Remediation of heavy metals in contaminated soil by using nano-bentonite, nano-hydroxyapatite, and nano-composite

Soil and water contaminants have an impact on ecosystems, agricultural productivity, groundwater, and human health. Therefore, it is necessary to develop new technologies to treat pollution, one of these techniques is the use of nanomaterials (NMs). This study aimed to evaluate the efficiency of bentonite nano-sheet structure (n-Be), hydroxyapatite nanoparticles (HapNP), and their nano-composite (n-Be/HapNC) on immobilizing nickel (Ni), copper (Cu), and lead (Pb) in peanut-cultivated soil. The prepared materials were characterized by X-ray powder diffraction, atomic force microscopy, surface area, and Fourier transform infrared. Eight levels of material were used T1 (bentonite, 1 t ha(-1)), T2 (hydroxyapatite, 1 t ha(-1)), T3 (HapNPs, 50 kg ha(-1)), T4 (HapNPs, 100 kg ha(-1)), T5 (n-Be, 50 kg ha(-1)), T6 (n-Be, 100 kg ha(-1)), T7 (n-Be/HapNC, 50 kg ha(-1)), and T8 (n-Be/HapNC, 100 kg ha(-1)). The results indicated that the available Ni, Cu, and Pb showed a significant decline in the treated soil, in comparison to untreated. Levels of Ni exhibited a decrease in the following order: T8 < T6 < T7 < T5. Similar patterns were observed for Cu and Pb levels, where treatment T8 exhibited the greatest decline compared to the control. Uptake of heavy metals (HM) by peanut components (leaves, stems, and seeds) showed significant declines for the treatments, compared to the control. Treatment (n-Be/HapNC, 100 kg ha(-1)) showed the lowest transfer coefficient of Ni (0.53) and Cu (0.048) compared to control (0.71 and 0.097), respectively. Treatments of NMs significantly exhibited increases in fresh weight, pods, and seeds, compared to the control. From all findings, it is obtained that nano-forms of such materials can immobilize HM in contaminated soil, enhance its characteristics, decrease HM-uptake by plants, and are considered good immobilizers for HM in soil. These materials play a role in treating contaminated soil and thus making it suitable for agriculture.

Automated summary

The use of nanomaterials such as bentonite nano-sheet structure, hydroxyapatite nanoparticles, and their nano-composite has been proven to be effective in immobilizing nickel, copper, and lead in contaminated soil, reducing heavy metal uptake by plants, and improving crop growth and yield.