Preparation of Biochar by KCl-Activated Walnut Shell Pyrolysis and Its Adsorption Performance for Methylene Blue
A biochar from KCl activated walnut shell pyrolysis is prepared and used to adsorb methylene blue.The biochar prepared by KCl activation turns out to be superior to the biochar obtained by direct pyrolysis in adsorption capacity.In order to find out the reason,the biochars are treated by loading KCl and water wash,respectively.Combined with the results of SEM,FT-IR,XRD and N2 adsorption-desorption characterizations,it is found that KCl has no effect on methylene blue adsorption.Meanwhile,the KCl would block the pores of the biochar,reduc-ing the adsorption capacity of methylene blue.The KCl activation can promote the formation of the pore structure of biochar,especially the meso-micropore less than 3 nm.This is the reason for the increase of adsorption capacity.The theoretical fitting of adsorption isotherms suggests that Langmuir equation has a higher fitting degree to the ex-perimental data.The thermodynamic calculation proves that the adsorption of methylene blue on biochar is a spon-taneous physical adsorption process.
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维普
