| The treatment of wastewater contained acid red73(AR73) have been paid more attention by people. Acid red73is persistant organic and difficult to be wiped out, and if it is treated undeservedly, that also may lead to "secondary pollution", which brings about more serious environment pollution. With regard to dye wastewater, adsorption method is a fast effective decolorization method. As magnetic adsorbent, Fe3O4could not only achieve fast effective decolorization, and also could be separated from wastewater fast. Thus we could recycle the nano-magnetic adsorbent Fe3O4adsorbed, which makes Fe3O4not run off with wastewater effectively. It is a practical and economic method of wastewater treatment. In the adsorption process, the adsorption between magnetic power Fe3O4and wastewater is directly contiguous adsorption of AR73on the surface of nano-magnetic particles. Less adsorbate molecules need spread inside the adsorbent. Therefore, adsorption resistance between adsorbate and adsorbent is weaker. When adsorbate contact adsorbent, adsorbent will adsorb AR73on the surface of adsorbent, then magnetic Fe3O4particles could be separated from wastewater faster under the action of magnetic field.In the experiments, nano-magnetic Fe3O4particles prepared from pickling spent liquor were used as an adsorbent whose adsorption mechanism of AR73on the surface of Fe3O4was explored with the methods of single-factor experiments, adsorption-dynamic and adsorption-thermodynamic analysis. And through the test of surface properties of nano-magnetic Fe3O4by XRD, The reason of that nano-magnetic Fe3O4particles could adsorb wastewater contained acid red73in so short time and the feasibility of that nano-magnetic Fe3O4particles could be separated from wastewater fast were studied. The conclusions are as follow:(1). In20mins, the adsorption of AR73on the surface of nano-magnetic Fe3O4particles reached equilibrium. When the initial concentration of AR73was125mg/L, the equilibrium absorption capacity reached28.0mg/L. And as the tempertue of AR73rose, the adsorption capacity of AR73on the surface of nano-magnetic Fe3O4particles became lower. When the pH of AR73was5-6, the absorption efficiency got best. Therefore in adsorption process of AR73, adsorption time, temperature and pH of the pH all need be controlled.(2). The results of isothermal adsorption experiments revealed the behavior of AR73on the surface of Fe3O4accorded with the Langmuir isothermal. Under303K within20mins, the saturated adsorption capacity attained40.1mg/g. In Freundlich equation, the values of n all is greater than1, which revealed the adsorption of AR73on the surface of Fe3O4was favorable adsorption. On the basis of adsorption thermodynamics analysis, that△G＜0, Δ H＜0and ΔS＜0showed the adsorption of AR73on the surface of Fe3O4was a spontaneous, exothermic, and entropy-decreasing process.(3) By using different adsorption kinetics equation fit the adsorption process of AR73on the surface of nano-magnetic Fe3O4particles, the results showed the adsorption process accorded well with the pseudo-second order kinetic equation, and the correlation index got higher than0.9998. Due to the Arrhenius equation lnK=lnA-Ea/RT, the calculation obtained reaction activation energy Ea was49.05kJ/mol.(4). By XRD analysis before and after adsorbingm, we obtained the adsorption between magnetic power Fe3O4and wastewater is directly contiguous adsorption of AR73on the surface of nano-magnetic particles. Less adsorbate molecules need spread inside the adsorbent. Thus nano-magnetic Fe3O4particles could adsorb wastewater contained acid red73in so short time, then the aim of wastewater getting effluent standard could come true.According to conclusions above, adsorption of AR73on the surface of Fe3O4could get quick adsorption decolorization effect. And magnetic Fe3O4particles could be separated from wastewater fast under the action of magnetic field. Therefore, we achieved dual-purpose of quick adsorption decolorization and resources recovery. |
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