Nanocatalytic-Phytoremediation Synergistic Strategy: Functional Carbon Nanodots Enhancing Nonylphenol Biodegradation in Contaminated Soil

The remediation of nonylphenol (NP)-contaminated soils remains challenging due to NP’s persistence and ecotoxicity. Here, we present a sustainable nano-phytoremediation strategy that integrates functional carbon nanodots (FCNs) with Tagetes patula L. to effectively enhance phytoremediation efficiency. FCNs at 20 mg kg⁻¹ demonstrated improvements of 55.9% and 118.3% compared to Tagetes patula L. alone in soils contaminated with 5 mg kg⁻¹ and 50 mg kg⁻¹ NP, respectively. The maximum remediation efficiencies for NP in the FCNs-Tagetes patula L. synergistic system reached 77.0% and 59.0% in these two NP-contaminated soils. The synergistic mechanisms underlying FCN-mediated enhancement of phytoremediation were systematically investigated through three dimensions: nano-catalytic degradation pathways, endogenous regulation of plant physiology, and exogenous modulation of rhizosphere microenvironment. First, FCNs functioned as nanocatalysts to facilitate the NP oxidative decomposition via their unique chemical properties. Second, FCNs enhanced the tolerance, biodegradation efficiency, and ornamental value of Tagetes patula L. by activating NP-degradation pathways and alleviating NP-induced stress. Third, FCNs improved soil self-purification capacity by optimizing rhizosphere soil properties and microenvironment through up-regulating physiochemical properties, enzymatic activities, and beneficial microbiome recruitment. This study clarifies the fate of FCNs and NP in plant-soil system and establishes an innovative FCNs-phytoremediation synergy for effective soil remediation.