Search | Engineering

订阅投稿

首页工程期刊工程焦点工程成就工程前沿关于我们 English

资源类型

期刊论文 3

年份

2020 1

2009 1

2003 1

关键词

催化裂化 1

异构烷烃 1

汽油 1

烯烃 1

芳烃 1

展开︾

检索范围：

排序：展示方式：

diffusion coefficient and microstructure parameters in concrete: A comparative analysis using NMR, MIP

Yurong ZHANG, Shengxuan XU, Yanhong GAO, Jie GUO, Yinghui CAO, Junzhi ZHANG

《结构与土木工程前沿（英文）》 2020年第14卷第6期页码 1509-1519 doi: 10.1007/s11709-020-0681-9

摘要： Permeability is a major indicator of concrete durability, and depends primarily on the microstructure characteristics of concrete, including its porosity and pore size distribution. In this study, a variety of concrete samples were prepared to investigate their microstructure characteristics via nuclear magnetic resonance (NMR), mercury intrusion porosimetry (MIP), and X-ray computed tomography (X-CT). Furthermore, the chloride diffusion coefficient of concrete was measured to explore its correlation with the microstructure of the concrete samples. Results show that the proportion of pores with diameters<1000 nm obtained by NMR exceeds that obtained by MIP, although the difference in the total porosity determined by both methods is minimal. X-CT measurements obtained a relatively small porosity; however, this likely reflects the distribution of large pores more accurately. A strong correlation is observed between the chloride diffusion coefficient and the porosity or contributive porosity of pores with sizes<1000 nm. Moreover, microstructure parameters measured via NMR reveal a lower correlation coefficient versus the chloride diffusion coefficient relative to the parameters determined via MIP, as NMR can measure non-connected as well as connected pores. In addition, when analyzing pores with sizes>50 µm, X-CT obtains the maximal contributive porosity, followed by MIP and NMR.

关键词： permeability microstructure NMR MIP X-CT

HTML PDF 收藏

Selective sorption of perfluorooctane sulfonate on molecularly imprinted polymer adsorbents

Shubo DENG, Danmeng SHUAI, Qiang YU, Jun HUANG, Gang YU

《环境科学与工程前沿（英文）》 2009年第3卷第2期页码 171-177 doi: 10.1007/s11783-009-0017-4

摘要： Perfluorooctane sulfonate (PFOS), as a potential persistent organic pollutant, has been widely detected in water environments, and has become a great concern in recent years. PFOS is very stable and difficult to decompose using conventional techniques. Sorption may be an attractive method to remove it from water. In this study, the molecularly imprinted polymer (MIP) adsorbents were prepared through the polymerization of 4-vinylpyridine under different preparation conditions in order to remove perfluorooctane sulfonate (PFOS) from water. The MIP adsorbents using perfluorooctanoic acid (PFOA) as the template had good imprinting effects and could selectively remove PFOS from aqueous solution. The sorption behaviors including sorption kinetics, isotherms, and effect of pH, salt, and competitive anions were investigated. Experimental results showed that the sorption of PFOS on the MIP adsorbents was very fast, pH-dependent, and highly selective. The achieved fast sorption equilibrium within 1 h was attributed to the surface sorption on the fine adsorbents. The sorption isotherms showed that the sorption selectivity of PFOS on the MIP adsorbents decreased at high PFOS concentrations, which may be due to the double-layer sorption and the formation of PFOS micelles on the sorbent surface. The sorption of PFOS on the MIP adsorbents was mainly dominated by the electrostatic interaction between the protonated vinylpyridine on the adsorbent surface and the anionic PFOS. The prepared MIP adsorbents can potentially be applied in water and wastewater treatment for selective removal of PFOS.

关键词： perfluorooctane sulfonate (PFOS) molecularly imprinted polymer (MIP) adsorbents selective sorption electrostatic interaction

HTML PDF 收藏

多产异构烷烃的催化裂化工艺技术开发与工业应用

许友好,张久顺,龙军,何鸣元,徐惠,郝希仁

《中国工程科学》 2003年第5卷第5期页码 55-58

摘要：

从催化裂化反应机理出发，提出了两个反应区的概念，设计了具有两个反应区的串联提升管反应器并形成相应的工程技术，在此基础上进行了中小型探索试验和工业试验。1.4 Mt/a多产异构烷烃的催化裂化装置试验标定结果表明：与现有的催化裂化工艺相比，该工艺不仅优化了产物分布，干气和油浆产率分别下降了0.41%和0.99%，液体收率增加了1.17%，而且所生产的汽油烯烃含量下降约14.1%，异构烷烃增加约为12.9%，硫的质量分数ω（s）下降26.5%,诱导期增加,汽油的RON下降而MON增加,总的抗爆指数略有下降。

关键词：催化裂化汽油烯烃异构烷烃芳烃