Adjustment Of Space Structure Of Bentonite And Its Application In Water Treatment

With the rapid development of industry and agriculture,environmental pollution problems have become increasingly prominent and worse.Heavy metal ions and organic compounds have been two major sources of pollution in wastewater.Treat these two pollutants together may greatly improve the efficiency.In the existing wastewater treatment agents,bentonite has a good adsorption capacity,cation exchange capacity,large surface area,low cost and non-toxic,so it is the focus in recent years.However,due to its silicone unit having a highly hydrophilic structure and the interlayer cations hydrolysis,so it is poor for some hydrophobic organic pollutants.Based on this,the subject designed and prepared different modified bentonite to adjust its space structure to improve the adsorption ability for heavy metal ions and organic compounds in wastewater.In this paper,different modified bentonite have been prepared by cation exchange method,the microstructure,surface morphology and other properties of characterized and analyzed by XRD,FTIR,TGA-DTA,SEM and BET.Corresponding research have been done to explore its adsorption capacity and photocatalytic ability,specific contents are as follows:(1)CTMAB-Al/Ce modified bentonite are prepared,the preparation conditions of CTMAB-Al/Ce modified bentonite are investigated,the microstructure,surface morphology and properties are studied,and the optimum conditions are as follows:the best preparation conditions for aluminum cerium molar ratio is 5,hydroxyl aluminum molar ratio is 2.6,(Al+Ce)/raw bentonite is 14mmol/g,temperature is 60℃,aging time is 3 h,CTMAB added in an amount 1.OCEC;in this prepared condition,the layer spacing increases,the specific surface area increases,the pore size becomes small,the overall slice becomes thin、soft and fuzzy compared with raw bentonite,and to some extent,thermal stability also improved.(2)Based on single factor experiment,response surface methodology is employed to optimize the main influences of adsorption property by CTMAB-Al/Ce modified bentonite,and the quadratic multinomial mathematical model is also established.The results showed that when the dosage of the adsorbent is 7.5g/L,adsorption time is 37min,pH is 6.1,the removal of Cd2+is 99.00%,the removal of phenol is 95.48%.The results indicate that R2 in the established quadratic model is 0.9843 and 0.9995 with better fitness and higher significance.The removal of Cd2+and phenol under the optimum condition are 98.35%and 94.99%respectively,the relative error is found to be 0.66%and 0.52%.Compared with the raw bentonite,the adsorption property of modified bentonite seems better.(3)Prepared cerium-doped titania/CTMAB bentonite,discussed their preparation conditions,and studied its structure,morphology and other properties.The results showed that the ratio of titanium and bentonite was 15mmol/g,ratio of cerium and titanium was 0.5/100,calcination temperature was 500℃;and the photocatalytic ability for fluroxypyr was best under optimal prepared conditions.XRD,IR and thermal analysis showed that the prepared material have successfully got into the layer of bentonite,scanning analysis showed fuzzy and softer contour.When the catalyst is added in an amount of 1g/L,the photocatalytic ability for fluroxypyr was about 90%with cerium-doped titania/CTMAB modified bentonite photocatalyst.Degradation kinetic corresponds to the first order reaction equation,which indicates the concentration of the reactants and the degradation rate was linearly correlated.Compared with the raw bentonite,the consequent of photocatalytic degradation with prepared material is much higher than the raw bentonite,which indicates a good modification effect.