活性炭的光催化再生机理

通过研究催化剂的改性、再生温度、外加氧化剂对活性炭光催化再生反应速度的影响，结合光催化与活性炭的吸附理论，分析了活性炭的光催化再生机理．研究表明，活性炭的光催化再生由三个准一级反应组成．再生初期，再生反应速度由TiO2光催化降解吸附质的速率决定；反应的第二个阶段由光催化反应速度和吸附质的解吸速度共同决定；再生后期，再生反应速度由吸附质在活性炭上的解吸速率所决定．活性炭表面及其大孔内负载的Ti0：是使苯酚降解转化分解为无机物的降解中心．正是由于降解中心的存在及其表面苯酚浓度趋于零的状态，使得已吸附于活性炭孔内的苯酚不断向这个中心扩散，形成活性炭孔内苯酚的浓度差．在浓度差的作用下，扩散作用持续进行，导致活性炭内吸附位的逐步空出，从而实现活性炭的光催化再生．

MECHANISM FOR THE PHOTOCATALYTIC REGENERATION OF EXHAUSTED ACTIVATED CARBON

The effects of catalyst modification, regeneration temperature and oxidation additive on the rate of activated carbon phtocatalytic regeneration were investigated. Combined with the theory of adsorption with photocatalysis mechanism, the mechanism for the photocatalytic regeneration of exhausted saturated with phenol was elucidated. Photocatalytic regeneration process consist of three first - order reactions. During the early stage of regeneration, photocatalytic oxidation of organic adsorbate was the controlling step. Afterwards, desorption of organic adsorbate from inner to exterior surface of activated carbon was the controlling step. For TiO2 - activated carbon composite system, loaded TiO2 photocatalyst was the degradation center, where adsorbate was degraded. The concentration difference of TiO2 center and activated carbon make the adsorbed phenol desorpted and moved to TiO2. Photocatalytic regeneration of the exhausted activated carbon can be achieved because of the successive desorption - degradation process.