Research On The Preparation Of Different Kinds Of Biochar And Adsorption Of Cadmium Ions

In this study,corn stalks,maple poplar branches and peanut shells were used as biomass materials,and anaerobic pyrolysis of three biomass materials was carried out at 450?,550?and 650?.The three biochars prepared at 650?were modified by BaTiO₃ to finally obtain 12 kinds of biochar.Six biochars modified by 650?and BaTiO₃ were characterized by scanning electron microscopy,nitrogen adsorption,infrared spectroscopy and X-ray diffraction.The adsorption test of divalent cadmium ions in solution was carried out to investigate the effects of pH,biochar dosage,adsorption time and initial concentration of cadmium ions on adsorption,and the adsorption process and quasi-first-order kinetic model,quasi-secondary The kinetic model,the Langmuir model,and the Freundlich model were fitted.Finally,three kinds of biochar prepared at 650?with better adsorption effect were selected for simulated wastewater adsorption test.The results showed that:?1?The three biochars are rich in pores and rough outer walls.The shape,pore volume,pore size,specific surface area and surface functional groups of different types of biochar are very different.Barium titanate has better crystallization effect on biochar.?2?The adsorption capacity of biochar increased with the increase of pyrolysis temperature of biochar.The adsorption capacity of three biochars prepared at 650?before BaTiO₃ modification was the largest.Among different types of biochar,peanut shell biochar has the best adsorption effect on cadmium ion,and the adsorption rate is the fastest.Under the same conditions,the adsorption equilibrium can be reached within 10 min,and the adsorption amount reaches 19.64 mg/g.The adsorption equilibrium time of corn stalk biochar and maple poplar biochar was 20 h and 16 h,respectively,and the adsorption capacity was 9.99mg/g and 13.81 mg/g.?3?The adsorption capacity of three biochars changed after BaTiO₃ modification.The adsorption capacity of BaTiO₃ modified Fengyang twig biochar was significantly improved,and the adsorption capacity could reach 19.94mg/g.The adsorption capacity of BaTiO₃ modified peanut shell biochar and BaTiO₃modified corn stover biochar was not obvious.The former had an increased adsorption capacity and the latter decreased.In addition,pH has a great influence on the adsorption performance of biochar,and the optimum pH of adsorption is 6;the adsorption rate is proportional to the dosage of biochar;the adsorption capacity of three biochars prepared at 650?is stronger;relatively speaking,peanut Shell biochar and BaTiO₃ modified Fengyang twig biochar have the strongest adsorption capacity.This research is of great significance for the future treatment of heavy metal-containing wastewater.