负载型二氧化钛光催化剂对染色废水光催化降解性能的研究

文章为了解决二氧化钛光催化剂分离困难的问题,使用负载型二氧化钛光催化剂与紫外光灯组成非均相光催化体系,并讨论其对酸性红18和活性紫145染料溶液的光催化氧化降解情况。经过实验分析和讨论得知:在紫外光灯照射的条件下,负载型二氧化钛光催化剂实现了对酸性红18和活性紫145两种染料溶液的光催化氧化降解,两种染料的去除百分率分别为99.1%和78.2%;通过反应动力学分析,酸性红18染料溶液的光催化氧化降解速率更高,约为活性紫145染料溶液的2.5倍,经过130min的反应后,酸性红18染料溶液基本呈现无色透明的状态。     

响应曲面法-LSSE模型联合优化光催化降解亚甲基蓝

应用响应曲面法与LSSE模型确定了光催化降解亚甲基蓝的最佳工艺参数。先通过LSSE方法进行光距模拟,当紫外功率为60 W时,最佳光距为3 cm;通过响应曲面法模拟光催化降解实验,得到最佳工艺参数为pH=11、水膜厚度5 mm、光距3 cm、光照3 h,降解效果最佳。     

石墨相氮化碳在玉米赤霉烯酮降解中的应用

采用传统的热裂解法合成了光催化材料——石墨相氮化碳（g-C3N4）,研究了其对玉米赤霉烯酮（ZEN）的降解效率。通过X射线衍射（XRD）、傅里叶变换红外（FTIR）、X射线光电子能谱（XPS）、扫描电子显微镜（SEM）和透射电镜（TEM）对g-C3N4结构进行了解析。光催化降解实验表明,在紫外光（254 nm,包括 185 nm）下,g-C3N4可诱导光催化效应,释放活性氧自由基,降解ZEN。对ZEN光催化降解的实验条件进行了探索。结果表明,当光催化材料的质量为20 mg,紫外灯的波长为254 nm（功率为50 W）,初始浓度为0.5 μg/mL,照射时间为60 min时,ZEN 的降解率为96.0%。同时,对ZEN粉末样品的光催化降解实验条件进行了优化。结果表明,当光催化材料的质量为800 mg、紫外灯的波长为254 nm（功率为50 W）、照射时间为50 min时,ZEN的降解率为80.0%。该结果为光催化降解ZEN提供了理论参考和实践依据。     

三种失活酵母对苹果汁中展青霉素去除研究

研究了固定化失活酵母、磁性固定化失活酵母和失活酵母粉去除苹果汁中展青霉素。比较了三种处理对展青霉素的去除效果以及对苹果汁感官品质的影响。试验结果为:三种处理方法中,固定化失活酵母对展青霉素的去除率最高可达70.4%。固定化失活酵母处理对苹果汁感官品质无显著影响,磁性固定化失活酵母处理后苹果汁的色值和透光率显著下降。     

高效液相色谱和液相色谱串联质谱技术在检测苹果制品中展青霉素的研究进展

展青霉素是一种有害的真菌毒素代谢物,主要对人类的中枢神经系统造成影响,且对消化系统和肾脏也造成不同程度的毒害影响。展青霉素在食品中的污染是世界各地普遍存在的问题,尤其在苹果汁、苹果脯、苹果蜜饯、苹果酱等食物中。考虑到它的毒性和广泛性,很多管理机构对食品基体中展青霉素的含量做出了严格的限制。因此控制展青霉素污染对于保障食品安全具有重要意义。目前液相色谱技术是苹果制品中展青霉素的主要检测方法。本文系统地总结了检测苹果制品中展青霉素的前处理方法,并综述了高效液相色谱和液相色谱联用质谱技术在苹果制品中展青霉素检测的最新研究进展。     

锐钛矿型TiO2的制备与光催化性能研究

以溶胶-凝胶法制备锐钛矿型纳米TiO2光催化荆,采用X射线衍射、透射电镜、热重分析、红外光谱等技术对样品进行表征.以甲基橙的光催化降解为反应模型.分析了焙烧温度、反应体系中催化剂投加量、溶液pH值对光催化性能的影响,并研究了甲基橙的光催化反应动力学.结果表明.采用适宜的制备方法和光催化降解工艺,纯锐钛矿型纳米Ti02能够获得较高的光催化活性.在焙烧温度450～500℃,催化剂加入量为1.0～1.5g/L和反应液pH值为2～4的条件下,紫外光照30 min时甲基橙的降解率达98%,甲基橙的光催化反应动力学符合Langmiur-Hinshelwood模型,反应速率常数k=0.429 mg(L·min).表观吸附平衡常数K=0.0379 L/mg.     

负载纳米TiO2薄膜光催化降解活性红MS

采用溶胶·凝胶法制备纳米TiO2,通过二浸二轧(70%～80%)→烘干(80℃×3 min)→焙烘(80℃×2 min)制备织物负载纳米TiO2薄膜.在紫外灯照射下,用织物负载纳米TiO2薄膜对活性红MS进行光催化降解试验,考察了无机盐(氯化钠和碳酸钠)对织物负载纳米TiO2薄膜光催化降解性能的影响.结果表明,织物负载纳米TiO2薄膜光催化降解活性红MS的降解率可达93.7%,且随氯化钠浓度的升高而降低,随碳酸钠浓度的升高而提高,在碳酸钠浓度为0.094 mol/L时达到最佳.     

α-SiW_(11)Fe/PANI/ZnO复合催化剂的制备及光催化降解刚果红

制备了α-SiW_(11)Fe/PANI/ZnO三元复合催化剂,并用红外光谱、紫外光谱、XRD、SEM进行表征。并以模拟污染物刚果红为光催化降解探针来评价α-SiW_(11)Fe/PANI/ZnO的光催化活性。结果表明:α-Si W_(11)Fe/PANI/Zn O在紫外灯照射下降解100 m L刚果红的最佳条件为:p H=5,刚果红初始质量浓度15 mg/L,催化剂用量40 mg/L,脱色率可达91.88%。光催化降解刚果红符合准一级动力学模型。     

干酪乳杆菌清除苹果汁展青霉素对苹果汁品质的影响

目的：本课题组前期筛选到一株可以高效清除苹果汁中展青霉素的干酪乳杆菌Lactobacillus casei YZU01。本文主要研究L. casei YZU01清除苹果汁展青霉素过程中对苹果汁品质的影响。方法：以未添加和添加展青霉素的苹果汁作为对照,分别利用高效液相色谱法、p H计检测法、紫外分光光度法、比色法检测L. casei YZU01降解苹果汁展青霉素过程中苹果汁的有机酸（柠檬酸、酒石酸、富马酸、乙酸和L-苹果酸）和糖含量（葡萄糖和半乳糖）、酸度、非酶褐变指数和透光率、色度等苹果风味和品质相关指标。结果：L. casei YZU01清除苹果汁展青霉素过程中,苹果汁柠檬酸、酒石酸、富马酸和乙酸的含量增多,L-苹果酸、葡萄糖和半乳糖的含量减少,柠檬酸含量从0.18 g/kg上升至2.11 g/kg,酒石酸含量从2.3 g/kg上升至3.4 g/kg,富马酸含量从0.12 g/kg上升至0.15 g/kg,乙酸含量从0.00 g/kg上升至0.66 g/kg,L-苹果酸含量从7.31 g/kg下降至5.26 g/kg,葡萄糖含量从38.59 g/kg下降至1.59 g/kg,半乳糖含...     

TiO2光催化降解乳酸反应动力学研究

以TiO2为催化剂,紫外灯为光源,对乳酸的光催化降解进行动力学研究.乳酸降解反应动力学拟合结果表明,降解动力学规律符合Langmuir-Hinshelwood动力学模型,反应速率常数k=0.0085g/(L·min),一级反应动力学模型与实验数据拟合较好,方差R2大于0.99,乳酸初始降解速率r0随乳酸初始浓度增大而增大.     

Patulin reduction in apple juice from concentrate by UV radiation and comparison of kinetic degradation models between apple juice and apple cider

Patulin, a mycotoxin produced by several genera of fungi, including Byssochlamys, Aspergillus, and Penicillium, has been an important concern in apple cider and apple juice due to its toxicity and health consequences. In this study, the effects of UV on the patulin level, physical and chemical properties, and sensory attributes in apple juice from concentrate were investigated. Kinetic modeling of patulin reduction by UV radiation in apple juice from concentrate was calculated and compared with the degradation rate observed previously in apple cider. From an initial patulin contamination of approximately 1,000 ppb (μg/liter), the UV exposure, ranging from 14.2 mJ/cm(2) (one pass) to 99.4 mJ/cm(2) (seven passes), was successful in reducing patulin levels by 72.57% ± 2.76% to 5.14% ± 0.70%, respectively. Patulin reduction by UV radiation followed first-order kinetic modeling in a fashion similar to first-order microbial inactivation. An exponential correlation between UV exposure and the percentage of patulin remaining was observed, giving an r(2) value of 0.9950. Apple juice was repeatedly exposed to 14.2 mJ/cm(2) for each treatment, and patulin levels were significantly decreased when compared with the level obtained with the previous UV exposure treatment. While there were no significant differences in the percentages of titratable acidity and ascorbic acid (P > 0.05), there were minor yet random sampling differences in pH and degrees Brix (1 °Brix is 1 g of sucrose in 100 g of solution; the °Brix represents the soluble solids content of the solution as percentage by weight [%, wt/wt]) (P ≤ 0.05). A significant difference (P ≤ 0.05) in sensory perception for the finished apple juice was detected between the control and the full seven-pass UV radiation treatment using an experienced consumer panel and a triangle test. Patulin reduction by UV radiation from both the current study and a previous study involving apple cider was compared, which showed that both matrices strongly fit a first-order kinetic degradation model. However, the kinetic constant for degradation in apple juice was approximately 5.5 times greater than that observed in an apple cider matrix.     

温度、pH值和光照对石榴汁花色苷稳定性的影响

研究了温度、pH值、光照对石榴汁花色苷稳定性的影响。结果表明,石榴汁花色苷降解符合一级反应模型;石榴汁花色苷受热容易分解;pH值较低时,其稳定性高;在较高剂量日光灯照射下,其花色苷容易分解,在散射光和黑暗环境下花色苷降解趋势相近。     

Rapid degradation of the mycotoxin patulin in man quantified by stable isotope dilution assays

The absorption and degradation of the mycotoxin patulin in man was quantified by using a recently developed stable isotope dilution assay. Application of this currently most sensitive method revealed a patulin content less than 200 ng l -1 in the blood serum of five consumers of apple juice. Likewise, no patulin was found in the serum of a volunteer, whose blood was drawn shortly after consumption of a juice containing a maximum tolerable amount of patulin. In further in vitro experiments, the degradation of patulin by reacting it with whole blood was investigated. After addition of 100 μg patulin to 9 ml blood, only 6.1% of the mycotoxin was detected after 2 min. It was concluded, therefore, that even high naturally occurring concentrations of patulin in foods are quickly degraded before reaching other tissues than the gastrointestinal tract.     

臭氧对苹果汁中棒曲霉素的降解效果研究

主要研究臭氧对苹果汁中棒曲霉素(Pat)的降解效果及对果汁品质的影响。研究采用臭氧对水和苹果汁中500、250、200、100、50μg/LPat浓度进行5、10、15、20、30min的降解处理。结果表明,臭氧处理对各浓度的Pat都有降解作用,浓度越低,降解效果越好。随着处理时间延长降解效果越好,15min以后降解率不再增加。臭氧处理15min,50μg/L的Pat降解效率最佳,在该条件下,臭氧对苹果汁的pH、VC含量、可溶性固形物和色值均没有明显的影响,因此,臭氧处理是高效、安全、低廉的Pat降解方法。     

Long-term survey of patulin in apple juice concentrates produced in Turkey.

A liquid chromatographic method described by us elsewhere was evaluated for a long-term survey of patulin in apple juice concentrates. Patulin was separated on a reversed phase C18 LC column with water-acetonitrile (99:1) as the mobile phase and quantitated with a photodiode array (PDA) detector. Relatively low amounts of patulin (< 5 micrograms/l for single strength juice at 11.2 degrees Bx) were detected in apple juice concentrates and confirmed by PDA detector, comparing the corresponding UV spectra with that of patulin standard. Four hundred and eighty two apple juice concentrates produced through 1996-99 were analysed for their patulin contents. Year-to-year variations in patulin levels of apple juice concentrates were found out to be statistically significant. Patulin contamination levels of apple juice concentrates tended to decrease through the years and averaged 63, 43, 19 and 31 micrograms/l in 1996, 1997, 1998 and 1999, respectively. Percentages of concentrates exceeding the maximum permitted concentration of 50 micrograms/l were 52%, 34%, 8% and 8% for 1996, 1997, 1998 and 1999, respectively.     

Occurrence of patulin in organic, conventional, and handcrafted apple juices marketed in Belgium

The aim of this research was to compare the occurrence of patulin in a large group of organic, conventional, and handcrafted apple juices marketed in Belgium. An analytical procedure based on high-performance liquid chromatography with UV detection was validated and used to analyze 177 apple juice samples: 65 organic, 90 conventional, and 22 handcrafted. Patulin was detected in 22 samples (12%), and quantification was possible in 10 (6%) of these samples. The patulin content was higher than the European legal limit of 50 microg/liter in two samples of organic apple juice. Although, the incidence of patulin in organic (12%), conventional (13%), and handcrafted (10%) apple juices was not significantly different (P = 0.863), the mean concentration of patulin in contaminated samples was significantly higher in organic (43.1 microg/liter) than in conventional (10.2 microg/liter) (P = 0.02) and handcrafted (10.5 microg/liter) (P = 0.037) apple juice. The highest patulin concentrations were found in the most expensive apple juices because of the higher price of organic apple juice. This relation was not observed when only conventional apple juices were analyzed.     

Quantitative analysis of patulin in apple juice by thin-layer chromatography using a charge coupled device detector

A method was developed and validated in-house for the detection and quantification of patulin in apple juice concentrate using a charge coupled device (CCD) on thin-layer chromatography (TLC) plates. Samples were extracted with ethyl acetate and then cleaned-up by extraction with a sodium carbonate solution. The method showed a mean recovery of 95%. The quantification and detection limit were 14 µg l^?1 and 0.005 µg per spot, respectively. The CCD camera is sufficiently sensitive to detect changes in spot fluorescence intensity caused by small differences in mycotoxin concentration under homogeneous illumination from a UV light source. The results of validation confirmed the efficiency of the method, which is sensitive enough to be used to quantify patulin in apple juice by producers or for government monitoring/survey programs. The method was applied to the analysis of 16 apple juice concentrate samples and patulin levels ranged from 15 to 46 µg l^?1. This study demonstrated the applicability of the TLC–CCD technique as a tool for monitoring patulin in apple juice.     

Fate of patulin in the presence of the yeast Saccharomyces cerevisiae

Patulin is known to become analytically non-detectable during the production of cider from contaminated apple juice. The fate of [¹⁴C]-labelled patulin during the alcoholic fermentation of apple juice was studied. Three commercial cider strains of Saccharomyces cerevisiae degraded patulin during active fermentative growth, but not when growing aerobically. The products of patulin degradation were more polar than patulin itself and remained in the clarified fermented cider. Patulin did not appear to bind to yeast cells or apple juice sediment in these model experiments. HPLC analysis of patulin-spiked fermentations showed the appearance of two major metabolites, one of which corresponded by both TLC and HPLC to E-ascladiol prepared by the chemical reduction of patulin using sodium borohydride. Using a diode array detector, both metabolites had a λ_max = 271nm, identical to that of ascladiol. Thenmr spectrum of a crude preparation of these metabolites showed signals corresponding to those of the E-ascladiol prepared chemically and a weaker set of signals corresponding to those reported in the literature for Z-ascladiol.     

利用Saccharomyces cerevisiae KD控制苹果汁中棒曲霉素的污染

研究一株食品生产用酿酒酵母Saccharomyces cerevisiae KD在培养基及市售100%苹果汁中对棒曲霉素污染的控制作用。通过高效液相色谱法对棒曲霉素进行定量,分析起始棒曲霉素浓度、菌体接种量和培养基pH对S. cerevisiae KD去除棒曲霉素活力的影响;利用酶标仪监测S. cerevisiae KD的生长状况,且通过检测可溶性固形物、酸度、总酚、黄酮含量对菌体发酵后苹果汁的品质进行了评估。结果表明:有氧条件下S. cerevisiae KD能够在28 h内完全去除培养基中的棒曲霉素,其去除机理包括物理吸附和酶解;在较低的起始棒曲霉素浓度和较高的菌体接种量条件下,S. cerevisiae KD对棒曲霉素的去除率较高,但在培养后期,不同菌体接种量下棒曲霉素的去除率接近一致;实验还发现酸性条件有利于S. cerevisiae KD去除棒曲霉素。此外,S. cerevisiae KD对棒曲霉素的耐受性较强,甚至在棒曲霉素浓度高达100 mg/L的环境中依然能较好生长。在市售100%苹果汁中,S. cerevisiae KD也能高效控制棒曲霉素的污染,且与Lactococcus lactis MG1363联合发酵2 d后,果汁中已无棒曲霉素检出,总酚含量显著高于发酵前苹果汁(p<0.05),发酵果汁的品质较好。结论:S. cerevisiae KD可有效控制食品中棒曲霉素的污染,具有潜在的应用前景。     

二氧化钛负载聚酯织物的制备及其光催化性能

为解决印染废水的降解问题,采用同质涂层法将氮掺杂二氧化钛粉末负载于聚酯（PET）织物上。研究了氮掺杂二氧化钛负载PET织物在太阳光照射下对亚甲基蓝水溶液的光催化降解效率及重复利用性。结果表明：氮掺杂二氧化钛负载PET织物具有良好的光催化性能,经过150 min的太阳光照射后,放有原PET 织物的亚甲基蓝溶液的降解率仅为8.2%,而放有光催化PET织物的亚甲基蓝溶液的降解率提高至94.8%;且织物在重复洗涤5 次后对亚甲基蓝的降解率仍在88%以上,表明同质涂层法制备的光催化功能层具有较好的耐久性;光催化PET 织物在pH值为9.0 的碱性溶液和晴天条件下的催化活性更高,而NaCl溶液和亚甲基蓝溶液浓度的提高会抑制光催化反应的进行。