Preparation Of Cu Modified Adsorbent And Its Adsorption Performance For Tetracycline In Water

With the producing and using of antibiotics,wastewater containing antibiotics enters the water and soil through natural circulation.While adversely affecting animals and plants,it is also enriched by the food chain and endangering human health.Wastewater treatment such as biochemical method,advanced oxidation method,and adsorption method have their own characteristics.Among them,the adsorption is simple and its conditions are mild.Therefore,this paper mainly studies the removal of tetracycline(TC)in antibiotics by adsorption method,and aims to develop a new efficient and clean adsorbent.In this paper,Cu-modified SBA-15 adsorbents were prepared by pH precipitation,hydrazine hydration reduction and carbon reduction,and the prepared adsorbents were characterized by XRD,BET,TEM,XPS and other methods.The adsorption performance of the prepared adsorbent on TC in water was evaluated by static adsorption experiments.FT-IR was used to explore the mechanism of TC adsorption.First,Cu(?)was loaded on the surface of SBA-15 molecular sieve as Cu(NO3)2·3Cu(OH)2 by pH precipitation to prepare Cu(?)/SBA-15 adsorbent.The maximum adsorption capacity of the adsorbent 769.23 mg/g at 313 K.By examining the influence of precipitation pH and copper content on adsorption performance,it was found that the optimal precipitation pH was 6.2 and the optimal copper loading was 15%.The characterization of the sample by nitrogen adsorption-desorption experiment found that after the SBA-15 molecular sieve is loaded with copper,the pore volume and pore size have increased,which has changed in favor of mass transfer.Adsorption experiments show that the adsorption process of TC on the adsorbent conforms to the pseudo-second-order kinetic model and the adsorption equilibrium conforms to the Langmuir model.The adsorption thermodynamic enthalpy change AH is 65.15 kJ·mol",which indicates that the TC adsorption on the surface of Cu(?)/SBA-15 is a chemical adsorption of a single molecular layer,and there is electron sharing between the TC and Cu(?)/SBA-15.By FT-IR characterization analysis,it was found that the adsorption mechanism of the adsorption process was the formation of complexes between the electron-donating group-NH2 in TC and the Cu(II)in the adsorbent to form a complex,and the-OH in the TC and adsorbent Hydrogen bonding.However,the stability of Cu(OH)2 is poor,there is a weak hydrolysis equilibrium in water,and some Cu(?)will enter the water with adsorption.In order to prevent the secondary pollution of Cu(?),Cu2O/SBA-15 adsorbent was prepared by the hydrazine hydration reduction,and the optimal dosage of hydrazine hydrate was investigated.Compared with CuO/SBA-15 and SBA-15,Cu2O/SBA-15 shows better adsorption performance,and its maximum adsorption capacity is 961.54 mg/g at 313 K.The results of adsorption kinetics,isotherm and thermodynamics show that the adsorption of TC on Cu2O/SBA-15 is a chemical adsorption,which conforms to the monolayer adsorption model,and its adsorption thermodynamic enthalpy change ?H is 66.88 kJ·mol-1.TEM and BET characterization results show that there is no significant difference in physical properties between Cu2O/SBA-15 and CuO/SBA-15.According to the results of FT-IR analysis,the main difference between the two is that Cu(?)in Cu2O/SBA-15 can form a ? complex with the benzene ring of TC,and the unit cell structure of Cu2O is more conducive to electron migration,which promotes electron migration with the adsorption of TC on Cu2O/SBA-15.In order to improve the cleanliness of the preparation process and reduce the pollution in the reduction process,the carbonized carbon of glucose was used instead of hydrazine hydrate as a reducing agent,and Cu(?)was reduced to Cu(?)to prepare a Cu2O/C/SBA-15 adsorbent.By optimizing the preparation conditions of the adsorbent,it was found that the Cu2O/C/SBA-15 obtained by reduction at 573K had the best adsorption performance,and its maximum adsorption capacity is as high as 934.57 mg/g at 313 K.TEM results showed that the load of C and Cu had no significant effect on the structure of SBA-15 molecular sieve.The results of adsorption kinetics,isotherm and thermodynamics show that the adsorption of TC on Cu2O/C/SBA-15 is a chemical adsorption process,and its adsorption thermodynamic enthalpy change ?HH is 60.57 kJ·mol-1.According to the results of FT-IR analysis,the adsorption mechanism of TC on Cu2O/C/SBA-15 is that Cu(?)can form a ? complex with the benzene ring of TC and share electrons with-NH2.