Adsorption of benzene and toluene from waste gas using activated carbon activated by ZnCl2

A series of activated carbons with high surface area were prepared from walnut shell using chemical activation with ZnCl2. In this research the carbonization stage was carried out at 500℃. The performance of the synthesized carbons evaluated in adsorption of benzene and toluene from waste gas. The influence of impregnation ratio on the characteristics of synthesized activated carbons as well as their adsorption capacity was investigated. The ratio of activation agent to walnut shell was selected in the range of 0.5-2.0 wt/wt. The synthesized activated carbons were characterized using XRD, SEM, BET and FTIR techniques. The highest activated carbon production yield was obtained at impregnation ratio of 1.5 wt/wt. The XRD analysis illustrated that peaks intensity decreased with increasing impregnation ratio showing that amorphous property of samples was increased. The SEM analysis revealed successful pore development in synthesized activated carbons obtained at high impregnation ratios. The surface area of the activated carbons increased with increasing impregnation ratio and its maximum value reached 2643 m2.g 1 at impregnation ratio of 2/1. FTIR analysis indicated that the relative amount of different acidic surface groups on synthesized carbons was a function of impregnation ratio. Experimental results for benzene and toluene adsorption showed a high potential of employing synthesized impregnated activated carbon for treatment of waste gas. Generally, the amount of VOC adsorbed on the surface was affected by physicochemical properties of synthesized activated carbons.     

Selenium and arsenic content of agricultural soils from Bangladesh and Nepal

Arsenic (As) contamination of the available domestic drinking water from shallow aquifers to villagers in Bangladesh often exceeds the newest WHO standard of <10 µg As L^?1 and the older Bangladeshi standard of <50 µg As L^?1. An estimated 9.2 million shallow tube wells in Bangladesh deliver water to 97% of the rural population, placing an estimated 57 million people at risk for arsenicosis. The contamination of drinking water by As extends to W. Bengal, India and Nepal. The same shallow aquifers used for domestic water are also used to irrigate food crops, particularly rice. Irrigation adds As to soils and increases exposure of the population to additional As via foods consumed. Selenium (Se), an essential trace mineral found in soils, is absorbed by plants, entering the human food chain. It was suggested that a low dietary intake of Se may be contributing to the problem of human arsenicosis in Bangladesh. Dietary Se acts as a natural antidote to As by (1) accelerating As excretion, (2) sequestering As by complexation and (3) as an antioxidant component of the enzyme glutathione peroxidase that may counteract the prooxidant effects of As that contribute to arsenicosis and cancer. Analysis of 70 agricultural soil samples from Bangladesh by fluorimetry, ICP-AES and Neutron Activation Analysis showed the soils analyzed to be high in As (～33 µg g^?1) and biologically low in soluble Se (～0.02 µg g^?1). A low dietary intake of Se related to low soil content and this mineral in foods may be contributing to human arsenicosis in the Ganges–Brahmaputra delta.     

Effect of a popular Middle Eastern food (Falafel) on rat liver

The aim of this study was to evaluate the effect of short-term consumption of oil and frying oil extracted from falafel patties, and then to study the long-term effect of consumption of falafel patties on rat liver gross morphology and serum liver enzymes. The frying oil quality was assessed using thiobarbituric acid reaction on rat liver homogenate. Frying oil and oil extracted from falafel patties were administered to male Wistar albino rats via gavage for 5 days. Blood samples were collected and the activities of alkaline phosphatase (ALP), aspartate aminotransferase, alanine aminotransferase (ALT), and bilirubin levels were determined. Livers were weighed and gross morphology was assessed. For the long-term effect of falafel consumption, rats were fed falafel patties for 30 days, and then blood samples were collected and assayed for the above-mentioned parameters. Short-term consumption of falafel extracts and frying oil did not cause any significant difference in the liver function tests and liver gross morphology. Whereas, long-term consumption of falafel patties caused a significant increase in ALP, ALT, bilirubin level and increased liver weight/body weight ratio denoting hepatotoxicity. This indicates that consumption of large amounts of falafel on daily basis might lead to hepatotoxicity.     

Protective effects of quercetin against sodium fluoride-induced oxidative stress in rat erythrocytes

Protective effects of quercetin against oxidative stress induced by sodium fluoride intoxication in rat erythrocytes were evaluated. Rats were divided into five groups consisting of 10 in each for this experiment. The animals of group I received water and standard diet to serve as control group, the animals of groups II and III were treated with quercetin (10 and 20?mg?kg^?1 body weight), administrated intraperitoneally for 7 days followed by sodium fluoride (600?ppm) in drinking water for the next 7 days. The animals of group IV were treated with vitamin C (10?mg?kg^?1) intraperitoneally for 7 days followed by sodium fluoride treatment for next 7 days serving as positive control group. The animals of group V were treated only with sodium fluoride (600?ppm) for the same time and were used as control group. Blood sample were collected via retro-orbital puncture. The antioxidant enzymes, superoxide dismutase, and catalase, as well as the levels of reduced glutathione and lipid peroxidation end products were measured in erythrocytes. There was a significant increase in lipid peroxidation along with a decrease in superoxide dismutase activity in the erythrocytes of sodium fluoride-treated animals. Quercetin treatment prior to fluoride administration normalized the levels of all parameters measured in the rat erythrocytes.     

Bioremediation of toxic metals mercury and cesium using three types of biosorbent: bacterial exopolymer,gall nut,and oak fruit particles

Cesium and mercury are two mono-valent elements which can be found in toxic industrial, medical, and nuclear wastes. Their presence in the environment has deleterious effects on the ecosystem, living organisms including humans. Due to the chemical nature of these metals, bioremediation by conventional methods is more difficult to achieve compared to other metals. In this study, we used three biosorbents (oak powder, gall nut, and bacterial exopolymer) for the bioremediation of Hg and Cs. Bio-polymer was produced in the GMS mineral broth. Synthetic wastes of Hg(NO₃)₂ and isotope Cs-133 as the single-metal solutions were used. The biorefining process was carried out in glass columns, made of Pyrex, with dimensions 20?×?7/2?cm² with a V-shaped bottom. The samples were analyzed using atomic absorption. The experimental results showed that eliminated metal percent by oak powder, gall nut, and bacterial exopolymer were, respectively, of 94.8%, 96%, and 13.8% for Hg and 7.8%, 4.4%, and 69.4% for Cs. The tests revealed that Ca⁺⁺, when used as flocculant, played a key role in both biosorption and bio-precipitation rates. Consequently, it was concluded that the investigated biosorbents could be use as an integrated biosorption system for the refinement of mixed wastes.     

Integrating livelihoods and conservation in protected areas: understanding the role and stakeholder views on prospects for non-timber forest products,a Bangladesh case study

Protected areas (PAs) represent a key global strategy in biodiversity conservation. In tropical developing countries, the management of PAs is a great challenge as many contain resources on which local communities rely. Collection and trading of non-timber forest products (NTFPs) is a well-established forest-based livelihood strategy, which has been promoted as a potential means for enhanced conservation and improved rural livelihoods in recent years, even though the sustainability or ecological implications have rarely been tested. We conducted an exploratory survey to understand the role and stakeholder views on conservation prospects and perceived ecological feasibility of NTFPs and harvesting schemes in a northeastern PA of Bangladesh, namely the Satchari National Park. Households (n?=?101) were interviewed from three different forest dependency categories, adopting a stratified random sampling approach and using a semi-structured questionnaire. The study identified 13 locally important NTFPs, with five being critically important to supporting local livelihoods. Our study suggests that collection, processing and trading in NTFPs constitutes the primary occupation for about 18% of local inhabitants and account for an estimated 19% of their cash annual income. The household consensus on issues relating to NTFPs and their prospective role in conservation was surprisingly high, with 48% of respondents believing that promotion of NTFPs in the PA could have positive conservation value. The majority (71%) of households also had some understanding of the ecological implications of NTFP harvesting, sustainability (53%) and possible management and monitoring regimes (100%). With little known about their real application in the field, our study suggests further investigations are required to understand the ecological compatibility of traditional NTFP harvesting patterns and management.     

Green chemistry approach to analysis of formic acid and acetic acid in aquatic environment by headspace water-based liquid-phase microextraction and high-performance liquid chromatography

A simple and totally organic-free (green) method, viz. headspace water-based liquid-phase microextraction combined with high-performance liquid chromatography-ultraviolet detection has been successfully developed for analysis of formic acid and acetic acid in environmental water samples. A microdrop of an aqueous solution of sodium hydroxide was suspended from the tip of a microsyringe needle over the headspace of the stirred sample solution containing the analytes at pH 1.0 for a given time. The microdrop was then retracted into the microsyringe, diluted with HPLC mobile phase, and injected to HPLC. Optimum efficiency has been achieved for: 3.0 µL NaOH microdrop (0.1 mol L^?1) exposed for 15 min over the headspace of an aqueous sample of 6.5 mL at 55 °C, containing 15% w/v of Na₂SO₄, adjusted to pH = 1.0 and stirred at 750 rpm. Under these conditions, enrichment factors of 162 and 187, limits of detection of 0.3 and 0.1 µg L^?1 (S/N = 3) with dynamic linear ranges of 1–500 and 0.5–500 µg L^?1 were obtained for formic acid and acetic acid, respectively. A reasonable repeatability (5.8% ≤ RSD ≤ 8.8%, n = 6) and satisfactory linearity (r² ≥ 0.997) illustrated the performance of the method.     

天山西部伊犁河流域土壤盐分特征

采用相关分析法与主成分分析法研究了伊犁河流域土壤盐分特征.结果表明:研究区域耕层(3～20 cm)土壤53.68%样地为非盐渍化土壤,18.38%为轻度盐渍化,13.97%为中度盐渍化,8.82%为重度盐渍化,5.15%为盐土;土壤盐渍化类型以硫酸盐渍土为主,占68.41%.盐分组成中,阴离子以SO₄2-和Cl-为主,阳离子以Na+和Ca2+为主;土壤盐分与Cl-和SO₄2-分别呈极显著、显著正相关关系,揭示了土壤盐分大小与w(Cl-)和w(SO₄2-)有关;表层(0～3 cm)土壤盐分平均值占0～60 cm土层盐分平均值的60.19 %,即土壤盐分垂直分布呈现强烈表聚性.主成分分析结果表明,盐分,w(Cl-),w(SO₄2-),w(Mg2+)与w(Ca2+)可作为研究区域土壤盐渍化状况的特征因子.不同土地利用类型条件下,耕层土壤盐分平均值从高到低依次为草地、旱田、稻田、林地.不同灌溉条件下,井灌农田耕层土壤盐分平均值为1.12 g/kg,渠灌农田耕层土壤盐分平均值为0.73 g/kg,渠灌农田耕层土壤盐分平均值比井灌农田小0.39 g/kg.不同时期耕层土壤盐分平均值从高到低依次为非灌溉期、夏灌期、秋灌期.      

Wrong-way driving crashes: A multiple correspondence approach to identify contributing factors

Objective: Wrong-way driving (WWD) crashes result in 1.34 fatalities per fatal crash, whereas for other non-WWD fatal crashes this number drops to 1.10. As such, further in-depth investigation of WWD crashes is necessary. The objective of this study is 2-fold: to identify the characteristics that best describe WWD crashes and to verify the factors associated with WWD occurrence.

Methods: We collected and analyzed 15 years of crash data from the states of Illinois and Alabama. The final data set includes 398 WWD crashes. The rarity of WWD events and the consequently small sample size of the crash database significantly influence the application of conventional log-linear models in analyzing the data, because they use maximum-likelihood estimation. To overcome this issue, in this study, we employ multiple correspondence analysis (MCA) to define the structure of the crash data set and identify the significant contributing factors to WWD crashes on freeways.

Results: The results of the present study specify various factors that characterize and influence the probability of WWD crashes and can thus lead to the development of several safety countermeasures and recommendations. According to the obtained results, factors such as driver age, driver condition, roadway surface conditions, and lighting conditions were among the most significant contributors to WWD crashes.

Conclusions: Despite many other methods that identify only the contributing factors, this method can identify possible associations between various contributing factors. This is an inherent advantage of the MCA method, which can provide a major opportunity for state departments of transportation (DOTs) to select safety countermeasures that are associated with multiple safety benefits.     

Green Synthesis of Silver Nanoparticles and Study of Their Antimicrobial Properties

One of the major disadvantages of polymers when used in food-contact applications is that they are very susceptible to microbial attack. On the other hand, silver nanoparticles have received increased attention as novel antimicrobial agents. Therefore, the introduction of silver nanoparticles into conventional polymers results in new materials with improved properties. In this investigation, colloidal silver nanoparticles using an environmentally friendly procedure were synthesized. An aqueous solution of AgNO₃ was used as a silver precursor with ‘green’ reducing agents either different types of honey, or β-d-glucose. In the first case, different pH values, as well as the addition of poly(ethylene glycol), PEG were studied, while in the latter, the effect of reduction time in the presence of PEG with various average molecular weights was examined. Properties of the nanoparticles were measured using X-Ray diffraction, UV–Vis and FTIR spectroscopy. Using honey it seems that spherical particles are produced with the smaller average particle size obtained at pH 8.5. Use of honey has the advantage of being a natural product, although its main drawback is that its composition varies and it cannot be predefined to result in reproducible results. Use of β-d-glucose results in stable silver nanoparticles with small average particle size after 24 h reduction. The addition of low molecular weight PEG seems to be beneficial in the production of stable nanoparticles. Finally, the antimicrobial activity of the nanoparticles produced was investigated at different concentrations on both Gram positive and negative bacteria, such as Bacillus cereus, Bacillus subtilis, Escherichia coli and Staphylococcus aureus.