Preparation of 3D Cellulose-Carbon Quantum Dots Hydrogels for Adsorption of Mercury from Aqueous Solution

Hydrogels with high mechanical properties and excellent adsorption capacity are expected in wastewater treatment. Herein, 3D porous hydrogels were prepared by free radical copolymerization using carboxymethyl cellulose nanofibers (CNFs) grafted with N, S atom doped carbon quantum dots (N, S-CDs) and 1-Allyl-2-thiourea. N, S-CDs introduced in the hydrogel can uniformly disperse and increase the adsorption site of Hg(II) by grafting method. Meanwhile, the good mechanical strength of N, S-CDs is beneficial to improve the hydrogel mechanical properties. The experimental results show that the 3D porous hydrogel has great swelling properties (SR = 875.22 g/g) and mechanical properties (elastic modulus = 86.77 MPa). Moreover, compared with the hydrogel without N, S-CDs, the 3D porous hydrogel has an excellent Hg(II) adsorption capacity (943.77 mg/g). In addition, the 3D porous hydrogel has outstanding regeneration performance. The adsorption capacity accounts for 94.6% of the first adsorption capacity after 5 cycles. Therefore, the 3D porous hydrogels are considered as a promising adsorbent for the hazardous Hg(II) absorption.