The Role of Graphene Oxide and Zinc Oxide Nanoparticles in Enhancing the Effectiveness of Phytoremediation of Petroleum Hydrocarbon-Contaminated Soils Using Lolium perenne

Nanomaterials are gaining increasing importance in various scientific and technological fields, including ecological strategies for environmental remediation, such as the treatment of soils contaminated with petroleum hydrocarbons. This study aimed to evaluate the effectiveness of hydrocarbon-contaminated soil remediation using graphene oxide nanoparticles (GO-NPs) and zinc oxide nanoparticles (ZnO-NPs) in combination with bacterial consortium inoculation and phytoremediation with <i>Lolium perenne</i>. The study was conducted in two stages: laboratory-scale biodegradation experiments and semi-technical scale phytoremediation. The laboratory stage determined optimal nanomaterial doses based on respirometric and chromatographic analyses. During phytoremediation, the contents of total petroleum hydrocarbons (TPHs) and polycyclic aromatic hydrocarbons (PAHs) in soil, roots, and shoots were monitored. Biomass growth was recorded, and environmental toxicity was assessed using Phytotoxkit, Microtox, and Ostracodtoxkit tests. The addition of nanomaterials significantly enhanced soil remediation, with improvements in TPH and PAHs removal resulting from microbial biodegradation in both stages and, additionally, in the phytoremediation stage, from phytoextraction by plants. TPH biodegradation reached up to 81.85% in GO-NP variants and 80.9% in ZnO-NP treatments, while PAHs reached 73.19% and 70.66%, respectively. The biomass of <i>Lolium perenne</i> increased by 28.63% in GO-NP variants and by 22.21% in ZnO-NP treatments compared to the control. Total accumulation of TPH increased by 80.86% and 74.15%, and PAHs by 71.26% and 65.35%. Nanomaterial-amended variants also showed a reduction in toxicity units to 2.50-3.30. These results indicate that combining nanomaterials with bioaugmentation significantly enhances phytoremediation efficiency while reducing soil toxicity.