Sonocatalytic Degradation Of Methylene Blue By Using Biochar Derived From Sugarcane Bagasse

A number of biomass materials including agricultural wastes can be used to prepare biochar.When pyrolyzing agricultural wastes,oil and syngas are recovered while biochar is only a byproduct of the process.The carbonaceous biochar itself has abundant pore structure,big surface area and stable physic-chemical properties.Considering these advantages,biochar derived from sugarcane bagasse was utilized for the innovative sonocatalytic degradation of methylene blue.The possibility of applying biochar into sonocatalytic process was explored.The main results are listed as follows:?1?SEM?scanning electron microscope?analysis demonstrated that bagasse bicchars became thinner and finer after pyrolization.The sizes of biochars range from10?m to 50?m,which falls in the best particle size for sonocatalysis.Carbon content increased from 57.7%of the raw bagasse to 75.3%of the biochar pyrolyzed at 600°C,indicating a possible stability and chemical inertness.?2?A target pollutant methylene blue was subjected to sonocatalytic degradation process by using bagasse biochars.It was demonstrated that the biochar pyrolyzed at600°C had a better sonocatalytic performance,in which the K_app?pseudo-first-order kinetics?value of sonocatalytic process is 1.81 times that of the ultrasonication and adsorption process alone.This indicates a significant synergetic effect between ultrasonication and biochar adsorption.An increase in biochar dose could enhance the degradation performance to some extent.The highest degradation performance was observed at pH 5.Increased ultrasonication power had improved the degradation performance as well.Quenching tests by iso-proponal or KBr proved an OH radical oxidation mechanism occurred during the sonocatalytic process.?3?In view of the major role of OH radical,contribution of OH radical was evaluated by iso-proponal quenching method.As the dose of iso-proponal did not influence the contribution of OH radical evidently,a dose of 0.05mol/L was selected.Increase in the concentration of methylene blue or the dose of bagasse biochar had a certain impact on the contribution of OH radical.The effect of solution pH was profound while the highest contribution of OH radical occurred at neutral solution pH.The above demonstrates that bagasse biochar has excellent sonocatalytic performance,and bagasse biochar is probably applied into practical water treatment.