Interaction of heavy metal ions with an ion exchange resin obtained from a natural polyelectrolyte

An ion exchange resin was synthesized by using a natural polyelectrolyte, sodium alginate, and barium ion as a cross-linker reagent. Resin was characterized by TGA and SEM. Equilibrium and kinetic experiments of Pb²⁺, Hg²⁺, Ni²⁺, Co²⁺, Fe²⁺, and Fe³⁺ ions uptake by barium alginate beads were carried out in batch-type experiments under different values of pH. The removal efficiency increases with increasing pH. The uptake of metal ions occurs rapidly in the first hour. Maximum retention capacity was also determined being Fe(II) > Fe(III) > Co(II) > Ni(II) > Pb(II) > Hg(II) in mmol/g dry beads basis. Elution from the loaded resins at maximum capacity was studied by using HCl and HNO₃ as eluents at different concentrations.     

DOGR1 and DOGR2: Two genes from Saccharomyces cerevisiae that confer 2-deoxyglucose resistance when overexpressed

Saccharomyces cerevisiae contains two genes (DOG^R1 and DOG^R2) that are able to confer 2-deoxyglucose resistance when they are overexpressed. These genes are very similar, sharing 92% identity at the protein level. They code for two isoenzymes with 2-deoxyglucose-6 phosphate (2-DOG-6P) phosphatase activity. These enzymes have been purified and characterized. Dog^R1p shows an optimum pH of 6, an optimum temperature of 30°C and a K_M on 2-DOG-6P of 17 mM. Dog^R2p shows a similar optimum pH, but the optimum temperature is 40°C and it exhibits a K_M on 2-DOG-6P of 41 mM. Both enzymes require 10 mM-MgCl₂ for maximal activity and they are inhibited by inorganic phosphate.     

Mineralogical characteristics and treatment of refractory gold ores

Refractory gold ores and concentrates are characterised by low gold recoveries and high cyanide consumptions when subjected to direct cyanide leaching. Therefore an oxidation pretreatment step is required before cyanidation that will break up the sulphide lattice and render gold particles accessible to cyanide ions. The main three options for the treatment of refractory ores and concentrates include the traditional oxidation roasting, the modern pressure oxidation and the bacterial oxidation which is still at an advanced experimental stage. The present work focuses on the mineralogical factors influencing the refractoriness of gold, the main characteristics and developments of each process and provides economic comparative data from various operations worldwide. Environmental considerations are also briefly discussed.     

The effects of bio-mechanisms on acidic mine drainage in coal mining

The paper outlines the effects of acid mine drainage on the ecology of the surface environment and describes the details of a laboratory test programme that investigated the actual role of micro-organisms in the formation of acid mine water. An example of the corrosive effects of acid mine water on mine pumping equipment is given. The paper enumerates various techniques that can be used to protect pumping equipment and mitigate the effects of pumping acid mine water on the life of pumping equipment.     

Study of the SN2 Substitution Reactions Between Methyl Naphtalene-2-Sulfonate and Methyl 4-Nitrobenzene Sulfonate and Bromide Ions in Dodecyl Dibromide Dimeric Micellar Solutions in the Absence and Presence of Alcohols

The S_N2 substitution reactions between methyl naphthalene-2-sulfonate and methyl 4-nitrobenzenesulfonate with bromide ions were studied in alkanediyl-α,ω-bis(dimethyldodecylammonium) bromide, 12-s-12,2Br⁻ (s = 3, 4, 6), micellar solutions in the absence and in the presence of alcohols. The observed rate constant for the two processes was found to be sensitive to changes in micellar characteristics caused by the presence of alcohols. At high surfactant concentrations, kinetic data made evident the sphere-to-rod transition accompanying the increase in the dimeric surfactant concentration in all the micellar reaction media investigated. Kinetic results were quantitatively rationalized within the whole surfactant concentration range, below and above the second CMC, by using a new treatment based on the pseudophase kinetic model.     

Detection and identification of selected bacteria, inoculated on chicken breast, using near infrared spectroscopy and chemometrics

Near-infrared transflectance spectra of chicken breast muscle inoculated with Listeria innocua FH 2333, Pseudomonas fluorescens 2088, Pseudomonas putida 49128, Pseudomonas mendocina or Escherichia coli K12 were investigated in order to examine the potential of NIRS to detect microbes on a food matrix. Inoculated samples were stored at 36 °C for 24 h. Two control groups were used in this study, one of fresh uninoculated samples analysed directly after removal of the muscle from the carcass and another of uninoculated chicken stored at 36 °C for 24 h. The findings of this study suggest the NIR spectroscopy can detect and differentiate between inoculated and uninoculated chicken breast muscle. In addition, it can discriminate fresh from non-fresh (in this case samples that are inoculated or not and stored at 36 °C) samples. On the other hand, NIR spectroscopy failed to differentiate between the five different strains used as inoculates for this study. These results suggest that the make up of the microflora of chicken fillets is not the deciding factor in detecting and differentiating chicken fillet samples. Instead, it seems that the total quantity of microflora present in conjunction with the physical changes associated with spoilage and, in particular, the differences in microbial concentration and level of muscle decomposition of inoculated and uninoculated samples, may be responsible for the separations observed in this analysis. This reason could also be the deciding factor for the separations achieved between the fresh samples and the other two groups.     

Packaging optimisation for portioned Canestrato di Moliterno cheese

Different polymeric films and various headspace conditions (air, vacuum and four different modified atmosphere packaging) were combined to select a packaging system that assured the desired shelf life for two types of portioned Canestrato di Moliterno cheese ripened for 4 and 12 months. To evaluate the quality deterioration of the packaged cheese samples under refrigerated conditions, texture change, weight loss, water activity, moisture content, microbial contamination, pH and sensory attributes were monitored during storage. The results highlighted that a high‐barrier multilayer film delayed proliferation of moulds and gave the best results for both types of ripened cheese.     

Liquid phase equilibrium of phenol extraction from bio-oil produced by biomass pyrolysis using thermodynamic models

Utilization of biomass as a new and renewable energy source is being actively conducted by various parties. One of the technologies for utilizing or converting biomass as an energy source is pyrolysis, to convert biomass into a more valuable product which is bio-oil. Bio-oil is a condensed liquid from the vapor phase of biomass pyrolysis such as coconut shells and coffee shells. Biomass composition consisting of hemicellulose, cellulose, and lignin will oxidize to phenol which is the main content in bio-oil. The total phenolic compounds contained in bio-oil are 47.03% (coconut shell) and 45% (coffee shell). The content of phenol compounds in corrosive bio-oils still quite high, the use of this bio-oil directly will cause various difficulties in the combustion system due to high viscosity, low calorific value, corrosivity, and instability. Phenol compounds have some benefits as one of the compounds for floor cleaners and disinfectants which are contained in bio-oil.The correlation between experimental data and calculations shows that the UNIQUAC Functional-group Activity Coefficients (UNIFAC) equilibrium model can be used to predict the liquid–liquid equilibrium in the phenol extraction process of the coconut shell pyrolysis bio-oil. While the Non-Random Two Liquid (NRTL) equilibrium model can be used to predict liquid–liquid equilibrium in the extraction process of phenol from bio-oil pyrolysis of coffee shells.