| In recent years,with the rapid development of textiles,clothing and other industries,printing and dyeing wastewater has become the top priority of pollutant treatment.The printing and dyeing wastewater has complex composition,stable nature,wide spread range and difficult degradation.These problems have caused printing and dyeing wastewater treatment difficult,poor effect.Methylene blue(MB)is a widely used cationic dye that not only has the general characteristics of conventional contaminants,but is also toxic to human body.Therefore,the removal of MB wastewater is one of the focuses of printing and dyeing wastewater purification.Silicon-based materials(BG)have the characteristics of large specific surface area,large pore size,easy m odification,and therefore ha've wide applications in the adsorption and separation of wastewater.However,since the pure silicon-based material is composed of silicon oxide and lacks active adsorption sites,physical or chemical activities,the application in wastewater treatment is greatly restricted,so using lanthanum/titanium to doping silicon material,while it has better adsorption ability with photocatalytic ability,get the dye wastewater treatment of superior materials.In this experiment,three silicon-based materials that include lanthanum doped,titanium doped and lanthanum-titanium doped,were synthesized by sol-gel method with ethyl orthosilicate as precursor,sodium nitrate as mineralizer,butyl titanate as titanium source and lanthanum nitrate as lanthanum source.The results of projection electron microscopy(TEM),scanning electron microscopy(SEM),specific surface area distribution(BET)and elemental energy spectrum analyzer(EDAX)showed that the doping of lanthanum and titanium was successful and had a good pore structure.It is proved by experiments that the three materials have good removal ability for methylene blue solution.The adsorption and removal processes of MB by these three materials are in accordance with the quasi-second-order kinetic equation and the Freundich adsorption isotherm model.Among them,the R2 of the quasi-second-order kinetic equation is above 99.99%,and the R2 of the Freundich adsorption isotherm model can reach more than 98%.Compared with the three materials,BG-La-Ti has the best effect,not only has good photocatalytic ability,the photocatalytic removal rate of MB solution reaches 98%,and the removal rate after MB solution adsorption can reach 75%,and the adsorption capacity of the material itself is higher than that of undoped silicon-based materials in terms of adsorption concentration change,pH change,etc.The removal rate of MB solution at 80mg/L could reach 90%,and the removal rate of MB solution under strong acid environment could still reach 60%.The regenerative capacity of BG-La-Ti is also significantly improved compared with other materials.After 8 times of regeneration,the MB solution can still maintain a removal rate of nearly 90%.Due to the good performance of BG-La-Ti,the neutral red(NR)and Congo red(CR)adsorption and photocatalytic tests were carried out on BG-La-Ti materials.The results showed that the materials have good adsorption and photocatalytic performance for NR solution,basically the same as that of MB solution,however,the ability to remove CR solution is poor.The overall removal effect of BG-La on printing and dyeing wastewater is worse than BG-La-Ti,but it has excellent desorption capacity.It is proved by experiments that the doping of La and Ti improves the processing ability of the silicon-based material itself to the printing and dyeing wastewater,and proves the necessity of doping and the feasibility of the experiment.The overall removal effect of BG-La on printing and dyeing wastewater is worse than BG-La-Ti,but it has excellent desorption capacity.It is proved by experiments that the doping of La and Ti improves the processing ability of the silicon-based material itself to the printing and dyeing wastewater,and proves the necessity of doping and the feasibility of the experiment. |
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