The effects of titanium dioxide nanoparticles on cadmium bioaccumulation in ramie and its application in remediation of cadmium-contaminated soil

Cadmium (Cd) is a toxic heavy metal contaminant in agricultural soils. Phytoremediation using hyperaccumulator plants is a promising remediation strategy. This study investigated the effects of TiO2 NPs on Cd uptake and accumulation in the hyperaccumulator ramie (Boehmeria nivea L.) grown in Cd-spiked soil. The aim was to evaluate the potential application of TiO2 NPs to enhance the phytoextraction efficiency of ramie for removing Cd from contaminated soils. Ramie was cultivated in soil spiked with 5 mg/kg Cd, with or without 500 mg/kg TiO2 NPs. The results showed TiO2 NPs significantly increased Cd concentrations in roots, stems, and leaves of ramie by 35%, 75%, and 278% respectively, compared to control plants. Cd levels reached 146 mg/kg in roots and 102 mg/kg in leaves with TiO2 NPs. The bioconcentration factor rose from 21.6 to 29.2 and translocation factor from 0.3 to 0.7 with nanoparticles. This indicates TiO2 NPs increased Cd bioavailability in soil and translocation to shoots. The higher Cd accumulation, especially in leaves, demonstrates the potential of TiO2 NPs to improve ramie's phytoextraction capacity. With TiO2 NP treatment, soil Cd levels decreased by an estimated 20-30% after 8 weeks of ramie cultivation, indicating enhanced phytoextraction. This study provides evidence that the application of TiO2 NPs can enhance the efficiency of phytoremediation using hyperaccumulator plants like ramie for remediation of Cd-contaminated soils.