Study On Adsorption Of Methylene Blue By Platanus Orientalis Bark Biochar

Biochar is a carbonaceous material with high carbon content.It can be produced by pyrolysis under oxygen-limited conditions and other methods.It has wide biomass sources and low preparation costs.Large-scale application is anticipated concerning mitigation of global warming,soil remediation and environmental management.In this study,platanus orientalis bark biochar was prepared by pyrolysis under oxygen-limited condition.In order to explore its surface structure and properties,Fourier transform infrared spectrometer(FTIR),scanning electron microscope(SEM),X-ray photoelectron spectroscopy(XPS),Boehm titration and other methods were employed to check the effet of pyrolysis temperature and demineraliztion treatment..Methylene blue was selected as a target pollutant to investigate the effects of pyrolysis temperature for biochar preparation,solution pH and coexisting aions.The adsorption kinetics and thermodynamics experiments were also studied to discuss adsorption behavior and mechanism.SEM analysis demonstrated the platanus orientalis bark biochar was irregular flakes.The higher the pyrolysis temperature,the finer the biochar particles and the higher the surface carbon content on biochar surface.Hydrochloric acid treatment of platanus orientalis bark biochar BC(biochar)can remove inorganic matter such as ash within biochar to obtain D-BC(demineralized biochar,D-BC).FTIR spectroscopy analysis showed that the surface of biochar was rich in functional groups,and the increase in pyrolysis temperature will reduce the content of oxygen-containing functional groups,which is consistent with the results of Boehm titration.XPS analysis showed that the content of C-O and-C=O bonds decreased from 23.8% and23.3% on D-BC200(pyrolysis at 200 ?)to 19.6% and 17.6% in D-BC600(pyrolysis at 600 ?),respectively.This indicated that the proportion of oxygen-containingfunctional groups within all surface functional groups also declined with the increasing pyrolysis temperature.In order to explore the adsorption behavior and mechanism,four kinds of biochars including BC200,D-BC200,BC600 and D-BC600 were selected to remove methylene blue from water.The uptake of methylene blue increased with increasing solutionpH,while alkaline conditions were favorable for adsorption.Moreover,the adsorption capacity by D-BC200 and BC200 was much higher than those by D-BC600 and BC600.Concerning the adsorption kinetics,pseudo-second-order and Elovich kinetic models were better to describe the adsorption process by using the four biochars,indicating that the adsorption process might be chemical adsorption processwith a pronounced diffusion-controlled mechanism.Langmuir model was more suitable to describe the adsorption thermodynamic data,indicating a monolayer adsorption occurred.At 298 K,the maximum adsorption capacity of methylene blue on the four biochars,BC200,D-BC200,BC600 and D-BC600,reached 237.8,199.5,59.2 and 67.9 mg/g,respectively.In summary,platanus orientalis bark biochar can be used as an effective adsorbent in the field of water treatment,and will showsexcellent adsorption capability in terms of removal of organic contaminants.