Chemical activation of porous diatomite ceramic filter for the adsorption of TMA, H2S, CH3COOH and NH3: Isotherm and kinetic studies

Abstract

Air pollution is a major concern due to its toxicity. A porous diatomite ceramic filter (PDCF) was prepared and modified with H3PO4 and NaOH for the adsorption of TMA, H2S, CH3COOH and NH3. In this study, the effects of filter preparation conditions were investigated; (1) sintering temperature, (2) molding pressure, (3) amount of PEG (polyethylene glycol), (4) H3PO4 and NaOH. The best PDCF was obtained at 1100 ℃ and 2 MPa, which exhibited sufficient compressive strength (20 MPa), and density (1.1 g/cm3). Acid and base modification greatly altered surface properties by increasing surface area and porosity with a large number of reactive sites and functional groups, resulting in the improved adsorption capacity (62.0, 36.0, 62.0 and 17.0 mg/g for TMA, H2S, CH3COOH and NH3 respectively.) Isotherm and kinetic studies showed that Langmuir was the best fitted model for TMA, H2S, CH3COOH and NH3 adsorption. The adsorption of TMA, CH3COOH and NH3 followed the pseudo-second order model whereas the adsorption of H2S obeyed the pseudo-first order model. The spent PDCF can be successfully regenerated and had certain reusability. Finally, this study was expected to expand the utilization of diatomite as an acid and base modified PDCF for the adsorption of air pollutants.