Cyclodextrin-functionalized cellulose filter paper for selective capture of diclofenac

An environmentally friendly and low-cost material based on cellulose filter paper modified with β-cyclodextrin (β-CD) was designed to uptake and elute drugs for water purification. To carry out the work, a β-CD derivative was first obtained through reaction of β-CD with N-(hydroxymethyl) acrylamide (NMA), and then β-CD-NMA was grafted on cellulose by means of the Fenton’s reaction. The CD-grafted cellulose paper was characterized by ATR-FTIR analysis, SEM images, and mechanical properties. CD-functionalized (F1) and non-functionalized (NF) papers were tested in aqueous media containing an antibiotic (ciprofloxacin) or a non-steroidal anti-inflammatory drug (diclofenac) covering a wide range of salinity levels. Ciprofloxacin was similarly adsorbed by both papers through ionic interactions, while diclofenac was selectively and remarkably captured by the CD-functionalized filter (up to 25 mg g−1 from saline medium under biorelevant conditions; ca. 60 mg g−1 Langmuir isotherm model). Effects of diclofenac concentration, volume of medium, and incubation time on the amount adsorbed were investigated in detail. Elution tests involved the combination of several organic solvents and alkaline solutions and revealed that acetonitrile:NaOH 10 mM aq. solution (50:50, v/v) allows for an effective recovery of the previously trapped diclofenac. Application of ultrasounds shortened the process to 10 min. Reusability of F1 papers was also evaluated. Overall, the CD-grafted cellulose paper appears as a suitable material for bioremediation and analytical purposes.