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1.
制备了α-SiW11Cu/PANI/SnO2光催化剂,研究了其对刚果红溶液的降解性能。结果表明:刚果红初始质量浓度为15mg/L,溶液pH为1,催化剂用量为30 mg/L,在30 W紫外灯照射下,降解时间为200 min时,脱色率可达81.78%。光催化降解刚果红过程符合一级动力学方程,反应速率常数为0.008 80 min-1。  相似文献   

2.
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.  相似文献   

3.
《食品与发酵工业》2016,(12):105-110
为了提高油菜籽的干燥速率,降低其单位能耗,采用真空干燥技术对油菜籽干燥工艺进行考察。采用三元二次回归旋转组合设计方法对油菜籽工艺参数进行优化试验,选取真空度(X_1),物料厚度(X_2),温度(X_3)作为试验因子分别考察其对干燥速率(Y_1)、能耗(Y_2)的影响并建立回归模型。结果表明:因子对干燥速率的影响排序为:温度(X_3)真空度(X_1)物料厚度(X_2);对单位能耗的影响主次为,真空度(X_1)温度(X_3)物料厚度(X_2);真空度和物料厚度的交互作用对油菜籽干燥速率的影响极其显著,当物料厚度在0.92~1.23 cm,真空度在-0.07~0.045 MPa时油菜籽干燥速率最高。通过软件优化得到最佳工艺参数组合为:X_1=-0.066 MPa,X_2=1.5 cm,X_3=36.0℃,此时干燥速率为0.423 g/min,单位能耗为85.197 k J/kg,与单目标优化所得最优值接近,模型可靠。  相似文献   

4.
研究了β_2-SiW_(11)Ti/PANI/ZnO光催化降解龙胆紫染料废水及光催化性能的影响因素。结果表明,在pH为7、初始质量浓度为10 mg/L的龙胆紫溶液中投入20 mg/L催化剂,30 W紫外灯光照140 min学方程,反应速率常数为0.011 63 min-1,线性方程拟合常数为0.994 9。  相似文献   

5.
本文研究了紫外光照射技术对水模拟体系中吡虫啉和啶虫脒的降解作用,探讨了照射时间、紫外光强度、水模拟体系pH值和农药初始浓度等因素对降解效果的影响。结果表明,紫外光照射可有效降解水模拟体系中的吡虫啉和啶虫脒,且吡虫啉的降解效果优于啶虫脒。在本实验研究条件下,照射时间越长,紫外光强度越大,吡虫啉和啶虫脒的降解率越高;农药初始浓度越低,在相同照射时间下,吡虫啉和啶虫脒的降解率越高;中性和碱性的水模拟体系更利于啶虫脒的降解。采用紫外光强度为650μW/cm2的短波紫外光照射水体系30 min(pH 6,吡虫啉和啶虫脒初始浓度均为0.2μg/mL),吡虫啉和啶虫脒的降解率达到最大,分别为100%和46.30%。动力学研究表明,水模拟体系中吡虫啉和啶虫脒紫外光降解过程符合一级动力学模型(R2≥0.95)。  相似文献   

6.
《食品与发酵工业》2015,(12):108-113
为探讨低温下紫外光催化Ti O_2降解三甲胺气体的效果,以紫外灯为光源,研究了Ti O_2处理、紫外光处理、紫外光辐照催化Ti O_2处理3种方法降解三甲胺气体的效果,并探讨了三甲胺初始浓度和紫外光辐照强度对三甲胺光催化降解效果的影响。结果表明:Ti O_2光催化降解三甲胺效果显著,降解过程中ln(C_0/C_t)与时间t呈良好的线性关系,三甲胺的光催化降解遵循一级反应动力学过程;在光强为147μW/cm~2的条件下,当三甲胺的初始质量浓度在3~12 mg/m~3内时,随三甲胺初始浓度C_0的增加,其降解率逐渐降低,反应速率常数K也逐渐减小,K与C_0的线性关系为K=-0.002 4C_0+0.050 2(R~2=0.997 0);在三甲胺初始浓度为12 mg/m~3的条件下,当光强在28~170μW/cm~2内时,随紫外光辐照强度I的增加,三甲胺的降解率逐渐增大,反应速率常数K也逐渐增大,K与I的线性关系为K=0.005 0ln(I)-0.003 3(R~2=0.993 3)。  相似文献   

7.
采用共沉淀法并在600℃焙烧制备纳米CeO_2光催化剂,利用热重分析、傅立叶变换红外光谱(FT-IR)、X射线衍射(XRD)、N2吸附-脱附、扫描电子显微镜(SEM)等方法对纳米CeO_2粒子进行了表征,并研究了纳米CeO_2粒子催化剂对亚甲基蓝溶液的光催化降解行为。结果表明,在300 W汞灯照射下,对于初始质量浓度为5.0 mg/L和初始pH=11的亚甲基蓝溶液,加入600℃煅烧的纳米CeO_21.0 g/L,反应60 min,亚甲基蓝降解率可达87.05%。该光催化降解反应表现为一级动力学反应,反应速率服从多相催化动力学方程Langmuir-Hinshelwood方程,光催化剂表面反应速率常数k为0.138 5 mg/(L·min),吸附平衡常数Kdye为0.399 7 L/mg。  相似文献   

8.
低盐腌制榨菜保脆工艺的优化研究   总被引:2,自引:0,他引:2  
以榨菜脆度为评价指标,通过二次回归正交旋转组合设计,建立了接种乳酸菌低盐腌制榨菜的添加CaCl_2浓度(X_1)、盐浓度(X_2)和腌制时间(X_3)三因素与其脆度关系的回归模型为:y=155.415+0.093X_1+1.231X_2+1.449X_3-8.922X_1~2+0.973X_2X_1-5.448X_2~2+4.47X_1X_3-3X_3X_2-3.525X_3~2,经回归分析,各因子对腌制榨菜脆度影响的大小依次为腌制时间、盐浓度、添加CaCl_2浓度,方程较好地拟合了腌制榨菜脆度与各因子之间的关系.利用SAS软件RSREG等过程,得到CaCl_2浓度为0.25%、盐浓度为6.07%、腌制时间11.5d时,榨菜脆度值达到最佳155.6g,经重复实验验证与模型方程拟合较好.  相似文献   

9.
目的 根据农药的光解反应原理,建立一套毒死蜱的光降解模型,探究其光降解速率规律,同时对其降解产物进行物质鉴定,为今后毒死蜱光降解相关研究提供理论依据。方法 利用液相色谱四极杆飞行时间质谱仪(An ultra performance liquid chromatography(UPLC) -high resolution time of flight mass spectrometer(TOFMS))对毒死蜱溶液在紫外灯和氙灯照射下的降解行为进行研究,并对其降解产物鉴定。结果 10 mg /L 毒死蜱在紫外灯照射下降解半衰期为5.35h ,在氙灯照射下降解半衰期为19.01h;毒死蜱的降解速率随温度升高不断加快,在到达40℃以后速率不再上升,同时毒死蜱光解速率随浓度的升高而降低。结论 毒死蜱的光降解符合一级动力学规律,光降解速率次序为紫外灯>氙灯,降解产物包括2-甲氧基-3,5,6-三氯吡啶、3,5,6-三氯吡啶-2-醇(TCP)、等。  相似文献   

10.
从酶解反应机理出发,应用数学推导的方法,以鹰嘴豆蛋白为原料,考察底物浓度、酶浓度对鹰嘴豆蛋白水解度(DH)的影响,将水解试验结果用推导的动力学模型方程进行拟合,建立酶解动力学模型。结果表明:鹰嘴豆蛋白水解度随着初始底物浓度(S0)的上升而下降,随着初始蛋白酶浓度(E0)的增加而上升,碱性蛋白酶水解鹰嘴豆蛋白的速率动力学模型:R=(39.522E0-0.080 4S0)exp[-0.148(DH)],水解度-水解时间的动力学模型:DH=6.76ln[1+(5.85E0/S0-0.011 9)t],酶解反应速率常数k2为39.522 min-1,酶失活常数为6.371 min-1,该动力学模型对试验结果有很好的拟合度,对实际酶解过程具有一定的指导作用。  相似文献   

11.
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.  相似文献   

12.
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.  相似文献   

13.
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.  相似文献   

14.
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.  相似文献   

15.
16.
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.  相似文献   

17.
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.  相似文献   

18.
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.  相似文献   

19.
Capillary electrophoresis (CE) and polarized light microscopy (PLM) were utilized in the detection of the adulteration of locust bean gum with guar gum. For CE analyses, standards of locust bean and guar gums were extracted with 30% CH3CN, removing the residual proteins from the gum matrix. A 8.75 mM NaH2PO4-20.6 mM Na2B4O7 buffer, pH 9, was used to separate these proteins and to identify marker proteins that were present in the guar gum. These markers did not co-migrate with components in the extracts of mechanically processed locust bean gum, and are used as indicators of adulteration. Using PLM with toluidine blue and iodine staining techniques, unadulterated locust bean gum samples were distinguished from mixed samples through the differential staining of components in locust bean versus guar and tara gums. These experiments in the use of CE and PLM provide orthogonal and complementary methods for the verification of 'true' positives and the elimination of 'false' positives.  相似文献   

20.
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