Preparation,Properties And Characterization Of Bamboo-Based Activated Carbon For Bamboo Pyrolysis And Room Temperature Removal Of Formaldehyde

In this paper,the pyrolysis characteristics and pyrolysis kinetics of bamboo,Na OH/bamboo,H₂SO₄/bamboo were first studied by thermal analyzer（TG-DTA）.Suitable bamboo was selected for follow-up experiments M_xO_y（M=Co、Cd、Ce）to prepare bamboo-based activated carbon and screen out the transition metal-loaded bamboo-based activated carbon with better room temperature formaldehyde removal performance.On this basis,process factors such as dipping solution concentration,dipping time,activation temperature,activation time,and heating rate were studied.The law of influence on the yield of bamboo-based activated carbon and the removal performance of formaldehyde at room temperature.The specific surface area and pore size distribution of the prepared samples were analyzed by specific surface area tester（BET）,X-ray diffractometer（XRD）and Fourier infrared spectrometer were used（FT-IR）,scanning electron microscope（SEM）and other characterization methods to explore the removal performance of Co-loaded bamboo-based activated carbon on room temperature formaldehyde.Ag-doped bamboo charcoal-supported Co composites were prepared by doping noble metals,and optimized by response surface optimization method.The preparation process of Ag/Co/BC composites was combined with BET,XRD,FT-IR,SEM,XPS and other methods to explore the formaldehyde removal mechanism.The regeneration performance and service life after adsorption saturation were studied by thermal regeneration method.The main conclusions were as follows:（1）When the heating rate was 10°C/min and the temperature range was from room temperature to 1000°C,the pyrolysis reaction process of bamboo,Na OH/bamboo,H₂SO₄/bamboo and other samples were divided into four stages,namely dehydration and drying stage,preheating stage,carbonization.In the pyrolysis stage and high temperature carbonization stage,the weight loss rates were 63.6%,79.4%and 85.4%,respectively.（2）When the heating rate was 10℃/min,the activation energy Ea of bamboo in the pyrolysis range of 215-380℃was 11.56 KJ/mol and the pre-exponential factor was3.49×10~3min^-1.The activation energy of Na OH/bamboo in the pyrolysis range of785-945℃.The energy Ea was 24.51 KJ/mol and the pre-exponential factor was 0.99×10~3min^-1.The activation energy Ea of H₂SO₄/bamboo in the pyrolysis range of 170-270℃was2.11 KJ/mol and the pre-exponential factor was 0.18×10~3min^-1.The formaldehyde removal rates of BC,Na OH/BC and H₂SO₄/BC samples were 52.74%,52.86%and40.27%,respectively.（3）When the concentration of the immersion solution was 0.5 mol/L,the formaldehyde removal rates of M/BC（M=Co,Cd,Ce）bamboo-based activated carbon were 61.05%,37.42%and 58.01%,respectively.The optimal preparation process of Co/BC samples was as follows:immersion solution 1:6,immersion solution concentration0.9 mol/L,immersion time 24 h,heating rate 11℃/min,calcination temperature 300℃,calcination time 210 min.The room temperature formaldehyde removal rate of Co/BC samples was the highest of 86.76%.（4）The order of the influence of process factors on the formaldehyde removal rate of Co/BC samples:calcination temperature>calcination time>immersion solution concentration>immersion time>heating rate.The order of the influence of process factors on the yield of Co/BC samples:calcination temperature>immersion solution concentration>calcination time>heating rate>immersion time.When other conditions remain unchanged,the formaldehyde removal rate of Co/BC samples increases with the immersion.The increase of liquid concentration,impregnation time,calcination temperature and calcination time showed a trend of first increase and then decrease.（5）Fitting regression equation of formaldehyde removal rate of Ag/Co/BC samples:Y=+95.98-1.83*A+2.05*B-2.93*C-3.03*AB+1.16*AC-0.66*BC-7.01*A~2-6.21*B~2-3.43*C~2（R~2=0.9965,P value<0.0001）The optimized process conditions:Ag NO₃doped amount of 0.08 g,immersion solution concentration of 0.9 mol/L,immersion time of 24 h,heating rate of 11℃/min,calcination temperature of 300℃,calcination time of 210 min.The room temperature formaldehyde removal rate was 96.81%,the deviation from the predicted value was 0.34%,indicating that the prediction result of the model is relatively accurate.（6）The surface of Ag/Co/BC sample was rich in nitroso（-NO₂）or C=O groups,Co（II）-O,Si-O and other functional groups;the proportion of C-C on the surface decreases,and the O-C=O structure increases.Co²⁺/Co³⁺,O_I/O_IIwere 0.97 and 0.52,respectively.The specific surface area was 34.69 m~2/g,the average pore size was 13 nm less than that of the BC sample and the pore volume was 0.44 cm~3/g.