Experimental Study Of The Removal Of The Azo Dye Wastewater By Modified Zeolite

Azo dyes are a kind of industrial synthetic dyes, which are difficult to deal with and decomposed with a variety of carcinogenic aromatic compounds. Considering the limitations of the existing treatment process, a new alternative technology is necessary to find.Two kinds of modified zeolites with the adsorption performances for azo dye wastewater, such as neutral red and orange G solution, were prepared by using of inorganic modification process and the combination technology of inorganic modification and organic modification, respectively.In this paper, the optimum conditions for the preparation of the two kinds of modified zeolites were optimized, such as the effect of calcination temperature, water bath temperature, initial concentration of solution and other factors on zeolite modification and so on. The modified zeolites were characterized using specific surface area(BET),scanning electron microscopy(SEM), X-ray diffraction analysis(XRD), energy spectrum analysis(EDS) and Fourier transform infrared spectroscopy(FTIR) and so on.The influences of p H value, adsorbent dosage, temperature, adsorption time and the initial concentration of dye solution on the performances of two kinds of modified zeolites towards the neutral red and orange G solution were investigated. The adsorption kinetics,adsorption isotherm and thermodynamic properties of the modified zeolites for dye solution adsorption had been carried out, considering the coexistence of Cl-, SO42-, Ca2+,Na+ ions in solutions. The adsorption experiment of modified zeolite on neutral red solution and orange G solution were conducted to discuss the dynamic adsorption properties and the regeneration performance of modified zeolite. The results show that the adsorption kinetics of modified zeolite towars neutral red solution can be described by the pseudo-second-order kinetics equation. The Langmiur model is benefit for the description of the isotherm adsorption process. The analyzed results of D-R model confirem that the adsorption process is an ion exchange reaction. Thermodynamic parameters present like this, ΔG0<0, ΔH0>0, ΔS0>0, which reveals that the adsorption is a spontaneousendothermic process. As for the orange G solution adsorption, the adsorption isotherm fits better with the Langmiur model, and the secondary equation gives a better match to the batch sorption kinetics. D-R fitting dates show that the adsorption is controlled by chemical adsorption process. Thermodynamic parameters, ΔG0 is less than zero, ΔH0 is lower than zero, ΔS0 is more than zero, confirming that the adsorption is a spontaneous and exothermic process. Through the column adsorption experiment, the effects of zeolite column height, initial solution concentration and flow rate on the adsorption has been tested, which provides a theoretical basis for the practical application of the modified zeolites. The regeneration experiment indicates that the modified zeolite can be reused by the soaking of sodium chloride and sodium hydroxide mixed solution.