Air purifier devices based on adsorbents produced from valorization of different environmental hazardous materials for ammonia gas control

Abstract

The present study aimed to find a beneficial solution for waste recycling and disposal by converting it from an environmental load to products useful for air pollution control. This work investigated the possibility to convert cow dung, rice straw and Eichhornia crassipes (lotus plant) to activated carbons by chemical activation using phosphoric acid (H₃PO₄) impregnation. The prepared activated carbon samples were characterized using BET analysis for determination of the surface area and FTIR analysis was also used to give a basic understanding of the surface functional groups of the samples. The results showed that the prepared activated carbon from Eichhornia crassipes (ECAC) had the highest surface area (1200 m² g⁻¹) compared to activated carbons from both rice straw (RSAC, 900 m² g⁻¹) and cow dung (CDAC, 700 m² g⁻¹). The efficacy of the prepared activated carbon samples to remove ammonia gases was studied. It was noticed that the adsorption capacity of all prepared activated carbons was higher than that of the raw materials. Ammonia removal efficiency by ECAC was found to be 70% followed by RSAC 60% and finally CDAC 55%. Langmuir and Freundlich models were applied. It was recorded that Freundlich models fit the data well with R² of 0.999. Among all prepared carbons, the best ECAC was selected to develop a new air filter device. The performance of the new filter was examined in the field for removing ammonia gases from indoor air of a cow barn. It was found that the filter is effective to remove ammonia gases (70%) from the polluted area during the experimental period (15 days); the filter adsorption capacity was slightly decreased at the end of the experiment but it is still effective. Hence we can say that this new filter can act as an economic product used to remove air pollutants as well as a way to overcome the problem of different environmental pollutants and convert these wastes into useful products for the environment.