Two-parameter isotherms of methyl orange sorption by pinecone derived activated carbon

The adsorption of a mono azo dye methyl-orange [MeO] onto granular pinecone derived activated carbon [GPAC], from aqueous solutions, was studied in a batch system. Seven two-parameter isotherm models Langmuir, Freundlich, Dubinin-Radushkevic, Temkin, Halsey, Jovanovic and Hurkins-Jura were used to fit the experimental data. The results revealed that the adsorption isotherm models fitted the data in the order of Jovanovic [X[2]=1.374] > Langmuir > Dubinin-Radushkevic > Temkin > Freundlich > Halsey > Hurkins-Jura isotherms. Adsorption isotherms modeling showed that the interaction of dye with activated carbon surface is localized monolayer adsorption. A comparison of kinetic models was evaluated for the pseudo-second order, Elovich and Lagergren kinetic models. Lagergren first order model was found to agree well with the experimental data [X[2]=9.231]. In order to determine the best-fit isotherm and kinetic models, two error analysis methods of Residual Mean Square Error and Chi-square statistic [X[2]] were used to evaluate the data

[Evaluation of compressive strength in conventional and pack able composite materials]

The mechanical properties of composite resin have significant effect on performance and success of a restorative procedure. The aim of present investigation was to evaluate the compressive strength of conventional and pack able composite materials. A stainless steel mold of 4 mm in diameter by 6 mm in height was used to fabricate 50 study specimens. The cylindrical specimens were divided in five groups [n=10]. The materials used in this study were Alert, Charmfil Plus, P60, Z100 and Spectrum. Following photo polymerization by using Radi Plus light curing unit [SDI Limited], the specimens were stored in distilled water at 37°C for 48 hours. The specimens were subjected to compressive stress using mechanical testing machine [Zwick/Roell] at cross head speed of 0.5 mm/min. One-Way ANOVA and Tukey's Post-hoc tests were employed to determine group differences and the significance level if any of the restorative materials could show significant difference among others. There were significant statistical differences between groups [P < 0.05]. Z 100 showed the highest and Charmfil Plus demonstrated the lowest amount of compressive strength. There was no significant statistical difference between Z 100 and P 60, but, differences were significant between Z 100 and other materials. Based on the findings of this investigation, the compressive strength of packable composites was not proving better than conventional composites