Three-dimensional macroporous cellulose-based bioadsorbents for efficient removal of nickel ions from aqueous solution

We present a simple synthetic method for the preparation of cellulose-g-poly(acrylic acid-co-acrylamide) materials with three-dimensional macroporous structure, which can be used for the environmental application as the reusable bioadsorbents. In the grafting copolymerization process, the acrylic acid and acrylamide are cross-linked with cellulose molecules to form three-dimensional interconnected porous structure. Due to the macropores and the abundant functional groups, the cellulose-based bioadsorbents exhibit excellent adsorption performance for the removal of nickel ions from aqueous solution with a maximum adsorption capacity of 171.8 mg/g. The adsorption of bioadsorbents to Ni2+ is accurately described by a pseudo-second-order kinetic model and the initial concentration-dependent adsorption isotherm suggests a Langmuir isotherm model. Furthermore, the cellulose-based bioadsorbents can be easily separated from the aqueous solution after adsorption and regenerated using 0.2 M HCl solution, which exhibits high adsorption capacity after six adsorption-desorption cycles. Importantly, the biodegradation rate of 53.1 wt% for the bioadsorbents is found after being incubated in the soil extraction solution for 90 days. Therefore, the eco-friendly cellulose-based bioadsorbents could be used for water purification effectively.