Biomaterial Database

Adsorption of humic acid onto nanoscale zerovalent iron and its effect on arsenic removal. 2007

Abul B M Giasuddin, and Sushil R Kanel, and Heechul Choi

Department of Environmental Science and Engineering, Gwangju Institute of Science and Technology (GIST), 1 Oryong-dong, Buk-Gu, Gwangju 500-712, Korea.

Batch experiments were performed to investigate the feasibility of humic acid (HA) removal by synthetic nanoscale zerovalent iron (NZVI) and its interaction with As(III) and As(V), the most poisonous and abundant of groundwater pollutants. High-resolution transmission electron microscopy (HR-TEM) and X-ray diffraction (XRD) were used to characterize the particle size, surface morphology of the pristine NZVI and HA-treated NZVI (NZVI-HA), and the zero valence state of the pristine NZVI. It was determined that HA was completely removed by NZVI (0.3 g/L) within a few minutes, at a wide range of initial pH values (approximately 3.0-12.0). Fourier transform infrared (FTIR) and laser light scattering (zeta potential measurement) studies confirmed that NZVI-HA forms inner-sphere surface complexation at different initial pH conditions. The effects of competing anions showed that there was complete removal of HA in the presence of 10 mM NO(-3) and SO4(2-) whereas HA removal was observed 0%, 18% and 22% in presence of 10 mM H2PO4(2-), HCO(3-) and H4SiO4(0), respectively. However, the presence of 2 mM CA2+ and Mg2+ enhanced HA removal from 17 mg g(-1) to 76 mg g(-1) and 55 mg g(-1), respectively. Long-term time-resolved studies of XRD and field emission scanning electron microscopy (FE-SEM) with energy-dispersive X-ray (EDX) revealed the formation of various types of new iron oxides (magnetite, maghemite, and lepidocrocites) during the continuous reaction of HA in the presence of water and NZVI at 1, 30, 60, and 90 days. In addition, the surface-area-normalized rate constant (ksa) of adsorption of As(III) and As(V) onto NZVI was reduced in the presence of HA (20 mg L(-1)), from 100% to 43% and 68%, respectively. Our results show the potential use of NZVI in removing HA and its possible effects on arsenic removal during the application of NZVI in groundwater remediation.

UI	MeSH Term	Description	Entries
D007501	Iron	A metallic element with atomic symbol Fe, atomic number 26, and atomic weight 55.85. It is an essential constituent of HEMOGLOBINS; CYTOCHROMES; and IRON-BINDING PROTEINS. It plays a role in cellular redox reactions and in the transport of OXYGEN.	Iron-56,Iron 56
D008854	Microscopy, Electron	Microscopy using an electron beam, instead of light, to visualize the sample, thereby allowing much greater magnification. The interactions of ELECTRONS with specimens are used to provide information about the fine structure of that specimen. In TRANSMISSION ELECTRON MICROSCOPY the reactions of the electrons that are transmitted through the specimen are imaged. In SCANNING ELECTRON MICROSCOPY an electron beam falls at a non-normal angle on the specimen and the image is derived from the reactions occurring above the plane of the specimen.	Electron Microscopy
D010316	Particle Size	Relating to the size of solids.	Particle Sizes,Size, Particle,Sizes, Particle
D006812	Humic Substances	Organic matter in a state of advanced decay, after passing through the stages of COMPOST and PEAT and before becoming lignite (COAL). It is composed of a heterogenous mixture of compounds including phenolic radicals and acids that polymerize and are not easily separated nor analyzed. (E.A. Ghabbour & G. Davies, eds. Humic Substances, 2001).	Humic Acid,Humic Acids,Humic Substance,Sodium Huminate,Acid, Humic,Acids, Humic,Huminate, Sodium,Substance, Humic,Substances, Humic
D006863	Hydrogen-Ion Concentration	The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH	pH,Concentration, Hydrogen-Ion,Concentrations, Hydrogen-Ion,Hydrogen Ion Concentration,Hydrogen-Ion Concentrations
D000327	Adsorption	The adhesion of gases, liquids, or dissolved solids onto a surface. It includes adsorptive phenomena of bacteria and viruses onto surfaces as well. ABSORPTION into the substance may follow but not necessarily.	Adsorptions
D001151	Arsenic	A shiny gray element with atomic symbol As, atomic number 33, and atomic weight 75. It occurs throughout the universe, mostly in the form of metallic arsenides. Most forms are toxic. According to the Fourth Annual Report on Carcinogens (NTP 85-002, 1985), arsenic and certain arsenic compounds have been listed as known carcinogens. (From Merck Index, 11th ed)	Arsenic-75,Arsenic 75
D014874	Water Pollutants, Chemical	Chemical compounds which pollute the water of rivers, streams, lakes, the sea, reservoirs, or other bodies of water.	Chemical Water Pollutants,Landfill Leachate,Leachate, Landfill,Pollutants, Chemical Water
D014961	X-Ray Diffraction	The scattering of x-rays by matter, especially crystals, with accompanying variation in intensity due to interference effects. Analysis of the crystal structure of materials is performed by passing x-rays through them and registering the diffraction image of the rays (CRYSTALLOGRAPHY, X-RAY). (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)	Xray Diffraction,Diffraction, X-Ray,Diffraction, Xray,Diffractions, X-Ray,Diffractions, Xray,X Ray Diffraction,X-Ray Diffractions,Xray Diffractions
D017550	Spectroscopy, Fourier Transform Infrared	A spectroscopic technique in which a range of wavelengths is presented simultaneously with an interferometer and the spectrum is mathematically derived from the pattern thus obtained.	FTIR,Fourier Transform Infrared Spectroscopy,Spectroscopy, Infrared, Fourier Transform