Effect of acid treatment on the chemical composition and the structure of Egyptian diatomite
Effect of acid treatment on the chemical composition and the structure of Egyptian diatomite
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DOI：
10.1016/j.minpro.2014.09.001
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发表时间：
2014-11-10
影响因子：
--
通讯作者：
Enke, Dirk
中科院分区：
文献类型：
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作者：
Alyosef, Hallah Ahmad;Ibrahim, Suzan;Enke, Dirk
本研究使用的是来自埃及埃尔法耶姆省Kasr El-Sagha地区的埃及硅藻土。采用两段法成功地制备出高纯度硅藻土。在第一阶段，对埃及硅藻土样进行了几种机械技术(磨损洗涤和水力旋流分级)，以去除大部分伴生的脉石矿物，如无机碳酸盐、硅砂和粘土。然后将粒度为-45微米的馏分进行热化学处理。第二阶段先将硅藻土样品在1023K下焙烧1h，然后用王水(5M HCl+5M HNO3)、5M硫酸或5M盐酸对焙烧后的硅藻土样进行热酸化处理，制得3种硅藻土的改性形式。对精制产物进行了X射线衍射、X射线荧光、低温氮吸附、压汞和扫描电子显微镜等表征。可以获得高纯度(>；96wt.%SiO_2)的二氧化硅材料和可接近且相互连接的介孔结构。此外，所有样品都显示出大量的直径约为1微米的大孔和广泛分布的较大的间质大孔。经盐酸处理后，产物的比表面积为120~150m(2)g(-1)，非晶相含量为63wt.%。(C)2014爱思唯尔B.V.保留所有权利。
In this study Egyptian diatomaceous earth from Kasr El-Sagha locality in El Fayium province, Egypt was used. A highly purified diatomite has been prepared successfully by using a two stage process. In the first stage, samples of Egyptian diatomite were subjected to several mechanical techniques (attrition scrubbing and hydrocyclone classification) to remove most of the accompanied gangue minerals like inorganic carbonate, silica sand, and clay. The fraction with a particle size of -45 mu m was then submitted to a thermo-chemical treatment. This second stage started with a calcination of the diatomite samples at 1023 K for 1 h. Three modified forms of diatomite were then prepared by hot acidification of the calcined diatomite samples with aqua regia (5 M HCl + 5 M HNO3), 5 M sulphuric acid or 5 M hydrochloric acid. The refined products were characterized by X-ray diffraction, X-ray fluorescence, low temperature nitrogen adsorption, mercury intrusion and scanning electron microscopy. Silica materials with high purity (>96 wt.% SiO2) and an accessible and interconnected mesopore structure could be obtained. Additionally, all samples displayed a large amount of macropores of about 1 mu m diameter and a broad distribution of larger interstitial macropores. The treatment with hydrochloric acid led to products with a specific surface area between 120 and 150 m(2) g(-1) and 63 wt.% of amorphous phase. (C) 2014 Elsevier B.V. All rights reserved.