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瓶装天然矿泉水霉菌菌相分析 总被引:5,自引:0,他引:5
对瓶装天然矿泉水霉菌菌相进行了研究分析,335份样品霉菌检出率为65.4%,检出24属7166株霉菌中,产毒菌属占有较大比例,优势菌群为头孢霉属,曲霉属和枝孢霉属,它们是土壤,空气和植物体中的常见菌,也是通常造成瓶装矿泉水成品发生霉菌性沉淀的主要原因,结合菌相分析,讨论了优势菌属的自然分布及生态特性,导致污染的原因和预防对策。 相似文献
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Ketza River mine tailings deposited underwater and those exposed near the tailings impoundment contain approximately 4 wt % As. Column-leaching tests indicated the potential for high As releases from the tailings. The tailings are composed dominantly of iron oxyhydroxides, quartz, calcite, dolomite, muscovite, ferric arsenates, and calcium-iron arsenates. Arsenopyrite and pyrite are trace constituents. Chemical compositions of iron oxyhydroxide and arsenate minerals are highly variable. The XANES spectra indicate that arsenic occurs as As(V) in tailings, but air-drying prior to analysis may have oxidized lower-valent As. The EXAFS spectra indicate As-Fe distances of 3.35-3.36 A for the exposed tailings and 3.33-3.35 A for the saturated tailings with coordination numbers of 0.96-1.11 and 0.46-0.64, respectively. The As-Ca interatomic distances ranging from 4.15 to 4.18 A and the coordination numbers of 4.12-4.58 confirm the presence of calcium-iron arsenates in the tailings. These results suggest that ferric arsenates and inner-sphere corner sharing or bidentate-binuclear attachment of arsenate tetrahedra onto iron hydroxide octahedra are the dominant form of As in the tailings. EXAFS spectra indicate that the exposed tailings are richer in arsenate minerals whereas the saturated tailings are dominated by the iron oxyhydroxides, which could help explain the greater release of As from the exposed tailings during leaching tests. It is postulated that the dissolution of ferric arsenates during flow-through experiments caused the high As releases from both types of tailings. Arsenic tied to iron oxyhydroxides as adsorbed species are considered stable; however, iron oxyhydroxides having low Fe/As molar ratios may not be as stable. Continued As releases from the tailings are likely due to dissolution of both ferric and calcium-iron arsenates and desorption of As from high-As bearing iron oxyhydroxides during aging. 相似文献
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AD Beaton CL Cardwell RS Thomas VJ Sieben FE Legiret EM Waugh PJ Statham MC Mowlem H Morgan 《Environmental science & technology》2012,46(17):9548-9556
Microfluidic technology permits the miniaturization of chemical analytical methods that are traditionally undertaken using benchtop equipment in the laboratory environment. When applied to environmental monitoring, these "lab-on-chip" systems could allow high-performance chemical analysis methods to be performed in situ over distributed sensor networks with large numbers of measurement nodes. Here we present the first of a new generation of microfluidic chemical analysis systems with sufficient analytical performance and robustness for deployment in natural waters. The system detects nitrate and nitrite (up to 350 μM, 21.7 mg/L as NO(3)(-)) with a limit of detection (LOD) of 0.025 μM for nitrate (0.0016 mg/L as NO(3)(-)) and 0.02 μM for nitrite (0.00092 mg/L as NO(2)(-)). This performance is suitable for almost all natural waters (apart from the oligotrophic open ocean), and the device was deployed in an estuarine environment (Southampton Water) to monitor nitrate+nitrite concentrations in waters of varying salinity. The system was able to track changes in the nitrate-salinity relationship of estuarine waters due to increased river flow after a period of high rainfall. Laboratory characterization and deployment data are presented, demonstrating the ability of the system to acquire data with high temporal resolution. 相似文献
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ABSTRACT: The sensory evaluation of alkali‐ion water and bottled mineral water was performed by panelists and their preferences for the taste of alkali‐ion water was surveyed. Consequently, alkali‐ion water made from tap water was found to taste better than any bottled mineral water; however, the activated carbon filtration water, which was also made from tap water, was found to taste better than alkali‐ion water. Furthermore, smell, taste, feeling in the throat, aftertaste, and general impression of the mineral water, alkali‐ion waters, and activated carbon filtration water were evaluated using the 1‐pair comparison method. Consequently, alkali‐ion water and activated carbon filtration water were more highly rated than commercial bottled mineral water. 相似文献
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Kinetics of Water Uptake by Food Powders 总被引:1,自引:0,他引:1
The water uptake by several food materials that included animal and vegetable proteins and starch materials was studied. The amount q of water taken up by a sample powder during time t was described by the equation q = Qt/(B + t), where Q is the total water uptake of equilibrium and B is the time required to sorb Q/2. The rate of water uptake was proportional to the square of the amount of water that must still be absorbed to reach equilibrium. A specific rate constant for the process was calculated as (BQ)?1. 相似文献
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高健 《皮革制作与环保科技》2022,3(2):10-12
本文首先从离子交换树脂结构和分类、离子交换原理、离子交换树脂应用范围、离子交换树脂回收再利用等方面阐述离子交换树脂水处理工艺,然后从仪器和试剂、离子交换树脂复苏类型、复苏原理及复苏结果等方面阐述离子交换树脂再生复苏工艺,再从仪器和试剂、复合材料制备与测定、吸附量测定、有机染料测定、测定结果分析等方面阐述离子交换树脂活性... 相似文献
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用于水处理的天然高分子及其衍生物主要有纤维素、淀粉、木质素、壳聚糖,本文简要概述了四类天然高分子水处理剂在染料废水处理中的应用研究现状。 相似文献
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用于水处理的天然高分子及其衍生物主要有纤维素、淀粉、木质素、壳聚糖,本文简要概述了四类天然高分子水处理剂在染料废水处理中的应用研究现状. 相似文献
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以木瓜皮为原料,分别研究了离子交换树脂法和酸提法提取果胶的动力学模型,获得速率常数和表观活化能,经过有效性检验和模型预测能力验证,模型均能很好预测果胶提取的动力学过程。离子交换法提取果胶的活化能Ea为23.68kJ/mol,与酸提法获得的37.88kJ/mol相比明显降低,离子交换树脂法提取木瓜皮中果胶明显优于酸提法。在树脂用量为5%、料液比为1∶30(g/mL)、浸提液pH值为1.5条件下,离子交换树脂法提取木瓜皮中果胶的最佳浸提温度为80℃,动力学分析优化最佳结果,得Tmax=117.3min,果胶得率达17.47%,与试验结果相吻合。 相似文献
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Kinetics of liquid water sorption by soybean (Glycine max) and pigeonpea (Cajanus cajan) seeds was studied at several temperatures. The data could be accurately correlated in terms of an empirical model involving a single rate constant. The temperature dependence of the rate constant followed Arrhenius relation. Swelling of grains due to water sorption was slightly less than the volume of water imbibed. This loss related to the energy of activation of the water sorption process. 相似文献
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本文在对低温灭菌技术系统研究的基础上,针对目前国内天然饮用矿泉水生产中灭菌工艺所存在的问题,结合笔者多年矿泉水生产的工艺实践,提出了实用有效的矿泉水生产新工艺,实践证明,按此新工艺,配合严格的生产管理,可以确保生产出绝对无菌的饮用矿泉水。 相似文献
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The kinetics of the decomposition and isomerization of glucose and fructose in pure water and water containing sodium chloride (1–20 % w/w) under subcritical conditions at 180–220 °C was investigated. The addition of sodium chloride in subcritical water accelerated the decrease of glucose, and the rate was expressed by the Weibull equation. Although the isomerization of glucose to fructose was observed in parallel with decomposition, the yield of fructose was lower at higher sodium chloride concentrations. Mannose was also formed from glucose with very low yield. It was seen that fructose decomposed much faster than glucose, in pure and salty subcritical water. The decomposition of fructose obeyed first-order kinetics in the initial stages of the reaction and could be expressed by the autocatalytic model in the later stages. The formation of glucose and mannose from fructose was not observed under any of the conditions investigated. 相似文献