Prevalence of Arsenicosis in Terai, Nepal

This paper summarizes the findings of surveys on arsenicosis cases conducted during 2001-2004 in terai, Nepal, by governmental and non-governmental organizations in their respective project areas and by some national and international institutes. Studies were conducted in six arsenic-contaminated districts of terai, namely Nawalparasi, Bara, Parsa, Rautahat, Rupandehi, and Kapilvastu. In these districts, arsenic contamination in tubewells varied from 2.1% to 25.7%. The prevalence of arsenicosis was, on average, 2.2% and varied from 0.7% in Kapilavastu district to 3.6% in Nawalparasi district. In the community-based study, the highest prevalence (18.6%) of arsenicosis was found in Patkhouli village of Nawalparasi, where 95.8% of tubewells were contaminated with arsenic. The prevalence of arsenicosis was higher in older age-groups (>50 years) of both the sexes. Males suffered more from arsenicosis than females (odds ratio: 2.50, 95% confidence interval 1.80-3.47). Skin manifestations, such as melanosis and keratosis, were the common symptoms of arsenicosis. Most patients were identified in the early or mild stage of the disease. They are expected to recover if further exposure to arsenic could be avoided by providing arsenic-safe drinking-water through intervention measures

Conversion of carbon based food wastes to electrodes for energy storage applications

The global energy demand has escalated during last few decades due to the population growth, urbanization and industrialization. On the other side, rapid and continuous exploitation of non-renewable fossil fuels have raised the concerns on environmental degradation. This necessitates developing efficient energy storage systems besides energy production to help match the supply and demand. Carbon materials have been extensively studied as electrodes for energy storage applications. However, carbon materials used as electrodes in commercial energy storage systems at present are derived from non-renewable fossil fuels. Thus, there is need to explore alternative sustainable carbon precursors. This will help reduce the sole dependency on nonrenewable fossil fuels and also contribute in creating healthy environment. Biomass are rich in carbon content, and are low cost, easily available, abundant, renewable and environmentally-friendly. Food waste is an inevitable by-product produced in different stages of the food supply chain. Fruit peels waste as bio-waste are neglected reusable resource which offer a big potential for employing it as precursor for the production of value-added products such as porous carbons. Therefore, comprehensive study is needed to evaluate the potential of employing this underutilized sustainable resource for preparation of value-added useable products such as porous carbon. Further investigations are also needed to evaluate the electrochemical performance of these carbons as electrodes for energy storage applications, and development of high performance energy storage devices. This has motivated this study to explore fruit peels waste as precursor materials for energy storage applications such as vanadium redox flow battery (VRB) and high energy supercapacitors. High surface area activated carbons (ACs) were synthesized by carbonization followed by chemical activation from the five screened precursors, and the assynthesized ACs were subjected to extensive characterizations. Two AC samples synthesized from orange peels waste and lychee peels waste were further screened for evaluating them as electrode materials for energy storage applications. The orange peel-derived ACs modified graphite electrodes demonstrate improved electrocatalytic activity in both positive and negative side redox couples compared with the pristine graphite electrode. The improved electrode activities are attributed to the synergistic effects of high surface area of the ACs and rich oxygen functionalities on the surface of ACs. The results suggest the OP-ACs to be promising electrodes for VRB applications and can be incorporated into making conducting plastics electrode to lower the VRB cell stack weight and cost. The lithium ion capacitors (LICs) fabricated using OP-AC2 with pre-lithiated graphite (LiC6) delivered specific energy of ~106 Wh kg–1 . A systematic improvement from the specific energy of ~8 to 106 Wh kg–1 is noted from aqueous to LIC assembly. The other porous carbon synthesized from lychee peel waste (LP-AC) with surface area of 1601 m2 g -1 was evaluated as electrode material for supercapacitors in symmetric (LP-AC||LP-AC) and asymmetric (Gr/PANI||LP-AC) cell configurations. Performance tests showed that the asymmetric cell assembly could deliver specific capacitance of ~141 F g-1 at 0.5 A g-1 and specific energy to ~50 Wh kg-1 as compared to the specific capacitance of 105 F g-1 at a current density of 0.25 A g–1 and specific energy of 9.4 Wh kg-1 for the symmetric cell configuration. The asymmetric cell also showed good cycling stability with ~88% of the initial specific capacitance retained after 5000 cycles. To sum up, this study successfully demonstrated the feasibility of converting selected fruit peels waste to value-added porous carbons as promising electrodes for energy storage applications. For the first time, this study evaluated performance of the OP-AC and the T-OP-AC modified electrodes for VRB applications. The fabrication of whole LIC assembly using OP-AC to deliver high energy was also reported for the first time. For the first time, the porous AC synthesized from a new precursor, i.e. lychee peel, was reported as pseudocapacitive electrode for aqueous supercapacitors. The utilization of this renewable resource contributes not only in waste management but also generates value-added products for promising applications, and contribute in reducing sole dependency on fossil fuels for energy.Doctor of Philosophy (CEE

Prevalence of Arsenicosis in Terai, Nepal

This paper summarizes the findings of surveys on arsenicosis cases conducted during 2001-2004 in terai, Nepal, by governmental and non-governmental organizations in their respective project areas and by some national and international institutes. Studies were conducted in six arsenic-contaminated districts of terai, namely Nawalparasi, Bara, Parsa, Rautahat, Rupandehi, and Kapilvastu. In these districts, arsenic contamination in tubewells varied from 2.1% to 25.7%. The prevalence of arsenicosis was, on average, 2.2% and varied from 0.7% in Kapilavastu district to 3.6% in Nawalparasi district. In the community-based study, the highest prevalence (18.6%) of arsenicosis was found in Patkhouli village of Nawalparasi, where 95.8% of tubewells were contaminated with arsenic. The prevalence of arsenicosis was higher in older age-groups (>50 years) of both the sexes. Males suffered more from arsenicosis than females (odds ratio: 2.50, 95% confidence interval 1.80-3.47). Skin manifestations, such as melanosis and keratosis, were the common symptoms of arsenicosis. Most patients were identified in the early or mild stage of the disease. They are expected to recover if further exposure to arsenic could be avoided by providing arsenic-safe drinking-water through intervention measures

Sal wood sawdust derived highly mesoporous carbon as prospective electrode material for vanadium redox flow batteries

This work reports the development of a prospective electrode material for the use in vanadium redox flow batteries. The developed electrode material was a high surface area activated carbon (1857 m² g⁻¹) with a large mesoporosity (1280 m² g⁻¹) that was derived using biomass residues, Sal wood sawdust (Shorea robusta), as a feedstock. The physico-chemical and electrochemical properties of Sal wood sawdust activated carbon were extensively characterized applying cyclic voltammetry and electrochemical impedance spectroscopy. The graphite plate electrode based on Sal wood sawdust activated carbon exhibited higher electro-catalytic activity and lower charge transfer resistance towards both positive and negative redox couples than when applying pristine graphite plate electrode. Further investigations on the application of static cell at higher current densities (20–80 mA cm²) revealed higher efficiencies for the Sal wood sawdust activated carbon modified graphite plate electrode in comparison with the pristine graphite plate electrode. Thus, the Sal wood sawdust can be suitable as carbon precursor for preparation of electrodes to be utilized in practical applications, such as in vanadium redox flow batteries.Economic Development Board (EDB)Nanyang Technological UniversityThe authors would like to thank Moe Ohnmar Oo (Laboratory Manager), Arjun Bhatarai and Purna C. Ghimire from Energy Research Institute @Nanyang Technological University (ERI@N) for the cooperation in this research. Finally, the authors acknowledge the Nanyang Environment and Water Research Institute, Nanyang Technological University (Singapore) and Economic Development Board (Singapore) for financial support of this research

Sal wood sawdust derived highly mesoporous carbon as prospective electrode material for vanadium redox flow batteries

Summarization: This work reports the development of a prospective electrode material for the use in vanadium redox flow batteries. The developed electrode material was a high surface area activated carbon (1857 m 2 g −1 ) with a large mesoporosity (1280 m 2 g −1 ) that was derived using biomass residues, Sal wood sawdust (Shorea robusta), as a feedstock. The physico-chemical and electrochemical properties of Sal wood sawdust activated carbon were extensively characterized applying cyclic voltammetry and electrochemical impedance spectroscopy. The graphite plate electrode based on Sal wood sawdust activated carbon exhibited higher electro-catalytic activity and lower charge transfer resistance towards both positive and negative redox couples than when applying pristine graphite plate electrode. Further investigations on the application of static cell at higher current densities (20–80 mA cm 2 ) revealed higher efficiencies for the Sal wood sawdust activated carbon modified graphite plate electrode in comparison with the pristine graphite plate electrode. Thus, the Sal wood sawdust can be suitable as carbon precursor for preparation of electrodes to be utilized in practical applications, such as in vanadium redox flow batteries.Παρουσιάστηκε στο: Journal of Electroanalytical Chemistr