Characteristics of Carbonate Formation from Concentrated Seawater Using CO2 Chemical Absorption Methodology.

Carbon capture and storage is a popular CO2-reduction technology, and carbon capture and utilization (CCU) technology has been reported frequently over the years. However, CCU has certain disadvantages, including the requirement of high energy consumption processes such as mineral carbonation. In addition, stable metal sources are required to fix CO2. This study used concentrated seawater to supply metal ions. In addition, the selected 5 wt % amine solution changed CO2 into aqueous CO2 to reduce the additional energy required to form the metal carbonate under moderate conditions. As a result, precipitates were formed because of the reaction of carbonate radicals with metal ions in the seawater. These precipitates were analyzed by X-ray diffraction and field-emission scanning electron microscopy, and they were found to mostly consist of CaCO3 and NaCl. Furthermore, it was verified that the conversion solution maintained its CO2-loading capacity even after the solids and liquid were filtered twice. Therefore, the proposed method permits a substantial reuse of CO2 and waste seawater when sufficient metal ions are supplied. Therefore, methods to improve their purity will be developed in future studies.

Effects of sodium laurylsulfate on crystal structure of calcite formed from mixed solutions.

Sodium laurylsulfate (SLS), an anionic surfactant, was used for tailoring calcite via a solution route. SLS was dissolved in calcium and carbonate source solutions at various concentrations and critical micelle concentrations (CMCs). The crystallized particles were characterized using X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), laser-scattering particle size measurements, and thermogravimetric analysis (TGA). Energy dispersive spectroscopy (EDS) analysis was carried out to measure sulfur profiles on the surface of the particles. SLS tended to produce small calcite particles in the carbonate source solution, whereas this effect was not obvious in the calcium source solution. It is believed that the electrostatic repulsion force in the carbonate source solution contributes to the different particle refining effects of SLS seen in the two solutions.

Mechanical characteristics and morphological effect of complex crossed structure in biomaterials: fracture mechanics and microstructure of chalky layer in oyster shell.

The complex crossed structures with a polymorph of calcite, termed a chalky layer, which make up much of the shell of an oyster, are composed of flames and leaflets. Two layers, folia and the chalky layer in the giant Pacific oyster (Crassostrea gigas) were examined using SEM (scanning electron microscope), micro-area-XRD (X-ray diffraction) and FT-IR (Fourier transform infrared spectrometer) to determine their morphologies and component characteristics. The chalky layer was also tested using microindentation to assess its mechanical properties, and a microcrack was generated to study the fracture mechanism of the chalky layer. From an analysis of the secondary protein structure, it was shown that the ordered structures of the two layers, α-helix and ß-structure, are similar but that the unordered structures are different. Moreover, the foliated rods at the interface of the chalky layer play a key role in the crystal growth of the chalky layers. Comparing the morphology and the preferred orientation of foliated laths, the advantages of the relatively high density and low hardness of the chalky layer have interesting implications regarding the development of sophisticated complex composites.

Flow-injection chemiluminescence determination of aspartic acid in tea leaves using tris (2,2'-bipyridyl) ruthenium (II)-Ce(IV) system.

A flow injection chemiluminescence (CL) determination of aspartic acid is described. In this work, it was observed that aspartic acid could enhance the chemiluminescence (CL) emission of Ru(bipy)3(2+)-Ce(IV) system and this enhancement effect was dependent on the concentration of aspartic acid, based on which, CL system was established for the determination of aspartic acid. Under the optimum experimental conditions, the linear range and detection limit are 2 x 10(-7)-1.3 x 10(-5) M and 1.5 x 10-(8) M, respectively. The R.S.D. is 1.75%. (n = 10). The proposed method has been applied to detect the content of aspartic acid in tea leaves with satisfactory results. The possible mechanism of the CL reaction was discussed.

Optical flow-through sensor for the determination of norfloxacin based on emission of KMnO(4)-Na (2)SO (3)-Tb (3+) system.

A simple and selective method to determine norfloxacin using an optical flow-through sensor has been developed. The present sensor was prepared by packing anionic ion exchange resin in a glass tube, followed by introducing KMnO(4) solution to the glass tube for immobilization on resin. The optical sensor is based on the emission intensity from the Tb(III) solution sensitized by norfloxacin. The excitation of norfloxacin occurred by the chemiluminescence from the reaction of KMnO(4) and Na(2)SO(4) solutions. The effects of pH, concentration of Tb(III) ion, KMnO(4) and Na(2)SO(4) solutions and flow rate of the norfloxacin solution on the chemiluminescence intensity were studied to find the optimum experimental conditions. The emission intensity increased linearly with increasing norfloxacin concentration from 1.0 x 10(-3) to 1.0 x 10(-8) M and the detection limit (3sigma) was 8.7 x 10(-9). The applicability of the present method was demonstrated by determination of norfloxacin in various pharmaceutical preparations and serum sample.

Simultaneous determination of acetylsalicylic acid and caffeine in pharmaceutical formulation by first derivative synchronous fluorimetric method.

A sensitive, rapid, and specific assay has been developed for the simultaneous determination of acetylsalicylic acid and caffeine in commercial tablets based on their natural fluorescence. The mixture of these drugs was resolved by first derivative synchronous fluorimetric technique using two scans. At Deltalambda=106 nm, using first derivative synchronous scanning, only acetylsalicylic acid yields a detectable signal at 316 nm (peak to zero method) which is unaffected by caffeine. At Deltalambda=30 nm, the signal of caffeine at 288 nm (peak to zero method) is not affected by acetylsalicylic acid. The range of application is between 0.021 and 41.62 microg ml(-1) (correlation coefficient, R=0.9995) for acetylsalicylic acid and between 0.4486 and 44.86 microg ml(-1) (correlation coefficient, R=0.99786) for caffeine. The recovery range of 98.40-102% for acetylsalicylic acid and 90-100.5% for caffeine from their synthetic mixture was reported. Overall recovery of both compounds about 97-99% for acetylsalicylic acid and 97-98% for caffeine was obtained from real sample analysis. The detection limits are 0.0013 microg ml(-1) and 0.0306 microg ml(-1) for acetylsalicylic acid and caffeine, respectively. The relative standard deviation (n=10) for 20 microg ml(-1) of acetylsalicylic acid is 2.75% and for 2.2 microg ml(-1)of caffeine is 1.7%.