In this study, removal of Ni and Cu ions from aqueous media was assessed by the adsorption of Al₂O₃ nanoparticles (ANPs), with surface modification by natural organic matter (NOM). The obtained materials (NOM–ANPs) were characterized by Fourier transform infrared spectroscopy. Then, batch adsorption methods were carried out as a function of contact time, adsorbate concentration, pH and temperature. Kinetic experiments revealed that the pseudo-second-order model exhibited the best correlation with the adsorption data, the estimated maximum adsorption capacity of Ni and Cu could reach 15.38 and 62.50 mg g⁻¹ respectively at 303 K, displaying higher efficiency for Ni and Cu removal than previously reported adsorbent materials reported in the literature. Thermodynamic studies exposed the feasibility and endothermic nature of the system. The experimental results show the technical feasibility of NOM–ANPs, its easy synthesis, economic and a promising advanced adsorbent in environmental pollution cleanup.

This study aims to explore the stability of TiO₂ nanoparticles in soil suspensions and their transport behavior through real soil columns. A classical filtration theory was used to describe transport behaviors of TiO₂ nanoparticles. The results illustrated that TiO₂ nanoparticles could remain suspended in soil suspensions even after settling for 8 d. At comparatively higher dissolved organic matter (DOM) and low ionic strength (IS) containing soils, considerable portion of TiO₂ nanoparticles (32–34%) suspensions was observed in sedimentation experiments after 24 h. In addition, zeta potential (ZP) of soil suspensions as a function of soil pH, suggested that ZP played significant role than soil pH. In soils containing comparatively higher DOM, a considerable portion of TiO₂ nanoparticles (51.8–90.6%) readily passed through soils columns, while TiO₂ nanoparticles were retained by soils with comparatively higher ISs. The estimated travel distances of TiO₂ nanoparticles in soils ranged from 45.03 to 625.86 cm, representing potential environmental risk of TiO₂ nanoparticles to the environment.