Assessment of adsorptive filter for removal of formaldehyde from indoor air

We varied face velocities and initial formaldehyde concentrations to investigate the formaldehyde removal performance of coconut shell activated carbon (AC) adsorptive filter media. AC surface were rather uneven, with coarse and small pores, and with amorphously formed irregular layer structures. C, O, Mg, P etc. were detected, which showed the existence of MgO in AC. The AC surface area was 1333.3304 m ² g ^–1 , and ketone-C=O bonds were successfully grafted onto the carbon. At any given face velocity, the experimental results indicate that the adsorption capacity increased and the breakthrough time decreased as the initial concentration increased. The breakthrough behavior of the AC adsorptive filter could henceforth be evaluated with confidence using the breakthrough curves predicted by the Yoon-Nelson model. Of the three kinetic models that were assessed, the experimental and calculated results show that the correlation coefficient and mean absolute performance error (MAPE) of the pseudo-second-order model generated the best approximation of the kinetic dynamics of the adsorption process—better than those of the pseudo-first-order model and intraparticle diffusion model. Both the intraparticle diffusion model and the membrane diffusion affected the overall rate of the adsorption process by more than one step. The equilibrium data of the AC adsorptive filter media was found to best fit the Langmuir model. The D-R equation predicted the equilibrium capacity of AC at a relative pressure of 0.151.