好氧颗粒污泥对水中结晶紫的吸附机制

Adsorption of Crystal Violet from Aqueous Solutions by Aerobic Granular Sludge

针对印染废水色度高,脱色难度大的问题,该试验利用好氧颗粒污泥(AGS)对碱性染料结晶紫(CV)进行吸附试验,研究了不同p H、吸附剂投加量、初始CV浓度、温度和Na Cl浓度对吸附过程的影响。通过吸附等温线、吸附动力学、热力学和傅里叶红外光谱(FTIR)对吸附机制进行描述。p H为12、AGS投加量为2 g/L、温度为35℃时吸附效果最好,平衡吸附量(qe)与CV染料初始浓度呈正相关性,但与Na Cl浓度呈负相关性。Freundlich较Langmuir等温线更适合描述试验数据。吸附动力学符合准二级动力学模型。热力学分析表明吸附是一个自发的吸热过程(Gibbs自由能(ΔG°<0),焓变(ΔH°>0),熵变(ΔS°>0)),且吸附亲合力较好。FTIR分析表明,AGS吸附剂上官能团在吸附CV染料过程中发挥重要作用。试验表明AGS可以作为吸附剂以去除水中的CV染料。

The ability of aerobic granular sludge（ AGS） to adsorb crystal violet（ CV） from aqueous solutions was studied. Adsorption studies were carried out at different p H,adsorbent dosage,initial dye concentrations,Na Cl concentration and temperature. Adsorption mechanism was measured through the adsorption isotherm and adsorption dynamics,thermodynamics and Fourier transform infrared spectroscopy（ FTIR）. The experimental results showed that the best adsorption condition was p H value of 2. 0,adsorbent dosage of 2 g /L and temperature at 35 ℃. Equilibrium adsorption capacity（ qe） was positive correlation with initial concentration of dye,but negative correlation with Na Cl concentration. Adsorption datas were modeled using Langmuir and Freundlich adsorption isotherms. Equilibrium data of the adsorption process fitted very well to the Freundlich model. The results of kinetics study showed that the pseudo-second-order model fitted to the experimental data well. The thermodynamic parameters were evaluated. ΔH° 0,ΔS° 0 and ΔG° 0 demonstrated that the adsorption process was spontaneous and endothermic for dye. Furthermore the positive value of ΔS° reflected good affinity of the CV dye. The FTIR analysis indicated that functional groups on aerobic granular sludge would play an important role for the adsorption of the studied dye. These results showed that aerobic granular sludge could be effectively used as a low-cost adsorbent for the removal of CV dye from wastewater.