KAGAKU KOGAKU RONBUNSHU, Vol.39, No.1, 18-27, 2013
Parametric Study of Low Concentration Toluene Adsorption on Activated Carbon by MTZ Method and Nonlinear Regression using LDF Model
This research aimed to develop a new VOC abatement system that allows reduction of energy consumption and unit cost by applying adsorption technology to medium and small low-concentration VOC treatment units. Experiments were carried out using toluene as VOC adsorbate and a commercially available coconut shell-based granular activated carbon as adsorbent. The main experimental parameters studied were feed toluene concentration in the range of 50-1600 ppm (mainly below 500 ppm, at which self-sustaining combustion is difficult), superficial gas velocity (0.18, 0.36 and 0.55 m.s(-1)) and adsorption temperature (30, 50, 110, and 180 degrees C). Experimental equilibrium data and breakthrough curves were obtained, and overall mass transfer coefficients were estimated by the MTZ method based on the experimental breakthrough data. By applying the linear driving force model based on gas phase concentration (hereafter, the LDFC model) with the Langmuir isotherm, overall mass transfer coefficients were estimated by means of numerical curve-fitting (hereafter, the LDFC curve-fitting method) which depends on the theory of nonlinear regression. The validity in application and effectiveness in practical use of the LDFC method were evaluated by comparison of overall mass transfer coefficients estimated by this method with those estimated by the MTZ method from experimental data. In the given range of experimental conditions, adsorption isotherms could be predicted by the Langmuir model, and it was determined numerically that inlet toluene concentration only slightly affected the overall mass transfer coefficients, but superficial gas velocity and adsorption temperature influenced them strongly. The LDFC model and its curve-fitting method were found to be valid for application and had high potential for effective practical use for development and design of adsorption system and related technologies.
Keywords:Adsorption;VOC Abatement;TSA;Activated Carbon;Toluene;MTZ;LDF;Overall Mass Transfer Coefficient;Nonlinear Regression