Decolourization Properties Of Water-soluble Dyes With Attapulgite Clay

Attapulgite clay classified as Hormotes is a kind of natural nonmetal mineral, which is mainly composed of attapulgite. Attapulgite, also named as palygorskite, is crystal hydrated magnesium aluminum silicate with a unique layer-chain structure, which gives attapulgite's virtues of high surface area, inert chemical property and excellent adsorptive property. Attapulgite clay has a wide variety of industrial applications. There were many researches done about attapulgite clay and its modification products used as sorbents in waste water treatment, but few attentions has been paid on the adsorption mechanism of water-soluble dyes.A study on adsorption properties of water-soluble dyes with attapulgite clay was made. The effects of various experimental parameters were investigated by using a batch adsorption technique on Methylene Blue and Tracid Brilliant Blue RAW in water solution, such as the effect of particle size of attapulgite, shaking rate, shaking time, temperature, pH value and initial dye concerntration. Modification and regeneration methods of attapulgite clay were studied. Finally, the adsorption mechanism of Methylene Blue and Tracid Brilliant Blue RAW onto attapulgite clay on basis of adsorption thermodynamics and kinetics were investigated.The results showed that shaking helped adsorption and the adsorption finished in short time. Temperature and pH value almost have no obvious effect on adsorption behavior of attapulgite clay. Attapulgite clay presented better adsorption capability to water soluble dyes than activated carbon, except reactive dyes. The adsorption capability of attapulgite clay could be enhanced by modification and good adsorption efficiency was regained even after ten cycles of thermo-regeneration. The adsorption data of Methylene Blue onto attapulgite clay fitted well to the Langmuir isotherms, while the adsorption of Tracid Brilliant Blue RAW followed both Langmuir isotherms and Freundlich isotherms. Good correlation coefficients of Methylene Blue and Tracid Brilliant Blue RAW were obtained for the pseudo-second order kinetics model, which was in according with Saeid Azizian's theoretics.