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Removal of Arsenic(III) from Groundwater using Low-Cost Industrial By-products-Blast Furnace Slag
Kanel, Sushil Raj,Choi, Heechul,Kim, Ju-Yong,Vigneswaran, Saravanamuthu,Shim, Wang Geun IWA Publishing 2006 Water quality research journal Vol.41 No.2
<P>Blast furnace slag (BFS), a steel industrial by-product, was tested for the removal of As(III), which is a highly toxic, mobile and predominant species in anoxic groundwater. Batch adsorption experiments were performed to determine the feasibility of BFS as an adsorbent for removing As(III) from groundwater as As(III) concentration and the pH of water were varied. The maximum As(III) adsorption capacity by BFS was 1.40 mg As(III)/g of BFS at 1 mg/L As(III) initial concentration, at 25°C, which was calculated using the Langmuir isotherm. The homogeneous surface diffusion model (HSDM) was successfully applied to predict the sorptive removal of As(III) onto the BFS. Kinetic studies indicated that the film diffusion as well as surface diffusion of As in the BFS was involved. It was found that the film diffusion coefficient (k<SUB>f</SUB>) was 5.27 × 10<SUP>-5</SUP> to 4.06 × 10<SUP>-6</SUP> m/s and surface diffusion coefficient (Ds) was 2.31 × 10<SUP>-14</SUP> to 7.13 × 10<SUP>-14</SUP> m<SUP>2</SUP>/s for the initial As(III) concentrations of 0.1 to 100 mg/L. Oxidation of As(III) to As(V) and its adsorption/precipitation onto BFS is involved during the As(III) removal mechanism. It was also found that H<SUB>4</SUB>SiO<SUB>4</SUB><SUP>0</SUP>, PO<SUB>4</SUB><SUP>3-</SUP>, NO<SUB>3</SUB><SUP>-</SUP>, SO<SUB>4</SUB><SUP>2-</SUP> and HCO<SUB>3</SUB><SUP>-</SUP> are potential interferences in the As(III) adsorption reaction. Results suggest that 99.9% As(III) at 1 mg/L can be removed by 10 g/L BFS, which can be used as a permeable reactive barrier (PRB) material to remove As(III) from groundwater. Details of As(III) adsorption and coprecipitation systems and interferences of As(III) molecular interactions were also studied.</P>
Transport characteristics of surface-modified nanoscale zero-valent iron in porous media
Kanel, S.R.,Choi, H. IWA Publishing 2007 Water Science & Technology Vol.55 No.1
<P>Highly efficient, versatile, adsorbent, nanoscale zero-valent iron (NZVI) was synthesised and encapsulated by an anionic polymer to make it a mobile delivery vehicle (DV-NZVI) for in-situ groundwater and soil remediation. NZVI was found to be highly dispersed with surfactant within a size of 1-100 nm. Laboratory column experiments were conducted by employing glass beads as a porous medium to delineate the characteristics of DV-NZVI transport as a reactive material in saturated zones under a number of conditions. It was observed that there was an optimum concentration of polymer, i.e. 6 g/L, for maximum transport of DV-NZVI, at which point, as the flow rate increases, the transport of DV-NZVI increases. Similarly, at the optimum concentration we observed that as the depth of porous media increased, the breakthrough of DV-NZVI was retarded. These results confirmed that DV-NZVI has significant potential for use as a colloidal reactive barrier material in deep groundwater systems in lieu of pump and treat approaches and conventional permeable reactive barriers (PRB).</P>
Women’s Political Representation in Nepal : An Experience from the 2008 Constituent Assembly
Tara KANEL Asian Center for Women's Studies : Ewha Womans Uni 2014 Asian Journal of Women's Studies(AJWS) Vol.20 No.4
In Nepal, a constituent assembly was elected in 2008 to draft a new constitution for the nation. The assembly worked for four years but was dissolved without completing its task. Nonetheless, it had made decisions on most constitutional provisions apart from the provision of federal structures. Political forces agreed thereafter that the new assembly will create a constitution based on the constitutional provisions decided by the dissolved assembly. Women comprised almost 33 percent of the constituent assembly in 2008. However, to what extent did the presence of a ‘critical mass’ of women in the assembly contribute to progress towards gender equality? This article, reviews existing literature, with a view toquery the effects of ‘critical mass,’ arguing that despite the sizeable presence of women in the assembly, they were unable to influence the culture of this male-dominated political institution. The alliance among women for advancing women’s interests was far from possible. In this respect, the assembly was not very different from the parliaments of the past, which only had a nominal women’s representation. The size of women’s presence has no particular relationship with a ‘women-friendly’ policy in Nepal, no more than seen in the studies of western parliaments.
Application of Surface Modified Iron Nano Particle in Groundwater Remediation
Sushil Raj Kanel,Hee Chul Choi 대한환경공학회 2005 대한환경공학회 학술발표논문집 Vol.2005 No.12
A highly efficient and versatile adsorbent, iron-nano-particle (INP) was synthesized in laboratory and stabilized by surfactant to make it mobile which is termed as surfactant stabilized iron nano particle (S-INP). The INP was dispersed in an aqueous phase in water using sonication to obtain S-INP. From scanning electron microscope (SEM), transmission electron microscopy (TEM) and atomic force microscope (AFM) its size and morphology was analyzed. X-Ray Diffraction and X-Ray photoelectron spectroscopy confirmed the chemical composition. The transport of S-INP was studied in laboratory column experiments by employing various porous media to delineate the characteristics of S-INP transport in the porous media under various experimental conditions. The potential application of S-INP for soil and groundwater treatment was tested with arsenic (As), which is highly toxic and carcinogenic element exists in groundwater. The results confirmed that S-INP has great potential to be used as an adsorbent for in-situ as well as for ex-situ treatment for arsenic remediation.
Removal of Arsenate from Groundwater by Nano Scale Zero-Valent Iron
Sushil Raj Kanel,최희철(Hee Chul Choi) 대한환경공학회 2005 대한환경공학회 학술발표논문집 Vol.2005 No.12
A highly efficient, versatile adsorbent, Nano-scale zero valent iron (NZVI) was synthesized and tested for the removal of aqueous phase arsenate, As(V), which is a highly toxic, mobile, and predominant arsenic species in oxidizing and aerobic groundwater. Batch experiments were performed to determine the feasibility of NZVI as an adsorbent for As(V) at neutral pH. The kinetics of As(V) sorption was found to be rapid and occurred on a scale of minutes. Initial As(V) concentration (1 mg/L) was almost completely adsorbed by 0.1 gL(-1) NZVI within 10 min. Laser light scattering (electrophoretic mobility measurement) confirmed NZVI-As (V) inner-sphere surface complexation. The sorption ability of NZVI was also monitored for 2 months to check for its long-term potential use as a colloidal reactive barrier material in deep groundwater treatment. We used SEM, BET surface area analyzer, and XRD to characterize particle size and morphology, specific surface area, and corrosion layers formed on pristine NZVI and As(V)-treated NZVI. Hydride Generator Atomic Absorption Spectrophotometer determined arsenic. The results confirmed that NZVI has great potential to be used in ex-situ as well as in-situ remediation as a colloidal reactive barrier material in lieu of pump and treat approaches.
S. R. Kanel,A. B. M. Giasuddin,Hee Chul Choi 대한환경공학회 2004 대한환경공학회 학술발표논문집 Vol.2004 No.12
Zero-valent iron (ZVI) and a byproduct of steel industry, oxygen gas sludge (OGS), were tested for the removal of As(Ⅲ), which is a highly toxic, mobile and predominant arsenic species in anoxic groundwater. Batch experiments were performed to determine the feasibility of ZVI and OGS as an adsorbent for As(Ⅲ) treatment in groundwater at wide range of pH 3-12. Kinetic studies have been described with the mechanism of adsorption. The effects of competing anions showed HCO₃(-), H₄SiO₄(0), and H₂PO₄<sup>2-</sup> are potential interferences in the As(Ⅲ) adsorption reaction. Our results suggest that OGS and ZVI is a suitable candidate for in-situ groundwater treatment as a permeable reactive barrier material.