Conversion of Fly Ash to Swelling Mica: A New Approach for Recycling Fly Ash

Swelling mica exhibits unique characteristics for purification of drinking water contaminated by heavy metals and for selective removal of Sr²⁺ and Ba²⁺ ions from nuclear waste solution. As a new approach to recycle fly ash, conversion of fly ash to swelling mica has been attempted and ion-exchange properties of fly ash-derived swelling mica (referred to hereinafter as FA-swelling mica) were examined in this study. Thermal treatment of fly ash with MgO in the presence of excess NaF led to the formation of swelling mica along with trace quantities of impurities. A swelling mica of good quality was obtained from the reactant ratio of fly ash 1 g : MgO 0.75 g : NaF 1.75 g. Unlike gel or kaolinite-derived synthetic Na-4-micas, FA-swelling mica exhibited heterogeneity in its framework. Its uptake capacity for Sr²⁺ ions was estimated to be 17.4 meq/100 g from 0.1 mM SrCl₂ aqueous solution and 5.0 meq/100 g from 0.5 N NaCl solution containing the same Sr²⁺ concentration. These capacities are less than that of metakaolin-derived Na-4-mica. However, its ion exchange capacity for divalent transitional metal ions was estimated to be 284 meq/100 g from their inaqueous solutions and 206 meq/100 g from the 0.5 N NaCl solution containing the mixed metal ions of Cd²⁺, Co²⁺, Mn²⁺, Ni²⁺ and Zn²⁺ each at 1 mN concentration. These capacities are comparable to that of metakaolin-derived Na-4-mica. Its selectivity for transition metal ions is as follows: Zn²⁺ > Ni²⁺ Co²⁺ Cd²⁺ > Mn²⁺ and this is consistent with the G° values from Gibbs-Duhem equation. These results clearly showed that fly ash could be converted to swelling mica with high uptake capacity for divalent transitional metal ions. Therefore, conversion of fly ash to highly pure swelling mica will lead to a resource from waste.     

Security enhancement in video based on gatefold technique for copyright protection

Multimedia Tools and Applications - Watermarking of multimedia gives more attention to the research society. This paper presents the non-blind watermarking technique on video; initially, a...     

Effects of 4-n-nonylphenol on aquatic hyphomycetes

We measured the removal of 4-n-nonylphenol (between 50 and 500 μg L⁻¹) from an aqueous solution with or without linden and oak leaf disks. More 4-n-NP was removed when the leaves were first exposed for 3 weeks in a stream, which allowed colonization by aquatic hyphomycetes. The response of fungal sporulation rates from beech, linden, maple and oak leaves to increasing levels of 4-n-NP was complex. Linear regressions were non-significant, arguing against a no-threshold model. The response at the lowest concentration (50 μg L⁻¹) was between 7% (beech) and 67% (maple) higher than in the absence of 4-n-NP, however, the difference was not significant. The number of sporulating species of aquatic hyphomycetes was significantly higher at the lowest concentration than in the control treatment without 4-n-NP. The composition of the fungal community was affected by leaf species but not by 4-n-NP concentration. The results suggest the presence of a weak hormeotic effect. The known ability of aquatic hyphomycetes and other fungi to degrade nonylphenols and related substances, combined with fungal resilience in their presence, makes decaying leaves potential candidates for bioremediation.     

Preparation of microwave-processed oil-free potato snacks with assorted natural flavours: Application of advanced chemometrics

Generally, potato chips are produced by deep-fat frying with 35%–40% oil in the final product, which is considered unhealthy. Therefore, we attempted to prepare microwave-processed oil-free potato snacks, fat-free alternative for potato chips, assorted with natural flavours (tomato, mint and pepper) and evaluated their proximate composition, microbiological analysis and sensory evaluation coupled with advanced chemometrics. The proximate analysis revealed the presence of carbohydrates (53–58 g/100 g), energy (190–214 kcal/100 g) and negligible fat (≤0.15%) with a microbial load of 2.50–9 CFU/100 g. Samples assorted with mint and tomato flavours received higher sensory scores (7.65–8.80) for all sensory attributes compared with control (6.61–7.55). From the chemometric analysis, the high similarities in samples assorted with mint and tomato flavours confirmed by principal component analysis loadings of 0.69 and 0.71, respectively, and hierarchical clustering (cluster 1 with 2 sub-clusters). Therefore, the microwave processing can be a suitable technique to produce oil-free potato snacks with natural flavourings while preserving their quality attributes.     

Some studies on polyblends of poly(p-phenyleneterephthalamide) and nylon-6

Polyblends of poly(p-phenyleneterephthalamide) (PPTA) and nylon-6 have been prepared by coprecipitation from solutions of the polymers in concentrated sulphuric acid. The behaviour of solutions of the polyblends in concentrated sulphuric acid was investigated. The polyblends were characterized by differential scanning calorimetry, X-ray diffraction and density measurements. The polymers were found to form a miscible blend with the composition 62.7 wt% nylon-6 and 37.3 wt% PPTA. The blends could be compacted to hard dense solids by high pressure compaction.