Preparation Of Chemically Modified Peanut Shell Adsorbent And Its Removal For Antibiotics And Dyes From Water

Water is an important environmental element on which all life depends.However,with the rapid development of industrial revolution and global economy,water shortage,water pollution and other problems have become increasingly prominent.Due to the dependence and abuse of antibiotics,they become an emerging pollutant discharged into the environment,which makes all kinds of water environment suffer from organic pollution.In addition,a large amount of dye wastewater produced in industrial production activities is also one of the sources of organic water pollution.The removal of these organic pollutants from wastewater is of no delay.Adsorption method is considered as a promising wastewater treatment technology because of its advantages of high efficiency,low cost and flexible operation.In recent years,biomass adsorbents prepared from agricultural wastes have attracted great attention in the study of wastewater treatment.Such adsorbents not only meet the minimum cost and highest efficiency of adsorption technology,but also realize the resource utilization of waste,which is an environment-friendly adsorbent.Herien,peanut shell(PS)was used as raw material,sodium hydroxide and carbon disulfide as modifiers,xanthate modified peanut shell(XMPS)biomass adsorbent was prepared through xanthation proecss for the removal of ciprofloxacin(CIP)and methylene blue(MB)in water.And the influence of experimental factors such as the amount of adsorbent,initial concentration of pollutants,contact time,p H,temperature,ionic strength on the adsorption reaction were explored.The materials were characterized by SEM,BET,FTIR,XPS and Zeta potential test.The adsorption properties,kinetic and thermodynamic characteristics of XMPS for CIP and MB were studied,and the possible adsorption mechanism of CIP and MB were discussed.BET analysis showed that XMPS was mesopore material with an average pore diameter of 7.12 nm.Chemical modification reduced the specific surface area of the material.FTIR spectra showed that there were active groups such as benzene ring,hydroxyl group and carbonyl group on the surface of XMPS,and the oxygen-containing functional groups of the material were favorable for adsorption.The experimental results showed that the adsorption capacity of PS modified by xanthate was significantly improved:at T=303 K,both the removal rate of CIP and MB in the single system by 0.1 g/L XMPS were more than 90%.The adsorption process of CIP and MB on XMPS had a higher degree of fit with the pseudo-second-order kinetic model,and the correlation coefficients were 0.9996 and0.998,respectively.Intra-particle diffusion model showed that both the adsorption process of CIP and MB on XMPS were controlled by both intrapellule diffusion and membrane diffusion.Thermodynamic analysis results of CIP and MB show thatΔH~0,ΔG~0andΔS~0were all negative at all temperatures,indicating that the adsorption reaction of CIP and MB on XMPS were a process of spontaneous exothermic and entropy reduction.The adsorption behavior of CIP and MB by XMPS was different.For CIP adsorption,the optimum p H range of XMPS was 6～8,while the alkaline condition was more favorable for the adsorption of MB.The adsorption isotherm model of XMPS for CIP was more consistent with Langmuir model,indicating that the adsorption of CIP on XMPS was monolayer adsorption,and the maximum adsorption capacity of XMPS for CIP reached 480.489 mg/g.The adsorption isothermal model of XMPS for MB was more consistent with the Freundlich model,which showed that the adsorption surface of XMPS and MB was not uniform.Combined with the kinetic and adsorption isotherm model analysis,and the comparison of the changes of FTIR before and after adsorption,it can be seen that the adsorption process of XMPS on CIP involved physical adsorption and chemical adsorption,and MB adsorption was mainly chemical adsorption.The adsorption mechanism of CIP included electrostatic action,hydrophobic action,hydrogen bond andπ-πaction.MB adsorption mechanism involved electrostatic interaction,hydrogen bonding andπ-πinteraction.Ionic compounds can inhibit the adsorption of CIP and MB on XMPS,and the higher the concentration of ions added,the more obvious the inhibition effect.The higher the ion charge,the stronger the inhibition.After three cycles of XMPS,the CIP removal rate remained at 70%and the CIP adsorption capacity stabilized at about 130 mg/g,indicating that XMPS is a kind of stable adsorbent.In conclusion,xanthate modification successfully transformed natural PS into a good biomass adsorbent,which can efficiently adsorb and remove antibiotics and dyes from water.