Preparation And Photocatalytic Activity Of N-TiO₂/ Bacteria Residue Activated Carbon Under Visible Light Irradiation

In this study,the gentamycin bacteria residue and the lincomycin bacteria residue were used as raw material,the bacteria residue activated carbon was prepared,then N-TiO₂ was loaded on the activated carbon by equivalent-volumetic impregnation method,finally N-TiO₂/bacteria residue activated carbon composite photocatalysts were prepared.The composite photocatalysts were characterized by DTA-TG,BET,SEM,TEM,UV-Vis,FTIR and XPS.The photocatalytic performances of the composite photocatalysts were respectively investigated using methyl orange solution and acetone gas as model rganic pollutants under visible light irradiation.The results were as follows.1)The optimum preparation conditions were as follow.For the gentamycin bacteria residue activated carbon the conditions were 1:3 of activation ratio,800℃of activation temperature,1 h of activation time,and for lincomycin bacteria residue activated carbon the conditions were 1:1 of activation ratio,700℃of activation temperature and 3 h of activation time.The adsorption values of iodine were 1 119.3 mg·g^-1 and 1 275.1 mg·g^-1,respectively.The BET specific surface area of the prepared activated carbon was 718.6m²·g^-1 and 2 161 m²·g^-1,respectively.The two activated carbon showed good adsorption characterizations for acetone gas,and the lincomycin bacteria residue activated carbon was slightly better than the gentamycin bacteria residue activated carbon.2)The optimum preparation conditions were as follow.For the N-TiO₂-U（urea as dopant sources）the conditions were 5:1 of N:Ti mole ratio,500℃of calcina-tion temperature and 2 h of calcination time.For N-TiO₂-A（ammonia as dopant sources）1:1 of N:Ti mole ratio,400℃of calcination temperature and 1h of calcination time.The band-gap energy of N-TiO₂-U and N-TiO₂-A was 2.3 eV and 2.95 eV respectively,and both of the photocatalysts had a good response to visible light.The main combination forms of N and TiO₂ in the N-TiO₂ were the interstitial nitrogen,nitrogen molecule,and substitutional nitrogen.N-TiO₂-U and N-TiO₂-A showed good visible light photocatalytic activities to methyl orange solution and acetone gas,and the former had a better photocatalytic activity than the latter for methyl orange,whereas the latter had a better photocatalytic activity than the former for acetone.3)The optimum loading rate was 25%for N-TiO₂/bacteria residue activated carbon composite photocatalyst.The specific surface area was 1 452 m²·g^-1（N-TiO₂-U/AC）and 1718 m²·g^-1（N-TiO₂-A/AC）.The photodegradation efficiency of N-TiO₂/AC to methyl orange solution increased with the increase of illumination intensity and decrease with initial concentration.The photocatalytic efficiency of N-TiO₂/AC to acetone gas increased with the increase of illumination intensity.and in the initial stage of light,the removal rate of acetone increased with the increase of initial concentration.In late stage of light,the removal rate of acetone decreased with the increase of initial concentration.