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

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 2MPa, 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.