Application of Zr(IV) tungstate for removal of metal ions from aqueous solutions

A heteropolyacid Zr(IV) tungstate-based cation exchanger has been synthesized. An amorphous sample, prepared at pH 1.2 and having a Na⁺ ion exchange capacity of 0.92?meq?g^?1, was selected for further studies. Its physicochemical properties were determined using Fourier transform infrared spectrometer, X-ray diffraction, thermogravimetric, and scanning electron studies. To understand the cation exchange behavior of the material, distribution coefficients (K _d) for metal ions in various solvent systems were determined. Some important binary separations of metal ions, namely Mg²⁺–Bi³⁺, Cd²⁺–Bi³⁺, Fe³⁺–Bi³⁺, Th⁴⁺–Bi³⁺, and Fe³⁺–Zn²⁺, were achieved on such columns. The practical utility of these separations was demonstrated by separating Fe³⁺ and Zn²⁺ ions quantitatively in commercial pharmaceutical formulation. The cation exchanger has been successfully applied also for the treatment of industrial wastewater and a synthetic mixture. All the results suggests that Zr(IV) tungstate has excellent potential for the removal of metals from aqueous systems using packed columns of this material.     

Elements of fishing community resilience to climate change in the coastal zone of Bangladesh

Resilience has been conceptualized in various ways by anthropologists, ecologists, systems scientists and engineers; the boundaries of resilience are subjective and context dependent. Consequently, choosing the standards and metrics for assessing resilience remains key challenges for policy makers. In this study, using multicriteria evaluation of 40 basic criteria of human, physical, financial, natural and social assets, we have identified several elements, such as experienced fishermen, natural abundance of hilsa (Tenualosa ilisha), ability to assert decision on fish selling, nets and boats ownership, social harmony and capacity of buying food as essential livelihood assets for the fishermen at Hatiya Island, Bangladesh. These assets may enhance the relative resilience of the fishing community of the island to climate change by as much as 20–40%. The results of this study will improve our understanding of the elements that lead to resilience at the community level.     

Feedstocks,catalysts, process variables and techniques for biodiesel production by one-pot extraction-transesterification: a review

Environmental Chemistry Letters - Biodiesel is a sustainable alternative to petroleum diesel. The main bottlenecks in the commercialization of biodiesel are production costs and suitable industrial...     

Quantitative assessment of medical waste generation in the capital city of Bangladesh

There is a concern that mismanagement of medical waste in developing countries may be a significant risk factor for disease transmission. Quantitative estimation of medical waste generation is needed to estimate the potential risk and as a basis for any waste management plan. Dhaka City, the capital of Bangladesh, is an example of a major city in a developing country where there has been no rigorous estimation of medical waste generation based upon a thorough scientific study. These estimates were obtained by stringent weighing of waste in a carefully chosen, representative, sample of HCEs, including non-residential diagnostic centres. This study used a statistically designed sampling of waste generation in a broad range of Health Care Establishments (HCEs) to indicate that the amount of waste produced in Dhaka can be estimated to be 37 ± 5 ton per day. The proportion of this waste that would be classified as hazardous waste by World Health Organisation (WHO) guidelines was found to be approximately 21%. The amount of waste, and the proportion of hazardous waste, was found to vary significantly with the size and type of HCE.     

Disaster coordination preparedness of soft-target organisations

This paper introduces a network‐enabled model to examine the disaster coordination preparedness of soft‐target organisations (STOs). Little attention is devoted to this matter in recent research. This study places emphasis on such organisations and the proposed model tests hypotheses related to network relation and coordination preparedness. It analyses the data set entitled ‘Preparedness of large retail malls to prevent and respond to terrorist attack, 2004′, which contains 120 completed surveys of security directors of retail malls in the United States. ¹ 1 See http://www.icpsr.umich.edu/icpsrweb/TPDRC/studies/21140 .
The following questions form the basis of this study: ‘What do STOs need to be better prepared to respond to a disaster?’; ‘How does network relationship between STOs and emergency agencies affect the coordination preparedness of STOs for disaster recovery?’; and ‘Which centrality measure needs to be followed to measure network variables in order to analyse coordination preparedness?’ The results show that STOs with a high level of connectedness and strong ties to other emergency agencies are better prepared for disaster response.     

Stagnant surface water bodies (SSWBs) as an alternative water resource for the Chittagong metropolitan area of Bangladesh: physicochemical characterization in terms of water quality indices

The concern over ensuing freshwater scarcity has forced the developing countries to delve for alternative water resources. In this study, we examined the potential of stagnant surface water bodies (SSWBs) as alternative freshwater resources in the densely populated Chittagong metropolitan area (CMPA) of Bangladesh??where there is an acute shortage of urban freshwater supply. Water samples were collected at 1-month intervals for a period of 1 year from 12 stations distributed over the whole metropolis. Samples were analyzed for pH, water temperature (WTemp), turbidity, electrical conductivity (EC), total dissolved solids, total solids, total hardness, dissolved oxygen (DO), chloride, orthophosphates, ammonia, total coliforms (TC), and trace metal (Cd, Cr, Cu, Pb, As, and Fe) concentrations. Based on these parameters, different types of water quality indices (WQIs) were deduced. WQIs showed most of CMPA-SSWBs as good or medium quality water bodies, while none were categorized as bad. Moreover, it was observed that the minimal water quality index (WQI_m), computed using five parameters: WTemp, pH, DO, EC, and turbidity, gave a reliable estimate of water quality. The WQI_m gave similar results in 72% of the cases compared with other WQIs that were based on larger set of parameters. Based on our finding, we suggest the wider use WQI_m in developing countries for assessing health of SSWBs, as it will minimize the analytical cost to overcome the budget constraints involved in this kind of evaluations. It was observed that except turbidity and TC content, all other quality parameters fluctuated within the limit of the World Health Organization suggested standards for drinking water. From our findings, we concluded that if the turbidity and TC content of water from SSWBs in CMPA are taken care of, they will become good candidates as alternative water resources all round the year.     

Environmental variables and fisheries diversity of the Naaf River Estuary,Bangladesh

The Naaf River estuary is one of the large estuaries in the Bangladesh coastal region not to have been affected by extensive human disturbance. This research provides information about the fisheries diversity status by Estuarine Set Bag Net (ESBN) sampling relation to physicochemical variables in both spatio-temporal scales. About 25 km of the lower estuary was divided into six zones for sample collection by considering the accessibility and availability of the ESBN operation, fish landing centers and location of the fishing villages. In total 48 samples have been analyzed which were taken throughout March to October 2006. To quantify the species diversity, all fisheries data were analyzed by using EstimateS and EcoSim software which accounts the different diversity indices viz., species richness, Shannon–Wiener diversity Index, Dominance and Evenness index. The research results demonstrate that the Naaf River estuary is a habitat of 161 (species richness, Sobs = 161, Choa 1 = 162 ± 2.34, ACE = 161.73) different species which belong to 98 fin fishes, 23 shrimps and prawns, 13 crabs, 11 molluscs, 3 echinoderms, 4 other crustaceans; while 9 remain unidentified. Results on the aquatic environment, mainly salinity and turbidity were found to have a major influence on their occurrence and distribution. All the findings indicated that the Naaf River estuary is a highly productive system and provides a favourable environment for large variety of estuarine species assemblages.