Synthesis SBA-15 From Fumed Silica And Its Loaded La For Adsorption Properties Of Congo Red And As(Ⅴ)

With the improvement of people’s lives,the textile dye industry has developed rapidly,generating a large amount of printing and dyeing wastewater.Among them,the excessive pollution of dyes and heavy metals makes the treatment of printing and dyeing wastewater more difficult.In the current dye wastewater treatment technology,the adsorption method has always been a hotspot for researchers because of its advantages of large water treatment volume,convenient operation,and low cost.For the purpose of removing Congo red(CR)and arsenic(As(Ⅴ))at the same time,this paper uses industrial micro-silica fume(FS)and P123 as raw materials.Mesoporous SBA-15 sieve molecular with high surface area was obtained by adjusting the crystallization time,crystallization temperature and the ratio of raw material.And rare earth lanthanum(La)was loaded on the surface of the resulting SBA-15 to obtain efficient CR and As(Ⅴ)adsorbent.The results show that a longer crystallization time is beneficial to improve the order and specific surface area of the material;when the crystallization time is greater than 12 h,ordered mesoporous materials can be obtained,the specific surface area of SBA-15 increased from 597.27 m2/g to 939.41 m2/g with the increase of the crystallization time from 8 h to 48 h;crystallization temperature can enhance the order of the material by accelerating the nucleation rate and nucleation growth rate during the crystallization process;Ordered mesoporous channel can be obtained when the crystallization temperature is greater than 90℃;Low FS/P123 mass ratio is not conducive to the formation of ordered materials,and ordered mesoporous channels can be obtained when the FS/P123 mass ratio is greater than 0.43.In addition,by loading rare earth metals cerium(Ce),lanthanum(La),and yttrium(Y)on the surface of the resulting SBA-15,it was found that La has higher affinity for As(Ⅴ)than Y and Ce,so its composite material La/SBA-15 was used for further studies of CR and As(Ⅴ)in the later period.Through the study of the adsorption performance of single CR and As(Ⅴ),it is found that the adsorption behavior of As(Ⅴ)and CR on the surface of La/SBA-15 is more fitted with the Langmuir adsorption isotherm,indicating that the adsorption of As(Ⅴ)and CR on the surface of La/SBA-15 is monolayer.And the maximum monolayer adsorption capacity at 25℃ is 44.37 mg As(Ⅴ)/g and 373.49 mg CR/g,respectively.During the entire adsorption process,the adsorption behavior of CR and As(Ⅴ)on La/SB A-15 belongs to the pseudo-second-order model,illustrating that the"surface reaction" is the main rate control step of the adsorption;The reaction process of the adsorption of As(Ⅴ)and CR on La/SBA-15 is both Endothermic and spontaneous.The simultaneous removal of CR and As(Ⅴ)from a CR-As(Ⅴ)mixed pollutant system was studied.The results illustrated that the concentration of CR in the mixed system does not affect the adsorption capacity of La/SBA-15 on As(Ⅴ).However,the presence of As(Ⅴ)in the mixed system inhibited the adsorption performance of CR by La/SBA-15,and the inhibition of CR adsorption by La/SBA-15 increased with the increase of As(Ⅴ)concentration in the mixed solution.This is because at a pH of 6.0,the lanthanum hydroxyl group(La-OH)on the surface of La/SBA-15 connected the NH2 in the CR molecule through hydrogen bonding(La—O—H—N and La—O—H…N),and the mechanism of As(Ⅴ)removal is the ion exchange of-OH in lanthanum hydroxyl group wuth H2AsO4-.However,there was competitive adsorption in the simultaneous removal of CR and As(Ⅴ),and a more stable component can be formed through the ion exchange between the-OH on La-OH to H2ASO4-,which decreased the adsorption site for Congo red,leading to the decrease in the removal capacity of Congo red.