石墨炉原子吸收法测定铅的研究

铅作为一种具有很强毒性的重金属元素,所以对铅的测定是十分必要的,本文重点介绍对水中的铅含量的测定,本文针对上述问题主要介绍了石墨炉原子吸收法对铅的测定。首先介绍了石墨炉原子法,然后分析了实验的仪器以及方法,最后阐述了实验的结果。     

石墨炉原子吸收光谱法测定六堡茶中的铅和镉

本文用石墨炉原子吸收光谱法测定六堡茶中的铅和镉含量,优化了样品前处理条件和光谱仪的各项技术参数。结果表明:应用微波消解-石墨炉原子吸收法测定六堡茶样品中的铅和镉时,铅的加标回收率在93.1%~99.2%之间,镉的加标回收率在92.3~97.3%之间,相对标准偏差均小于5%。方法准确、方便,可满足检测六堡茶中的铅和镉要求。     

石墨炉原子吸收光谱法测定金银花中铅镉的研究

采用石墨炉原子吸收法(GFAAS)检测中药材金银花中微量重金属铅、镉的含量.考察了基体改进剂、灰化/原子化温度和常见共存离子等因素对测定的影响,建立以NH4H2PO4为基体改进剂石墨炉原子吸收光谱法测定金银花中微量铅、镉的方法.条件优化后的方法简便快速,重现性好,灵敏度、准确度高,铅的检出限为0.268 μg/L,镉的检出限为0.013 μg/L,回收率85%～110%.     

平台石墨炉原子吸收光谱法测定土壤保水剂中铅、镉

提出在不用任何基体改进剂的条件下,用平台石墨炉原子吸收法测定土壤保水剂中铅、镉的方法。经加标准回收实验表明铅平均回收率101%,镉平均回收率98.4%。本方法切实可行。     

汽油含铅量测定方法的研究——石墨炉原子吸收法

国家标准ＧＢ Ｔ 80 2 0 - 87《汽油铅含量测定 (原子吸收光谱法 )》 ,是将汽油试样用甲基异丁基甲酮稀释 ,加入磺和季铵盐与烷基铅化合物反应使之稳定。以氯化铅为标样 ,用火焰原子吸收光谱法测定试样中铅含量。采用上述处理方法 ,虽然稳定性高 ,重现性好 ,但灵敏度低 ,成本高 ,毒性大 ,会造成环境污染 ,还特别繁琐。本方法改善了以上方法的弊端。一、测定方法1 方法概要石墨炉原子吸收法测定铅含量是较灵敏的方法 ,可直接定性样品为有无铅汽油。有铅汽油 ,是以氯化铅为标样 ,用石墨炉原子吸收光谱法 ,在波长 2 83 3纳米处 ,测定试样中铅含…     

石墨炉原子吸收光谱法测定水中钒、钴、钼

本文主要介绍石墨炉原子吸收法测定水中钒、钴、钼的方法。本方法采用美国PE公司配有自动进样器的5100ZL塞曼光谱石墨炉原子吸收分光光度仪。在测定浓度范围内,V、Co、Mo的峰面积和质量浓度呈线性关系,相关系数均大于0.99,回收率在91%-104%之间,相对标准偏差在3.4%-7.0%之间。     

水源水及生活饮用水中铝的新法测定

叙述了采用硝酸镁作为基本改进剂,成功地用石墨炉原子吸收分光光度法直接测定饮用水及水源水中铝,为饮用水及水源水中痕量铝的测定提供了一种灵敏、准确、快捷的方法。     

水源水及生活饮用水中铝的新法测定

叙述了采用硝酸镁作为基本改进剂,成功地用石墨炉原子吸收分光光度法直接测定饮用水及水源水中铝,为饮用水及水源水中痕量铝的测定提供了一种灵敏、准确、快捷的方法。     

石墨炉原子吸收在土壤微量元素测试中的应用

本文阐述了用石墨炉原子吸收分光光度法测定土壤中铅、镉,改进了样品的处理方法,分析过程中的灯电流、灰化温度、原子化温度等因素对灵敏度的影响,确定了石墨炉的最佳条件,取得了可靠结果。     

ICP-MS法与石墨炉原子吸收法测定矿山废水中铊含量的比较

通过对比测定矿山废水中铊含量的ICP-MS法与石墨炉原子吸收法,为选矿废水中铊的测定提供可靠的方法,在确定ICP-MS法与石墨炉原子吸收法工作曲线的基础上,对矿山选矿废水中铊进行测定并确定最佳测定方法,检测结果中石墨炉原子吸收法的测定结果 1.57μg/L,加标回收率为94%~108%;ICP-MS法的测定结果为1.92μg/L,加标回收率为86%~98%;结果表明,对于复杂水体中铊的测定,石墨炉原子吸收法具有较高的抗干扰能力、重现性、准确度和精密度,即矿山选矿废水中铊的含量检测石墨炉原子吸收法优于ICP-MS方法。     

集中空调水系统节能优化策略及仿真研究

公共建筑集中空调水系统能耗占建筑总能耗比例较高,各设备的合理启停及控制参数的优化设置在系统节能中起到了关键作用。本文在满足末端冷负荷的前提下,以系统总能耗最小为目标,提出了冷水机组、水泵启停优化策略及控制参数全局优化方法。以冷冻水供水温度、冷却水流量作为独立优化控制参数建立集中空调水系统能耗模型。以某建筑为例,利用DeST软件模拟了建筑空调负荷变化,对所提出的优化方法进行了验证,结果表明：在负荷率5%~100%变化范围内,冷水机组平均COP提高了10.9%,平均节省能耗8.9%,水泵平均节省能耗18.6%;在夏季典型日,集中空调水系统平均节省能耗20.4%。     

Destruction of metal-resin adhesion due to water penetrating through the resin

Polymethyl methacrylate (PMMA) film bonded by 4-META dental adhesive resin to mild steel was used as a specimen to study the mechanism of water permeation into the adhesive interface. Degradation of the adhesion interface after immersion in water was investigated by measurement of peeling area after imposing thermal stress using liquid nitrogen. The amount of water penetrated at the interface was calculated from the solution to Fick's second equation. The degradation at the interface is discussed with respect to the water content. Water enters the interface by diffusion through the resin rather than by passage along the interface. The interface is broken by water when the water content at the interface reaches 48% of the equilibrium water concentration of PMMA. Observation through the PMMA film shows no change in the mild steel surface at 48% equilibrium water concentration; at 95% water content many small white spots appear on the surface. The surface colour gradually changes to black due to the formation of corrosion products.     

用混凝-超滤法处理低温低浊水

考察了采用混凝-超滤法处理低温低浊时期松花江水的中试试验效果,并与水厂常规处理水质进行了比较.试验结果表明:混凝-超滤法出水浊度恒低于0.3 NTU;投加20 mg/L聚合氯化铝,超滤膜对CODMn去除率达到50%~58%,膜出水色度为6~8度;此外,投加混凝剂可以使膜渗透性能得以改善.因此混凝-超滤法可以作为低温低浊水处理的有效方法.     

Measurement of water concentration in oil/water dispersions with a circular single-electrode capacitance probe

A new measurement method, called SeCaP, has been used to measure the water content in oil/water dispersions. The measuring principle is based on an oscillator working at approximately 20 MHz. The dielectric property of the medium adjacent to one single free electrode affects the frequency of the oscillator. The dispersion was produced by means of recirculation through a colloid mill. The concentration of water was first increased from zero to approximately 70%. Then, it was reduced from 100% to approximately 45%. The probe signal correlates very well with the water concentration in the dispersion, especially for the oil continuous case with a correlation coefficient of 0.9998. The instrument represents a new approach of measuring the water content in process streams in, for example, oil production facilities, where it is important to have reliable information on the amount of water that is flowing in the production tubing.     

煅烧高岭土/聚丙烯酸钠高吸水性复合材料的研制

以煅烧高岭土和丙烯酸为原料,采用溶液聚合法合成得到煅烧高岭土/聚丙烯酸钠高吸水性复合材料,讨论了丙烯酰胺用量、引发剂用量、交联剂用量、中和度及煅烧高岭土添加量对其吸水性能的影响,并用扫描电镜表征其表面形貌。结果表明:丙烯酰胺用量15%,引发剂用量0.25%,交联剂用量0.08%,中和度80%,煅烧高岭土添加量50%,复合材料吸蒸馏水达890g/g,吸生理盐水达70g/g,同时煅烧高岭土在材料中分散均匀。     

标准曲线配制对电感耦合等离子体质谱法测定饮用水中重金属元素的影响研究

采用容量法和称量法分别配制了ICP-MS法的标准工作曲线,并测定了生活饮用水中铅和镍的含量,对两种方法的不确定度进行评定。对不确定度的来源进行了全面分析,评定了各不确定度分量并合成了扩展不确定度。按照建立的不确定度评定方法得到容量法相对不确定度为urel(Pb)=2.8%,urel(Ni)=2.4%;称量法相对不确定度为urel(Pb)=1.6%,urel(Ni)=1.0%。所建立的不确定度评定程序适用于ICP-MS法测定饮用水中重金属元素含量的不确定度评定。通过比较两种方法的不确定度及相关分量贡献,从标准溶液配制的角度提出完善ICP-MS分析方法的途径,为加强饮用水中重金属检测、确保水质安全提供科学依据。     

Effects of ethanol to water ratio in feed solution on the crystallinity of spray-dried lactose

In the present study, the effects of ethanol to water ratio in feed solution on the physical properties of spray-dried alpha-lactose monohydrate were evaluated. Crystallinity of the spray-dried lactose was determined by isothermal microcalorimetry (IMC) and by differential scanning calorimetry (DSC). Water content of the spray-dried lactose was determined by thermogravimetric analysis and the surface area was evaluated by Brunauer, Emmett, and Teller (BET) method. The crystallinity of spray-dried lactose varied from 0% to 100%, depending on the ratio of ethanol to water in the feed solution. Lactose spray dried from pure ethanol was 100% crystalline and contained hydrate water. Lactose spray dried from pure water was 100% amorphous. The feed solution substantially affected the ratio of surface water to hydrate water, as the content of surface water increased and hydrate water decreased, while the crystallinity of spray-dried lactose decreased. Surface area of the spray-dried lactose increased as a function of amorphous content.     

Water reuse for irrigated agriculture in Jordan: challenges of soil sustainability and the role of management strategies

Reclaimed water provides an important contribution to the water balance in water-scarce Jordan, but the quality of this water presents both benefits and challenges. Careful management of reclaimed water is required to maximize the nutrient benefits while minimizing the salinity risks. This work uses a multi-disciplinary research approach to show that soil response to irrigation with reclaimed water is a function of the management strategies adopted on the farm by the water user. The adoption of management methods to maintain soil productivity can be seen to be a result of farmers' awareness to potentially plant-toxic ions in the irrigation water (70% of Jordan Valley farmers identified salinization as a hazard from irrigation with reclaimed water). However, the work also suggests that farmers' management capacity is affected by the institutional management of water. About a third (35%) of farmers in the Jordan Valley claimed that their ability to manage salinization was limited by water shortages. Organizational interviews revealed that institutional awareness of soil management challenges was quite high (34% of interviewees described salinization as a risk from water reuse), but strategies to address this challenge at the institutional level require greater development.     

含内热源大型不规则腔体高精度水循环控温方法研究

将用于测量辐射信号的球形实验装置置于直径为43 m、高为44 m的圆柱形实验厅内,球体外侧安装信号接收光电倍增管球壳层(PMTs),其运行会产生200 kW的高热。为维持球体表面水体温度稳定在(21±1)℃高精度恒温环境下,本文采用计算流体力学(CFD)技术,将球体浸没在循环水中并配合上下两段式布水方式进行精准控温。结果表明:上下两段布水方式可实现大型水体空间局部精确控温。考虑到不规则腔体流道限制,设计调整水循环布水角度,上布水口低温面积最大增幅达20%;提出增大上下布水器水量比以控制水体垂直温差,上下布水器水量之比为2.5∶1时控温能力最强,且降温最有效的区域是多孔介质PMT层与外水层;为得到不同热量下温度分布的统一规律,增大热源发热量,内水层上下布水口低温面积变化幅度有差异,上布水口低温面积缩小41%,下布水口缩小62%,但下布水口低温面积始终大于上布水口。     

Effects of Ethanol to Water Ratio in Feed Solution on the Crystallinity of Spray-Dried Lactose

ABSTRACT

In the present study, the effects of ethanol to water ratio in feed solution on the physical properties of spray-dried α-lactose monohydrate were evaluated. Crystallinity of the spray-dried lactose was determined by isothermal microcalorimetry (IMC) and by differential scanning calorimetry (DSC). Water content of the spray-dried lactose was determined by thermogravimetric analysis and the surface area was evaluated by Brunauer, Emmett, and Teller (BET) method. The crystallinity of spray-dried lactose varied from 0% to 100%, depending on the ratio of ethanol to water in the feed solution. Lactose spray dried from pure ethanol was 100% crystalline and contained hydrate water. Lactose spray dried from pure water was 100% amorphous. The feed solution substantially affected the ratio of surface water to hydrate water, as the content of surface water increased and hydrate water decreased, while the crystallinity of spray-dried lactose decreased. Surface area of the spray-dried lactose increased as a function of amorphous content.