Influence of phosphorus and nitrogen co-doping of activated carbon from littered cigarette filters for adsorption of methylene blue dye from wastewater

Abstract

Global access to sanitary water is of utmost importance to human health. Presently, textile dye water pollution and cigarette pollution are both plaguing the environment. Herein, waste cigarette filters (CFs) are converted into useful carbon-based adsorbent materials via a facile, microwave-assisted carbonization procedure. The CFs are activated and co-doped with phosphorus and nitrogen simultaneously to enhance their surface characteristics and adsorbent capability by introducing chemisorptive binding sites to the surface. The doped carbonized CF (DCCF) and undoped carbonized CF (CCF) adsorbents are characterized physically to examine their surface area, elemental composition, and surface charge properties. The maximum adsorption capacity of synthesized adsorbents was determined via batch adsorption experiments and Langmuir modelling. Additionally, the influence of different parameters on the adsorption process was studied by varying the adsorption conditions such as adsorbent dosage, initial concentration, contact time, temperature, and pH. The DCCF adsorbent showed a maximum adsorption capacity of 303 mg g− 1. Adsorption of both adsorbents fit best to Langmuir model and pseudo-second order kinetics, indicating chemisorptive mechanism. Both adsorbents showed endothermic adsorption process which is indicated by increasing adsorption capacity with increased temperatures. DCCF exhibited greater adsorption capability than CCF at all temperatures from 25 to 55 °C. The pH of the solution significantly affected the adsorption capacity of CCF while DCCF adsorption is favorable at a wide pH range due to low value of the adsorbent’s point of zero charge. Reusability results showed that both adsorbents can be used over several cycles for removal of dye. Thus, results conclude that the waste DCCF-based adsorbent does not only show a profound potential as a sustainable solution to combat textile dye water pollution but also addresses the valuable use of the CF pollution simultaneously. This approach, which can target two major pollutants, is attractive due to its ease of preparation, negligible cost, and versatility in application.