Biomimic hybrid polymer networks based on casein and poly(methacrylic acid). Case study: Ni2+ removal

Abstract

Mimicking the extraordinary performances of natural materials presents an attractive, but challenging approach in the synthesis of advanced functional materials. In the field of separation techniques, the design of a low-cost, regenerative, environmentally friendly sorbent and the utilization of most of its active centers to remove the targeted pollutant are everyday challenges. The combination of casein and poly(sodium methacrylate) (PMANa) in the form of a soft polymer network is proposed as a promising sorbent for the removal of Ni²⁺ from wastewater. Such a combination and an applied synthetic route form hybrid materials with better sorption properties than both their components alone. SEM and TEM show that caseinate micelles are dissociated and the more exposed protein structure is stabilized by the PMANa network and able to form various stable complexes. The achieved sorption capacity (224 mg g⁻¹) is among the highest reported in the literature. The very high removal efficiency in the wide range of the initial Ni²⁺ concentrations (0.05–200 ppm) and easy and complete regeneration without decrease in sorption capacities make these low-cost materials highly sensitive sorbents attractive for use under real conditions where it is necessary to avoid environmental risks and provide the recovery and reuse of the metal.