The heavy metal adsorption and plant cultivation performance of grafting modified plant medium made with recycled fibers

Abstract

This paper proposes an environmental friendly nonwoven geotextile with good heavy metal adsorption properties and beneficial promotion of plant cultivation to potentially replace the riverbank soil or cover on the shoreline surface to rebuild up a healthy ecosystem. In this paper, waste fibers were adopted and carded into even fiber web, followed by needle-punching technology with several layers of fiber web to strengthen the plant medium with satisfying mechanical properties. Then, the grafting modification was conducted on the needle-punched nonwoven geotextiles and the optimum combination of grafting factors were obtained via orthogonal experiments. The tensile, heavy metal adsorption and plant cultivation performances of modified and untreated plant medium were systematically compared and analyzed by infrared absorption spectrum, SEM, XRD, TG, ICP-OES, universal material testing machine, and contact angle tester. The results showed that β-cyclodextrin was well grafted on the substrate. The orthogonal experiments results showed that the best combination of Pb2+ and Cu2+ adsorption was 4% sodium hydroxide (NaOH), 2% β-cyclodextrin, 170 °C heating temperature, and 50 min heating. The adsorption effects of Pb2+ and Cu2+ were 14.32 mg/g and 38.99 mg/g, respectively. The grafted fabric was hydrophilic and a more suitable culture medium for plants. These results provide not only a novel solution for reuse of recycled fibers but also a feasible strategy to construct a new water ecosystem.