沸水萃取-紫外可见分光光度法测定金属镀层中六价铬含量的不确定度评定

建立沸水萃取-紫外可见分光光度法测定金属镀层中六价铬含量的不确定度评定方法。建立有效的数学模型,对影响测量过程的不确定度来源进行分析和评定。结果表明:当取置信概率为95%,包含因子K=2,该方法测定金属镀层中六价铬含量的扩展不确定度为U=0.0018μg/cm2,测量结果表示为0.0365±0.0018μg/cm2。样品表面积计算和测量重复性是影响该方法不确定度的主要因素。     

涡流涂镀层测厚仪开发与应用现状

在涂装施工和质量检验过程中，涂镀层厚度是一项重要的控制指标，涂镀层厚度的无损检测，迄今已采用了磁性法、涡流法、X射线光谱法、β射线反向散射法等多种检测方法但就上列各种方法应用的广度和深度来说，即磁性法和涡流法的应用更为普遍，其技术进展迅速。专家刘振作先生在本中阐述了涡流涂镀层测厚技术的基本原理与涡流测厚方法标准概况，重点介绍了涡流涂镀层测厚仪国内外典型产品的功能特征和应用现状。     

电镀黑铬太阳能选择性吸收器的热稳定性及耐蚀性(英文)

黑铬作为最具吸引力的太阳能选择性吸收材料之一,已得到实验证实并用于太阳能收集器.本文评价了黑铬太阳能选择性吸收器的热稳定性和耐蚀性.采用三价铬镀液,在铜基体上电沉积了黑铬镀层.另外,采用六价铬镀液制备了六价铬黑铬镀层作为对比.根据ISO/CD 12592.2标准,评价了热处理循环前后镀层的太阳能吸收,发射性能和热稳定性.分别采用扫描电镜和X射线衍射,表征了镀层的微观结构和化学组成.采用分光光度法测量了镀层的吸收率和发射率.结果表明,镀液中的配位剂对镀层的热稳定性有显著影响.与六价铬镀层相比,三价铬镀层具有更优异的热稳定性和耐蚀性.     

化工行业环境检测中萃取法的应用

化工行业容易产生工业废水,化工厂产生的气体不合理排放会导致大气污染,威胁人类的健康,因此对化工行业环境检测尤其重要。论述了萃取法在化工行业环境检测中的应用,介绍了固相萃取法、超临界CO_2萃取法、快速溶剂萃取法、液相微萃取法检测技术,分析了影响萃取效率的因素,探讨了萃取法环境检测存在的问题和改进措施。     

有机溶剂结合碱液萃取塑料中六价铬的测定研究

为了解决塑料中六价铬测定时萃取率低的问题,研究了有机溶剂结合碱液萃取测定塑料中六价铬的萃取率。实验结果表明:有机萃取溶剂N-甲基吡咯烷酮结合碱液,能完全溶解ABS、PC、PVC三种塑料,在超声萃取条件下,六价铬的萃取率能提高到80%以上,可满足测试质控要求;并且该方法对于样品的粒径1 mm×1 mm即可满足要求,与现行标准要求制样颗粒250μm相比,样品制备更为简单。     

烟用接装纸中六价铬的测定

建立了采用IC与ICP-MS联用测定烟用接装纸中六价铬的方法。采用磷酸氢二钾溶液萃取烟用接装纸中六价铬,然后用IC-ICP-MS分析。六价铬加标回收率83.7%~102.2%,RSD为7.2%,线性相关系数0.9998,检出限达到0.05mg/kg。本方法检出限低、准确度高、精密度好、简便快捷,适用于烟用接装纸中六价铬含量的检测。     

萃取分光光度法测定痕量六价铬的研究

pH为2.0的氯化钾-氯化氢缓冲溶液中,在常温下,六价铬与二苯偶氮羰酰肼(DPCO)反应生成稳定的络合物(六价铬与DPCO物质的量比为1∶2),在硫酸铵的作用下,该络合物中的六价铬可被聚乙二醇(PEG)相全部萃取,据此建立了测定痕量六价铬的新方法--萃取光度法.结果表明,在PEG相中络合物的最大吸收波长为548 nm,六价铬质量浓度在0～2.5 mg/L内符合比尔定律,方法的表观摩尔吸光系数为3.12×104 L/(mol·cm),多数常见离子不干扰测定.方法用于硝酸铬及氯化铬中痕量六价铬的测定,得到满意的结果.     

压力反馈式辊涂机涂层厚度调整技术

摘自：www．china—painting．net 为了改善钢板的耐侵蚀性，提高其对周围环境的抗侵蚀能力，利用表面工程技术对钢板的表面进行加工处理是目前本领域采取的一种有效的方法。按照表面工程技术形成表面涂镀膜层的技术可分为：表面转化技术、薄膜技术和涂镀层技术。     

三价铬电镀硬铬及镀层性能的研究

在甲酸盐体系中制备厚度为50μm硬铬镀层,并对镀层的沉积速率、硬度、粗糙度及耐磨耐蚀性能进行了考察.结果表明:在电镀初期镀层的厚度和沉积时间成正比,而且镀层外观质量良好,当电镀50min后镀层质量下降,镀层粗糙度随着镀层厚度的增加而增大;未经热处理,镀层的硬度及耐磨性能和六价铬镀层相差不大,经过600℃热处理后镀层的硬度增大,而耐磨性能反而减小;三价铬镀层比六价铬镀层更不容易被腐蚀,但一旦被腐蚀,前者的被腐蚀速率比后者的要大.     

六价铬的还原分离方法

从酸性或中性水溶液中分离六价铬,已知有离子交换树脂法、溶剂萃取法、还原分离法等。但是,从碱性水溶液中分离六价铬尚无有效的方法。     

三价铬钝化件六价铬检出阳性问题及其评价

简述了三价铬钝化层中检出六价铬的原因,评述了几种RoHS认证通常采用的六价铬检测标准,包括点滴法和水煮法.讨论了RoHS认证中三价铬钝化层中六价铬检测的有关问题.提出了一些避免三价铬钝化层中检出六价铬的建议,如:采用沸水提取法而不是碱液提取法,以降低六价铬检出几率;控制检测条件;调整钝化液配方和钝化工艺条件.     

Comparison of single and multilayer coatings based on ormosil and conversion layers for aluminum alloy corrosion inhibition

Corrosion resistance behavior of single and multilayer coatings based on ormosil, trivalent chromium conversion coating (tccc) and hexavalent chromium conversion coatings (hccc) on the surface of 2024-T3 aluminum alloy (AA) was investigated using potentiodynamic polarization curves and accelerated salt spray testing. The magnitude of the corrosion resistance for single layer coatings increased tccc < ormosil < hccc. Multilayer ormosil/ormosil coatings are subject to phase separation, leading to poor performance in the electrochemical and accelerated salt spray testing. The presence of either hccc or tccc in the multilayer film was found to augment the inherent corrosion resistance of the ormosil barrier film. Multilayer coatings composed of either tccc/ormosil or hccc/ormosil were found to exhibit R_corr values in the range 158–177 kΘcm². This implies that the environmentally-benign and nontoxic trivalent chromium conversion coating used in combination with an ormosil film may be a potential alternative for hexavalent chromium conversion coatings. Environmental Institute, 003, Life Science East, Stillwater, OK 74078.     

Solvent extraction of hexavalent chromium with tetrabutyl ammonium bromide from aqueous solution

The extraction of hexavalent chromium (Cr) from aqueous solutions by tetrabutyl ammonium bromide (TBAB) salt in dichloromethane was investigated. The results indicated that the maximum extraction efficiency of Cr(VI) was at pH 1±0.1. The strippant 0.1 M sodium hydroxide, completely stripped Cr(VI) from the loaded solvent. The stripped solvent can be reused for extracting Cr(VI). After five extraction cycles, the dichloromethane showed no significant loss in volume and retains the same extracting ability. The solvent extraction method was applied for the removal and recovery of Cr(VI) from real chromeplating wastewater and found to be satisfactory.     

锡-锌合金镀层的无铬和低铬钝化

目前，在锡－锌合金上进行铬酸盐钝化已得到广泛应用，但六价铬化合物具有很高的毒性，又是第一类致癌物质，因而现在迫切需要开发对锡－锌合金的代铬钝化工艺。主要研究了Sn-Zn合金镀层的无铬和低铬钝化处理，并改善了合金镀层的耐蚀性。     

Tribological and electrochemical behavior of thick Cr-C alloy coatings electrodeposited in trivalent chromium bath as an alternative to conventional Cr coatings

Alternative process to hexavalent chromium plating, substitute materials and new designs are urgently needed owing to the requirement of “clean” manufacture. This comparative study was conducted to systematically investigate the tribological and electrochemical behavior of the Cr-C alloy coatings electrodeposited from a trivalent chromium bath and the hard Cr coatings electrodeposited from conventional hexavalent chromium bath, using reciprocating ball-on-disc tribometer and electrochemical analyzer. The electroplated Cr-C alloy coatings with thickness of 50 μm and acceptable quality that can be used for wear resistance as well as corrosion resistance purposes were produced successfully. The results show that the as-deposited Cr-C alloy coatings exhibited crack-free surface and amorphous/microcrystalline structure. The following heat treatment resulted in the cracked surface and the increase in hardness for the electroplated Cr-C alloy coatings. In contrast, the conventional Cr coatings exhibited cracked surface and their hardness decreased with the increase in annealing temperature. The electroplated Cr-C alloy coatings after heat treatment at 200 °C for 1 h exhibited better wear resistance than the conventional Cr coatings. In regard to the electrochemical behavior, the as-deposited Cr-C alloy coatings exhibited better corrosion resistance than the conventional Cr coatings. Therefore, the electroplated Cr-C alloy coatings are environmentally acceptable candidates to replace the conventional Cr coatings.     

代硬铬镍基合金镀层的研究进展

为了实现清洁生产,改善生态环境,针对电镀行业中严重污染环境的六价硬铬电镀工艺,广大电镀工作者致力于代硬铬工艺的开发,其中电沉积合金镀层技术将是未来比较理想的代铬工艺.文中综述了近几年来国内外代铬镀层的最新研究进展.重点探讨了几类代铬合金镀层的工艺及耐磨、耐蚀等性能,并指出了目前存在的问题及今后的研究方向.     

Separation of Cr(VI) from Water by Green Reduction Reaction and Adsorptive Removal on Gelatin-Grafted-Yeast Biosorbent

A green chemical method was explored and described for separation and extraction of the toxic hexavalent chromium from aqueous solutions and real water samples. A green reduction reaction for the transformation of toxic hexavalent chromium into the nontoxic trivalent chromium ion was performed by using hydrogen peroxide. The produced Cr(III) was then extracted by biosorption on the surface of a novel and eco-friendly gelatin-grafted-baker’s yeast (Gelatin-Yeast) biosorbent. The investigated biosorbent was characterized by high capacity value of the reduced trivalent chromium species in pH 6.0 as 1.120 mmol g^?1. The biosorption processes were examined, monitored, and optimized in different experimental and controlling parameters. The potential applications of Gelatin-Yeast for separation and removal of Cr(VI) from real industrial and sea water samples were also studied.     

电刷镀n-Al2O3/Ni-Co镀层组织与性能的研究

针对镀硬铬中污染环境和危害人体健康的六价铬,为实现清洁生产,改善生态环境,开展了电刷镀n-Al2O3/Ni-Co纳米复合镀层的研究。测试了纳米微粒的质量浓度对n-Al2O3/Ni-Co纳米复合镀层表面形貌和硬度的影响;并对比了n-Al2O3/Ni-Co纳米复合镀层和硬铬镀层的硬度、耐磨性能和抗高温氧化性能;利用XRD测定了n-Al2O3/Ni-Co纳米复合镀层的结构和晶粒尺寸。研究结果表明:纳米微粒的质量浓度为20 g/L时,镀层具有最优的表面形貌和硬度;室温条件下,n-Al2O3/Ni-Co纳米复合镀层的硬度和耐磨性能都明显优于硬铬镀层的;高温条件下,n-Al2O3/Ni-Co纳米复合镀层的抗高温氧化性能与硬铬镀层的相当。     

An economic and sensitive method for extracting chromium speciation in airborne inhalable dust,using a green sample treatment coupled with electrothermal atomic absorption

ABSTRACT

A new approach of cloud point extraction CPE procedure is optimized for hexavalent chromium determination in airborne dusts. Triton X-114 is used as a surfactant and 1-(2-pyridylazo)-2-naphthol as a specific complexing agent for the trivalent chromium’s removal from the aqueous phase to isolate hexavalent chromium compounds. The parameters influencing the extraction protocol (pH, surfactant concentration, and temperature are optimized. The obtained detection and quantification limits are 0.1 and 0.4 μg/L, respectively. The linearity is verified, with a regression coefficient close to 0.999 and the extraction recovery exceeds 99%. The method was successfully applied to analyze airborne samples collected from workplaces.     

第四讲——铅

介绍了一种用于简单判定废水中六价格含量是否达到GB21900-2008<电镀污染物排放标准>限值(0.2 mg/L)的方法.采用150℃干燥后的分析纯重铬酸钾制备不同六价铬质量浓度的标准溶液.以硫酸溶液酸化后加入二苯碳酰二肼指示剂,用目视比色法对经化学法处理的废水中六价铬的含量进行判定.该方法操作简单,适用于无仪器分析...