| BTEX(benzene,toluene,ethylbenzene and xylene),as a typical volatile organic compound,is commonly found in lakes and oceans.Worse,BTEX solubilized by surfactants are still highly toxic by more difficult to degrade.Solubilized BTEX would be a greater threat to the ecological environment.In this paper,water containing solubilized toluene was select as the research object,and utilizing TiO2/PC-CS composite,whcih was prepared by sol gel-hydrothermal method,with bifunctional domains as photocatalyst.The hydrophobicity,surface functional,crystal structure,microstructure,specific surface area and pore structure of the composites were characterized by contact angle,FT-IR,XRD,SEM and N2 adsorption/desorption curves,respectively.The solubilization performances of toluene with three kinds of surfactants were studied and the adsorption kinetics,isotherm and thermodynamics propertys of TiO2/PC-CS composite to toluene were studied,respectively.The photocatalytic degradation process and mechanism of toluene solubilized with three different surfactants was research,and the main contents are as follows:The results of composite material characterization reveal that:(1)the porous carbon born with a well-developed pore structure,and the carbon spheres carbon with various from 2 to 7 ?m were evenly distributed in the surface and pores of the porous carbon;(2)The result of contact angle reflects that surface of composite material converted from hydrophobic to hydrophilic before and after loading carbon sphere and nano TiO2 particles;(3)FT-IR indicated the formation of Ti-O-C bond at the interface between TiO2 and PC-CS;(4)XRD indicated that the TiO2 in composite is still anatase,and PC-CS did not affect the crystalline structure of titanium dioxide;(5)The N2 adsorption/desorption curves showed that the composite TiO2/10%(PC-CS)is mesoporous material with a specific surface area of 79.836 m2·g-1,and the pore size was mainly distributed at around 39nm.The results of solubilization experiments showed that the solubilities of toluene increased by 27,20 and 28 times,respectively,when the concentrations of K12,TX-100 and AES were 8mM,0.2mM and 0.625mM(CMC).With increasing concentration of surfactant,the solubilization of toluene showed a linear increasing trend at 25?.The results of adsorption experiments showed that:(1)In the range of 20??40?,the adsorption process of toluene solubilized onto TiO2/10%(PC-CS)in K12,TX-100 and AES reaches equilibrium at 12 h,which were all in accordance with quasi-second-order kinetics model;(2)Adsorption process belongs to Langmuir isothermal adsorption model,which suggests a single layer molecular of toluene onto TiO2/10%(PC-CS);(3)During adsorption process,Gibbs free energy ?G<0,adsorption enthalpy AH>0,adsorption entropy change AS>0,so it is proved that adsorption is a spontaneous,endothermic,and the entropy process.The results of photocatalytic degradation showed that:(1)At 25?,when the concentration of TiO2/10%(PC-CS)was lg/L and toluene was solubilized in K12 at a concentration of 8 mM,TX-100 at a concentration of 0.2 mM and AES at a concentration of 0.625 mM,respectively,the degradation rate of toluene in 1000mg/L could reach 80.60%,87.45%and 81.12%,respectively,of which the best photocatalytic degradation effect was obtained under the condition of TX-100 solubilization;(2)At 25?,when the concentration of TiO2/10%(PC-CS)was lg/L and toluene was solubilized in TX-100 at a concentration of 0.2 mM?0.4 mM and0.6 mM,the photocatalytic degradation rate of toluene in 1000mg/L could reached 87.45%?77.20%and 60.94%respectively.Moreover,best photocatalytic degradation effect was obtained in the case of TX-100 at the critical micelle concentration,the photocatalytic degradation is the best;(3)The photocatalytic degradation process of toluene solubilized with TiO2/10%(PC-CS)in different surfactants was consistent with the quasi-first order kinetic equation and the correlation coefficients are above 0.93;(4)After recycling using TiO2/10%(PC-CS)for 8 times,its degradation rate to toluene was still maintain over 70%. |
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