the basis of this finding, isotherms for the <1 kDa low molecular weight DOM fraction of the whole water were measured, and molar concentrations were computed based on an average molecular weight determined using size-exclusion chromatography. The IAST model was modified to incorporate surface area reduction due to pore blockage by DOM and to reflectthe hypothesis thatTCE molecules can access adsorption sites which humic molecules cannot, thus preventing competition on these sites. The model was calibrated with data for TCE uptake by carbon preloaded with the <1 kDa low molecular weight DOM fraction and was verified by predicting TCE uptake by carbon preloaded with whole natural waters for both constant GAC dose (hence constant DOM loading) and variable GAC dose (hence variable DOM loading) TCE isotherms. Preloading by DOM reduced volume in GAC pores having widths smaller than 1.25 nm (likely accessible only to TCE) to a greater extent than total pore volume, suggesting preferential blockage of micropores. Such preferential pore blockage may explain, in part, why increased DOM loading decreases the fraction of the total surface area on which no competition between TCE and DOM occurs.     

Iron optimization for Fenton-driven oxidation of MTBE-spent granular activated carbon

Fenton-driven chemical oxidation of methyl tert-butyl ether (MTBE)-spent granular activated carbon (GAC) was accomplished through the addition of iron (Fe) and hydrogen peroxide (H2O2) (15.9 g/L; pH 3). The Fe concentration in GAC was incrementally varied (1020-25 660 mg/kg) by the addition of increasing concentrations of Fe solution (FeSO4-7H2O). MTBE degradation in Fe-amended GAC increased by an order of magnitude over Fe-unamended GAC and H2O2 reaction was predominantly (99%) attributed to GAC-bound Fe within the porous structure of the GAC. Imaging and microanalysis of GAC particles indicated limited penetration of Fe into GAC. The optimal Fe concentration was 6710 mg/kg (1020 mg/kg background; 5690 mg/kg amended Fe) and resulted in the greatest MTBE removal and maximum Fe loading oxidation efficiency (MTBE oxidized (microg)/ Fe loaded to GAC (mg/Kg)). At lower Fe concentrations, the H2O2 reaction was Fe limited. At higher Fe concentrations, the H2O2 reaction was not entirely Fe limited, and reductions in GAC surface area, GAC pore volume, MTBE adsorption, and Fe loading oxidation efficiency were measured. Results are consistent with nonuniform distribution of Fe, pore blockage in H2O2 transport, unavailable Fe, and limitations in H2O2 diffusive transport, and emphasize the importance of optimal Fe loading.     

Enhancing activated carbon adsorption of 2-methylisoborneol: methane and steam treatments

This research investigated methods for tailoring a commercial, lignite-based granular activated carbon (GAC) to enhance its adsorption of 2-methylisoborneol (MIB) from natural water. Tailoring efforts focused on heat treatments in gas environments comprising steam and/or methane, since these gases can alter GAC pore structure and surface chemistry. Heat treatments that combined methane and steam enhanced MIB adsorption considerably, causing a 4-fold improvement (over untreated GAC) in fixed-bed adsorption performance relative to initial MIB breakthrough. These favorable effects, observed in rapid small-scale column tests, occurred following simultaneous and separate (sequential) applications of methane and steam. Moderately low temperature steam treatments also improved MIB uptake in fixed-bed adsorption tests but to a lesser extent (approximately 1.5-fold). In contrast, methane treatments alone, at various temperatures, led to significant carbon deposition within the GAC pore structure. As a result, total pore volume was reduced and MIB adsorption performance declined.     

稳定态二氧化氯对鲜切马铃薯贮藏性及酶褐变的初步研究

本文对不同浓度二氧化氯（ClO2）对鲜切马铃薯褐变和贮藏性的影响进行了研究。实验结果表明ClO2处理时间越长效果越好，浓度却不一定越大越好。不同浓度二氧化氯（ClO2）处理均对PPO和POD酶产生抑制作用，其中二氧化氯240mol／L处理10min、360mol／L处理5min和360m01／L处理10min处理效果最好；马铃薯的PPO、POD活性很高且两者之间具有相关性，与褐变度数值相吻合：经过不同浓度二氧化氯（ClO2）处理的样品之间蛋白质含量有差异，但不太明显。     

食品包装用吸湿剂的研究进展

食品包装用吸湿剂作为食品流通过程中的重要组成部分, 在防止食品受潮变质, 延长食品保质期, 保留食品的口感和风味方面起着关键作用。本文综述了目前在食品中常用的4种包装用吸湿剂, 包括生石灰吸湿剂、蒙脱石吸湿剂、硅胶吸湿剂和氯化钙吸湿剂。其中, 生石灰吸湿剂吸湿能力与外界空气的湿度高低无关、价格低廉, 但存在安全隐患; 蒙脱石吸湿剂空气湿度较低时吸湿能力较强、绿色环保、无毒无味、价格低廉, 但在空气湿度高时吸湿能力下降、吸湿时伴有体积的膨胀; 硅胶吸湿剂吸湿性能好、无毒无味、化学性质稳定, 但其成本高、吸附大量水后易破裂, 且再生温度高, 难降解; 氯化钙吸湿剂吸湿性能好、价格低廉, 但吸湿后易液解成溶液。此外, 还列举了纤维吸湿剂、复合吸湿剂、高吸水树脂吸湿剂和其他新型材料吸湿剂, 展开介绍了这些新型吸湿剂的优势和一些食品包装用吸湿剂研究新技术。目前食品包装用吸湿剂研究热点主也要集中在2个方面: 高吸湿性能且低成本食品吸湿剂的研发和高环保、低污染、低浪费的生产工艺的研发。     

二氧化氯吸收塔的材料选用及制造安装

介绍了二氧化氯吸收塔结构,对各部位材料的选用进行探讨,重点对陶瓷填料的选择进行了对比,并阐述了二氧化氯吸收塔制造安装的要点,表明可以制造出价格合理、经久耐用的二氧化氯吸收塔。     

Impact of natural organic matter on monochloramine reduction by granular activated carbon: the role of porosity and electrostatic surface properties

Steady-state monochloramine reduction in fixed-bed reactors (FBRs) was quantified on five types of granular activated carbon (GAC) using two background waters-one natural source water (LAW) containing 2.5-3.5 mg/L organic carbon and one synthetic organic-free water (NW). While more monochloramine was reduced at steady-state using NW compared to LAW for each GAC and empty-bed contact time studied, the differences in removal varied considerably among the GACs tested. Physical characterization of the GACs suggested that the degree of interference caused by natural organic matter (NOM) increased with increasing GAC surface area contained within pores greater than 2 nm in width. Acid/base and electrostatic properties of the GACs were not found to be significant in terms of NOM uptake, which indicated that size exclusion effects of the GAC pores overwhelmed the impact of the GAC surface chemistry. Therefore, selection of GAC to limit the impact of NOM on monochloramine reduction in FBRs should be based on pore size distribution alone, with the impact of NOM decreasing with decreasing mesoporosity and macroporosity.     

二氧化氯漂液制备研究

针对二氧化氯漂后白度高的特点,分析了二氧化氯的性质与漂白、漂液制备的关系以及漂液的作用,进而联系了典型工艺在二氧化氯制备中的主要区别,并通过实例验证了不同还原剂工艺的二氧化氯制备结果及漂液制备条件,归纳了漂液的应用效果。通过研究,总结出整体二氧化氯漂液制备的有关因素,为可行性研究提供有关参考。     

Evaluation of chlorine, chlorine dioxide, and a peroxyacetic acid-based sanitizer for effectiveness in killing Bacillus cereus and Bacillus thuringiensis spores in suspensions, on the surface of stainless steel, and on apples

Chlorine (10 to 200 microg/ml), chlorine dioxide (10 to 200 microg/ml), and a peroxyacetic acid-based sanitizer (40 and 80 microg/ ml) were evaluated for effectiveness in killing spores of Bacillus cereus and Bacillus thuringiensis in suspensions and on the surface of stainless steel and apples. Water and 5% horse serum were used as carriers for spore inoculum applied to the surface of stainless steel coupons, and 5% horse serum was used as a carrier for inoculum applied to apples. Inocula were dried on stainless steel for 5 h and on apples for 22 to 24 h before treating with sanitizers. At the concentrations of sanitizers tested, sensitivities of planktonic B. cereus and B. thuringiensis spores were similar. A portion of the spores surviving treatment with chlorine and, more markedly, chlorine dioxide had decreased tolerance to heat. Planktonic spores of both species were more sensitive to sanitizers than were spores on the surface of stainless steel or apples. At the same concentrations, chlorine was more effective than chlorine dioxide in killing spores in suspension and on stainless steel. The lethality of chlorine dioxide was markedly reduced when inoculum on stainless steel coupons was suspended in 5% horse serum as a carrier rather than water. Chlorine and chlorine dioxide at concentrations of 10 to 100 microg/ml were equally effective in killing spores on apples. Significant reductions of > or = 3.8 to 4.5 log CFU per apple were achieved by treatment with 100 microg/ml of either of the two sanitizers. The peroxyacetic acid sanitizer (40 and 80 microg/ml) was ineffective in killing Bacillus spores in the test systems investigated. Results provide information on the effectiveness of sanitizers commonly used in the food processing industry in killing Bacillus spores in suspension, on a food-contact surface, and on a ready-to-eat food.     

二氧化氯结合加热法处理蛋源对液蛋产品特性的影响

通过优化二氧化氯结合加热法处理新鲜鸡蛋提高其杀菌效率,缩短其消毒时间,并对蛋液的理化及功能性质进行分析。结果表明,最佳蛋源前处理方法为浓度为125 mg/L的二氧化氯溶液浸泡5 min后,65℃热水冲洗120 s,对蛋壳表面的微生物的杀菌率达到99.9%。前处理方法对蛋液起泡性、泡沫稳定性、挥发性盐基氮没有显著影响;经前处理后的蛋液储存8周后,菌落总数、起泡性和挥发性盐基氮均明显优于对照组。该方法可以有效延长液蛋制品的保质期。