Gas circulating fluidized beds photocatalytic regeneration of I-TiO2 modified activated carbons saturated with toluene

This paper demonstrated a new regeneration method of modified activated carbon saturated with toluene using gas circulating fluidized beds photocatalysis (GCFBP). The AC was impregnated with a photocatalyst to yield light regenerable composite, namely iodine-doped titanium dioxide (IT/AC). IT/AC samples were characterized by XRD, FESEM, BET and adsorption valves of methylene blue. The results showed that loaded limited amount of I-TiO2 had little influence on the structure and adsorption properties of activated carbon. The adsorption kinetics of toluene on IT/AC composites showed best agreement with Yoon-Nelson model. Gas circulating fluidized bed reaction system was beneficial to migration of toluene on composites. The rate-limiting process was toluene adsorption from the cycle gas and photochemical oxidation of toluene. In addition, experimental results showed that IT/AC composites exhibited good recycling stability, reusability, and in situ renewability. The regenerated efficiency of composites saturated with toluene with light irradiation of 60 min and gas flow of 4 L/min was 95.98% (particle size 40-60 mesh) and 85.15% (particle size 20-40 mesh), respectively. The regenerated efficiency after three times regeneration can reach 87.09% (40-60 mesh) and 77.85% (20-40 mesh). The regenerated efficiency of GCFBP increased 80% more than that of gas circulating fluidized bed (GCFB) and 20% more than that of acyclic gas-phase photocatalysis. The removal efficiency of toluene in recycle gas reached 88.3% after 150 min reaction. The regeneration kinetics of GCFBP were consistent with the improved Langmuir-Hinshelwood model. (C) 2016 Elsevier B.V. All rights reserved.