Table 6.
Contaminant | Salt; Concentration | nTiO2 Crystalline Phase; Concentrations Used; Primary (PS) or Hydrodynamic Size (HS) | Plant Species | Application Method | Ameliorative Effects | Ref. |
---|---|---|---|---|---|---|
Cu | CuSO4·5H2O; 1, 2 mg L−1 |
Anatase; 10 mg L−1; HS 374 nm (1 h in suspension); HS 1064 nm (48 h in suspension) | Glycine max L. | Hydroponic system (6 days) | Decreased the translocation factor of Cu | [159] |
Pb | Pb(NO3); 10 mg kg−1 |
P25; 5 mg kg−1; HS ~130 nm | Lactuca sativa L. | In soil (12 days) | Decreased the relative membrane permeability; increased pigment contents; promoted gas exchange, including the net photosynthetic rate | [155] |
Al | AlCl3·6H2O; 50 mg kg−1 |
P25; 5 mg kg−1; HS ~130 nm | Lactuca sativa L. | In soil (12 days) | Decreased the relative membrane permeability; promoted gas exchange; increased the effective efficiency of photosystem II | [155] |
Sb | K2H2Sb2O7⋅4H2O; not stated |
Not stated; 100–250 mg kg−1; PS 15–40 nm | Sorghum bicolor | In soil (80 days) | Increased the germination rate | [156] |
As | Sodium arsenate; 10 µmol L−1 |
Not stated; Chemical NPs: 2500 mg L−1; HS 64.3 nm. Green NPs: 1000 mg L−1; HS 53.2 nm | Vigna radiata L. | Seeds treated prior germination and during the germination period | Increased biomass and seedling length; decreased H2O2 and MDA contents; increased the protein content, and gene expression of SOD and CAT | [166] |
2,4-Dichloro phenoxyacetic acid | 1000 µM | Not stated; PS < 100 nm; HS 260 nm | Azolla pinnata R.Br | Pre-treatment with TiO2 (3 days) followed by exposure to 2,4-D in a hydroponic system | Modulated K, N, P accumulation; increased biomass; increased the activity of the enzyme invertase; promoted the nitrogen metabolism | [167] |
Tetracycline | 1, 5, 10 mg L−1 | Rutile; 40, 100, 200 mg L−1; PS 5–15 nm | Arabidopsis thaliana L. | Hydroponic system (12 days) | Increased fresh biomass (40 mg L−1); altered the activity of antioxidant enzymes; changed the expression of genes encoding GST, MDHAR, GR, SiR, APR, APT | [161] |
5–20 mg L−1 | Anatase; 500, 1000, 2000 mg L−1; PS 10–25 nm | Oryza sativa L. | Hydroponic system (10 d) | Increased shoot and root biomass; decreased tetracycline content in shoots and roots; modulated nutrient accumulation; decreased antioxidant enzymes activity; showed antagonist effect with tetracycline | [160] |