Investigation on the surface active sites variation of mineral dusts

摘要

The paper analyzed the groups naked and the transformed of fibro us brucite, wollastonite, chrysotile asbestos, sepiolite, palygorskite, clinopti lolite, crocidolite and diatomaceous earth mineral dusts by using IR under acid and alkali etched, strong mechanical and polarized molecular interaction. The re sults 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 play the main role i n small molecular substance. The shape of dusts affects their distributions and densities of active sites. The strong mechanical and weak chemical force make th e active site feature of minerals change, the powder process brings about more n aked surface groups and more combined types. The dust activity relates to the ty pe, contribution, and naked level of surface groups. The studied dust surface gr oups are mainly as follows: OH -, Mg(OH) -, Si-O-Si, Ca-O-Si, -Mg-O H 2, -Al(Si)-OH,-Mg(Ca)-OH 2,Ca-O, -Si...OH, Mg(Fe)-OH. Due to the diffe rence of surface composition and structure, the minerals have a large disparity on activity and character of surface groups. The one side surface group of chrys otile layer is the same as fibrous brucite and stripped layer with more naked gr oup. The fibrous sepiolite and palygorskite surface OH - similar to crocidolit e is naked with their surface structural defects and cleavage. The more deve lopm ent of mineral defects, the higher of OH -(H 2O +)content, the main H 2O + of clinoptilolite is partly transformed into H +, NH + 4 or OH -. The acid etched process may change OH - concentration, distribution and increase the de fects 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, palygo rskite and clinoptilolite. Some surface groups of remnant differ from original d usts. The surface process of small polarized molecular or middle moleular′s bra nch may produce ionation and new coordinate bond, and change the active properti es and level of original dusts, such as the porous minerals producing S i-O-Al,Si-O-Si [ZJDX,4S,S;DX,12S,S] H H acid site may act as some assistance catalysis in bioche- mistry process.