Evaluation of rare earth (Yb,La) doped (Sm3Fe5O12) garnet ferrite membrane for LT-SOFC

Rare earth element doping is a popular methodology for improving the electrical and electrochemical properties of materials. Inspired by this ideology, garnet ferrite material Sm₃Fe₅O₁₂ (SFO) doped by rare earth (Yb, La) metal ions to form Sm_3-0.5Yb_0.5Fe₅O₁₂ (SYFO) and Sm_3-0.5La_0·5Fe₅O₁₂ (SLFO). The samples are synthesized by sol gel auto combustion and have been applied as electrolyte membrane for the first time in low temperature solid oxide fuel cell (LT-SOFC). The results indicate that the as-prepared materials have triple charge transport (H⁺/O^?2/e^?) carrier which promotes the hydrogen oxidation reaction (HOR) and oxygen reduction reactions (ORR) in SOFC at triple phase boundary region (TPB). Electrochemical impedance spectroscopy (EIS) reveals that the polarization resistance of SLFO membrane significantly reduces from 0.92 Ω-cm² to 0.45 Ω-cm² and the power output improve from 310 mW/cm² to 650 mW/cm² at 550 °C temperature in comparison with that of SYFO and SFO electrolyte supported cells. UV-vis diffused spectroscopy explains the semiconducting nature of the prepared materials due to the existence of optical bandgap in the semiconductor region. The further investigation also verifies the protonic conduction of SLFO membrane by constructing oxygen ion blocking fuel cell with configuration of Ni-NCAL/BZCY/SLFO/BZCY/Ni-NCAL having 427.94 mW/Cm² fuel cell performance with 1.03 OCV at 550 °C temperature.     

Adsorption performance of amine functionalized cellulose grafted epichlorohydrin for the removal of nitrate from aqueous solutions

Cellulose grafted epichlorohydrin (Cell-g-E) copolymer was synthesized and functionalization carried out using polyethylenimine (Cell-g-E/PEI). Characterization studies using FTIR, XRD and TGA, confirmed the grafting and functionalization process. Batch adsorption reaction was carried out for removal/recovery of nitrate ions and maximum adsorption capacity was obtained at pH 4.5. Kinetic studies explained pseudo-second-order as the best fit. Isotherm studies conducted at different temperatures revealed applicability of Freundlich isotherm model. Comparative studies proved effectiveness of Cell-g-E/PEI to other reported adsorbents. The adsorption process was spontaneous and exothermic. Batch adsorption/desorption studies for over six cycles showed the repeatability and regeneration capability of the adsorbent.     

Highly sensitive spectrometric method for determination of hydroquinone in skin lightening creams: application in cosmetics

A highly sensitive, simpler, faster and economical UV/visible spectrophotometric method has been established for the estimation of hydroquinone (HQ) in dilute organic matrices. The method is based on using ammonium meta‐vanadate as an oxidizing catalyst for conversion of HQ to p‐benzoquinone (BQ) in the presence of oxygen. As a result of higher absorption of UV light by BQ than by HQ, its signal has been utilized for determining HQ at the trace level. The effect of various parameters such as amount of oxidizing agent, stability time, temperature, acids and bases, solvents and interference by various compounds has been studied upon the absorption of BQ as HQ. Under optimized conditions, Beer’s Law was obeyed in the range of 0.025–2.00 μg ml^?1 HQ at 245.5 nm using 1 : 1 (V/V) 2‐propanol/water system with a lower detection limit of 7 ng ml^?1 and linear regression coefficient of 0.9998. Relative standard deviation of 1.5% was observed for 0.5 μg ml^?1 HQ solution (n = 11). The newly developed method has been successfully applied to diluted samples of various skin lightening creams for free HQ determination at the trace level. Comparison of the results obtained by the proposed method with those by a previously reported method proved its validity.     

Removal and recovery of phosphate ions from aqueous solutions by amine functionalized epichlorohydrin-grafted cellulose

A novel cellulose grafted epichlorohydrin functionalized polyethylenimine (Cell-g-E/PEI) graft copolymer was synthesized using cellulose, epichlorohydrin and polyethylenimine in the presence of azetobis isobutyro nitrile (AIBN) as the initiator and N,N′-Methylene bisacrylamide (MBA) as the crosslinking agent. The graft copolymer, Cell-g-E/PEI was characterized using TGA/DTG, XRD, FTIR, and SEM-EDS to evaluate the structural and morphological characteristics of the graft copolymer. The effectiveness of the Cell-g-E/PEI, as adsorbent for the removal and recovery of phosphate ions from aqueous media was studied. The effects of pH, contact time, and initial sorbate concentration were studied to optimize the conditions for maximum adsorption. The adsorption process, which was pH dependent, shows maximum removal (> 99.0%) at pH 4.5. Kinetic study showed that 180 min of contact at 100 mg/L could adsorb about 99.6% of phosphate onto Cell-g-E/PEI. A pseudo-second-order kinetic model described successfully the kinetics of sorption of phosphate. Adsorption equilibrium data were correlated with the Langmuir, Freundlich and Redlich–Peterson isotherm models. The best fit was obtained with Freundlich model. Desorption of phosphate was studied by using 0.1 M HCl. Adsorption/desorption for more than six cycles showed the possibility of repeated use of this graft copolymer for the removal and recovery of phosphate from aqueous solutions.     

Compositional and thermal characterization of genuine and randomized lard: A comparative study

Composition and thermal characterization of genuine and randomized lard were investigated comparatively in an attempt to find common merits that assess lard detection. The investigation included compositional and positional distribution of fatty acids, triacylglycerol profiling by gas chromatography (GC) and reversed-phase high-performance liquid chromatography (RP-HPLC), as well as thermal behavior by differential scanning calorimetry (DSC) of both samples. Individual and total saturated and unsaturated fatty acid composition in total fats of both genuine and randomized lard were identical. On the other hand, the results of pancreatic lipolysis/GC analysis showed that the average percent palmitic acid [PAEF(%)] and myristic acid [MAEF(%)] enrichment factors of genuine (280 and 270) and randomized lard (110 and 98) were quite different. Thus, application of PAEF to detect randomized lard is of no value. However, normalization of fatty acid distribution by randomization in 2-monoacylglycerols made the individual and total saturated and unsaturated fatty acids almost identical to that of total fat and neutral triacylglycerols (TG) of lard. TG compositional analysis by GC revealed that both genuine and randomized lard had six dominant TG (C_46′C_48′C_50′C_52′C_54′ and C₅₆) with quite different concentrations. TG with C₅₂ represent the major constituent of genuine and randomized lard. TG profiling of samples was also carried out by RP-HPLC with a refractive index detector. The same peaks were eluted in both samples, but the area % of major peaks changed due to randomization. 2-Palmitooleostearin (SPO) was found in high proportion in lard. However, the ratios of SPO to 2-palmitooleolinolein of both genuine and randomized lard are close (0.6±0.05) and significantly distinguishable from that of beef (4.24), mutton (6.17), chicken (0.21), and turkey (0.14) fats. The DSC thermogram and thermodynamics of phase transitions of both samples were quite different and do not reveal common characteristic(s) that could be used for immediate detection of lard substances in fat admixtures.