Wimol Naksata

Single and binary adsorption of Cd (II) and Zn (II) ions from aqueous solutions onto bottom ash

Bottom ash, a waste obtained from coal-burning power plant, was used as a low cost adsorbent for the removal of Cd (II) and Zn (II) ions from single and binary systems in batch experiments. The results of adsorption capacity showed that bottom ash could be considered as a potential adsorbent. The uptake of Zn (II) ion was greater than that of Cd (II) ion. For single adsorption, based on the correlation coefficient (R2) values, both Langmuir and Freundlich isotherms suitably described the adsorption equilibrium data in the initial metal ion concentration range of 10–50 mg/L. The multicomponent isotherms, including the extended Langmuir and IAST-Freundlich isotherms, were used to predict the binary adsorption of Cd (II) and Zn (II) ions. Furthermore, the appropriate multicomponent isotherm was investigated by minimizing the average relative error (ARE) function. It should be confirmed that the extended Langmuir isotherm fitted the binary adsorption equilibrium data satisfactorily.

Ring-Opening Polymerization of ε-Caprolactone Using Novel Tin(II) Alkoxide Initiators

Two novel tin(II) alkoxides, namely: tin(II) hexoxide, Sn(OC6H13)2, and tin(II) octoxide, Sn(OC8H17)2, have been synthesized for use as coordination-insertion initiators in the bulk ring-opening polymerization of ε-caprolactone. The kinetics of the polymerization reactions were studied at 140 °C by dilatometry. It was found that both alkoxides were slow to dissolve in the ε-caprolactone monomer due to their molecular aggregation in the solid state. As a result, the slow solubilization of the initiators gave rise to deviations from the expected first-order kinetics. Instead, the kinetic results adhered more closely to zero-order kinetics with apparent zero-order rate constants k0 of 6.58 x 10-2 and 4.63 x 10-2 mol l-1 min-1 for the hexoxide and octoxide respectively

Kinetic and mechanism of arsenic ions removal by adsorption on leonardite char as low cost adsorbent material

Adsorption is one of the important techniques in arsenic removal from aqueous solutions. In this study, the As removal efficiency of Leonardite char by a prepared Leonardite carbonized at 450oC was investigated as a function of solution pH, contact time, kinetic and As(III) or As(V) concentration. The surface complexation modeling was used to describe As(III) and As(V) adsorption on the minerals which found in Leonardite char. In the batch experiment, 10.0 mg/L As(III) or As(V) pH 7.0 and 50 mL of aqueous solution was as high as 90% adsorbed. The results showed that Leonardite char could be used as effective adsorbent for the removal of arsenic from aqueous solution. This research supports effort to water with arsenic level lower than 10 mg/L. The maximum adsorption capacity was calculated by fitting the Langmuir and Freunchlich equations to the adsorption isotherms. The Leonardite char will be used as a low-cost adsorbent, for arsenic ions removal in water.

Effect of sodium dodecylbenzene sulfonate on the dispersion stability of ceramic glaze suspension

Sodium dodecylbenzene sulfonate (SDBS) was used to render the stability of ceramic glaze dispersion which is composed of limestone, feldspar, quartz, kaolin and ferric oxide. The measured zeta potential showed negative values for the systems in deionized water and 0.001 M MgCl2 media at pH above 2, but a positive value was observed in 0.1M MgCl2 at pH higher than 6.7. Adsorption of SDBS in aqueous suspensions of ceramic glaze in deionized water and in 0.001 M MgCl2, within the concentration range studied, followed both the Langmuir and Freundlich isotherms, but the Freundlich isotherm was more favored. Adsorption of SDBS in 0.1M MgCl2 corresponded to the Freundlich isotherm. From dispersion stability investigation, SDBS could render the suspension in deionized water and in 0.001 mM MgCl2 more than in 0.1 mM MgCl2.

Utilization of leonardite and coal bottom ash for production of ceramic floor tiles

The aim of this research was to exploit leonardite and coal bottom ash (CBA), which are waste products from coal power plants, for investigating their potential as raw materials in the production of ceramic floor tiles. The developments of ceramic body were mixed with traditional raw materials. Different proportions of ceramic materials were studied in order to explore the proper composition with a variety of wastes containing leonardite and coal bottom ash from 20% up to 80%. Unglazed tiles were produced by shaping through dry pressing and single firing. The physical, chemical, and mechanical properties of the samples were investigated. The total waste (CBA and leonardite) contained in the production was close to 42.8%, and it presented properties that are adequate for it to be classified in groups within the ISO 13006 standard, and yielded the highest flexural strength which enabled the obtained ceramic floor tile bodies to satisfy the requirement to be classified in group BIIa. The chemical resistances of the products were classified in the category UA group which passed the minimum requirement for classification as chemical attack, set by standard EN 14411.