Study On The Effects Of Hydrophobic And Hydrophilic On Coal’s Surface Which Functioned By Ultraviolet

Use the of surface properties of coal separate coal and gangue by flotationseparation technology plays an important role in coal preparation. In recentyears, with the development of society, the features of coal resources isincreasingly becoming "poor, fine and complex, difficulty " to the direction ofdevelopment. The smaller of coal particle size, the lower of the quality, thespecific surface area is larger, the surface energy and surface activity ishigher.These reasons make the flotation selectivity variation. Research showsthat the difference of coal is only as the diffierent of functiona group’s number.The Surface of coal’s hydrophobicity and hydrophilicity. Therefore, in order tochange the wettability of coal has become an urgent research topic through somemeans of oxygen-containing functional groups on coal surface the number andtype of change.Coal is a kind of organic rock, as asphalt, rubber, is a macromoleculematerial as the main ingredient is hydrocarbonan and carbon.So,coal is similarto the oxidation mechanism. And coal is a kind of organic macromolecules,Informed by the free radical reaction mechanism of coal, coal has a largenumber of free radicals which was produced by physical broken or chemicalchange. Coal has similar composition and structure of the other hydrocarbonmolecules. By the above conditions, we concluded that coal should have lightoxidation properties. Light oxidation of hydrocarbon molecules produce newpolycyclic aromatic hydrocarbon, so as to change the surface properties of coal. In this paper we use the long flame coal, coking coal as the object of study,find change of contact angle and Zeta potential of coal sample shined indifferent time, different power of ultraviolet rays,, to investigate the effect ofultraviolet light on the different degree of metamorphism of coal sample, andmade a preliminary inference from the mechanism.The conclusions are asfollows:(1) The free radical content in coal is very sensitive to ultraviolet light, inthe ultraviolet irradiation, the free radical reaction of coal reaction, the covalentbond formation of new aromatic hydrocarbon. The type of surface oxygenfunctional groups changed, lead the hydrophobic and hydrophilicity of the coal’ssurface changed;(2) The same UV power irradiation at different time, different equilibriumcontact angle of coal samples with different wettability, and wavy changes.(3) When the UV intensity is weaker, the change, coking coalcharacteristic change lower than long flame coal which metamorphic degreelower.But when the ultraviolet intensity is stronger, both of two kinds of coal’scontact angle has great change over the shine time. The equilibrium contactangle of the two kinds of coal has larger difference at the same time, but thewave shape is similarity.(4) When measurement the Zeta potential of coal, both of the two kinds ofcoal are negative potential, under the UV’s treatment,the two kinds of coal’sZeta potential and eventually all close to-12, but when the UV weaker, there isdifferent Zeta potential rate between the two kinds of coal samples. At the sametime, the Zeta potential of different coal sample is different too. The reason forthis situation is that coking coal is a high rank coals, has compact structure. Inthe strong ultraviolet light, the covalent bond are broken then combined intonew polycyclic aromatic hydrocarbons.but UV can not make the aromatic groupof itself easily broken then lead to fluctuations decrease. But the long flame coalcontains a large amount of covalent bond free group, the free radical formation of oxygen containing functional groups by new UV treatment, so under UVirradiation, the Zeta potential of the surface fluctuation.