TEMPO-oxidized cellulose hydrogel for efficient adsorption of Cu2+ and Pb2+ modified by polyethyleneimine

In this study, the hydrogel was prepared by dissolving and regenerating poplar cellulose in NaOH/urea/water system. The TEMPO-oxidized cellulose hydrogels (TCH) were prepared using microwave-assisted accelerated TEMPO-oxidation system. Polyethyleneimine (PEI) was grafted onto TCH with glutaraldehyde as a cross-linking agent and the products named as TCP. The hydrogels were characterized by SEM, FTIR, XPS, and elemental analyzer. The maximum adsorption capacities of Cu2+ and Pb2+ by TCP were 109.89 mg/g and 279.32 mg/g, respectively. TCP was a single molecule adsorption process with better fitting of the Langmuir model. Adsorption kinetics showed that the Pb2+ adsorption rate of TCP was higher than that for Cu2+. The Cu2+ affinity of TCP was higher than the Pb2+. The adsorption capacity of TCP for Cu2+ and Pb2+ was 58.26 mg/g and 91.96 mg/g, respectively, after five cycles. This study provided a promising option of preparing an efficient and recyclable adsorbent in treating wastewater containing heavy metal, such as Cu2+ and Pb2+.

Automated summary

The study prepared hydrogels by dissolving and regenerating poplar cellulose in NaOH/urea/water system, and then used microwave-assisted accelerated TEMPO oxidation to produce TEMPO-oxidized cellulose hydrogels (TCH) which were then grafted with polyethyleneimine (PEI) to form TCP. TCP showed high adsorption capacities for Cu2+ and Pb2+ and exhibited better fitting with the Langmuir model, with higher affinity to Cu2+ and faster adsorption rate for Pb2+ compared to Cu2+. Overall, TCP demonstrated promising potential as an efficient and recyclable adsorbent for treating heavy metal-containing wastewater.