Degradation of 2,4-D in soils by Fe sub(3)O sub(4) nanoparticles combined with stimulating indigenous microbes

• Published in: Environmental science and pollution research international Vol. 19; no. 3; pp. 784 - 793
• Main Authors: Fang, Guodong, Si, Youbin, Tian, Chao, Zhang, Gangya, Zhou, Dongmei
• Format: Journal Article
• Language: English
• Published: 01.03.2012
• ISSN: 0944-1344; 1614-7499
• DOI: 10.1007/s11356-011-0597-y

Purpose: Degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) in soils by Fe sub(3)O sub(4) nanoparticles combined with soil indigenous microbes was investigated, and the effects of Fe sub(3)O sub(4) nanoparticles on soil microbial populations and enzyme activities were also studied. Methods: The soils contaminated with 2,4-D were treated with Fe sub(3)O sub(4) nanoparticles. The microbial populations and enzyme activities were analyzed by dilution plate method and chemical assay, respectively, and the concentration of 2,4-D in soil was determined by high-performance liquid chromatography (HPLC). Results: The results indicated that Fe sub(3)O sub(4) nanoparticles combined with soil indigenous microbes led to a higher degradation efficiency of 2,4-D than the treatments with Fe sub(3)O sub(4) nanoparticles or indigenous microbes alone. The degradation of 2,4-D in soils followed the pseudo first-order kinetic. The half-lives of 2,4-D degradation (DT sub(50)) of the combined treatments were 0.9, 1.9 and 3.1 days in a Red soil, Vertisol and Alfisol, respectively, which implied that the DT sub(50) of the combination treatments were significantly shorter than that of the treatments Fe sub(3)O sub(4) nanoparticles or indigenous microbes alone. The effects of Fe sub(3)O sub(4) nanoparticles on soil microbial populations and enzyme activities were also investigated and compared with the alpha -Fe sub(2)O sub(3) nanoparticles. The results suggested that the alpha -Fe sub(2)O sub(3) nanoparticles had only comparatively small effects on degradation of 2,4-D in soils, while the Fe sub(3)O sub(4) nanoparticles not only degraded 2,4-D in soils but also increased the soil microbial populations and enzyme activities; the maximum increase in enzyme activities were 67.8% (amylase), 53.8% (acid phosphatase), 26.5% (catalase) and 38.0% (urease), compared with the untreated soil. Moreover, the introduction of Fe sub(3)O sub(4) nanoparticles at the different dosage resulted in a variable degradation efficiency of 2,4-D in soil. Conclusion: The method of combining Fe sub(3)O sub(4) nanoparticles with indigenous soil microbes may offer great benefits for the application of nanotechnology in remediation of herbicide contaminated soil.