Investigation on the surface active sites variation of mineral dusts

来源期刊：中南大学学报(英文版)2001年第3期

论文作者：DONG Fa-qin WAN Pu FENG Qi-ming SONG Gong-bao PENG Tong-jiang

文章页码：169 - 174

Key words：mineral dusts; surface group; active site

Abstract: The paper analyzed the groups naked and the transformed of fibrous brucite, wollastonite,chrysotile asbestos, sepiolite, palygorskite, clinoptilolite, crocidolite and diatomaceous earth mineral dusts by using IRunder acid and alkali etched, strongmechanical and polarizedmolecular interaction. The results show that the active site focuses on ends in stick dusts and on defects or hole edges in pipe dusts. The inside active sites of dusts playthe main role in small molecular substance. The shape of dusts affects their distributions and densities of active sites. The strongmechanical andweak chemical force make the active site feature of minerals change, the powder process brings about more naked surface groups and more combined types. The dust activity relates to the type, contribution, and naked level of surface groups. The studied dust surface groups are mainly as follows: OH^-, Mg(OH)^-, Si-O-Si, Ca-O-Si,-Mg-OH₂,-Al(Si)-OH,-Mg(Ca)-OH₂,Ca-O,-Si…OH,Mg(Fe)-OH. Due to the difference of surface composition and structure, the minerals have a large disparity on activity and character of surface groups. The one side surface group of chrysotile layer is the same as fibrous brucite and stripped layer with more naked group. The fibrous sepiolite and palygorskite surface OH^-similar to crocidolite is nakedwiththeirsurface structural defects and cleavage. The more developmentof mineral defects, the higher of OH^-(H₂O⁺)content, the main H₂O⁺of clinoptilolite is partly transformed into H⁺, NH⁺₄or OH^-. The acid etched process may change OH^-concentration, distribution and increase the defects and porosity of mineral fiber surface. The alkali etched has no effect on Si-O, Si-OH etc. and destroyed Al-O,Al-OH-acid site of sepiolite, palygorskite and clinoptilolite. Some surface groups of remnant differ from original dusts. The surface process of small polarized molecular or middle moleular′s branch may produce ionation and new coordinate bond, and change the active properties and level of original dusts, such as the porous minerals producing acid site may act as some assistance catalysis in biochemistry process.