Reusing cellulose acetate microplastic fibres derived from discarded cigarette butts as superior adsorbent for lead ions: UV ageing, adsorption mechanisms and DOM investigation

Abstract

Cigarette butts (CBs), the residual components of cigarettes post-consumption, are primarily composed of cellulose acetate microplastic fibres (CA MP_f), which significantly contribute to the global excess of non-biodegradable plastic trash. Consequently, for the first time, this study examines the reusability of hazardous CA MP_f by extracting it from discarded CBs, recycling it, and employing as an effective adsorbent for Pb (II) removal from aquatic environments. Further, the UV ageing characteristics, adsorption behavior, and dissolved organic matter (DOM) investigation of CA MP_f embedded within CBs have been examined, to comprehend the heavy metal adsorption characteristics in water environment. Subsequently, under UV irradiations, a novel cow urine-based ageing approach for CA MP_f has been explored to enhance the ageing properties, which was not previously the subject of any research. Notably, the cow urine-aged CA MP_f demonstrated a remarkable increase in removal efficacy (96 %) for Pb (II), compared to the pristine CA MP_f. The lower half-life capacity of 1.748 min and higher HCC of 60 mg/L obtained for aged CA MP_f revealed rapid adsorption potential and higher removal efficiency. The DOM investigation of pristine and cow urine-aged MP_f shows possible leaching of humic acid-like components as environmental pollutant “vectors.” CA MP_f's reusability as an adsorbent guarantees a sustainable approach and is aligned with the Sustainable Development Goal.