Composite microbeads of cellulose acetate upcycled from waste for water remediation

The rising level of contaminants in the environment highlights the urgent need for the development of effective sorbents that can be applied to remediate contaminated water. Additionally, if sorbents can be prepared by recycling waste, this is a further added value. This study has aimed to develop a sustainable nanocomposite sorbent of cellulose acetate (CA), a bioplastic that can be recycled from different types of waste, including filters from cigarette butts. After an efficient cleaning protocol, the recovered CA was used to prepare microspheres via an emulsion precipitation technique, in combination with activated carbon as adsorption filler (20 % w/w). The sorption performance of this material was evaluated in flow-through systems, i.e. glass cartridges packed with the microspheres, by simulating a filter for water remediation at the laboratory scale. An experimental 23 factorial design was performed to define the best operational conditions of the instrumental setup, defining the flow rate, amount and chemical nature of the packed microbeads. The adsorption performance was tested towards 40 common contaminants chosen as model compounds. To investigate the retention behaviour of the individual analytes, the Gompertz mathematical model was chosen, as it is useful for fitting the sigmoidal release pattern of contaminants from the packed cartridge. Competitive removal studies revealed differential retention based on analyte polarity, with retention capacities spanning from 2.2 - 4.2 mu g of each contaminant per gram of sorbent, with a total loading capacity on the order of 125 mu g/gsorbent. The adsorption studies demonstrated the composite potential for water remediation operations, coupled with advantages in terms of recyclability and sustainability of the material.