Removal of an azo-metal complex textile dye from colored aqueous solutions using an agro-residue

The pine leaves which are an agricultural residue were used in its natural form as biosorbent for the removal of Acid Yellow 220 (AY 220) dye from aqueous solutions. The sorption experiments were carried out as a function of solution pH, biosorbent dosage, biosorbent size, dye concentration, temperature, contact time and ionic strength. The sorption isotherms closely followed the Langmuir model. The monolayer sorption capacity of the pine leaves for AY 220 was found as 40.00 mg g^{− 1}. It was shown that pseudo-second order equation could best describe the sorption kinetics. The thermodynamic data indicated that the sorption system was spontaneous, endothermic and physical process. Based on the results of present investigation, the pine leaves could be used as a suitable alternative biosorbent for the elimination of AY 220 from aqueous solutions.     

Removal of Pb2+ and Cd2+ ions from aqueous solutions using guanidine modified hydrogels

In this study, experimental measurements have been made on the batch adsorption of cadmium and lead ions from aqueous solutions using poly(guanidine modified 2‐acrylamido‐2‐methylpropan sulfonic acid/acrylic acid/N‐vinylpyrrolidone/2‐Hydroxyethyl methacrylate), P(AMPSG/AAc/NVP/HEMA) hydrogels. The guanidyl end group bearing AMPSG monomer was synthesized from the reaction of AMPS and guanidine. The hydrogels were prepared by UV‐curing technique. The morphology of the dry H10‐hydrogel sample was examined by SEM. The influence of the uptake conditions, such as pH, functional monomer per cent, contact time, initial feed concentration, and foreign metal ions on the metal ion binding capacity of hydrogel, was also tested. The selectivity of the hydrogel toward the different metal ions tested was Hg(II) > Pb(II) > Au(III) > Cd(II). The adsorption isotherm models were applied to the experimental data, and it was seen that the Langmuir isotherm model was the best fit for the adsorption of Cd(II) and Pb(II) ions on P(AMPSG/AAc/NVP/HEMA) hydrogel. It was found that adsorbed lead and cadmium ions on P(AMPSG/AAc/NVP/HEMA) hydrogel can be effectively desorbed by acid leaching and the regenerated P(AMPSG/AAc/NVP/HEMA) hydrogel can be reused almost five times less without any loss of adsorption capacity. Copyright © 2009 John Wiley & Sons, Ltd.     

A monostyryl-boradiazaindacene (BODIPY) derivative as colorimetric and fluorescent probe for cyanide ions

We developed a novel boradiazaindacene derivative to detect cyanide ions in solution at micromolar concentrations. This structurally simple chemosensor displays a large decrease in emission intensity and a reversible color change from red to blue on contact with cyanide ions. Highly fluorescent polymeric films can be obtained by doping with the chemosensor. Such polymeric materials can be used for the sensing of the cyanide ions in polymer matrices.     

Emission of Toxic HCN During NOx Removal by Ammonia SCR in the Exhaust of Lean‐Burn Natural Gas Engines

Reducing greenhouse gas and pollutant emissions is one of the most stringent priorities of our society to minimize their dramatic effects on health and environment. Natural gas (NG) engines, in particular at lean conditions, emit less CO₂ in comparison to combustion engines operated with liquid fuels but NG engines still require emission control devices for NO_x removal. Using state‐of‐the‐art technologies for selective catalytic reduction (SCR) of NO_x with NH₃, we evaluated the interplay of the reducing agent NH₃ and formaldehyde, which is always present in the exhaust of NG engines. Our results show that a significant amount of highly toxic hydrogen cyanide (HCN) is formed. All catalysts tested partially convert formaldehyde to HCOOH and CO. Additionally, they form secondary emissions of HCN due to catalytic reactions of formaldehyde and its oxidation intermediates with NH₃. With the present components of the exhaust gas aftertreatment system the HCN emissions are not efficiently converted to non‐polluting gases. The development of more advanced catalyst formulations with improved oxidation activity is mandatory to solve this novel critical issue.     

The effects of substituting Sn for Ni on the thermal and some other characteristics of NiTiSn shape memory alloys

Journal of Thermal Analysis and Calorimetry - In this study, the thermal stability and phase transformation of Ni50-xTi50Snx (x?=?0.5, 1.0, 1.5, 2.0, 2.5, 3.0, and 3.5 at%) SMAs have...     

Enantioselective sulfa-Michael addition reaction of methyl thioglycolate to chalcones derivatives with sterically encumbered quinine squaramide organocatalyst

Asymmetric organocatalytic sulfa-Michael reactions give access to enantiomerically enriched sulfur containing adducts that can be used as valuable chiral building blocks. A variety of chalcone derivatives were allowed to react with methyl thioglycolate under optimized conditions, in the presence of a bifunctional quinine derived sterically encumbered squaramide organocatalyst, giving rise to excellent stereoselectivities, up to 99%?ee. The designed catalyst system proved to be efficient even at gram scale and under milder reaction conditions.