Pre-grafting effect on improving adsorption efficiency of cellulose based biosorbent for Hg (II) removal from aqueous solution

Abstract

Pre-grafting technique with excellent biocompatibility is introduced to cellulose based adsorbent material which greatly enhances the adsorption properties like adsorption capacity, equilibrium time and regeneration performance. • Pre-grafting technique greatly enhances the adsorption performance of adsorbent. • Adsorption capacity is retained more than 85% after five cycles of regeneration. • Pre-grafting technique based on cellulose has excellent biocompatibility. Adsorption technique is considered to be an effective way to remove heavy metal species from aqueous solutions and cellulose based materials are widely used as good candidates of adsorbents. However, low grafting efficiency of functional groups has been a major challenge reducing the heavy metal adsorption capacity of cellulose based adsorbents. In this work, a diethylenetriaminepentaacetic acid modified cellulose is synthesized by an efficient catalyzed approach on the basis of glycidyl methacrylate pre-grafting (G-DMC). As a contrast, epichlorohydrin is employed as coupling side chain to react with the same polyacid (DMC) to evaluate the effect of pre-grafting. It is verified that “pre-grafting technique” significantly improves the load efficiency of polyacid and enhances the adsorption performance that the as-prepared adsorbent using pre-grafting technique shows much higher adsorption capacity ( Q m ) towards mercury in aqueous solutions with Q m of 443.8 mg/g, which is 3.5 folds of the epichlorohydrin grafted one. In addition, the kinetic adsorption experiments confirm that G-DMC achieves its adsorption equilibrium in a shorter time of 10 min. After five cycles of regeneration process, G-DMC could maintain 88.13% of its original adsorption capacity. Moreover, the live/dead cell fluorescence staining demonstrates the good biological safety of the material that the cell viability of murine L929 fibroblasts could retain close to 100% after 24 h of cultivation with G-DMC. Thus, this pre-grafting strategy is expected to provide an environmentally friendly method to amplify the adsorption capacity of the designed receptor for guest species.