甲醛污染日益严重，有效降解甲醛是亟需解决的现实问题。以生物质材料、不同变质程度的煤、石油焦等为原料制得的活性炭具有比表面积大、吸附效率高等优点，在吸附、分离甲醛污染物方面具有显著优势。综述了活性炭吸附机理及改性机理、TiO2光催化反应原理、提高光催化活性的途径、TiO2负载等，分析比较了活性炭和TiO2/AC对甲醛的吸附降解性能，并对活性炭改性、TiO2/AC吸附-光催化的未来方向进行了展望。活性炭以物理吸附为主，在一定压力、温度条件下会发生脱附，造成二次污染。通过酸化改性可改变活性炭的孔径分布和表面酸性官能团含量，将物理吸附转变为物理-化学联合吸附，可有效提高甲醛分子在活性炭表面的吸附。除了活性炭吸附甲醛外，TiO2无毒无害、安全绿色、光催化效率较高，是公认的较理想光催化降解甲醛等污染物的材料，根据TiO2光催化原理，通过—OH和—O-2两种氧化能力极强的活性物种，甲醛等污染物能被催化降解为CO2、H2O或其他无机小分子。然而，TiO2量子效率低、可见光吸收范围窄、重复利用率低等问题限制其大规模工业应用。金属离子掺杂进TiO2后形成电子、空穴的浅捕获势阱，非金属阴离子取代TiO2氧位后，改变结构的畸变程度，一定程度上减少了电子-空穴对的复合。通过复合敏化可将禁带宽度不同的半导体组合形成一个异质结，拓宽复合催化剂的光谱响应范围。将TiO2负载在活性炭上制得TiO2/AC吸附催化协同材料，有利于解决催化剂难以回收利用的问题，通过活性炭对甲醛的吸附与浓缩，为光催化提供良好的反应环境，提高降解速率。通过控制活化与炭化过程，开发出具有特异吸附能力的活性炭；随着对TiO2机理的深入探究，制备去除效率高、吸附容量大、能耗低、具有选择性的TiO2/AC材料，提升吸附催化协同材料的制备水平，有利于实现高效清洁降解甲醛的技术目标。

Based on the increasingly serious formaldehyde pollution,the effective degradation of formaldehyde has become a practical problem urgently to be solved. Activated carbon prepared from biomass materials,coal with different metamorphic degrees and petroleum coke has the advantages of large specific surface area,high adsorption efficiency,which has significant advantages in adsorption and separation of formaldehyde pollutants.The activated carbon adsorption mechanism and modification,TiO2 photocatalytic reaction principle,ways to improve the photocatalytic activity,TiO2 load were reviewed,and the adsorption and degradation properties of formaldehyde on activated carbon and TiO2/AC were analyzed and compared,and the future research direction of activated carbon modification and TiO2/AC adsorption-photocatalysis was also prospected. Activated carbon is mainly physical adsorption,which will desorb under certain pressure and temperature conditions,resulting in secondary pollution. The pore size distribution and surface acid functional group content of activated carbon can be changed by acidification modification,and the physical adsorption can be changed into physical-chemical combined adsorption,which can effectively improve the adsorption of formaldehyde molecules on the surface of activated carbon. In addition to adsorption by activated carbon,TiO2 is non-toxic,harmless,safe and green,with high photocatalytic efficiency,and is generally recognized as an-ideal-material for photocatalytic degradation of pollutants such as formaldehyde. According to the photocatalytic principle of TiO2,pollutants such as formaldehyde can be catalyzed into CO2,H2O or other inorganic small molecules through two active species with strong oxidation capacity —OH and —O-2. However,the large-scale industrial application will be limited due to the problems of low quantum efficiency,narrow absorption range of visible light and low reusability of TiO2. After metal ions are doped into TiO2,a shallow trapping potential well of electrons and holes is formed. After nonmetallic anions replace the oxygen position of TiO2,the degree of structural distortion is changed,which reduces the electron-hole pair recombination to a certain extent. Semiconductor with different band gap width can be combined to form a heterojunction by compound sensitization,which can broaden the spectral response range of the compound catalyst. TiO2/AC adsorption and catalytic co-material prepared by supporting TiO2 on activated carbon is conducive to solving the problem difficult recycling of catalyst. The absorption and concentration by activated carbon provides a good reaction environment for photocatalysis and improves the degradation rate. Activated carbon with specific adsorption ability can be developed by controlling activation and carbonization process. With the in-depth study of TiO2 mechanism,TiO2/AC materials with high removal efficiency,large adsorption capacity,low energy consumption and selectivity are prepared to improve the preparation level of adsorption catalytic co-materials,which is conducive to the realization of the technical goal of efficient and clean degradation of formaldehyde.

0 引言

1 活性炭及改性

   1.1 活性炭吸附甲醛

   1.2 活性炭改性吸附甲醛

2 TiO2光催化甲醛

   2.1 光催化降解甲醛机理

   2.2 光催化高效降解甲醛途径

3 TiO2/AC吸附-光催化协同降解甲醛

4 结语与展望