Structure And Nanoporosity Of Modified Carbonaceous Materials And Their Relationships With Sorption Behaviors Of Typical Organic Contaminants

In this study,black carbon was produced by slow pyrolysis under an oxygenlimited condition at 500? from a Maoming oil shale,and was modified by some chemical methods?oxidation,hydrolysis,and activation?.Activated and oxidized black carbon samples were produced from a shale kerogen at temperature ranging from 250 to 500? by chemical activation treatments?ZnCl₂,KOH?,and then by oxidative treatments?H₂O₂,NaClO?.The samples were characterized by using elemental analysis,Fourier transformed infrared spectroscopy?FTIR?,solid-state 13 C NMR,X-ray photoelectron spectroscopy?XPS?surface analysis,CO2 adsorption analysis,and then used to investigate the sorption behavior of phenanthrene?Phen?and nonylphenol?NP?.Moreover,Polanyi-Dubinin?PD?,combined linear partitioning and Polanyi-Dubinin?LPPD?,and Dubinin-Radushkevitch?DR?were used to calculate the sorption volume of the hydrophobic organic contaminants?HOCs?.The results were as follows.The sorption of Phen on the modified black carbon was typically nonlinear.In addition,the H₂O₂ oxidation,NaClO oxidation,and HCl hydrolysis reduced the sorption nonlinearity,while the ZnCl₂ activation and KMnO4 oxidation enhanced the sorption nonlinearity.The H₂O₂ oxidation exhibited the highest sorption affinity,while the NaClO oxidation reduced strongly the sorption affinity.The sorption affinity?log K'FOC?was positively correlated with nanopore volume?Vo?and specific surface area?SSA?.Moreover,the nanopore model analysis demonstrated that the nanopore-filling mechanism was the dominant sorption mechanism of Phen on the modified black carbon.For the ZnCl₂-H₂O₂ and ZnCl₂-NaClO treatment samples,the results showed that with increasing pyrolysis temperature,nanopore volume?Vo?and specific surface area?SSA?of all the samples gradually increased,reaching a maximum value at 500 oC.It is noted that the ZnCl₂ activation and of H₂O₂ oxidation treatment gave a maximum nanopore volume of 227 ?L/g and a specific surface area of 567 m2/g at 500 oC.Moreover,both of the sorption isotherms of Phen and NP were nonlinear,and the sorption affinity K'F of Phen and NP increased with the increasing pyrolysis temperature,reaching the maximum values at 500 oC.Furthermore,the sorption affinity?K'F?of Phen and NP was positively correlated with nanopore volume?Vo?at 0¹.1 nm and 1.1² nm and specific surface area?SSA?for the ZnCl₂ activated and H₂O₂ or NaClO oxidized samples.At the same time,the sorption volumes of Phen fitted by DR model were positively correlated with nanopore volume?Vo?at 0¹.1 nm and 1.1² nm,and were better with the nanopore volume?Vo?at 1.1² nm.The nanopore model analysis showed that the nanopore filling was the main sorption mechanism of Phen on the ZnCl₂ activated and H₂O₂ or NaClO oxidized samples,and there is additional mechanisms for the sorption of NP.Moreover,there was molecular sieve effect in the sorption of Phen and NP.In addition,it was found that the content of non-protonated aromatic carbon on ZnCl₂ activated and oxidized samples was the main factor affecting its nanopore volume,sorption capacity,sorption nonlinearity and nanopore filling volume.For the KOH-H₂O₂ and KOH-NaClO treatment samples,the results showed that the nanopore volume?Vo?and specific surface area?SSA?of all samples were increasing with the increase of pyrolysis temperature,and were lower than that of ZnCl₂ activation samples.The yields of the KOH activated samples were significantly lower than that of ZnCl₂ activation samples.Moreover,it is noted that the KOH activated samples were mainly increase the volume of nanopore size less than 0.7 nm,which can reach to 53.6% after 400 oC.In addition,the sorption affinity?K'F?of Phen and NP increased first and then decreased with the increase of pyrolysis temperature,and reached the maximum values at 400 ?,and it was significantly lower than that of ZnCl₂ activated samples.And the sorption affinity?K'F?of Phen and NP was negatively correlated with polarity index??N+O?/C?and hydrophilic index?O/C?for KOH activated and H₂O₂ or NaClO oxidized samples.The sorption nonlinearity?n?was positively correlated with H/C value,indicating that as the aromatic degree increase,the nonlinearity of sorption increase.The nanopore model analysis showed that the nanopore filling was the main sorption mechanism of Phen on the KOH activated and H₂O₂ or NaClO oxidized samples,and there is additional mechanisms for the sorption of NP.Moreover,there was molecular sieve effect in the sorption of Phen and NP.