Study on Adsorption of Methylene Blue with Organic Rectorite

The natural rectorite (REC) is a clay mineral with regular interlayer structure. The special structure of rectorite rendered it strong adsorption capacity. According to the cation-exchange mineral characters, rectorite was inserting-layer modified with three novel Gemini surfactants by conventionl method to form three kinds of organic-modified rectorite (OREC), termed (12-2-12)-REC, (12-3-12)-REC, (18-3-18)-REC. Through FTIR and XRD analysis, it confirmed the cation exchange reaction between REC and surfactant. This paper studies on the adsorption of REC and three kinds of OREC for methylene blue and the influence of main factors were discussed. The results indicated that the interlayer distance of the three ORECs((12-2-12)-REC, (12-3-12)-REC, (18-3-18)-REC) were enlarged from 2.49nm to 3.77nm, 3.00nm, 3.33nm, respectively. Besides, the adsorption results showed that the OREC with larger interlayer spacing displayed more excellent adsorption capacities than the OREC with smaller interlayer spacing in the same work condition. The MB adsorption of three kinds of OREC can be described as Freundlich isotherm model and Langmuir isotherm model, but the adsorption of (18-3-18)-REC is more likely described as Freundlich isotherm model. The max adsorption amount of the three ORECs((12-2-12)-REC, (12-3-12)-REC, (18-3-18)-REC) can be reached 45.56mg/g, 37.81mg/g, 40.82mg/g at 25 degrees C, respectively.