Cellulose Based Cryogels as Adsorbents for Organic Pollutants

Abstract

Cryogels of hydroxypropyl methylcellulose (HPMC) and bacterial cellulose nanocrystals (CNC) were prepared with 0, 5, or 15 wt% contents of CNC. Two types of CNC were used, namely, CNC‐SO 4 and CNC, with ζ‐potential values of − (46 ± 1) mV and − (5 ± 1) mV, respectively. Regardless the CNC type or content, all cryogels presented similar density, capillarity constant, contact angle, swelling rate values, and morphology. However, the addition of only 5% of CNC‐SO 4 to HPMC cryogels increased the compressive modulus from (120 ± 15) kPa to (150 ± 19) kPa. The cryogels were tested as adsorbents for 17α‐ethinyl estradiol (EE) and methylene blue (MB). In the dilute range, the pollutants removal efficiency of reinforced cryogels was considerably larger than that of neat cryogels. In the more concentrated range, all adsorbents presented similar efficiency. The adsorption isotherms of EE and MB onto cryogels fitted with sigmoidal and Freundlich adsorption models, indicating higher affinity for aerogels with 5% CNC‐SO4. Cryogels could be recycled 10 and 5 times, respectively, for MB and EE adsorption/desorption under flow without losing efficiency, disclosing their potential for preconcentration of pollutants, and environmental remediation.