Research On Adsorption Of Acid Orange Ⅱ In Water On To Rectorite/PVA Microspheres

Rectorite is an novel environmental material, which is arosing many researchers'attention. HDTMA was employed to modify raw rectorite, HDTMA-modified rectorite was prepared into rectorite/PVA microspheres using PVA as the immobilized material, the optimum conditions for the preparation were determined by orthogonal test, and the rectorite/PVA microspheres were characterized. The results show that the optimum conditions are HDTMA-modified rectorite dosage is 4%, PVA dosage is 10%, sodium alginate dosage is 0.2%, and calcium chloride dosage is 1%. The microsphere has a great deal of pores, the average pore diameter is 1.921nm, the specific surface area is 7.85m2/g, and the loss rate is 3.77%. In this paper, the adsorption characteristics of acid orangeⅡon to rectorite/PVA microspheres were studied under the condition of static and dynamic state, respectively. The results show that the rectorite/PVA microspheres are provided with good discolored effect for acid orangeⅡ, and different environmental conditions play different roles during the adsorption process. Under the condition of static state, the adsorption equilibrium of acid orange II onto the microsphere can be carried out during 24 hours, and the decolor rate can reach 99%. The isothermal adsorption law can well be described by Freundlich and Langmuir models. The enthalpy of activation for the adsorption (ΔH~0) is larger than zero, andΔH 0 < - TΔS~0 for the adsorption system, which indicate that the influence of activation entropy (ΔS~0) on the adsorption is more remarkable thanΔH~0, I.e. increasing temperature properly is benefit to accelerate adsorption reaction. The adsorption kinetics law conforms to the Lagergren pseudo-first-order equation, pseudo-second-order equation, Bangham model and Elovich model. The adsorption process is mainly controlled by outer diffusion. Under the condition of dynamic state, the adsorptive capacity increases with the initial concentration of acid orangeⅡincreasing, and the final concentration also increases; the adsorptive capacity increase with the height of the adsorption column increasing; the adsorptive capacity becomes greater if the flowing velocity of acid orangeⅡis slower; the adsorption efficiency has little difference at initial pH from 4 to 10.