Preparation Of CTAB Modified Sepiolite And Its Adsorption On Congo Red And Bisphenol A

Dye wastewater and environmental endocrine disrupting substances are toxic,difficult to degrade and other characteristics,is the focus of the current environmental issues,the ecological environment and human health have a great impact.Sepiolite as an inexpensive clay mineral adsorbent has been widely used in wastewater treatment,but the hydrophilicity makes it limited in organic wastewater treatment.In this paper,the use of CTAB modified sepiolite for Congo red and bisphenol A adsorption study,the current by the dye wastewater and environmental endocrine disrupting substances pollution of water treatment is of great significance.（1）The sepiolite was modified by CTAB and then subjected to further thermal activation to obtain a series of modified sepiolite with a CTAB dosage of 0.3 to 1.0times sepiolite cation exchange capacity（0.3¹.0CEC）,it is referred to as H-XCEC-S,where X represents the CTAB amount is a multiple of seawater cation exchange capacity,H and S represent activation treatment and sepiolite.The preparation conditions are as follows:the modification time is 24 h,the modification temperature30℃,the heat activation temperature is 120℃,the heat activation time is 2 h.Among them,H-0.5CEC-S had the best red adsorption performance for Congo red,and H-0.8CEC-S had the best adsorption effect on bisphenol A.（2）The optimum adsorption conditions for H-0.5CEC-S for Congo red were as follows:M=1g/L,p H=7,t=120 min,the saturated adsorption capacity of H-0.5CEC-S and S for Congo red was 649.98 mg/g and 88.50 mg/g,respectively.The second-order kinetics model and the Langmuir isotherm adsorption model can better describe the adsorption of Congo red by H-0.5CEC-S.At the temperature of 288K,298K and 308K,the theoretical saturated adsorption capacity is 578.03 mg/g,675.67mg/g,740.74 mg/g.Thermodynamic parameters analys areΔG<0,ΔH>0,ΔS>0,H-0.5CEC-S adsorption behavior of Congo red is spontaneous endothermic process.（3）The optimum adsorption conditions for H-0.8CEC-S for bisphenol A were as follows:M=1g/L,p H=10,t=240 min,the saturated adsorption capacity of H-0.5CEC-S and S for bisphenol A was 46.31 mg/g and 16.79 mg/g,respectively.The second-order kinetics model and the Langmuir isotherm adsorption model can better describe the adsorption of bisphenol A by H-0.8CEC-S.At the temperature of 291K,301K and 311K,the theoretical saturated adsorption capacity was 52.08 mg/g,46.62mg/g,40.58 mg/g.Thermodynamic parameters analys areΔG<0,ΔH<0,ΔS<0,H-0.8CEC-S adsorption behavior of bisphenol A is spontaneous exothermic process.（4）SEM,pI,BET,TG/DSC,XRD characterization,CTAB modified sepiolite surface became smooth,loose shape,hydrophobic enhancement;H-0.5CEC-S,H-0.8CEC-S The isoelectric point increased from 8.72 to 8.97 and 9.08,respectively,and the specific surface area decreased from 25.44 m²/g to 12.35 m²/g and 8.96 m²/g,respectively.The spacing between the sepiolite d_（110）=12.07 nm remained unchanged,indicating that CTAB was not inserted into the sepiolite layer,but covered with the outer surface of the sepiolite and the inner surface of the channel,so the adsorption occurred mainly on the sepiolite surface;before and after adsorption FT-IR,XPS characterization,H-0.5CEC-S adsorption on Congo red and H-0.8CEC-S adsorption of bisphenol A coordination effect,π-πaccumulation and ion exchange.Comprehensive characterization analysis results,the adsorption of H-0.5CEC-S on Congo red was mainly the interaction between-SO3-groups and the electrostatic attraction of H-0.5CEC-S and the exchange of Br-,-SO3-and-N=Hydrogen bonding of the N-group.H-0.8CEC-S on the adsorption of bisphenol A is mainly Br-ion exchange,as well as BPA-,HBPA2-and H-0.8CEC-S surface electrostatic attraction,-OH group hydrogen bonding.