High efficiency chlorine removal from polyvinyl chloride (PVC) pyrolysis with a gas–liquid fluidized bed reactor

In this research a gas–liquid fluidized bed reactor was developed for removing chlorine (Cl) from polyvinyl chloride (PVC) to favor its pyrolysis treatment. In order to efficiently remove Cl within a limited time before extensive generation of hydrocarbon products, the gas–liquid fluidized bed reactor was running at 280–320 °C, where hot N₂ was used as fluidizing gas to fluidize the molten polymer, letting the molten polymer contact well with N₂ to release Cl in form of HCl. Experimental results showed that dechlorination efficiency is mainly temperature dependent and 300 °C is a proper reaction temperature for efficient dechlorination within a limited time duration and for prevention of extensive pyrolysis; under this temperature 99.5% of Cl removal efficiency can be obtained within reaction time around 1 min after melting is completed as the flow rate of N₂ gas was set around 0.47–0.85 Nm³ kg^?1 for the molten PVC. Larger N₂ flow rate and additives in PVC would enhance HCl release but did not change the final dechlorination efficiency; and excessive N₂ flow rate should be avoided for prevention of polymer entrainment. HCl is emitted from PVC granules or scraps at the mean time they started to melt and the melting stage should be taken into consideration when design the gas–liquid fluidized bed reactor for dechlorination.     

Incorporating uncertainty in a chemical leaching assessment

Pesticide leaching models are being used to assist in the regulation and management of pesticides by indicating their potential for leaching to groundwater. Uncertainty in model input data is not, regrettably, included in most pesticide leaching assessments. In the work described here, we use logarithmic transformations of the attenuation factor (AF), a simple process-based index model, to represent uncertainty in a pesticide leaching assessment. Characterization of a wide range of pesticides as `leachers' or `non-leachers' for a specific Hawaii hydrogeological setting is facilitated by comparing the log-transformed AF, designated AFR, for each chemical with two reference chemicals for which leaching behavior in Hawaii is known. Defining a mean and uncertainty interval for the AFR index of each chemical being ranked provides a practical method of incorporating data uncertainty into a regulatory protocol.     

Determination of the insecticide diflubenzuron in mushrooms by kinetic method and high-performance liquid chromatographic method

In the present study, a new sensitive and simple kinetic-spectrophotometric method for the determination of the insecticide diflubenzuron [1-(4-chlorophenyl)-3-(2,6-diflubenzoil)urea] is proposed. The method is based on the inhibited effect of diflubenzuron on the oxidation of sulphanilic acid (SA) by hydrogen peroxide in phosphate buffer in presence Cu(II) ion. Diflubenzuron was determined with linear calibration graph in the interval from 0.31 to 3.1 μg mL^?1 and from 3.1 to 31.0 μg mL^?1. The optimized conditions yielded a theoretical detection limit of 0.18 μg mL^?1corresponding to 0.036 mg Kg^?1mushroom sample based on the 3S_b criterion. The RSD is 5.03–1.83 % and 2.81–0.71 % for the concentration interval of diflubenzuron 0.31–3.1 μg mL^?1and 3.1–31.0 μg mL^?1, respectively. The reaction was followed spectrophotometrically at 370 nm. The kinetic parameters of the reaction are reported, and the rate equations are suggested. The developed procedure was successfully applied to the rapid determination of diflubenzuron in spiked mushroom samples of different mushroom species. The HPLC method was used like a comparative method to verify results.     

Preparation of Soybean Oil Polymers with High Molecular Weight

The cationic polymerization of soybean oils was initiated by boron trifluoride diethyl etherate in supercritical carbon dioxide medium. The resulting polymers had molecular weight ranging from 21,842 to 118,300 g/mol. Nuclear magnetic resonance spectroscopy and gel permeation chromatography analysis confirmed the polymerization had occurred. Parameters affecting the polymerization were studied, which included initiator amount and reaction time. Results show that the longer reaction time, up to 3 h, favored the higher molecular weight of polymers at conditions of 140 °C and initiator BF₃·OEt₂ (2.5 g, 0.018 mol). When reaction time was increased further, the molecular weight of polymers stayed the same or slightly decreased. Increased concentration of initiator gave the higher molecular weight of polymers. The high molecular weight polymers were possibly formed through two path ways: polymerization and intermolecular Diels-Alder reaction.     

GIS-based Probability Assessment of Natural Hazards in Forested Landscapes of Central and South-Eastern Europe

We assessed the probability of three major natural hazards—windthrow, drought, and forest fire—for Central and South-Eastern European forests which are major threats for the provision of forest goods and ecosystem services. In addition, we analyzed spatial distribution and implications for a future oriented management of forested landscapes. For estimating the probability of windthrow, we used rooting depth and average wind speed. Probabilities of drought and fire were calculated from climatic and total water balance during growing season. As an approximation to climate change scenarios, we used a simplified approach with a general increase of pET by 20%. Monitoring data from the pan-European forests crown condition program and observed burnt areas and hot spots from the European Forest Fire Information System were used to test the plausibility of probability maps. Regions with high probabilities of natural hazard are identified and management strategies to minimize probability of natural hazards are discussed. We suggest future research should focus on (i) estimating probabilities using process based models (including sensitivity analysis), (ii) defining probability in terms of economic loss, (iii) including biotic hazards, (iv) using more detailed data sets on natural hazards, forest inventories and climate change scenarios, and (v) developing a framework of adaptive risk management.     

Water for human and livestock consumption in rural settings of Ethiopia: assessments of quality and health aspects

The study aimed to assess the quality and health aspects of water intended for human and livestock consumption in two rural districts of the Rift Valley of Ethiopia. The study involved two parts: the first consisted of a questionnaire survey and farmers’ group discussions, complemented by secondary health data, and the second part determined the chemical (total dissolved solids, pH, manganese, hexa-valent chromium, fluoride) and microbiological quality of different water sources during dry and wet seasons. The result showed a lack of sustainable access to safe water in the communities. Industrial pollution and mismanagement of water sources by human and livestock was found to be a source of potential health risk. Potentially linked human health problems like malaria, diarrhoea and gastrointestinal parasites were common in the districts. Overall, 76 % of the assessed water sources (n?=?25) failed to comply with World Health Organization guidelines for human drinking water, for at least one assessed parameter, mostly irrespective of the season. The non-compliance was mainly attributed to Escherichia coli contamination and/or high fluoride concentration. At least 20 % of the water samples were also found to be unfit for livestock consumption based on assessed chemical parameters in both dry and wet seasons. To minimize the health risk associated with mismanagement and poor quality of water sources in the area, targeted action in the protection of surface water sources should be given priority.     

Effects of dietary copper exposure on accumulation,growth, and hematological parameters in Cyprinus carpio

The influence of dietary copper (Cu) exposure on accumulation, growth, and hematological parameters was investigated in Cyprinus carpio after sub-chronic ingestion of 0, 250, 500, 750 or 1000?mg?kg^?1 for 60 days. The profile of Cu accumulation among tissues in C. carpio was dependent on the exposure period and Cu concentration. Liver of C. carpio was the predominant storage tissue and the order of Cu accumulation in tissues was liver?>?intestine?> gill?>?kidney?>?muscle. Cu concentration at >125?mg?kg^?1 reduced growth rate, and was inversely related to growth. The RNA?:?DNA ratios were not affected by exposure and there was no correlation between growth rate and RNA?:?DNA ratio in liver and muscle. There were no significant effects of exposure on blood parameters except for magnesium. Cu exposure time and dose increased the serum glutamic-oxaloacetic transaminase (SGOT) and serum glutamic-pyruvic transaminase (SGPT) activity levels.     

Treatment of mature landfill leachate by biofilters and Fenton oxidation

A series of processes by biofilter and Fenton oxidation to treat mature landfill leachate has been devised. At a hydraulic loading rate of 20 l m^?3 d^?1, a biofilter packed with aged refuse is found to remove 80% of chemical oxygen demand (COD), 89% of ammonia nitrogen and 96% of total phosphorus (TP). Particularly, TP levels dropped below 1 mg l^?1. The optimal condition for Fenton oxidation was selected to be an initial pH of 5, a dosage of 0.01 and 0.02 mol l^?1 of FeSO₄ and H₂O₂, respectively, and a duration of 3 h, where COD removal efficiency reaches 58.6%, and BOD₅/COD ratio is raised from 0.05 to 0.20. Subsequent treatment by a biofilter packed with slag reduces COD, ammonia nitrogen levels to less than 100, 25 mg l^?1, respectively. A pilot scale experiment conducted in situ demonstrates that this series of processes exhibits a high efficiency in removing pollutants from mature landfill leachate and it is viable for application.     

Biocontrol of weeds: Overcoming evolution for efficacy

Abstract

Inundatively used mycoherbicides have been uneconomical and ineffectual, mainly because a large inoculum is required to overcome weeds’ innate defenses, as well as the need for long dew periods to become established. Weed defenses can be suppressed by specific chemical agents, or overcome biologically (using mixed organisms and/or engineering enhanced pathogenicity), and better formulants replace the long dew periods.