Influences Of Pyrolysis Temperature On Ulva Prolifera-derived Biochar Properties And Sorption Characteristics Of Ofloxacin

Ulva prolifera is massively abundant due to their high photosynthetic efficiency,and it can be easily acquired because of its accessibility,longevity,and benthic nature.However,due to their characteristics of rapid growth and environmental tolerance,U.prolifera become “pest” species in eutrophic environments.Consequently,the conversion of biomass to biochar as one potential end-use will improve the resource utilization of U.prolifera.Investigation on the characteristics of heavy metals and dissolved organic matter(DOM)of biochar could provide valuable information for guiding us in the production and application of biochar.In addition,the overuse of antibiotics has led to the increasingly serious pollution of antibiotics in the water environment.However,the knowledge of the sorption of antibiotics by U.prolifera-derived biochar(U.P-biochar)is limited.In this thesis,some research about these two aspects have been studied,main results were summarized as followings:(1)Biochar was produced from U.prolifera by using oxygen-limited and temperature-controlled pyrolysis at temperatures of 200,300,400,500 and 600 ?.The effects of pyrolysis temperature on the yield,the bulk and water-soluble heavy metal(Cu,zinc,Cr,Cd,Pb,As,Hg)contents in biochars were investigated.The results showed that the yield of biochar decreased with the increase of pyrolysis temperature.The contents of water-soluble heavy metals in biochars were lower than those in raw biomass,and the pyrolysis temperature was negatively correlated with the content of water-soluble heavy metals,indicating that the pyrolysis process could reduce the dissolution of these heavy metals.(2)The effects of various pyrolysis temperatures and extraction salinities on the fluorescence features of DOM from U.P-biochar was investigated under aseptic conditions using fluorescence excitationemission matrix(EEM)spectroscopy with parallel factor(PARAFAC)analysis and self-organizing maps(SOM).Four humic-like substances and one protein-like substance were identified by the PARAFAC model.The contents and compositions of PARAFAC components depended more on the pyrolysis temperature than on the extraction salinity.A high pyrolysis temperature could enhance the release of humic-like DOM from biochar.(3)The influences of water washing treatment on property of U.P-biochars and its sorption capacity of ofloxacin(OFL)were investigated.The water washing treatment significantly changed the elemental composition,point of zero charge and FTIR spectra of biochars,and decreased the sorption capacity of OFL.The effects of pyrolysis temperature on biochar sorption of OFL were closely dependent on the solution pH.The washed and unwashed biochars prepared at 200 showed higher sorption c? apacity of OFL at neutral condition,subsequently the kinetics,isotherms and thermodynamics were further exploring.The results indicated that two-compartment first-order model and Freundlich model can be suitably employed to describe the sorption behaviors of OFL on the U.P-biochars.In addition,the sorption of OFL by the U.P-biochars was spontaneous and endothermic.