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451.
452.
研究了用1-(2,6-二氯-4-硝基苯)-3-(4-硝基苯)-三氮烯(DCNPNPT)分光光度法快速直接测定锌的方法。在表面活性剂TritonX-15的存在下,pH=9.5~10.5的Na2B4O7-NaOH介质中,DCNPNPT与锌( )可生成1∶3的橙黄色络合物。最大吸收波长为445nm,同时在535nm配合物有一最大负吸收,建立以535nm为参比波长,445nm为测定波长的双峰双波长法进行测定,表观摩尔吸光系数可达1.12×105L/(mol·cm)。用拟定的方法测定矿山废水中的锌,与原子吸收法测定的结果十分吻合,结果令人满意。 相似文献
453.
454.
系统分析了EDTA容量法测定硫酸根离子的误差产生环节,并对各个环节提出了相应的误差控制办法。文中着重分析了由移液过程和滴定过程所产生的误差,最后指出,作为测定硫酸根离子的方法标准,EDTA容量法无法保证应有的精度,应由离子色谱法取代之 相似文献
455.
Urea hydrolysis and recovery of nitrogen and phosphorous as MAP
from stale human urine 总被引:1,自引:0,他引:1
LIU Zhigang ZHAO Qingliang WANG Kun LEE Duujong QIU Wei WANG Jianfang 《环境科学学报(英文版)》2008,20(8):1018-1024
Laboratory-scale tests for magnesium ammonium phosphate(MAP)precipitation following urea hydrolysis of human urine were conducted using orthogonal experiment design.The effects of initial pH,temperature and the volumetric ratios of stale urine to fresh urine,on urea hydrolysis in urine were studied to determine the final hydrolysis time to recover most nitrogen from separated human urine by MAP.With a volumetric ratio of stale to fresh urine>10% and at temperature≥20℃,urea hydrolysis could be completed i... 相似文献
456.
Adsorption behavior of Azo Dye C. I. Acid Red 14 in aqueous solution
on surface soils 总被引:2,自引:1,他引:1
QU Baocheng ZHOU Jiti XIANG Xuemin ZHENG Chunli ZHAO Hongxi ZHOU Xiaobai 《环境科学学报(英文版)》2008,20(6):704-709
Azo dyes have received considerable attention because of their association with various human health problems. The aim of the investigation is to determine the adsorption behavior ofazo dyes in aqueous solution on DG06, GSE17200, and GSE17201 soils using C. I. Acid Red 14 (AR14) as example. The experimental results indicate that the Freundlich model expresses the adsorption isotherm better than the Langmuir model and the pseudo-second-order model achieves adsorption of AR14 on the three soils well. Based on the pseudo-second-order model, the adsorption thermodynamic of AR14 on DG06 soil have been studied and the thermodynamics parameter of AGO is determined and AGO value shows the adsorption process of AR14 on DG06 is mainly physical in nature. Furthermore, the effects of temperature, pH and salinity (NaC1) on adsorption have been investigated. The decrease in pH or the increase in salinity enhances the adsorption of AR14 by DG06, GSE17200, and GSE17201. 相似文献
457.
围绕如何测度并改善天然气安全这一核心议题,引入并修正了APERC能源安全"4A"分析框架,运用层次分析法与德尔斐法,构建了天然气安全评价指标体系,对主要天然气净进口国和净出口国的天然气安全状况进行了量化评估。评估发现:(1)天然气安全四维度(资源可利用性、经济可承受性、贸易可获得性与环境可接受性)的不可或缺性意味着综合表现优异的国家安全水平更高;(2)8个二级指标中,可采储量、个体可承受性等指标的权重更大;(3)天然气净出口国在资源可利用性、经济可承受性和贸易可获得性方面有优势,整体表现优于进口国。就中国而言,可从加快资源开发、完善市场机制、扩大进口渠道和提高资源利用效率四个方面提高天然气安全水平。 相似文献
458.
为了研究环境激素4-t-OP(对叔辛基酚)的生物降解,从扬州市汤汪生活污水处理厂二沉池污泥中筛选得到1株能以4-t-OP为唯一碳源进行生长的降解菌株,标示为TW30,16S rRNA测试其为不动杆菌属(Acinetobacter sp.),通过摇瓶试验测试其降解活性.结果表明:在40℃、初始pH为6.0、ρ(4-t-OP)为5 mg/L的无机盐培养基中,5 d后降解率可达99.03%;降解过程满足一级反应模型,降解速率常数(k)为0.875 d-1,半衰期(t1/2)为0.8 d.这说明TW30是一株高效的4-t-OP降解菌.此外,培养温度的升高和额外Ca2+、Mn2+的加入可以提高TW30降解4-t-OP的效率,而在5~25 mg/L范围内提高初始ρ(4-t-OP)以及额外加入磷酸盐、NH4+、Mg2+、Fe2+、Na+、Zn2+、Cu2+等无机盐和葡萄糖、CH3COO-等碳源则会降低降解率. 相似文献
459.
SO_4~(2-) and NO_3~- are important chemical components of fine particulate matter(PM_(2.5)),especially during haze periods.This study selected two haze episodes in Beijing,China with similar meteorological conditions.A monitoring-modeling approach was developed to estimate the secondary conversion ratios of sulfur and nitrogen based on monitored and simulated concentrations.Measurements showed that in Episode 1(24th–25th October,2014),the concentrations(proportions)of SO_4~(2-) and NO_3~- reached 35.1μg/m~3(14.9%) and 55.0μg/m~3(22.9%),while they reached 14.4μg/m~3(9.3%) and 59.1μg/m~3(38.1%)in Episode 2(26th–27th October,2017).A modeling system was applied to apportion Beijing's SO_4~(2-) and NO_3~- in primary and secondary SO_4~(2-)/NO_3~- emitted from local and regional sources.Thus,secondary conversion contributions considering the local and regional level were defined.The former primarily focused on Beijing atmospheric oxidation ability and the latter mainly considered the existence form of Beijing SO_4~(2-)/NO_3~- under the regional transport impacts.Finally,secondary oxidation ratios were estimated through combining secondary conversion contribution coefficients for simulated and monitored concentrations.At regional level,sulfur oxidation ratios in polluted(clean)days during two sampling periods were0.57–0.72(0.07–0.52)and 0.74–0.80(0.08–0.61),nitrogen oxidation ratios were 0.20–0.29(0.05–0.15)and 0.34–0.38(0.02–0.29),indicating that atmospheric oxidation was enhanced when considering regional transport through 2014–2017.At the local level,sulfur oxidation ratios were 0.66–0.71(0.04–0.48)in haze(clean)days,while nitrogen oxidation ratios were0.16–0.29(0.02–0.16).The atmospheric oxidation ability markedly increased in PM_(2.5)pollution days,but changed only slightly between the two periods. 相似文献
460.
Pure and Mg-doped self-assembled ZnO nano-particles for the enhanced photocatalytic degradation of 4-chlorophenol 总被引:1,自引:0,他引:1
N. Clament Sagaya Selvam S. Narayanan L. John Kennedy J. Judith Vijaya 《环境科学学报(英文版)》2013,25(10):2157-2167
A novel self-assembled pure and Mg doped ZnO nano-particles (NPs) were successfully synthesized by a simple low temperature co-precipitation method. The prepared photocatalysts were characterized by X-ray diffraction, high resolution scanning electron mi- croscopy, high resolution transmission electron microscopy, diffuse reflectance spectroscopy and photoluminescence (PL) spectroscopy. The results indicated that the prepared photocatalysts showed high crystallinity with a uniform size distribution of the NPs. The degradation of cholorphenols is highly mandatory in today's scenario as they are affecting the environment adversely. Thus, the photocatalytic degradation of 4-chlorophenol (4-CP), a potent endocrine disrupting chemical in aqueous medium was investigated by both pure and Mg-doped ZnO NPs under UV-light irradiation in the present study. The influence of the Mg content on the structure, morphology, PL character and photocatalytic activity of ZnO NPs were investigated systematically. Furthermore,the effect of different parameters such as 4-CP concentration, photocatalyst amount, pH and UV-light wavelength on the resulting photocatalytic activity was investigated. 相似文献