Study On Nickel Incorporated Carbon Nanofibers And Its Adsorption Performance On Sulfadiazine And Acetaminophen

Pharmaceutical and Personal Care Products(PPCPs)are a new type of emerging organic compounds with rapid growth in recent years.PPCPs are widely used and extremely difficult to degrade,which leads to their widespread in water environment,and is potentially harmful to the environment.However,traditional water treatment technologies cannot effectively remove PPCPs in water,resulting in the continuous pollution of water.Therefore,it is of great research significance to develop an effective PPCPs removal technology.Adsorption technology is a PPCPs treatment technology with high removal efficiency,easy operation and low cost.Adsorbents play an important role in the adsorption process.Carbon nanofiber(CNF)is considered as a great adsorbent for its abundant pore structure,stable chemical properties and good mechanical strength.Whereas,the disadvantages of low reaction efficiency,low recovery rate and complex operation for CNF greatly limit its practical application.Hence,in this study,new magnetic nickel-doped carbon nanofiber composites(Ni@CNF)with high adsorption efficiency and recovery rate were successfully synthesized based on the electrostatic spinning method.In addition,their adsorption properties for sulfadiazine(SDZ)and paracetyl phenol(APAP)were systematically studied,and the adsorption mechanism and kinetic analysis were mainly explored.Nanofiber adsorbents with four Ni loadings,CNF,3%Ni@CNF,6%Ni@CNF and9%Ni@CNF,were prepared by electrostatic spinning technology combined with pre-oxidation and calcination.The adsorbents have abundant surface functional groups,huge specific surface areas and complex pore structures.Among Ni@CNF with different Ni contents,the adsorption capacity of SDZ rises gradually with the increasing Ni content,and the removal efficiency of SDZ(2.5 mg/L)over9%Ni@CNF is up to 98.9% within 25 minutes.The isotherm of the SDZ adsorption over9%Ni@CNF is more consistent with the Langmuir model,and SDZ is mainly chemically adsorbed by 9%Ni@CNF,which has a maximum adsorption capacity at 318 K of 103.2 mg/g.Moreover,9%Ni@CNF shows good applicability to a variety of organic pollutants,and displays excellent stability and reusability over 5 consecutive cycles.The adsorption mechanism of SDZ on Ni@CNF is elucidated by means of DFT theoretical calculation,nitrogen adsorption-desorption and X-ray photoelectron spectroscopy(XPS)characterization.These results show that 9%Ni@CNF has a large external specific surface area and abundant pore structure,which provide more active sites for SDZ adsorption.After the adsorption of SDZ,the O vacancies near the bivalent Ni,Ni-N and Ni atoms in 9%Ni@CNF increased significantly,indicating the interaction between Ni and N,Ni and O atoms in SDZ.Furthermore,DFT theoretical calculation shows that during the SDZ adsorption process on Ni@CNF,Ni-O and Ni-N bonds are formed between Ni and O,N atoms in SDZ.With the increment of Ni content,the adsorption capacity of SDZ on Ni@CNF increases gradually.Among CNF,3%Ni@CNF,6%Ni@CNF and 9%Ni@CNF,the adsorption capacity of APAP rises gradually with the increase of Ni content,and the removal rate of APAP(2.5 mg/L)on 9%Ni@CNF is 88.2% within 25 min,which is much higher than that on CNF(28.7%).When the p H of adsorbent solution is acidic,the adsorption of APAP on 9%Ni@CNF is promoted;while alkaline,its adsorption rate of APAP decreases sharply,which is related to the electrostatic attraction and electrostatic repulsion between adsorbent and adsorbent.In the binary and ternary systems of APAP,SDZ and carbamazepine(CBZ),9%Ni@CNF still shows superior adsorption capacity.The isotherm of APAP adsorption on 9%Ni@CNF is more consistent with the Freundlich model,indicating that the adsorption is non-uniform and multilayer,and the maximum adsorption capacity is 106.6 mg/g at 318 K.Combined with XPS,nitrogen adsorption and desorption characterization methods and the above DFT theoretical calculation,it can be seen that the active sites for the APAP adsorption are supplied by the large specific surface area,abundant pore structure,Ni elemental and oxygen-containing functional groups in the skeleton and adsorbent surface of 9%Ni@CNF.The SDZ adsorption on 9%Ni@CNF is decided by the chemical interaction between Ni and SDZ in 9%Ni@CNF.The main mechanism of the APAP adsorption on 9%Ni@CNF is the physical adsorption on the pores of 9%Ni@CNF.The 9%Ni@CNF adsorbent has stable adsorption performance for antibiotic pollutants in water,as well as pharmaceutical pollutants in water.The simulation experiment of actual water environment proves that 9%Ni@CNF has great potential to adsorb pollutants in water.The above research and analysis provide reliable theoretical calculation basis and experimental data support for the application of nickel based adsorbent in the field of water treatment.