Improvement of Physico-Mechanical Properties of Photo-Cured Chitosan Films with Ethylene Glycol Dimethacrylate and (2-Hydroxyethyl) Methacrylate

Chitosan, a natural polymer, was prepared by deacetylation of chitin which was obtained from dried prawn shell and was characterized. Thin chitosan film of chitosan was prepared by casting method from 0.2 % chitosan in 2 % acetic acid solution. Five formulations were developed with ethylene glycol dimethacrylate and (2-hydroxyethyl) methacrylate along with photo-initiator, Darocur-1664 (4 %). The chitosan film was soaked in the formulations at different soaking times and irradiated under UV-radiation at different intensities for the improvement of its physical and mechanical properties. The cured chitosan films were then subjected to various mechano-chemical tests like tensile strength, elongation at break, polymer loading, water absorption and gel content. The formulation containing 30 % ethylene glycol dimethacrylate and 66 % (2-hydroxyethyl) methacrylate showed the best performance at the 30th UV pass of UV-radiation for 3 min soaking time.     

Evaluation of compositional characteristics of organic waste shares in municipal solid waste in fast-growing metropolitan cities of India

Journal of Material Cycles and Waste Management - India currently has the second largest urban population worldwide, while facing an increasing burden on its urban solid waste infrastructure. To...     

Characterization of fluoride-tolerant halophilic Bacillus flexus NM25 (HQ875778) isolated from fluoride-affected soil in Birbhum District, West Bengal, India

A new Gram-positive, nonpigmented, rod-shaped fluoride-tolerant bacterial strain, NM25, was isolated from waterlogged muddy field soil collected from the fluoride endemic area of Rampurhat II block (average fluoride in water, 4.7 mg/l, and in soil, 1.5 mg/kg) in Birbhum District, West Bengal, India. The study was undertaken to characterize the fluoride-tolerant bacterial isolate, to determine its role in bioaccumulation of fluoride, and to analyze the water and soil quality of the bacterial environment. The isolate was positive for catalase, lipase, urease, protease, oxidase, and H₂S production, but negative for indole production, nitrate reduction, and Vogues–Proskauer test. The organisms were sensitive to recommended doses of ofloxacin, kanamycin, rifampicin, levofloxacin, vancomycin, gatifloxacin, gentamicin, doxycycline, streptomycin, and nalidixic acid but resistant to ampicillin. Based on the phenotypic characteristics, 16S rRNA gene sequence, and phylogenetic analysis, the bacterial isolate NM25 was identified as Bacillus flexus. The G+C content of the 16S rDNA was 53.14 mol%. This strain tolerated up to 20 % (w/v) NaCl in nutrient agar medium and was grown at the pH range 4–12. It reduced fluoride concentration up to 67.45 % and tolerated more than 1,500 ppm of fluoride in brain–heart infusion agar medium.     

Trends of Forest Dynamics in Tiger Landscapes Across Asia

Protected areas (PAs) are cornerstones of biodiversity conservation, but small parks alone cannot support wide-ranging species, such as the tiger. Hence, forest dynamics in the surrounding landscapes of PAs are also important to tiger conservation. Tiger landscapes often support considerable human population in proximity of the PA, sometimes within the core itself, and thus are subject to various land use activities (such as agricultural expansion and road development) driving habitat loss and fragmentation. We synthesize information from 27 journal articles in 24 tiger landscapes to assess forest-cover dynamics in tiger-range countries. Although 29% of the PAs considered in this study have negligible change in overall forest cover, approximately 71% are undergoing deforestation and fragmentation. Approximately 58% of the total case studies have human settlements within the core area. Most changes—including agricultural expansion, plantation, and farming (52%), fuelwood and fodder collection (43%), logging (38%), grazing (38%), and tourism and development (10%)—can be attributed to human impacts largely linked to the nature of the management regime. This study highlights the need for incorporating new perspectives, ideas, and lessons learned locally and across borders into management plans to ensure tiger conservation in landscapes dominated by human activities. Given the increasing isolation of most parks due to agricultural, infrastructural, and commercial developments at the periphery, it is imperative to conduct planning and evaluation at the landscape level, as well as incorporate multiple actors and institutions in planning, instead of focusing solely on conservation within the PAs as is currently the case in most tiger parks.     

Assessment of seawater impact using major hydrochemical ions: a case study from Sadras, Tamilnadu, India

The impact of seawater intrusion was investigated using major hydrogeochemical ions to evaluate the origin of salinity in Sadras watershed located between Buckingham Canal and Bay of Bengal in the southeastern coast of India. From empirical data collected twice during pre- and post-monsoon seasons, it was found that groundwater was slightly acidic to mildly alkaline, and more than 44% of groundwater samples had EC > 3,000 ??S/cm in both the seasons. Results of principle component analysis (PCA) showed that Na^?+?, Cl^???, Mg^2?+?, and SO $_{4}^{\,\, 2-}$ concentrations had the highest loading factor and the samples affected by saline/seawater were separated from the cluster. Hydrochemical processes that accompany the saline/seawater were identified using ionic changes. It was observed during sampling periods that the mixing due to saline/seawater intrusion varied from 4.82?C7.86%. Negative values of ionic change (e _change) for Na^?+? and K^?+? decreased with the increasing fraction of seawater. Furthermore, salinity, sodium adsorption ratio, percentage of sodium Na (%), and exchangeable sodium percentage in well samples showed that groundwater was unsuitable for irrigation purposes.     

Effect of magnetic field on the removal of copper from aqueous solution using activated carbon derived from rice husk

Adsorptive removal of copper by activated carbon derived from modified rice husk (ACRH) was studied in the presence and absence of magnetic field (MF). The ACRH was prepared from the normal rice husk treated by NaOH solution and subsequent pyrolysis at 450 °C in the absence of oxygen. The physicochemical properties of ACRH's were determined before and after the adsorption process to delineate the adsorption mechanism. The BET analysis confirmed that the fabricated ACRH has a specific surface area of 8.244 m²/g with a mesopore to micropore ratio of 0.974. It was observed that the micropore structure gradually replaced the mesopores, and the surface area of the micropore increased (from 0.9219 to 4.1764 m²/g), and the pore diameter was also decreased from 180.381 to 46.249 Å after pyrolysis. The CHNO/S test result reveals that the carbon content was increased from 42 to 67.8% in the ACRH after pyrolysis. The batch sorption studies were performed by varying the initial adsorbate concentration, temperature, agitation speed, pH, adsorbent dose and contact time for magnetic and non-magnetic conditions to analyze the effect of the magnetic field. The univariate studies show that the maximum experimental adsorption capacity was 4.522 mg/g and 3.855 mg/g, respectively, for these two conditions (representing the magnetic impact) at 25 °C with an adsorbent dose of 2 g/L and an agitation speed of 150 rpm. It was also observed that the removal efficiency was 94.55% and 77.96% (magnetic and non-magnetic condition) at pH 7 with a concentration of 10 mg/L in 2 h. The test result on the impact of exposure time on the magnetic field suggested that the magnetic memory influenced the removal efficiency; after 40 to 60 min, the maximum removal efficiency was achieved, around 80 to 90%. The pseudo-second-order kinetic model was best fitted with the experimental data with a rate constant as 0.1749 and 0.1006 g/mg/min for these two conditions. The Temkin model delineates the adsorption isotherm suggesting the heat generated during the adsorption process is linearly abate with the coverage of the surface area of the adsorbent. The thermodynamic model confirms that the copper adsorption is spontaneous (ΔG = ? 3.91 kJ/mol and ? 6.02 kJ/mol), wherein the negative enthalpy value (ΔH = ? 36.74 kJ/mol and ? 25.74 kJ/mol) suggested that the process is exothermic irrespective of magnetic interference. The significant enhancement of copper removal was observed by incorporating the magnetic field, showing an increase in sorption capacity by 17.48% and a reduction of reaction time by 88.12%.

     

Comparison of drinking water,raw rice and cooking of rice as arsenic exposure routes in three contrasting areas of West Bengal,India

Remediation aimed at reducing human exposure to groundwater arsenic in West Bengal, one of the regions most impacted by this environmental hazard, are currently largely focussed on reducing arsenic in drinking water. Rice and cooking of rice, however, have also been identified as important or potentially important exposure routes. Quantifying the relative importance of these exposure routes is critically required to inform the prioritisation and selection of remediation strategies. The aim of our study, therefore, was to determine the relative contributions of drinking water, rice and cooking of rice to human exposure in three contrasting areas of West Bengal with different overall levels of exposure to arsenic, viz. high (Bhawangola-I Block, Murshidibad District), moderate (Chakdha Block, Nadia District) and low (Khejuri-I Block, Midnapur District). Arsenic exposure from water was highly variable, median exposures being 0.02 μg/kg/d (Midnapur), 0.77 μg/kg/d (Nadia) and 2.03 μg/kg/d (Murshidabad). In contrast arsenic exposure from cooked rice was relatively uniform, with median exposures being 0.30 μg/kg/d (Midnapur), 0.50 μg/kg/d (Nadia) and 0.84 μg/kg/d (Murshidabad). Cooking rice typically resulted in arsenic exposures of lower magnitude, indeed in Midnapur, median exposure from cooking was slightly negative. Water was the dominant route of exposure in Murshidabad, both water and rice were major exposure routes in Nadia, whereas rice was the dominant exposure route in Midnapur. Notwithstanding the differences in balance of exposure routes, median excess lifetime cancer risk for all the blocks were found to exceed the USEPA regulatory threshold target cancer risk level of 10⁻⁴–10⁻⁶. The difference in balance of exposure routes indicate a difference in balance of remediation approaches in the three districts.     

Perceptions and patterns of human–elephant conflict at Barjora block of Bankura district in West Bengal, India: insights for mitigation and management

Human–elephant conflict is an issue of great concern regarding the growing competition between people and wildlife for food and shelter throughout Asia and Africa. The situation the Asian elephant faces is much critical. According to IUCN (Big hopes for endangered Asian Elephants, News Release, Gland, 2006), one of the prime factors to the decline of elephant population in India is the increasing trend in human–elephant conflict. Barjora block of Bankura district in West Bengal is one of the severe conflict prone zones in West Bengal, where elephant raid in every year has now become an inevitable phenomenon. As a result, crop damage, infrastructural damages, disturbances of daily activities, occurrence of human death and injuries have no doubt annihilated and frustrated the social fabric of life. This paper is an empirical attempt to address various consequences of human–elephant encounters which have an adverse impact on social, economic as well as the cultural life of the people. Instead of pursuing some traditional mitigation techniques, we argued much on understanding peoples’ perception to explore some sustainable mitigation measures to ensure the interest of both human and elephant and also to safeguard ecological integrity.     

Thermocatalytic Degradation of High Density Polyethylene into Liquid Product

Thermocatalytic degradation of high density polyethylene (HDPE) was carried out using acid activated fire clay catalyst in a semi batch reactor. Thermal pyrolysis was performed in the temperature range of 420–500 °C. The liquid and gaseous yields were increased with increase in temperature. The liquid yield was obtained 30.1 wt% with thermal pyrolysis at temperature of 450 °C, which increased to 41.4 wt% with catalytic pyrolysis using acid activated fire clay catalyst at 10 wt% of catalyst loading. The composition of liquid products obtained by thermal and catalytic pyrolysis was analyzed by gas chromatography-mass spectrometry and compounds identified for catalytic pyrolysis were mainly paraffins and olefins with carbon number range of C₆–C₁₈. The boiling point was found in the range of commercial fuels (gasoline, diesel) and the calorific value was calculated to be 42 MJ/kg.     

Trace element concentration in groundwater of Pesarlanka Island, Krishna Delta, India

There is a growing concern over the potential accumulation of trace element concentration in groundwater of coastal aquifer owing seawater encroachment in the last several decades. A total of 29 groundwater samples collected from Pesarlanka Island, Krishna delta, Andhra Pradesh, India were analyzed for 13 trace elements (B, V, Mn, Fe, Ni, Co, Cu, Zn, As, Sr, Cd, Ba, and Pb) using inductively coupled plasma mass spectrometry. The results reveal that B, Fe, Ni, As, Sr, and Pb vary from 11.22 to 710.2, 1.25 to 684.6, 0.02 to 37.33, 27.8 to 282.3, 164.1 to 7,009, and 1.97 to 164.4 μg/l, respectively. Ba, Cd, Co, Cu, Ni, V, and Zn are almost within permissible limits for drinking water, but As, Fe, Mn, Pb, B, and Sr are above the permissible limit. The toxic element Pb is 1.64 times more than the maximum permissible limits of drinking water. The minimum value of As is also 2.78 times more, whereas the maximum is 28.2 times the permissible limit. The spatial distributions of alkaline earths (Sr, Ba), transition metals (V, Co, Ni, Fe), metallic elements (Cu, Pb), and (As) were found in considerable variation in the entire Island. Good cross-correlations were found between As, B, Co, and Sr with total dissolved solids and among other trace elements such as B, As, Co, and Sr. The variability observed within the groundwater samples is closely connected to the sea spray input; hence, it is primarily a consequence of geographical and meteorological factors, such as distance from the ocean and time of year. The trace element levels, in particular those of heavy metals, are very low, suggesting an origin from natural sources rather than from anthropogenic contamination. A few trace elements (Sr and B) are found as sensitive parameters responding to changes in fresh to saline groundwater environment. The highly elevated trace elements in this area which may be attributed to marine sediments or death and decay of plants are presented in this paper.