Adsorption And Photodegradation Of Phenanthrene On The Soil Mineral Surface

Soil mineral is one of the important factore affectting photochemical degradation of polycyclic aromatic hydrocarbons?PAlIls?in soil environment.Iin this paper,silicate clay rminerals-kaolinite and Montmorillonite,Metal oxide minerals-birnessite were selected for analysising effect of different cation-saturated and pH adjusted clays or binessite influence the behavior of adsorption and photodegradation of phenanthrene.At the same time,selected black soil in Northeast as the tested soil,removed or not with organic matter for particle size fractioned soil.Studied on the adsorption and photodegradation behavior of PAHs in four different soil particle size fractions.The main results are as follows:?1?For kaolinite,montmorillonite,birmessite,cation-saturated minerals have more effective adsorption capacity of phenanthrene than original minerals,and for same types of silicate clay minerals,Na+ saturated 1:1 type kaolinite has stronger adsorption ability than the saturated 2:1 type montmorillonite of Na+?Ca2+ saturated mineral is the opposite,and has its own strong oxidation characteristics of birmessite has the most strong adsorption capacity of phenanthrene than kaolinite and montmorillonite.However,under ultraviolet radiation,the rates of phenanthrene photodegradation on original kaolinite,montmorillonite,and bimessite are greater than the degradation rates of phenanthrene on saturated mineral surface.In addition,rate of phenanthrene degradation on kaolinite is the fastest in all without ion and metal ion saturation in minerals,and then followings are birmessite and montmorillonite.It can be found from the infrared spectrum diagram that the aromaticity of-mineral surface is improved after UV radiation;at the same time,GC-MS detection of different mineral surface phenanthrene photodegradation products are roughly the same,mainly for phthalic acid derivatives,esters and the open-loop further oxidized to generate carboxylic acids,alcohols and alkane material.With the long radiation period,these organisms will completely minered into water,carbon dioxide and other small molecules.?2?Kaolinite is a typical low charge or zero charge phyllosilicates clay minerals,with pH 3,5,7,9,phenanthrene in the photodegradation removal rates are in the range of 97 to 98%.The pH change of polycyclic aromatic hydrocarbons in the kaolinite surface photolysis was less affected.However,the phenanthrene degradation under different pH conditions of montmorillonite is differeremt,the rates of phenanthrene photodegradaiton on montmorillonite pH value with 3,5,7,9 after 80h are 94%,93%,98%,97%,the removal rates of phenanthrene on acid treated montmorillonite surface are less than the alkaline treated surface of montmorillonite.?3?Northeast black soils are dealt with:no organic removed clay?WN?,no organic removed did not remove the orgalic matter of the silt and fine sarnd?WFX?,organic removed clay?QN?,organic removed silt and fine sand?QFX?.Adsorption of Polycyclic aromatic hydrocarbons in above four different compositions can be well fitted by linear equotion and Freundlich equotion.The abilities of four compositions adsorption with phenanthrene are:WN>WFX>QN>QFX?Kf:5₉679>5.7230>5.3951>3.1887,Kd:13.293>8.1318>7.8914>7.8148?,the 'adsorption capacities of no organic removed particle group is greater than organic removed particle groupe.The photodegradation of Polycyclic aromatic hydrocarbons in the different particle size fractions shows,the rate of phenanthrene photodegradation of on organic removed silt and fine sand reaches 66.26%,59.73%for organic removed clay,and only 17.52%and 11.22%with no organic removed clay,silt and fine sand.