| In this paper,according to the research status and development trend of bamboo charcoal at home and abroad,the effects of the preparation process and process factors of sodium hydroxide and boric acid modified bamboo charcoal（N/BC,B/BC）on the formaldehyde removal performance of modified bamboo charcoal at room temperature were studied by orthogonal test and single-factor test,respectively.The preparation technology conditions of the N/B/BC samples were optimized by using orthogonal test and Box-Behnken design method.The samples were characterized by scanning electron microscope（SEM）,energy dispersive spectrometer（EDS）,thermogravimetric（TG-DTG）,N2adsorption-desorption,Fourier infrared spectrometer（FT-IR）,Raman spectroscopy（Raman）,X-ray diffraction（XRD）and X-ray energy spectrometer（XPS）,and the mechanism of formaldehyde removal at room temperature of N/B/BC samples was discussed.The main conclusions were as follows:（1）The order of the influence of process factors on formaldehyde removal rate at room temperature of N/BC samples was:solid-liquid ratio>activation time>activation temperature>impregnation time>concentration of Na OH.When other preparation processes remained constant,the formaldehyde removal rate of N/BC sample showed a change rule of first increased and then declined with the increased of concentration of Na OH,solid-liquid ratio,impregnation time,activation temperature and activation time.When the concentration of Na OH was 1.6 mol/L,solid-liquid ratio was 1:5,impregnation time was 24 h,activation temperature was 700°C,and activation time was 120 min,the formaldehyde removal rate of N/BC sample was 84.26%at room temperature.（2）When other preparation processes remained constant,the formaldehyde removal rate of B/BC sample showed a change rule of first increased and then declined with the increased of concentration of boric acid,solid-liquid ratio,impregnation time,activation temperature and activation time.When the concentration of boric acid was 0.4 mol/L,solid-liquid ratio was 1:7,impregnation time was 18 h,activation temperature was 600°C,and activation time was 30 min,the formaldehyde removal rate of B/BC sample was 82.58%at room temperature.（3）The regression equation of the formaldehyde removal rate of N/B/BC sample was:Y=91.74-0.081A+0.64B-0.82C+0.66AB+0.63AC+0.4BC-6.45A~2-0.99B~2-4.02C~2（R~2=0.9796,p value<0.0001）.The optimized preparation process conditions were obtained:the concentration of ammonium acetate was 1.4 mol/L,ratio of solid-liquid was 1:6,impregnation time was 24.92 h,processing temperature was 89.57℃,processing time was 12 h.After optimization,the formaldehyde removal rate of samples at room temperature was89.96%-93.54%,with an average of 91.65%.The maximum deviation from the predicted value（91.87%）was 1.91%,and the average deviation was 0.22%,which means that the predication result of the model was relatively accurate.（4）Many ammonium acetate particles were attached to the surface of N/B/BC sample,and its specific surface area,micropore volume,total pore volume and average pore size increased to 240.09 m~2/g,0.09 m L/g,0.12 m L/g and 4.53 nm,which were 1.21 times,1.13times,2.25 times and 1.90 times of B/BC sample,respectively.The formaldehyde removal rate of the N/B/BC sample was 96.59%within 10 h,11.08%higher than that of the B/BC sample,and it had good regeneration performance,that the formaldehyde removal rate could still reach 70.02%within 10 h after 5 times of regeneration.（5）The process of removing formaldehyde from N/B/BC samples at room temperature was:HCHO contacted the outer surface of the sample and was adsorbed by the interaction force of oxygen-containing functional groups and nitrogen-containing functional groups.At the same time,it entered the pore structure and was adsorbed by the interaction force between the pores,and finally reacted with the ammonium acetate particles on the surface of the sample.The entire adsorption process continued. |
