Interactions of anionic dyes with silica–aminopropyl: 1. A quantitative multivariate analysis of equilibrium adsorption and adsorption Gibbs free energies

In this work silica–aminopropyl (Sil–NH2) was synthesized and employed to evaluate the quantitative roles of temperature, pH, dye concentration, and Hg(II) or anionic surfactant SDB interferents in the adsorptions of blue and red remazol dyes in aqueous medium using four distinct 24 factorial designs. The results were analyzed statistically using multiple regressions, Student's t-test, analysis of variance, and F-test. Polynomial modelings were used to define the most important factors affecting dye adsorption. The results indicate that the principal effects of dye concentration and pH, as well as most of the interactions of all factors, are statistically very important in relation to the equilibrium adsorption quantities. However, the adsorption Gibbs free energies are influenced, in general, only by pH, dye concentration, and some binary interactions. Temperature changes do not affect the ΔG values significantly.

Graphical abstractSilica–aminopropyl (Sil–NH2) was employed to evaluate the adsorptions of remazol dyes in aqueous medium by 24 factorial designs. The ΔadsGΔadsG values are influenced by pH, dye concentration, and some binary interactions.Figure optionsDownload full-size imageDownload as PowerPoint slide