Study On Preparation Of Acid Activated Bentonite And Its Adsorption Behavior On Oil Soluble Pigment

Bentonite in Liaoning is rich in resources,but there is a problem of low level deep processing,low added value bentonite products and serious waste of resources.The development and application research of bentonite in this area is weak.According to the present situation,the paper setted it as the object of research,purification tests of bentonite and study on preparation of acid activated bentonite were carried out in the basis of mastering ore properties,the activation mechanism of bentonite was also discussed.The adsorption isotherm,adsorption kinetics and adsorption thermodynamics were used to research the adsorption behavior of bentonite and acid activated bentonite on oil soluble pigment.The main conclusions were obtained as follows:（1）The bentonite used for research belonged to calcium based bentonite ore in low grade,methylene blue adsorption was 28.43 g/100g,montmorillonite content was64.31%,and its swelling property was not good.XRD semi quantitative results showed that,the samples contained montmorillonite 59.73%,cristobalite 8.40%,feldspar 10.46%,quartz 19.34%,calcite 2.07%.（2）Purification test showed that sodium polyacrylate was an effective dispersant for this bentonite.The content of montmorillonite and cristobalite as well as classified products’s natural whiteness increased as the particle size became finer.The content of feldspar,calcite,and quartz decreased as the particle size became finer.XRD semi quantitative results showed that,the productivity of-10μm+5μm particle size was23.71%,the content of montmorillonite was 78.77%,the quartz was 9.77%,the cristobalite was 10.19%;the productivity of-5μm particle size was 16.49%,the content of montmorillonite was 85.55%,the quartz was 3.07%,the cristobalite was10.53%.It was difficult to further improve the content of montmorillonite in the fine paiticle because the cristobalite was also enriched in the fine particle.（3）Acid activated bentonite preparation process research showed that acid activated bentonite with 224 mmol/kg activity and 90.3%decolorization rate was prepared in the optimal conditions.The optimal conditions for preparing the acid activated bentonite were followed,10%sulfuric acid dosage as activating agent,700W microwave power,liquid solid ratio of 2:1,activation time of 3 minutes.Activation mechanism showed that,it was easier for H⁺to replace Na⁺、K⁺and Ca²⁺which were in montmorillonite interlayer,the Mg²⁺,Fe³⁺and Al³⁺in octahedron of montmorillonite were relatively difficult to dissolve.Different color-causing ion dissolution,improving the whiteness of acid activated bentonite.Increasing the dosage of sulfuric acid would destroy parts of the crystal structure of montmorillonite,enhance the intensity of diffraction peak of quartz and cristobalite.Diffraction peak of d_（001）tended to be wide and flat,the crystallinity of acid activated bentonite reduced.In the process of acidification,H⁺partially replaced the Al³⁺in octahedron of montmorillonite,which made the induction of the metal ions on the O-H bond of the electron cloud,the O-H bond weakened,leading to the Al-O-H stretching vibration frequency to the high frequency region.Compared with bentonite,acid activated bentonite’s surface and the edge became more rough,specific surface area and pore volume became larger and it had more pore,as well as better adsorption property.（4）The adsorption behavior of bentonite on oil soluble green pigment and oil soluble yellow pigment was in accordance with the Langmuir model and the pseudo two order kinetics model.Bentonite adsorbed oil soluble green pigment reaction was an endothermic（ΔH>0）,non spontaneous（ΔG>0）,entropy decrease（ΔS<0）process;Bentonite adsorbed oil soluble yellow pigment reaction was an endothermic（ΔH>0）,non spontaneous（ΔG>0）,entropy increase（ΔS>0）process.The adsorption behavior of acid activated bentonite on oil soluble green pigment and oil soluble yellow pigment was in accordance with the Freundlich model and the pseudo two order kinetics model.Acid activated bentonite adsorbed oil soluble green pigment and oil soluble yellow pigment reaction was both an endothermic（ΔH>0）,spontaneous（ΔG<0）,entropy increase（ΔS>0）process.It was easier for acid activated bentonite to absorb oil soluble pigment than bentonite.