Naked oats biochar-supported nanoscale zero-valent iron composite: effects on Cd immobilization and enzyme activities in Ulansuhai River sediments of China
- 203 Downloads
This investigation aimed to synthesize biochar-supported nanoscale zero-valent iron (BC-nZVI) to immobilize cadmium (Cd) in contaminated sediments of shallow grass-type rivers in typical cold and arid regions in northern China and reduce the bioavailability of Cd. Besides, the influence of multiple factors on the immobilization effect was discussed. In particular, the effects of the addition of humic acid (HA) on the fraction of Cd and enzyme activities were investigated.
Materials and methods
In this study, BC-nZVI was synthesized and all materials were characterized by field emission scanning electron microscopy (FESEM), energy dispersive spectrometer (EDS), x-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The remediation effect of BC-nZVI on Cd-contaminated sediments was evaluated through sequential extraction experiments. Batch tests such as experiments of iron-to-carbon ratio, dosage, and incubation time were examined; the effect of HA concentration on Cd immobilization was highlighted, and corresponding enzyme activities (catalase, urease, and alkaline phosphatase) were tested for further illustration.
Results and discussion
BC-nZVI could immobilize Cd efficiently, with the maximum residual percentage of Cd increasing by 19.57 to 81.98% after 35 days of incubation, at 1:3 iron-to-carbon ratio and 0.05 g dosage. Sequential extraction experiments indicated that most labile fractions of Cd were transformed into stable fraction. When 10 and 20 mg kg−1 HA were added, immobilization was enhanced, and residual fraction increased to 89.43% and 88.70%, respectively. Meanwhile, exclusive of catalase, the activities of urease and alkaline phosphatase were enhanced with increased incubation time.
This study proved that BC-nZVI has a significant effect on Cd immobilization. The addition of HA greatly promoted the immobilization of Cd and enzyme activities in sediments. In conclusion, BC-nZVI is an effective substance that can be used to remediate sediments contaminated with heavy metals.
KeywordsBiochar Cadmium Enzyme activities Humic acid Nanoscale zero-valent iron
This study was financially supported by the National Natural Science Foundation of China (No. 21107041), the Young and Middle-Aged Academic Backbone Program of the Inner Mongolia University of Technology, the Natural Science Foundation of Inner Mongolia (No. 2017MS0216), and the Department of Education of Inner Mongolia Autonomous Region (No. NJZY17095).
- Calderon B, Fullana A (2015) Heavy metal release due to aging effect during zero valent iron nanoparticles remediation. Water Res 83:1–9Google Scholar
- Cheng H, Li M, Zhao C, Yang K, Li K, Peng M, Yang Z, Liu F, Liu Y, Bai R, Cui Y, Huang Z, Li L, Liao Q, Luo J, Jia S, Pang X, Yang J, Yin G (2015) Concentrations of toxic metals and ecological risk assessment for sediments of major freshwater lakes in China. J Geochem Explor 157:15–26CrossRefGoogle Scholar
- Cumbal L, Greenleaf J, Leun D, SenGupta A (2003) Polymer supported inorganic nanoparticles: characterization and environmental applications. React Funct Polym 54(1–3):167–180Google Scholar
- Nemati K, Abu Bakar NK, Abas MR, Sobhanzadeh E (2011) Speciation of heavy metals by modified BCR sequential extraction procedure in different depths of sediments from Sungai Buloh, Selangor, Malaysia. J Hazard Mater 192:402–410Google Scholar
- Sarwar N, Saifullah MSS, Zia MH, Naeem A, Bibi S, Farid G (2010) Role of mineral nutrition in minimizing cadmium accumulation by plants. J Sci Food Agric 90:925–937Google Scholar
- Su Y, Adeleye A, Huang Y, Sun X, Dai C, Zhou X, Zhang Y, Keller A (2014) Simultaneous removal of cadmium and nitrate in aqueous media by nanoscale zerovalent iron (nZVI) and Au doped nZVI particles. Water Res 63:102–111Google Scholar
- Xue W, Huang D, Zeng G, Wan J, Zhang C, Xu R, Cheng M, Deng R (2018) Nanoscale zero-valent iron coated with rhamnolipid as an effective stabilizer for immobilization of Cd and Pb in river sediments. J Hazard Mater 341:381–389Google Scholar