Adsorption and High-Temperature Nitrogen Desorption Performance and Mechanism of Granular Activated Carbon for Large-Air-Volume Low-Concentration PCE-Containing Waste Gas
To treat large-air-volume, low-concentration volatile organic compounds (VOCs) containing tetrachloroethylene (PCE) generated from rubber-metal bonding, this study systematically investigated the adsorption-desorption behavior and interaction mechanisms of PCE, toluene, and methyl isobutyl ketone (MIBK) on granular activated carbon (GAC). Static adsorption experiments showed that PCE adsorption capacity reached 556.6 mg·g−1, while dynamic multi-component adsorption capacity was 179.6 mg·g−1. Kinetic analysis indicated that PCE adsorption was controlled by both intraparticle diffusion and external surface adsorption, whereas toluene and MIBK were primarily intraparticle diffusion-limited. During high-temperature nitrogen desorption, PCE underwent dechlorination, hydrogenation, and recombination, producing trichloroethylene, 1,2-dichloroethane, 1,2-dichloropropane, and HCl, with HCl accounting for 3.61% of the chlorine molar content in adsorbed PCE. After four adsorption-desorption cycles, the iodine value of GAC dropped below the industry standard of 600 mg·g−1; however, water washing and alkali immersion extended the cycle life to 8 and 9 cycles, respectively. The HCl generation pattern in co-adsorption systems was consistent with single-PCE systems. A regeneration process combining alkali immersion and water washing was proposed and integrated into an engineering strategy. Compared to conventional activated carbon adsorption coupled with RTO incineration, the proposed classification strategy reduced annual costs by 49.5×10⁴ CNY. This work provides a cost-effective and safe solution for Cl-VOCs treatment.