| Nature Zeolite, as one of low-cost and easily obtaining materials, is one of attractive adsorbents. However, the adsorption and ion exchange capacity of nature zeolite is very limited due to its microporous channels may be plugged and some impurities may adhere to the surface. Because of magnesium hydroxide is high activity, powerful adsorption, it is called green disposing reagent of waste water treatment. In this paper, we use the magnesium hydroxide modified zeolite (MHMZ), to solve the problem of the separation of the magnesium hydroxide powder after water treatment. Loading of magnesium hydroxide modified zeolite can improve the surface character of the original nature zeolite, and enhance the ability to removal adsorbate in aqueous solution.The nature and modified zeolite was characterized by X-ray fluorescence (XRF), Fourier transform infrared spectrum (FT-IR), Scanning electron microscope (SEM), X-ray diffraction (XRD) and Scanning electron microscopy-Energy dispersive spectroscopy (SEM-EDS). The batch adsorption experiments were conducted, to study the adsorption behavior of MHMZ adsorb methyl orange (MO), Light Green SF yellowish (LG) and the cadmium (Cd2+) in the single system. The competitive adsorption of the binary system of MO and Cd2+and the ternary system of MO, LG and Cd2+were also presented.The influence of several operating parameters for adsorption of MO, LG and Cd2+in single system, such as contact time, pH, adsorbent adsorbent dosage, the salt concentration, temperature and initial concentration were investigated in batch mode. The results showed that the adsorption capacity of the modified zeolite was improved significantly, and the optimal adsorption time of MO, LG and Cd2+were2h,5h and5h, respectively. The maximum adsorption capacity of MO, LG and Cd2+were0.3016,0.1021and0.2745mmol·g-1at298K, respectively. The presence of salt inhibited the adsorption of MO, LG and Cd2+in aqueous solution. Through the mechanism analysis and verified experiments, the results showed that the adsorption of MO and LG is belong to the intermolecular interactions, and that the adsorption of Cd2+is belong to ion exchange. The presence of MO on dye/metal binary solutions enhances the adsorption of MO and Cd2+on MHMZ. And in the adsorption of ternary system of MO, LG and Cd2+, there is not only enhances the adsorption of dyes and Cd2+on dye-metal solutions, but also the competitive adsorption between MO and LG Through desorption and regeneration experiments, we were found the best desorption reagent for Cd2+was0.1mmol·L-1NaOH, and the best way of regeneration was microwave radiation for LG, but for the regeneration of MO was ineffective.Through the analysis of the adsorption isotherm models, the equilibrium data for the single system of MO, LG and Cd2+were fitted well by Langmuir, Temkin and Koble-Corrigan isotherm models, and for the adsorption of Cd2+also fitted well by Redlich-Peterson model. In addition, adsorption behavior of the binary system of MO and Cd2+, and the ternary system of MO, LG and Cd2+can be approximately described with Langmuir and Temkin isotherm models. According to the thermodynamic analysis, the result suggest the adsorption MO onto MHMZ was spontaneous, exothermic nature in the adsorption process, and the adsorption of the LG and Cd2+onto MHMZ were spontaneous, endothermic.It is necessary to analysis the kinetics in adsorption processes. The Elovich model was a good choice to describe all the adsorption behaviour in this paper. Beyond that, the Pseudo-first-order model was also a good choice to describe the adsorption behaviour of the single system of MO, LG and Cd2+. The kinetics data of binary system of MO and Cd2+was fitted well by Pseudo-second-order kinetics model, and the kinetics data of ternary system of MO, LG and Cd2+was fitted well by Pseudo-first-order kinetics model. The kinetics of mechanism was investigated by use the Intra-particle diffusion analysis, it can be concluded that the actual process for all adsorption processes may contain the surface adsorption and intra-particle diffusion. |
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